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prof. Ing. Jan Sýkora, CSc.

Garant a tutor programu Otevřené elektronické systémy

Všechny publikace

Asynchronous NOMA and PLNC with Iterative Decoding

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The article deals with single-carrier MAC (Multiple Access Channel), where the relative delay of sources is a fraction of the symbol period. We review the channel likelihood function and propose two approaches to deal with inter-symbol interference (ISI). We either track ISI or remove ISI by a one-step marginalization of the logarithm of the likelihood ratio (LLR). For ISI tracking, we model ISI as a virtual convolutional code observed in a multipath channel. We use both approaches to compare joint decoding (JD) of sources and hierarchical decoding (H-decoding) – decoding of XOR frame. We use concatenated convolutional codes as a channel code and BCJR (Bahl, Cocke, Jelinek, Raviv) decoding algorithm. The proposed methods are suitable for equally strong sources. In that case, we lose about 2 dB when using ISI elimination w.r.t. the ISI tracking.

Indoor-Positioning in DVB-T/T2 Single-Frequency Networks Using Inverse Passive Radar Approach

  • DOI: 10.1109/RADIOELEKTRONIKA61599.2024.10524075
  • Odkaz: https://doi.org/10.1109/RADIOELEKTRONIKA61599.2024.10524075
  • Pracoviště: Katedra elektromagnetického pole, Katedra radioelektroniky, Katedra měření
  • Anotace:
    Wide signal bandwidth and precisely time-synchronized single-frequency network predetermines DVB-T and its successor DVB-T2 for Signals of Opportunity (SoP) radio positioning. Previously published methods were based on demanding OFDM symbol synchronization, partial (synchronization subcarriers only) reconstruction, and conventional positioning calculation. Their presented error was around 100 meters and more for the outdoor scenario. Our contribution focuses on an indoor scenario and novel signal processing method using a less demanding computation of autocorrelation function of in single-network present signals. This approach, inverse to passive-radar, exploits total signal bandwidth and is independent of apriori knowledge of signal structure. Then, it is combined with a direct positioning - collective detection metric method for position calculation. Absolute and relative positioning is considered to achieve target error under 50 meters, focusing on positioning IRS (Integrated Rescue Systems) services in dense indoor environments.

Asynchronous WPNC with DFT Precoding and Symbol-Spaced Processing

  • Autoři: Hron, P., prof. Ing. Jan Sýkora, CSc., Clavier, L.
  • Publikace: IEEE Communications Letters. 2023, 27(9), 2279-2282. ISSN 1558-2558.
  • Rok: 2023
  • DOI: 10.1109/LCOMM.2023.3291594
  • Odkaz: https://doi.org/10.1109/LCOMM.2023.3291594
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses the problem of asynchronous reception in a 2-source Hierarchical MAC (H-MAC) in the context of a Wireless Physical Layer Network Coded (WPNC) system with a Hierarchical Decode and Forward (HDF) relaying strategy. In this work, we assume fractional symbol duration time delays and propose an OFDM-like transmitter side linear precoding together with symbol-spaced (SS) processing at the receiver. We derive an equivalent channel model and analyze its properties in the case of a root-raised-cosine (RRC) modulation pulse. We present a numerical evaluation of the Hierarchical Bit Error Rate (H-BER) for BPSK and QPSK alphabets.

Linear precoding for asynchronous WPNC 2-source hierarchical multiple access channel

  • Autoři: Hron, P., prof. Ing. Jan Sýkora, CSc., Clavier, L.
  • Publikace: 4th MC and 4th Technical Meeting. Nová Lovaň: Euracon, 2023.
  • Rok: 2023
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses the problem of asynchronous reception in a 2-source Hierarchical MAC (H-MAC) in the context of a Wireless Physical Layer Network Coded (WPNC) system with a Hierarchical Decode and Forward (HDF) relaying strategy. This work is motivated by the difficulty of precise synchronization among different sources of an H-MAC stage. Because of the non-orthogonal nature of the H-MAC even when the individual delays are known to the receiver a simple compensation is not possible. Compensation at the transmitters would require a channel state feedback channel which is not always available. In some scenarios with varying distances between individual nodes even the knowledge of the delays to the transmitter, a simple time base adjustment would not solve the problem w.r.t. all participating receivers. In this work, we assume delays of a fraction of the symbol time duration and propose a delay-independent transmitter-side linear precoding together with symbol-spaced and fractionally-spaced processing at the receiver. For each approach, we derive an equivalent channel model and analyze its properties in the case of an root-raised-cosine (RRC) modulation pulse. The proposed techniques are numerically evaluated in terms of Hierarchical Bit Error Rate (H-BER). We show that in some cases the asynchronous reception can lead to a performance boost.

Detection of XOR HNC map of 2 nonsynchronous BPSK sources in H-MAC - testbed verification

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In the report, we deal with the detection of symbolwise xor HNC map of 2 non-synchronous BPSK sources. The relative delay of frames is an integer multiple of the symbol period. We assume the second source to be delayed by n0 symbols w.r.t. the first source. It is shown that the detection can be decomposed to n0 independent subsequences/parts; further we propose three approximate detectors. Next we show that singular fading that is resolved by HNC map for synchronous sources is not resolved for channels with integer-symbol-period delay for the same HNC map. Neither simple differential encoding will help to resolve it. Finally, we mention that a HNC map should also resolve singular fading in the H-MAC channel with delay and we propose one such simple HNC map – the map with cyclic shift of one frame. A demonstration of the detection on experimental testbed is presented.

Exact Analytical H-BER for Ad Hoc XOR H-Map Detector for Two Differentially Modulated BPSK Sources in H-MAC Channel

  • DOI: 10.3390/math10060903
  • Odkaz: https://doi.org/10.3390/math10060903
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In the article, we present an ad hoc (AH) detector for two differentially encoded BPSK sources in the Hierarchical MAC (H-MAC), i.e., for the case when the receiver sees the superposition of non-orthogonal signals from individual sources. (Prefix “H-” means Hierarchical, it emphasizes that the entity is related to the many-to-one principle.) The AH detector decodes the XOR H-map of the two BPSK streams—in other words, it decides whether the transmitted symbols from the two sources are the same or opposite. The BER of the detection in H-MAC is denoted as H-BER. The H-BER is compared with the other two differential detectors, with the coherent (Coh) detector, and with an approximate coherent (ApC) detector. The exact analytical H-BER formula is derived for the ad hoc and coherent detectors. The proposed ad hoc detector is very simple for evaluation, does not require the estimation of subchannel phases, does not depend on noise variance, and it is uniformly only roughly 3.5 dB worse than the coherent one.

Noncoherent WPNC 2-source MAC channel demodulation methods

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses the problem of differential demodulation in a 2-source Hierarchical MAC (H-MAC) in the context of a Wireless Physical Layer Network Coded system with Hierarchical Decode and Forward relaying strategy. We consider a parametric H-MAC with known attenuation values but unknown phases. Component phases have generally a strong impact on the resulting superposed constellation and need to be accurately estimated to facilitate a coherent demodulation. The use of a differentially encoded modulation eliminates the need of precise channel phase tracking, which is a nontrivial problem in the WPNC scenario. At the same time it can operate with the same 3dB penalty as in a differential single user case. In this paper we summarize several differential demodulation procedures and additionally introduce new ad hoc methods, which can substantially reduce the computation complexity of the demodulation. We compare the various demodulation algorithms by means of evaluating the hierarchical bit error rate performance for different channel states. Additionally we analyze the robustness of differential demodulation w.r.t. channel phase noise.

Closed-Form Differential Hierarchical Demodulator of 2-source Hierarchical-MAC Channel

  • Autoři: Hron, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: IEEE Communications Letters. 2021, 25(11), 3704-3708. ISSN 1089-7798.
  • Rok: 2021
  • DOI: 10.1109/LCOMM.2021.3105814
  • Odkaz: https://doi.org/10.1109/LCOMM.2021.3105814
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses a problem of differential demodulation in a 2-source Hierarchical MAC (H-MAC) in the context of a Wireless Physical Layer Network Coded system with Hierarchical Decode and Forward strategy. We assume a parametric H-MAC with known attenuations but unknown phases. Component phases have generally strong impact on the resulting superposed constellation which poses high demands on the accuracy of their estimation. In this paper we propose multiple suboptimal closed-form differential demodulation methods which do not require explicit phase estimation and thus substantially simplify the receiver processing. We analyze and compare their performance. Particularly we measure the resulting hierarchical bit error rate for all proposed demodulation methods for different scenarios of a particular symbol alphabet and channel attenuation values. For comparison we include a reference scenario of a fully coherent demodulation.

SDR verification of noncoherent WPNC 2-source MAC channel reception

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper considers a noncoherent reception in a parametrized hierarchical MAC (H-MAC) stage in Wireless Physical Layer Network Coding (WPNC) networks with Hierar- chical Decode and Forward (HDF) relay strategy. We employ a differential PSK modulation on two source node transmitters and perform a hierarchical target symbol demodulation at a relay without the need of an explicit estimation of channel phases. Relative channel phase parametrization has generally a nonlinear impact on the resulting constellation, which poses high demands on its estimation accuracy in coherent reception settings. In this paper we present the results of an over-the-air verification of proposed differential demodulation algorithms together with a comparison with respect to results obtained by a computer simulation.

Distributed Network Tomography Applied to Stochastic Delay Profile Estimation

  • Autoři: Kolář, J., prof. Ing. Jan Sýkora, CSc., SPAGNOLINI, U.
  • Publikace: Radioengineering. 2020, 29(1), 189-196. ISSN 1210-2512.
  • Rok: 2020
  • DOI: 10.13164/re.2020.0189
  • Odkaz: https://doi.org/10.13164/re.2020.0189
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper is shown, how delay properties of the edges of a network with stochastic properties can be estimated cooperatively by individual nodes that retain the delay profiles of the entire network. The proposed algorithm adopts null-space projection-based consensus among agents to find individual entries from a set of arbitrary sum-cumulative entities associated with graph edges (e.g., delays associated with edges) based on sums over the network paths. The local estimates of delay profile are estimated using Least Squares (LS). A modified, tailored, iterative consensus algorithm is then employed to distribute information among the neighbors. The distributed network tomography is compared to the conventional centralized solution and also to iterative solvers based on Cimmino, CAV, and Landweber methods applied in a distributed manner.

SDR verification of Hierarchical Decision Aided 2-Source BPSK H-MAC CSE with Feed-Back Gradient Solver for WPNC Networks

  • DOI: 10.13164/re.2020.0573
  • Odkaz: https://doi.org/10.13164/re.2020.0573
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper considers a channel state estimation (CSE) pro- blem in a parametrized Hierarchical MAC (H-MAC) stage in Wireless Physical Layer Network Coding (WPNC) networks with Hierarchical Decode and Forward (HDF) relay strategy. The primary purpose is to present the results of a non-pilot based phase estimator performance evaluation. In particular, the performance comparison of a Matlab simulation and an over the air transmission using USRP N210 transceivers in terms of mean square error (MSE) and bit error rate (BER). Also, we analyze the properties of the Cramer Rao Lower Bound (CRLB) w.r.t. different channel parametrizations.

Update-Based Machine Learning Classification of Hierarchical Symbols in a Slowly Varying Two-Way Relay Channel

  • DOI: 10.3390/math8112007
  • Odkaz: https://doi.org/10.3390/math8112007
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper presents a stochastic inference problem suited to a classification approach in a time-varying observation model with continuous-valued unknown parameterization. The utilization of an artificial neural network (ANN)-based classifier is considered, and the concept of a training process via the backpropagation algorithm is used. The main objective is the minimization of resources required for the training of the classifier in the parametric observation model. To reach this, it is proposed that the weights of the ANN classifier vary continuously with the change of the observation model parameters. This behavior is then used in an update-based backpropagation algorithm. This proposed idea is demonstrated on several procedures, which re-use previously trained weights as prior information when updating the classifier after a channel phase change. This approach successfully saves resources needed for re-training the ANN. The new approach is verified via a simulation on an example communication system with the two-way relay slowly fading channel.

Hierarchical data decision aided 2-source BPSK H-MAC channel phase estimator with feed-back gradient solver for WPNC networks and its equivalent model

  • DOI: 10.3390/info10020040
  • Odkaz: https://doi.org/10.3390/info10020040
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper focuses on the channel state estimation (CSE) problem in parametrized Hierarchical MAC (H-MAC) stage inWireless Physical Layer Network Coding (WPNC) networks with Hierarchical Decode and Forward (HDF) relay strategy. We derive a non-pilot based H-MAC channel phase estimator for 2 BPSK alphabet sources. The CSE is aided only by the knowledge of H-data decisions. At HDF relay, there is no information on individual source symbols available. The estimator is obtained by a marginalization over the hierarchical dispersion. The estimator uses a gradient additive update solver and the indicator function (gradient) is derived in exact closed form and in approximations for low and high SNR. We analyze the properties of the equivalent solver model, particularly the equivalent gradient detector characteristics and its main stable domain properties, and also the detector gain and equivalent noise properties under a variety of channel parameterization scenarios.

Hierarchical extrinsic information performance analysis of H-soft aided 2-source BPSK H-MAC channel phase estimator for WPNC networks

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2019 25th Asia-Pacific Conference on Communications (APCC 2019). IEEE (Institute of Electrical and Electronics Engineers), 2019. p. 148-152. ISBN 978-1-7281-3679-0.
  • Rok: 2019
  • DOI: 10.1109/APCC47188.2019.9026459
  • Odkaz: https://doi.org/10.1109/APCC47188.2019.9026459
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The scope of the paper is the channel state estimation (CSE) problem in parametrized Hierarchical MAC (H-MAC) stage in Wireless Physical Layer Network Coding (WPNC) networks with Hierarchical Decode and Forward (HDF) relay strategy. We analyze the H-data soft aided phase estimator for2-source BPSK H-MAC channel. Particularly, we evaluate how hierarchical extrinsic soft H-data aid information affects the mean square error performance characteristics of the phase estimator.The numerical results show quite surprisingly that the impact of the extrinsic H-soft information is (apart of very low SNR and very low extrinsic information region) quite negligible. This result might greatly simplify the design of hierarchical soft-output demodulator for the parametric channel.

Non-pilot-aided phase estimator for 2-source BPSK NOMA channel with closed-form solver

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: The 22nd International Symposium on Wireless Personal Multimedia Communications WPMC 2019. Lisboa: Instituto de Telecomunicaçoes - Lisboa, 2019. ISSN 1882-5621. ISBN 978-1-7281-5419-0.
  • Rok: 2019
  • DOI: 10.1109/WPMC48795.2019.9096099
  • Odkaz: https://doi.org/10.1109/WPMC48795.2019.9096099
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    n this paper, we focus on developing the non-pilot-aided phase CSE (Channel State Estimator) for 2-source BPSK generic NOMA (Non-Orthogonal Multiple Access) scenario. Apart of the exact CSE form, we develop also the low-SNR approximation which allows us to find aclosed-form ML(Maximum Likelihood) solver. Both, exact and low-SNR (Signal to Noise Ratio) forms will be analyzed in terms of their fundamental mean-square error performance limits. We will use classical and mismatched model Cramer-Rao Lower Bound (CRLB) analysis.The numerical analysis shows that the mismatched low-SNR model CRLB nicely pairs the true estimator performance for low and medium SNRs.

Performance analysis of hierarchical decision aided 2-source BPSK H-MAC CSE with feed-back gradient solver for WPNC networks

  • Autoři: Hron, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of 2019 IEEE Microwave Theory and Techniques in Wireless Communications MTTW 2019. IEEE (Institute of Electrical and Electronics Engineers), 2019. p. 72-75. ISBN 978-1-7281-4473-3.
  • Rok: 2019
  • DOI: 10.1109/MTTW.2019.8897247
  • Odkaz: https://doi.org/10.1109/MTTW.2019.8897247
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses a problem of channel phase estimation in a 2-source Hierarchical MAC channel in a Wireless Physical Layer Coded (WPNC) system with Hierarchical Decode and Forward strategy. We assume a non-pilot based estimator, a pilot based one would require orthogonal pilot signal resources which are not available in a WPNC system. In such a system,the receiving relay node does not have the individual source data available and the only data related estimator aid is a many-to-one network coded data function. We analyze the properties of the estimator metric and the performance of the estimator with a feed-back gradient solver. Particularly we analyze: (1) mean square error (MSE) performance including its relation to Cramer-Rao Lower Bound (CRLB), and (2) we analyze properties of ambiguity modes of the estimator.

Performance analysis of hierarchical decision aided 2-source BPSK H-MAC CSE with feed-back gradient solver for WPNC networks

  • Autoři: Hron, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IRACON 10th MC meeting and 10th Technical meeting 2019. Brussels: COST Office, 2019.
  • Rok: 2019
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses a problem of channel phase estimation in a 2-source Hierarchical MAC channel in a Wireless Physical Layer Coded (WPNC) system with Hierarchical Decode and Forward strategy. We assume a non-pilot based estimator, a pilot based one would require orthogonal pilot signal resources which are not available in WPNC system. In such a system, the receiving relay node does not have the individual source data available and the only data related estimator aid is a many-to-one network coded data function. We analyze the performance of estimator with feed-back gradient solver. Particularly we analyze: (1) mean square error (MSE) performance including its relation to Cramer-Rao Lower Bound (CRLB), and (2) we analyze properties of ambiguity modes of the estimator.

Achievable Rates for HDF WPNC Strategy with Hierarchical Bit-Wise Network Coding Maps for Higher-Order Constellations in H-MAC Channel with Relative Fading

  • Autoři: prof. Ing. Jan Sýkora, CSc., Hron, P.
  • Publikace: 2018 European Conference on Networks and Communications, EuCNC 2018. IEEE (Institute of Electrical and Electronics Engineers), 2018. p. 11-15. ISSN 2475-6490. ISBN 978-1-5386-1478-5.
  • Rok: 2018
  • DOI: 10.1109/EuCNC.2018.8443240
  • Odkaz: https://doi.org/10.1109/EuCNC.2018.8443240
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses Wireless Physical Layer Network Coding (WPNC) with Hierarchical Decode and Forward (HDF) strategy. We analyze achievable hierarchical rates in one stage hierarchical MAC (H-MAC) channel for higher order component constellations with bit-wise Hierarchical Network Code (HNC) maps. This is motivated by a possible application of state-of-the-art binary (e.g. LDPC) codes over higher order constellations. We show that the bit-mapped binary codes do not have the same achievable rates as direct higher-order codes. On top of this, the individual bits in the HNC map might provide very uneven performance and it strongly depends on the combination of component alphabets. The results are supported by a validation with practical LDPC codes.

H-MAC channel phase estimator with hierarchical data decision aided feed-back gradient solver

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IRACON 8th MC meeting and 8th Technical meeting 2018. Brussels: COST Office, 2018.
  • Rok: 2018
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper focuses on the channel state estimation (CSE) problem in parametrized Hierarchical MAC (H-MAC) stage in Wireless Physical Layer Network Coding (WPNC) networks with Hierarchical Decode and Forward (HDF) relay strategy. We derive a non-pilot based H-MAC channel phase estimator for 2 BPSK alphabet sources. The CSE is aided only by the knowledge of H-data decisions. At HDF relay, there is no information on individual source symbols available. The estimator is obtained by a marginalization over the hierarchical dispersion. The estimator uses a gradient additive update solver and the indicator function (gradient) is derived in exact closed form and in approximations for low and high SNR. We analyze the properties of the equivalent solver model, particularly the equivalent gradient detector characteristics and its main stable domain properties under a variety of channel parameterization scenarios.

Hierarchical Data Decision Aided 2-Source BPSK H-MAC Channel Phase Estimator with Feed-Back Gradient Solver for WPNC Networks

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: The 14th International Conference on Wireless and Mobile Computing, Networking and Communications 2018. Piscataway: IEEE, 2018. p. 89-96. ISSN 2160-4894. ISBN 978-1-5386-6876-4.
  • Rok: 2018
  • DOI: 10.1109/WiMOB.2018.8589117
  • Odkaz: https://doi.org/10.1109/WiMOB.2018.8589117
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper focuses on the channel state estimation (CSE) problem in parametrized Hierarchical MAC (H-MAC) stage in Wireless Physical Layer Network Coding (WPNC) networks with Hierarchical Decode and Forward (HDF) relay strategy. We derive a non-pilot based H-MAC channel phase estimator for 2 BPSK alphabet sources. The CSE is aided only by the knowledge of H-data decisions. At HDF relay, there is no information on individual source symbols available. The estimator is obtained by a marginalization over the hierarchical dispersion. The estimator uses a gradient additive update solver and the indicator function (gradient) is derived in exact closed form and in approximations for low and high SNR. We analyze the properties of the equivalent solver model, particularly the equivalent gradient detector characteristics and its main stable domain properties under a variety of channel parameterization scenarios.

Hierarchical decoding with bit-wise soft-aided H-SODEM and iterative double-loop processing

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses Wireless Physical Layer Network (WPNC) coding using Isomorphic Layered Network Coded Modulation (NCM) in hierarchical MAC stage with Hierarchical Decode and Forward (HDF) strategy. We focus on using binary component codes in bit-wise mapped higher-order hierarchical constellations. This creates a complicated nonlinear block-like inter-bit structure binding and the bit-wise observation model cannot be any longer described by single-letter entities. The nonlinear inter-bit structural binding strongly depends on the source constellation bit mapping, actual bit-wise a priori PMFs, and also on the actual relative channel parametrization. We derive bit-wise soft-aided Hierarchical Soft-Output Demodulator (H-SODEM) and analyze the bit error rate properties of the dual-loop soft-aided bit-wise hierarchical decoding in 2-source H-MAC HDF scenario. This scheme is shown to significantly improve the performance w.r.t. classical uniform a priori case.

Iterative double-loop hierarchical decoding with soft-aided bit-wise H-SODEM in WPNC networks

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: The 10th International Symposium on Turbo Codes & Iterative Information Processing 2018. IEEE, 2018. ISSN 2165-4719. ISBN 978-1-5386-7048-4.
  • Rok: 2018
  • DOI: 10.1109/ISTC.2018.8625375
  • Odkaz: https://doi.org/10.1109/ISTC.2018.8625375
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses Wireless Physical Layer Network (WPNC) coding using Isomorphic Layered Network Coded Modulation (NCM) in hierarchical MAC stage with Hierarchical Decode and Forward (HDF) strategy. We focus on using binary component codes in bit-wise mapped higher-order hierarchical constellations and on the way how to improve the outer code iterative decoding. Soft bit-wise hierarchical decoding metric exhibits two important properties. (1) Unlike the single-user case, the hierarchical metric is many-to-one function of message symbols and even for perfect a priori soft-information, it contains hierarchical self-dispersion. (2) The bit-wise mapping itself creates a complicated nonlinear block-like inter-bit structure binding and the bit-wise observation model cannot be any longer described by single-letter entities. It also strongly depends on the source constellation bit mapping, actual bit-wise a priori PMFs, and also on the actual relative channel parametrization. We derive bit-wise soft-aided Hierarchical Soft-Output Demodulator (H-SODEM). We show how to cope with self-dispersion in specific cases. We analyze the bit error rate properties of the dual- loop soft-aided bit-wise hierarchical decoding in 2-source H-MAC HDF scenario and show significant performance improvement w.r.t. classical uniform a priori case.

Wireless Physical Layer Network Coding

  • DOI: 10.1017/9781316156162
  • Odkaz: https://doi.org/10.1017/9781316156162
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Discover a fresh approach for designing more efficient and cooperative wireless communications networks with this systematic guide. Covering everything from fundamental theory to current research topics, leading researchers describe a new, network-aware coding strategy that exploits the signal interactions that occur in dense wireless networks directly at the waveform level. Using an easy-to-follow, layered structure, this unique text begins with a gentle introduction for those new to the subject, before moving on to explain key information-theoretic principles and establish a consistent framework for wireless physical layer network coding (WPNC) strategies. It provides a detailed treatment of Network Coded Modulation, covers a range of WPNC techniques such as Noisy Network Coding, Compute and Forward, and Hierarchical Decode and Forward, and explains how WPNC can be applied to parametric fading channels, frequency selective channels, and complex stochastic networks. This is essential reading whether you are a researcher, graduate student, or professional engineer.

Achievable rates of hierarchical bit-wise mapped higher-order network coding maps in H-MAC channel with relative fading

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses Wireless Physical Layer Network Coding with Hierarchical Decode and Forward strategy. We analyze achievable hierarchical rates in one stage hierarchical MAC channel for higher order component constellations with bit-wise Hierarchical Network Code (HNC) maps. This is motivated by a possible application of state-of-the-art binary (e.g. LDPC) codes over higher order constellations. We show that the bit-mapped binary codes do not have the same achievable rates as direct higher-order codes. On top of this, the individual bits in the HNC map might provide very uneven performance and it strongly depends on the combination of component alphabets.

Design of adaptive constellations and error protection coding for wireless network coding in 5-node butterfly networks

  • Autoři: Procházka, P., Uřičář, T., Halls, D., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: EURASIP Journal on Wireless Communications and Networking. 2017, 2017(1), ISSN 1687-1499.
  • Rok: 2017
  • DOI: 10.1186/s13638-017-0935-y
  • Odkaz: https://doi.org/10.1186/s13638-017-0935-y
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper, we focus on the design of a reliable communication scheme for generic 5-node wireless butterfly networks (WBN). Since the WBN represents a natural extension of the basic two-way relay communication channel, we follow the paradigm of Wireless Physical Layer Network Coding and we show that the design of novel adaptive constellations is desirable to exploit the promising performance of wireless network coding in WBN. We introduce a systematic constellation design algorithm, and we show that the proposed constellations are capable of outperforming conventional point-to-point modulations in WBN over the whole range of channel signal to noise ratios. To further support the applicability of the proposed constellations in a practical system, we integrate a simple binary channel coding scheme, providing a robust adaptivemodulation and coding scheme for relaying in symmetric WBNs with arbitrary channel conditions.

Distributed Consensus Estimator of Hierarchical Network Transfer Function in WPNC Networks

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2017 23RD ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC): BRIDGING THE METROPOLITAN AND THE REMOTE. Piscataway (New Jersey): IEEE, 2017. p. 41-46. Asia-Pacific Conference on Communications. ISSN 2163-0771. ISBN 978-1-74052-390-5.
  • Rok: 2017
  • DOI: 10.23919/APCC.2017.8304060
  • Odkaz: https://doi.org/10.23919/APCC.2017.8304060
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Wireless Physical Layer Network Coding (WPNC) network nodes determine their front-end, back-end, and node processing operation based on the knowledge of the global Hierarchical Network Transfer Function (H-NTF). The H-NTF can be derived from the network connectivity state and it is essential to set up properly WPNC processing at each node. The data payload in WPNC network uses a common signal space of mutually interacting signals superposing on the receive node antenna. There are no orthogonalized communication links that would allow traditional control-data signaling based approaches to determine the network state. The procedure where each node establishes a complete picture of the network state must be performed before the payload phase such that the superposing non-orthogonal pilot signals fully respect the WPNC paradigm. This paper proposes a distributed consensus-based estimator of the network state which operates on a common signal space shared by all nodes in the network. The algorithm allows each node to find the global network state based only on local neighbor superposed pilot observation.

Cooperative Strategies and Networks

  • Autoři: prof. Ing. Jan Sýkora, CSc., Bota, V., Zhang, Y, Ruiz, S
  • Publikace: Cooperative Radio Communications for Green Smart Environments. Aalborg: River Publishers, 2016. p. 271-304. River Publishers Series in Communications. vol. 47. ISBN 978-87-93379-14-5.
  • Rok: 2016
  • DOI: 10.13052/rp-9788793379145
  • Odkaz: https://doi.org/10.13052/rp-9788793379145
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Cooperative strategies and networks play an important role in current state-ofart wireless communications. The cooperation can have many forms and can be utilised at various levels of the processing hierarchy. At the physical layer, the cooperative algorithms revolutionise the design of modulation, coding, and signal processing. It can be directly at the level of channel coding which is aware of and pro-actively utilises the network structure knowledge as is performed by physical layer network coding (PLNC). Apart of the coding itself, the cooperative and relay-aided processing can substantially increase the network performance, most notably by using virtual multiple-input multipleoutput (MIMO), distributed processing and smart interference cancellation. The cooperative network layer algorithms allows efficient coordination of the network and its resources.

Distributed Consensus Estimator of Hierarchical Network Transfer Function in WPNC Networks

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Wireless Physical Layer Network Coding (WPNC) network nodes determine their front-end, back-end, and node processing operation depending on the knowledge of the global Hierarchical Network Transfer Function (H-NTF). The H-NTF can be derived from the network connectivity state and it is essential in determining how to perform hierarchical decoding, what hierarchical network coding function to use, and how to encode the Network Coded Modulation at each node. The data payload in WPNC network uses a common signal space of mutually interacting signals that superpose on the receive nodes. There are no orthogonalized communication links that would allow traditional signaling based approaches to determine the network state. Also, the procedure where each node establishes a complete picture of the network state must be performed before the payload phase and with superposing non-orthogonal pilot signals that fully respect the WPNC paradigm. This paper proposes a distributed consensus-based estimator of the network state which operates on a common signal space shared by all nodes in the network. The algorithm allows each node to find the global network state based only on local neighbor superposed pilot observation.

Hierarchical pairwise error probability for hierarchical decode and forward strategy in PLNC

  • DOI: 10.1109/LCOMM.2015.2498164
  • Odkaz: https://doi.org/10.1109/LCOMM.2015.2498164
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Pairwise Error Probability (PEP) is an essential tool allowing to design practical optimized coding schemes. It reveals the connection between the performance and the decoding metric that is directly related to the codeword and/or constellation properties. The application of this principle to the hierarchical PEP used to describe the decoding performance of many-to-one message functions (Hierarchical Network Code maps) in Physical Layer Network Coding (PLNC) is addressed in this paper. Unlike for the single-user case, the hierarchical PEP reveals a complicated dependence on the structure of the hierarchical codeword/constellation. The structure is defined in terms of hierarchical distance and hierarchical self-distance spectra. We show that the Network Coded Modulation (NCM) minimizing the hierarchical decoding error probability should have zero selfdistance spectrum leading to self-folded NCM design criterion.

Constellations maximizing minimal distance for physical-layer network coding multiway relaying

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: IEEE 81st Vehicular Technology Conference VTC Spring 2015 Proceedings. New York: IEEE Vehicular Technology Society, 2015. ISSN 1550-2252. ISBN 978-1-4799-8088-8.
  • Rok: 2015
  • DOI: 10.1109/VTCSpring.2015.7145758
  • Odkaz: https://doi.org/10.1109/VTCSpring.2015.7145758
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper objects a design of constellations suitable for Physical-Layer Network Coding (PLNC) in a Multi-Way Relay Channel (M-WRC). We formulate the constellation design as a general constrained optimization problem maximizing minimal distance of network coding function decoding. The numerically obtained constellations are recognized to possess some regular structure. The optimal constellations for 2-WRC are power-balanced hexagonal constellations with particular type of indexing. As far as the optimization problem is numerically tractable, we declare optimality of power-scaled pre-rotated amplitude shift keying constellations for M-WRC with number of terminals >2. All optimums decode non-linear modulo-sum network coding function and offer considerable performance gains in comparison to canonical schemes. This work also demonstrates that PLNC strategy tailored to M-WRC overcome PLNC 2-WRC approach.

Critical Sequence Based Stage Scheduling Algorithm and Hierarchical Network Transfer Function for Half-duplex WPNC Networks

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Wireless Physical Layer Network Coding (WPNC) based communication networks deliver the information from sources to destinations through the complex relay network. In order to properly design Network Coded Modulation transmitted by network nodes and relay processing including the Hierarchical Network Code (HNC) maps, we need a formal description of the global network processing function. Any practical implementation also implies the half-duplex constrained relays which imposes the network to work in multiple stages. We present a polynomial based formalism defining the Hierarchical Network Transfer Function (H-NTF). It captures all phenomena related to the stage dependent transmit and receive act ivity over the network, including potential buffering, and mainly the hierarchy of forming the local HNC maps into the global hierarchical flow description. Using the polynomial formalism of H-NTF, we develop the half-duplex constrained stage scheduling algorithm. It starts with finding a minimal latency (or close to minimal) causal critical sequence with subsequent doubly (first Rx then Tx) greedy mapping of the node activity compliant with half-duplex constraint.

Hardware implementation of Distributed Learning Algorithm for mapping selection for Wireless Physical Layer Network Coding

  • Autoři: Hynek, T., Halls, D., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2015 IEEE International Conference on Communication Workshop. Pomona, California: IEEE Communications Society, 2015. pp. 2127-2132. ISBN 978-1-4673-6305-1.
  • Rok: 2015
  • DOI: 10.1109/ICCW.2015.7247496
  • Odkaz: https://doi.org/10.1109/ICCW.2015.7247496
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A wireless relay node employing Wireless Physical Layer Network Coding (WPLNC) must use a specific mapping in order to combine incoming signals. This mapping, however, cannot be selected arbitrarily. Together with the signals from the other network relays, it has to allow the destinations to be able to recover the source data from the available observations. Moreover the mapping should optimize a local relay utility function. This task can be easily solved in centralized networks. In decentralized ones, such as sensor or smart metering networks, a mapping assignment should be derived from mutual node communication, cooperation and/or signaling. In this paper we focus on the practical hardware implementation of such a distributed algorithm called a Distributed Learning Algorithm (DLA). In a two source, two relay and two destination network scenario we have implemented a non-cooperative game-based process that selects the WPLNC mapping of each individual relay node guaranteeing invertibility of WPLNC at the destinations as well as optimizing the relay's utility function, namely the output modulation cardinality. The implementation testbed is based on Software Defined Radio (SDR) modules and it is used to verify the algorithm properties in real-world conditions.

Hierarchical Network Transfer Function and Doubly-Greedy Half-Duplex Stage Scheduling for WPNC Networks

  • DOI: 10.1109/LCOMM.2015.2417874
  • Odkaz: https://doi.org/10.1109/LCOMM.2015.2417874
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Wireless Physical Layer Network Coding (WPNC) based communication networks deliver the information from sources to destinations through the complex relay network. To properly design the Network Coded Modulation transmitted by network nodes and the relay processing including the Hierarchical Network Code (HNC) maps, we need a formal description of the global network processing function. Any practical implementation also implies the half-duplex constrained relays which imposes the network to work in multiple stages. We present a polynomial based formalism defining the Hierarchical Network Transfer Function (H-NTF). It captures all phenomena related to the stage dependent transmit and receive activity over the network, including potential buffering, and mainly the hierarchy of forming the local HNC maps into the global hierarchical flow description. Using the polynomial formalism of H-NTF, we develop the half-duplex constrained stage scheduling algorithm. It starts with finding a causal minimal latency (or close to minimal) critical sequence with subsequent doubly (first Rx then Tx) greedy mapping of the node activity compliant with the half-duplex constraint.

Non-cooperative compute-and-forward strategies in Gaussian multi-source multi-relay networks

  • Autoři: Richter, J., Hejtmánek, J., Jorswieck, E.A., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2015 IEEE 82nd Vehicular Technology Conference VTC2015-Fall Proceedings. New York: IEEE Vehicular Technology Society, 2015. ISBN 978-1-4799-8091-8.
  • Rok: 2015
  • DOI: 10.1109/VTCFall.2015.7391036
  • Odkaz: https://doi.org/10.1109/VTCFall.2015.7391036
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Compute-and-forward is an emerging technique to increase throughput in interference networks. It allows the relays to decode an equation of codewords instead of each single codeword. Choosing the appropriate equation plays a crucial role on the performance. While there are several algorithms that solve this optimization problem, they all perform a local optimization. In large relay networks this can result in linear dependent equations at the destination and a large outage probability. In this paper we propose new non-cooperative strategies on how to choose the desired equations and enforce linear independent equations. This allows to solve the optimization problem in a localized and distributed manner. Further we compare the achievable sum-rate of those strategies and show that correlated signals have a huge impact on the performance.

Relaying in Butterfly Networks: Superposition constellation design for Wireless Network Coding

  • Autoři: Procházka, P., Uřičář, T., Halls, D., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2015 IEEE International Conference on Communication Workshop. Pomona, California: IEEE Communications Society, 2015. p. 2168-2174. ISBN 978-1-4673-6305-1.
  • Rok: 2015
  • DOI: 10.1109/ICCW.2015.7247503
  • Odkaz: https://doi.org/10.1109/ICCW.2015.7247503
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Wireless Physical Layer Network Coding (WNC) techniques exploit the inherent nature of wireless channels to improve the performance of wireless communication systems. Unlike conventional Network Coding, in WNC the transmitted signals constructively interact directly in the constellation space, thus inducing specific requirements on the source constellation design. Suitable multi-source constellations should enable direct decoding of WNC functions of user data (from the observed superimposed constellations at receiving nodes) and simultaneously they should allow delivery of partial information to nodes with worse channel conditions (exploiting the natural broadcast property of wireless channels). Source constellations possessing both the aforementioned attributes simultaneously can be desirable in a WNC-based system and thus proper constellation design can become a relatively challenging task. In this paper we focus on this problem and we introduce a systematic constellation design algorithm for a 5-node Wireless Butterfly Network (WBN) with WNC processing, where the basic principles of multi-source constellation design for WNC systems can be demonstrated. We show that the proposed constellations outperform the conventional approaches over the whole range of SNR conditions in the system.

Sequential Incomplete Information Game in Relay Networks Based on Wireless Physical Layer Network Coding

  • Autoři: Hynek, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Multiple Access Communications 8th International Workshop MACOM 2015 Proceedings. Cham: Springer, 2015. pp. 47-56. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-319-23439-7.
  • Rok: 2015
  • DOI: 10.1007/978-3-319-23440-3_4
  • Odkaz: https://doi.org/10.1007/978-3-319-23440-3_4
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A performance of a network based on Wireless Physical Layer Network Coding (WPLNC) crucially depends on local mapping functions selected by every individual relay. As a whole the mappings must enable the destination to recover desired source data but they must also be reasonable from relays’ point of view. This is important especially in distributed and decentralised networks where the relays’ mappings are not given in advance but they emerge from interaction among relays. In this paper we focus on a toy example of relay network where a sequential selection of the WPLNC mappings takes place. We assume that the first relay may suffer from low battery level which may affect its selection of WPLNC mappings and that the second relay can deduce the battery state from observed actions and alter its behaviour to cope with the situation. For this scenario we discuss and evaluate an existence of game equilibria.

Two-source Constellation Design for Wireless Network Coding in Butterfly Network

  • Autoři: Procházka, P., Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 12th MCM Dublin. Brussels: COST Office, 2015.
  • Rok: 2015
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The design of efficient constellations (signal sets) for wireless communication channels is a longlasting research problem. While relatively mature results are available for point-to-point wireless channels, we still have only some basic results for general multi-user channels. Another interesting research problem in the constellation design was revealed quite recently with the introduction of Wireless Network Coding (WNC). In this paper we focus on the WNC processing in Wireless Butterfly Network (WBN) and we introduce a systematic constellation design algorithm, eligible to produce suitable source constellations for arbitrary channel conditions in this network. The proposed 2-source constellations outperform the state-of-the-art solutions in a wide range of channel conditions, thus providing a first step towards an implementation of practical modulation-coding scheme in WBN.

Wireless physical layer network coding in potential presence of malicious relays - Incomplete information game approach

  • DOI: 10.1049/el.2015.0832
  • Odkaz: https://doi.org/10.1049/el.2015.0832
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A wireless physical layer network coding (WPLNC) technique in a decentralised and distributed relay network where a maliciously behaving relay may be present is studied. Most research has optimistically assumed altruistic cooperation of relays. The malicious node can lead to a significant disorder among the other relays by selecting its own WPLNC mapping. This scenario is described as a static (single-shot) incomplete information game where a node type - either friendly or malicious - of the relay is its private information. The focus is on the existence of particular equilibria given the probability of the presence of a malicious node.

Hexagonal constellations for adaptive physical-layer network coding 2-way relaying.

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: IEEE Communications Letters. 2014, 18(2), 217-220. ISSN 1089-7798.
  • Rok: 2014
  • DOI: 10.1109/LCOMM.2013.122713.132526
  • Odkaz: https://doi.org/10.1109/LCOMM.2013.122713.132526
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We focus on a constellation design for adaptive physical-layer network coding strategy in a wireless 2-way relay channel. It is well known that 4QAM constellations require extended-cardinality network coding adaptation to avoid all singular channel parameters at the Multiple-Access (MA) stage. The cardinality extension is undesirable since it introduces redundancy decreasing the data rates at the broadcast stage. In this paper, we target a design of constellations avoiding all the singularities without the cardinality extension. We show that such a constellation is 4-ary constellation taken from hexagonal lattice (4HEX) which keeps comparable error performance at the MA stage as 4QAM, however without the cardinality extension. The similar properties has been found also by unconventional 3HEX and 7HEX constellations.

Hierarchical Interference Cancellation in BPSK 3-Source Multiple Access Channel with Wireless (Physical Layer) Network Coding

  • Autoři: Uřičář, T., Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 9th MCM Ferrara. Brussels: COST Office, 2014. pp. 1-8.
  • Rok: 2014
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Successive Decoding with Interference Cancellation (SD-IC) is well understood to be a capacity achieving decoding strategy in Multiple Access Channels (MAC). This decoding technique allows a consecutive elimination of interfering signals during the successive decoding of particular user data. The ability to perfectly remove the interfering signal from the subsequent decoder processing (after corresponding user’s data have been successfully decoded) relies on a one-to-one mapping between the user data sequence and its signal space representation. However, this is not always guaranteed in Wireless (Physical Layer) Network Coding (WNC) systems, where only specific (“hierarchical") functions of user data are decoded. In this paperw we analyse this particular research problem in a simple binary 3-user MAC channel, which is capable to demonstrate the issues associated with successive decoding in WNC systems. We show that a hierarchical extension of conventional SD-IC processing appears to be a viable decoding strategy, even though it does not allow a perfect removal of interfering signals from the receiver observation.

Joint and recursive hierarchical interference cancellation with successive compute & forward decoding

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses Physical Layer Network Coding in multinode wireless relaying networks. We generalize Compute & Forward (CF) strategy by introducing the concept of Hierarchical Interference Cancellation (H-IFC) using Successive CF Decoding. This technique allows increasing the number of degrees of freedom in lattice misalignment equalizer while using all available hierarchical (many-to-one function) auxiliary codeword maps. The technique is not constrained to use linear map combinations and allows more freedom in choosing a given desired codeword map at the relay in a complicated multi-stage network. The H-IFC technique is developed in two, joint and recursive, forms. Numerical results show that the achievable computation rates can substantially outperform standard linear multi-map CF technique.

Practical Implementation of Cloud Initialization Procedure for Wireless Physical Layer Network Coding Clouds

  • Autoři: Hynek, T., prof. Ing. Jan Sýkora, CSc., Halls, D.
  • Publikace: Proceedings of 20th European Wireless (EW) Conference. Berlin: VDE VERLAG GMBH Berlin, 2014. pp. 751-756. ISBN 978-3-8007-3621-8.
  • Rok: 2014
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A relay in a network without any centralized controlling entity is subject to a lack of global network state knowledge. The only information that it can gain comes from its closest neighbors. This is the typical situation in wireless multi-node networks with many sources, destinations and relays. Our proposal assumes such a network that we call a cloud since it provides a service, reliable communication, to the network users - sources and destinations. The service is provided via a uniform interface and the users should not be involved or even interested in the internal cloud organization. This allows the user nodes to behave more or less selfishly. All of the tasks associated with service providing are delegated to the cloud and are solved by a distributed approach, as much as possible, without any controlling node. A technique known as Wireless Physical Layer Network Coding (WPLNC) is a potential enabling technology for such networks. In this paper a Software Defined Radio (SDR) implementation based on an OFDM physical layer of one of the algorithms that equips each network node with all the information necessary to start the WPLNC communication is presented.

Successive Decoding with Hierarchical Interference Cancellation in Wireless (Physical Layer) Network Coding Systems

  • Autoři: Uřičář, T., Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of 20th European Wireless (EW) Conference. Berlin: VDE VERLAG GMBH Berlin, 2014. pp. 745-750. ISBN 978-3-8007-3621-8.
  • Rok: 2014
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The intermediate network nodes (relays) in Wireless (Physical Layer) Network Coding (WNC) systems are allowed to process only some specific ("hierarchical") functions of user data (instead of separate decoding of individual user signals), which allows to overcome the rate limits induced by the conventional Multiple Access Channels capacity regions. Unfortunately, since the mapping between a specific decoded hierarchical function and the corresponding signal space representation is generally one-to-many, traditional successive decoding techniques with perfect interference cancellation (subtraction) of decoded signals cannot be directly employed in WNC systems. In this paper we show that even in this case the knowledge of hierarchical data can be efficiently exploited in the decoding process to significantly reduce the impact of interfering signal on the subsequent decoding operations in WNC systems.

Wireless (Physical Layer) Network Coding With Limited Hierarchical Side Information: Maximal Sum-Rates in 5-Node Butterfly Network

  • Autoři: Uřičář, T., Qian, B., prof. Ing. Jan Sýkora, CSc., Mow, W.H.
  • Publikace: IEEE Transactions on Wireless Communications. 2014, 13(10), 5582-5595. ISSN 1536-1276.
  • Rok: 2014
  • DOI: 10.1109/TWC.2014.2330591
  • Odkaz: https://doi.org/10.1109/TWC.2014.2330591
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Favorable characteristics of wireless channels (including the inherent broadcast and superposition nature) provide a fertile ground for the extension of conventional network coding (NC) principles to wireless communication networks. However, the research of emerging wireless (physical layer) network coding (WNC) techniques have already revealed several non-trivial research problems that do not appear in the conventional (wireline) NC systems, including the sensitivity to channel parametrization and challenging multi-source transmission synchronization. In this paper, we uncover another significant research challenge typical for multi-node WNC systems. We show that the performance of contemporary WNC bi-directional relaying strategies is dominated by the availability of a specific hierarchical side information (HSI), required for the successful decoding of desired information from hierarchical (WNC-coded) data streams. We analyze the impact of unreliable transmission of HSI on the performance of a wireless butterfly network (WBN), and we show that all state-of-the-art relaying strategies must be appropriately modified to avoid the deterioration of WBN performance in the limited HSI regime.

Bezdrátové síťové kódování fyzické vrstvy - jemný úvod do budoucnosti komunikací

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 39. Pravidelné setkání zájemců o mikrovlnnou techniku. Praha: Česká elektrotechnická společnost, 2013. ISBN 978-80-02-02488-0.
  • Rok: 2013
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Přednáška o úvodu do komunikačních technologií, založených na bezdrátovém síťovém kódování fyzické vrstvy

Dense Cooperative Wireless Cloud Network (DIWINE)

  • Autoři: prof. Ing. Jan Sýkora, CSc., Hrjehor, M.
  • Publikace: Future Network and MobileSummit 2013. Dublin: IIMC International Information Management Corporation Ltd, 2013. pp. 1-4. ISBN 978-1-905824-36-6.
  • Rok: 2013
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    DIWINE, an FP7 project running from January 2013 to December 2015, considers wireless communication in a dense relay/node scenario where Wireless Network Coding (WNC) messages are flooded via dense massively air-interacting nodes in the self-contained cloud while the PHY air-interface between the terminals (sources/ destinations) and the cloud is simple and uniform. A complex infrastructure cloud creates an equivalent air-interface to the terminal, which is as simple as possible. Source and destination air-interfaces are completely blind to the cloud network structure. The cloud has its own self-contained organising and processing capability. This concept facilitates energy-efficient, high-throughput and low-latency network communication performed directly at the PHY, which is capable of operating in complicated, dense, randomly defined network topologies and domains. The applications of the DIWINE paradigm are generic, being relevant to complex systems ranging from intelligent transport systems to healthcare and even machine-to-machine communication in wireless networks. However, in order to exhibit practical, highly focused and high impact results, DIWINE concentrates on two core application/demonstration cases: (i) smart metering networks and (ii) critical industrial monitoring and control applications. To this end, DIWINE algorithms and theoretical technology will be integrated into two industrial proof-of-concept demonstration platforms targeting the aforementioned applications. Both of these applications require low-latency, dense networking solutions and are sure to be integral to future European policy and society as evidenced by recent European Commission initiatives such as EUROPE 2020.

Generic Efficient FG-SPA Implementation Framework based on the best Linear Canonical Message Representation in MSE Sense

  • Autoři: Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: European Wireless 2013. Berlin: VDE VERLAG GMBH Berlin, 2013. ISBN 978-3-8007-3498-6.
  • Rok: 2013
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper focuses an implementing issue of the sum-product algorithm on factor graphs (FG-SPA) for a general system. The goal is to propose a message representation and corresponding update rules for both discretely and continuously valued variables with an acceptable exactness-complexity tradeoff that is applicable in a wide class of scenarios. We propose the update rules for a generic class of linear message representations with orthogonal canonical kernels. The proposed update rule design is combined with an already known message parameterization based on the Karhunen-Loeve Transform (KLT) of the message. This combination of the proposed generic update rules with the KLT-message representation forms a generic implementation framework of the FG-SPA applicable whenever the KLT is defined. This framework preserves the properties of the KLT-message representation that is the best linear approximation in the MSE sense. A particular example on a joint detection and phase estimation is shown to verify the proposed framework and to show its advantages against a conventional solution.

Generic FG-SPA update rules design of linear canonical message representation

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper focuses an implementing issue of the sum-product algorithm on factor graphs (FGSPA) in a general system. The overall goal is to propose a message representation and corresponding update rules for both discretely and continuously valued variables with an acceptable exactness-complexity trade-off. We propose the update rules for a generic class of linear message representations with orthogonal canonical kernels. The proposed update rule design is combined with an already known message parameterization based on the Karhunen-Loeve Transform (KLT) of the message. This combination of the proposed generic update rules with the KLT-message representation forms a generic implementation framework of the FG-SPA applicable whenever the KLT is defined. This framework preserves the properties of the KLTmessage representation that is the best linear approximation in the MSE sense. A particular example on a joint detection and phase estimation is shown to verify the framework and to compare the proposed method with a conventional solution

Network Coded Modulation for Random Channel Class in WNC with HDF Relaying Strategy

  • DOI: 10.1109/LCOMM.2013.031313.122517
  • Odkaz: https://doi.org/10.1109/LCOMM.2013.031313.122517
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A standard NCM (Network Coded Modulation) for WNC (Wireless Network Coding) with HDF (Hierarchical Decode & Forward) strategy requires that each node has full knowledge of the connectivity pattern to other nodes and this knowledge affects the design of NCM and HNC (Hierarchical Network Code) maps at each transmitting (source) and receiving (relay) node respectively. The final destination has to have full knowledge of all HNC maps used and the composite overall HNC map needs to be invertible to recover the source data. This approach collapses if nodes do not have a full knowledge of the connectivity pattern and thus cannot adjust their HNC maps properly. We design the NCM and HNC maps for WNC with HDF strategy that works regardless of this knowledge. It is based on a concept of a channel class which is a discrete (random) parameter describing the channel behavior and which becomes a part of HNC maps and the NCM hierarchical constellation. We analyze the rate regions for this design and compare it to the standard NCM and HNC map solution suffering from random channel outages.

Non-cooperative broadcast game for distributed decision map selection of relay wireless network coding processing

  • Autoři: Hynek, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2013 IEEE 14th Workshop on Signal Processing Advances in Wireless Communications. Piscataway: IEEE, 2013. pp. 51-55. ISSN 2325-3789. ISBN 978-1-4673-5577-3.
  • Rok: 2013
  • DOI: 10.1109/SPAWC.2013.6612010
  • Odkaz: https://doi.org/10.1109/SPAWC.2013.6612010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper deals with distributed decision map selection of individual relay wireless network coding (WNC) (a.k.a physical layer network coding (PLNC)) operation in a multi-source network scenario. Communication network consists of several independent selfish source nodes, one layer of relay nodes (named a cloud) and a set of destinations. Relays support the source to destination communication. Connectivity among the network nodes is random and is not globally known. For this network topology the paper provides a distributed game-theory based adaptive protocol. From feedback information each relay is able to adapt its WNC operation so as to optimize its utility while decodability of WNC at each destination is guaranteed. In this paper we present our initial effort together with illustrative examples of relay utility functions. WNC introduces novel utility functions that can be far different from the NC ones, e.g. minimal hierarchical constellation distance. Presented protocol is convenient for any Decode & Forward WNC operation for wireless as well as for wired networks.

On Indexing of Lattice-Constellations for Wireless Network Coding with Modulo-Sum Decoding

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2013 IEEE 77th Vehicular Technology Conference. Piscataway: IEEE, 2013. pp. 1-6. ISSN 1550-2252. ISBN 978-1-4673-6337-2.
  • Rok: 2013
  • DOI: 10.1109/VTCSpring.2013.6692659
  • Odkaz: https://doi.org/10.1109/VTCSpring.2013.6692659
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We consider wireless (physical-layer) network coding 2-way relaying where both terminals use constellations curved from a common lattice structure and the relay node decodes modulo-sum operation of transmitted data symbols at the multiple-access stage. Performance of such a system with additive white Gaussian noise is strongly determined by used constellation indexing. For some indexing, the minimal distance of modulo-sum decoding is 0 (some points of superimposed- constellation are equal despite corresponding to unequal modulo-sum of data symbols) which causes considerable loss in alphabet-constrained capacity. In this paper, we show that if indices form a modulo-arithmetic progression along each lattice (real) dimension (denoted Affine Indexing (AI)), the minimal distance of modulo-sum decoding equals to minimal distance of primary terminal constellation. Some canonical constellation shapes prevent existence of AI, therefore we propose a greedy- sphere packing algorithm for constellation shape design which jointly maximises minimal distance and keeps existence of AI.

Potential Games for Distributed Coordination of Wireless Network Coding Based Cloud

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper we provide an analysis of game theoretical approach to distributed selection of decision maps at each individual relay in complex multi-source multi-node network based on wireless network coding (WNC) (a.k.a physical layer network coding (PLNC)) principle. The wireless network consist of arbitrary number of independent selfish source nodes, one layer of relay nodes (named a cloud) and a set of destinations. Network connectivity is globally unknown. We propose a particular example of local relay utility function – an output hierarchical symbol cardinality. We show that the previously introduced distributed algorithm has promising properties in game theoretical sense with this utility function – existence of at least one Nash equilibrium, convergence of best/better reply dynamics to the equilibrium, etc. The proposed game is suitable for any Decode & Forward WNC for wireless as well as wire-line networks.

Superposition coding for wireless butterfly network with partial network side-information

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc., Qian, B., Mow, W.H.
  • Publikace: IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE WORKSHOPS 2013. Pomona, California: IEEE Communications Society, 2013. pp. 149-154. IEEE CONFERENCE PUBLICATIONS. ISBN 978-1-4799-0110-4.
  • Rok: 2013
  • DOI: 10.1109/WCNCW.2013.6533331
  • Odkaz: https://doi.org/10.1109/WCNCW.2013.6533331
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Although the 2-source wireless Butterfly Network (BN) represents a natural extension of the well-known 2-Way Relay Channel (2-WRC) scenario, a direct implementation of conventional Wireless Network Coding (WNC)/Physical Layer Network Coding (PLNC) principles in this network is not straightforward. While the information necessary for decoding of the desired data from WNC-coded data at each destination is naturally available in 2-WRC, in the BN the destinations can obtain such information only by overhearing the wireless transmission from the unintended source. Since the amount of such received “Network” Side-Information (N-SI) would be limited by the quality of the corresponding source-destination link, the assumption of perfect side-information is no longer valid in BN, rising many novel research challenges for the design of WNC-based BN. In this paper we propose the Superposition Coding (SC) based scheme as a feasible strategy for relaying in BN. We will show that by a proper optimization of its parameters (rates & power allocation of underlying SC messages), SC is able to achieve the upper bound of two-way rate in BN for both the zero and perfect N-SI case and moreover, it represents a viable solution even for the case where only partial N-SI is available at both destinations.

Wireless (physical layer) network coding in 5-node butterfly network: Superposition coding approach.

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc., Qian, B., Mow, W.H.
  • Publikace: COST IC1004 MCM Malaga. Brussels: COST Office, 2013.
  • Rok: 2013
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The availability of some specific form of side information is a crucial assumption for an application of Wireless Network Coding (WNC)/Physical Layer Network Coding (PLNC) principles in any wireless network. This Hierarchical Side Information (HSI) is required to enable a successful decoding of the desired data from the received hierarchical (WNC-coded) data stream at the destination node. In some basic network topologies (e.g. 2-Way Relay Channel), the HSI is made naturally available by storing the data sent in the previous communication round in the node's buffer. Unfortunately, this is not always possible in more advanced wireless network scena rios, where the HSI can be obtained only by overhearing the wireless transmission(s) from the unintended source(s). In such cases the amount of HSI would be obviously limited by the quality of the corresponding (source-destination) wireless link(s), and hence any WNC-based processing must take this partial availability of HSI into account. In this paper we will demonstrate this phenomenon on an example of 2-source, 5-node wireless butterfly network, where a superposition coding scheme will be introduced as a viable approach for the WNC-based relaying with generally partially available HSI.

Wireless-aware Network Coding: Solving a Puzzle in Acyclic Multi-stage Cloud Networks

  • Autoři: Uřičář, T., Hynek, T., Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the Tenth International Symposium on Wireless Communication Systems. Berlin: VDE VERLAG GMBH Berlin, 2013. pp. 612-616. ISSN 2154-0217. ISBN 978-3-8007-3529-7.
  • Rok: 2013
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    An immense number of mutually interacting nodes increases the complexity of wireless cloud networks design/analysis. This complexity is driven by an enormous amount of degrees of freedom in the system, which are available even if a logical network structure is clearly defined and channel characteristics are known (at least locally). These degrees of freedom comprise distribution of information through the cloud, terminal(s) & relay(s) node processing (modulation, coding, relaying techniques) etc. In this paper we try to develop a framework for analysis/design of such cloud networks. We propose a partitioning of the generally complex cloud analysis/design problem into three separate tasks, which can be analysed (to some extent) independently. By identifying the mutual relations among these three tasks (and the outer conditions) the entire cloud network can be designed/analysed, similarly as a large picture can be created by assembling interlocking jigsaw puzzle pieces. The idea of Wireless-aware Network Coding will be identified as a cornerstone of our framework, providing a primary insight into the information flows passing through the cloud network. This principle will be demonstrated in an analysis of a simple single-stage system.

Block-structure based extended layered design of network coded modulation for arbitrary individual using hierarchical decode & forward strategy

  • Autoři: Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 5th MCM Bristol. Brussels: COST Office, 2012. pp. 1-7.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses a joint network-channel coding design within network coded modulation with HDF strategy framework. The problem is situated into 2-source 1-relay 2-paths scenario, with a straightforward way of generalization. The principle of the proposed design consists in a predefined structure of linear channel encoders and hierarchical maps such that already known principles are employed. The layered design with minimal hierarchical cardinality is provided upon an equally long part of both source streams and the remaining part of the streams are encoded separately. The HNC maps are composed such that the codeword-blocks are decoded by a proper corresponding decoder. We proof a network consistency of this design and verify its properties by BER simulation.

Cooperative and distributed systems

  • Autoři: prof. Ing. Jan Sýkora, CSc., Bota, V., Javornik, T.
  • Publikace: Pervasive Mobile and Ambient Wireless Communications. London: Springer, 2012. p. 341-372. ISBN 978-1-4471-2314-9.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Pervasive Mobile and Ambient Wireless Communications reports the findings of COST 2100, a project of the European intergovernmental COST framework addressing various topics currently emerging in mobile and wireless communications. Drawing on experience developed in this and earlier COST projects, the text represents the final outcome of collaborative work involving more than 500 researchers in 140 institutions and 30 countries (including outside Europe). The book's subject matter includes transmission techniques, signal processing, radio channel modelling and measurement, radio network issues, and recent paradigms including ultra-wideband, cooperative, vehicle-to-vehicle and body communications. The research reported comes from a variety of backgrounds: academic, equipment-manufacturing and operational. The information contained in this book will bring the study reported to a wider audience from all those spheres of work. Pervasive Mobile and Ambient Wireless Communications will be of interest to researchers for its cutting-edge analysis and to practitioners for its functional usability.

Cooperative wireless network coding for uplink transmission on hierarchical wireless networks

  • Autoři: Burr, A., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 3rd MCM Barcelona. Brussels: COST Office, 2012. pp. 1-9.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper considers a very simple hierarchical wireless network in which two terminals transmit to a two relay base stations (RBS), which in turn communicate via wireless backhaul with a single hub base station. The objective of the proposed scheme is to allow the two RBSs to cooperate to serve both terminals without increasing the backhaul load compared to the non-cooperative case. This is implemented using adaptive wireless network coding, in which both RBSs employ wireless network coding using hierarchical decode and forward (HDF) with linear network coding maps adaptively chosen to optimise capacity.

Cooperative wireless network coding for uplink transmission on hierarchical wireless networks

  • Autoři: Burr, A., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2012 International Symposium on Signals, Systems, and Electronics (ISSSE). Red Hook: Curran Associates, Inc., 2012. pp. 1-5. ISSN 2161-0819. ISBN 978-1-4673-4454-8.
  • Rok: 2012
  • DOI: 10.1109/ISSSE.2012.6374305
  • Odkaz: https://doi.org/10.1109/ISSSE.2012.6374305
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper considers the application of wireless network coding as an alternative to network MIMO on the uplink of hierarchical wireless networks such as wireless access networks with wireless backhaul. We address linear network coding functions to be applied at the relay nodes, and show that the approach can benefit in a similar way to network MIMO from cross links between terminals and relays without increasing backhaul load.

Design and rate regions of network coded modulation for random channel class in WNC with HDF relaying strategy

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A standard NCM (Network Coded Modulation) for WNC (Wireless Network Coding) with HDF (Hierarchical Decode & Forward) strategy requires that each node has full knowledge of the connectivity pattern to other nodes and this knowledge affects the design of NCM and HNC (Hierarchical Network Code) maps at each transmitting (source) and receiving (relay) node respectively. The final destination has to have full knowledge of all HNC maps used and the composite overall HNC map needs to be invertible to recover the source data. This approach collapses if nodes do not have a full knowledge of the connectivity pattern and thus cannot adjust their HNC maps properly. We design the NCM and HNC maps for WNC with HDF strategy that works regardless of this knowledge. It is based on a concept of a channel class which is a discrete (random) parameter describing the channel behavior and which becomes a part of HNC maps and the NCM hierarchical constellation. We analyze the rate regions for this design and compare it to the standard NCM and HNC map solution suffering from random channel outages.

Hierarchical network code mapper design for adaptive relaying in butterfly network

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 3rd MCM Barcelona. Brussels: COST Office, 2012. pp. 1-9.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A majority of the research results on Wireless Network Coding (WNC) considers only a basic 2-Way Relay Channel (2-WRC) system scenario, where the Complementary Side Information (C-SI) is naturally available at both destinations. Although an extension of the WNC principles from the 2-WRC system to the butterfly network could seem relatively straightforward, several new unconventional phenomena of the WNC arise (and need to be considered). First of all, the nonreliable transmission of the C-SI can be overcome by an increased cardinality of the relay output. This opens a question how a suitable Hierarchical Network Code (HNC) mapper could be designed for a given quality of the C-SI link (and source alphabet cardinality). In this paper we focus on this problem. We introduce a systematic approach to the design of a set of HNC mappers, respecting the amount of available C-SI.

Initialization procedure of wireless network coding with hierarchical decode & forward strategy in random connectivity networks

  • Autoři: Hynek, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 5th International Workshop on Multiple Access Communications MACOM 2012. Berlin: Springer, 2012. pp. 13-24. ISSN 0302-9743. ISBN 978-3-642-34975-1.
  • Rok: 2012
  • DOI: 10.1007/978-3-642-34976-8_2
  • Odkaz: https://doi.org/10.1007/978-3-642-34976-8_2
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A Wireless Network Coding (WNC) a.k.a. a Physical Layer Network Coding in multi-source multi-node scenarios has shown its potential to increase network throughput compared to a communication based on an orthogonal separation of individual transmissions. In this paper we analyse necessary steps that have to be done to initialize the WNC communication including mainly establishing of relay operations. In our set-up a core network (we named it a cloud), that provides the WNC capabilities of reliable source -- destination communication, starts its operation with no system state (connectivity) knowledge. Our goal is to design an algorithm that is capable to gain this information directly from the received constellation that is formed by the superposition of unknown number of transmitting sources with random channel realization and provide it to any cloud node. The algorithm has to be designed to work with the minimum demands on source node cooperation, the most of the functionality is laid upon the cloud.

Lattice-constellation indexing for wireless network coding 2-way relaying with modulo-sum relay decoding

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 5th MCM Bristol. Brussels: COST Office, 2012. pp. 1-10.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper, we consider wireless network coding 2-way relaying where both terminals use constellations curved from a common lattice and the relay node decodes modulo-sum operation of transmitted data symbols at the multiple access stage. Performance of such a system in a 2- way relay AWGN channel is strongly determined by used constellation indexing. We show that if a mapping from constellation lattice-coordinates onto constellation indices is modulo-affine (we denote such constellation-indexing as an Affine Indexing (AI)) than minimal distance of modulosum decoding equals to minimal distance of primary lattice-constellations. If constellations are not indexed by AI, the resulting minimal distance is 0 which corresponds to considerable loss in alphabet constrained capacity. Some constellation shapes prevent existence of AI, unfortunately, including desirable sphere-like shapes. We propose sub-optimal greedy-sphere packing algorithm for constellation shape design which maximises minimal distance and keeps existence of AI.

Non-uniform 2-slot constellations for relaying in butterfly network with imperfect side information

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: IEEE Communications Letters. 2012, 16(9), 1369-1372. ISSN 1089-7798.
  • Rok: 2012
  • DOI: 10.1109/LCOMM.2012.071612.121194
  • Odkaz: https://doi.org/10.1109/LCOMM.2012.071612.121194
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Performance of Wireless-Network-Coding-based relaying strategies for 2-Way Relay Channel (2-WRC) could be seriously degraded due to an inherent wireless channel parameterization. Although some techniques dealing with this problem have been already introduced, they are still subject to several drawbacks (including a practical infeasibility of multi-node transmission phase pre-rotation or a sensitivity to channel estimation errors of adaptive solutions). Unfortunately, this detrimental channel parameterization effect endures even when the relay has perfect channel state information available. Based on the analysis of hierarchical minimum distance of source constellation alphabets, in this paper we target this problem from a different way. We propose a design of novel source constellation alphabets, the Non-uniform 2-slot (NuT) alphabets, which are robust to channel parameterization effects. These NuT constellations outperform traditional linear modulation schemes in Hierarchical-Decode-and-Forward and Denoise-and-Forward relaying strategies in Rician channels without sacrificing the overall system throughput.

Non-uniform 2-slot constellations: Design algorithm and 2-way relay channel performance

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST IC1004 4th MCM Lyon. Brussels: COST Office, 2012. pp. 1-7.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Performance of Wireless-Network-Coding-based relaying strategies for 2-Way Relay Channel (2-WRC) could be seriously degraded due to an inherent wireless channel parameterization. Although some techniques dealing with this problem have been already introduced, they are still subject to several drawbacks (including a practical infeasibility of multi-node transmission phase pre-rotation or a sensitivity to channel estimation errors of adaptive solutions). Unfortunately, this detrimental channel parameterization effect endures even when the relay has perfect channel state information available. Based on the analysis of hierarchical minimum distance of source constellation alphabets, in this paper we target this problem from a different way. We propose a design of novel source constellation alphabets, the Non-uniform 2-slot (NuT) alphabets, which are robust to channel parameterization effects. These NuT constellations outperform traditional linear modulation schemes in Hierarchical-Decode-and-Forward and Denoise-and-Forward relaying strategies in Rician channels without sacrificing the overall system throughput.

Optimised Constellation Prerotation for 3-Terminal 1-Relay Network with Wireless Network Coding

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: IEEE Communications Letters. 2012, 16(8), 1200-1203. ISSN 1089-7798.
  • Rok: 2012
  • DOI: 10.1109/LCOMM.2012.060812.120427
  • Odkaz: https://doi.org/10.1109/LCOMM.2012.060812.120427
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Wireless (Physical-Layer) Network Coding (WNC) is an interference harnessing physical-layer concept combining network coding principles and broadcast nature of the wireless medium. Significant capacity gains of WNC were shown in a wireless 2-Way Relay Channel (2-WRC). Extension of WNC to more complicated network topologies potentially offers even larger gains than in the 2-WRC. However, such an extension is generally non-trivial. In this paper, we show that it is feasible to achieve additional considerable capacity gains in comparison to bidirectional relaying approach in a three-terminal onerelay network. We focus on the constellation design for its uplink (Multiple Access Channel (MAC) stage). The throughput maximisation is achieved by an optimised prerotation of source constellations, effectively reducing a number of required MAC stages.

Suppression of relative-fading by diversity reception in wireless network coding 2-way relaying

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We identify two distinct sources of fading significantly degrading performance of coherent Wireless Network Coding (WNC) in a wireless 2-way relay channel: absolute-fading and relativefading. Absolute-fading corresponds to a standard small-scale fading of a wireless point-to-point channel when absolute values of channel parameters are insufficiently strong. Relative-fading is a unique paradigm of WNC occurring when a ratio of channel parameters is close to certain critical values. In this paper, we show that diversity reception techniques (essential to restrain absolute-fading) significantly suppresses relative-fading as well. We measure the impact of relative-fading on uncoded error performance and ergodic alphabet constrained capacity of representative QPSK alphabet in wireless Rayleigh/Rice channel. We conclude that relativefading is sufficiently suppressed by systems with a reasonable level of diversity which is typically assumed if only absolute-fading is present.

Systematic Design of Hierarchical Network Code Mapper for Butterfly Network Relaying

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 18th European Wireless Conference - EW 2012. Berlin: VDE Verlag, 2012. pp. 1-8. ISBN 978-3-8008-3426-9.
  • Rok: 2012
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A majority of the research results on Wireless Network Coding (WNC) considers only a basic 2-Way Relay Channel (2-WRC) system scenario, where the Complementary Side Information (C-SI) is naturally available at both destinations. Although an extension of the WNC principles from the 2-WRC system to the butterfly network could seem relatively straightforward, several new unconventional phenomena of the WNC arise (and need to be considered). First of all, the unreliable transmission of the C-SI can be overcome by an increased cardinality of the relay output. This opens a question how a suitable Hierarchical Network Code (HNC) mapper could be designed for a given quality of the C-SI link (and source alphabet cardinality). In this paper we focus on this problem. We introduce a systematic approach to the design of a set of HNC mappers, respecting the amount of available C-SI. Observed capacity gains of this (extended cardinality) relaying pave the way for an adaptive butterfly network, where the achievable throughput can be maximized by a suitable choice of the HNC map at the relay.

Two-mode limited feedback block-fading adaptive transmission with minimum guaranteed rate in MIMO channel

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Wireless Communications and Mobile Computing. 2012, 12(4), 352-366. ISSN 1530-8669.
  • Rok: 2012
  • DOI: 10.1002/wcm.968
  • Odkaz: https://doi.org/10.1002/wcm.968
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper develops an adaptive scheme relying on a part-time availability of the channel state information and supplying the constant minimum rate achievable for an arbitrary fading realization. The two-mode transmission is investigated with the instantaneous perfect channel state information being known at the transmitter in the limited portion of time. We derived a general procedure for a suitable probabilistic description of the channel under such a scheme. The first mode is without any feedback and it uses a simple uniform symbol energy assignment. The second one is the emergency mode with the perfect instantaneous channel state information. It is implemented by the channel inversion (or eigenmode sub-space channel inversion) guaranteeing the minimum required rate regardless of the channel observation.

Wireless network coding initialization procedure through multi-source automatic modulation classification in random connectivity networks

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In recent years a Wireless Network Coding (WNC) a.k.a. a Physical Layer Network Coding in multi-source multi-node scenarios has shown its potential to increase communication performance compared to a communication based on orthogonally separated users. This paper focuses on steps that have to be done before the WNC communication can begin. Within those steps especially relay network coding operation plays important role. In proposed set-up a core network (we named it a cloud), that provides the WNC capabilities of reliable source -- destination communication, starts its operation with no system state (connectivity) knowledge. The goal of this paper is to design a blind algorithm that is capable to gain network topology information directly from the received signal that is formed by the superposition of unknown number of transmitting sources with random channel realization. The algorithm is proposed to work with the minimum demands on source node cooperation. This set-up is well suited for ad-hoc communication networks.

A flexible Hardware-In-the-Loop test platform for physical resource sharing mechanisms in wireless networks

  • Autoři: Luo, J., Kortke, K., Keusgen, K., Li, L., Haardt, H., Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Future Network and MobileSummit 2011 Conference Proceedings. Dublin: IIMC International Information Management Corporation Ltd, 2011. pp. 1-8. ISBN 978-1-905824-23-6.
  • Rok: 2011
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Currently, a lot of research is being done to develop physical resource sharing mechanisms in wireless networks. These mechanisms are expected to enhance spectral efficiency, coverage, user satisfaction and operator revenue. In order to prove the feasibility of these mechanisms or to identify practical problems for mechanism optimization, a Hardware-in-The-Loop (HIL) test platform has been developed. This platform consists of multiple broadband wireless experimental devices and can be flexibly configured, allowing extensive signal transmission experiments. Furthermore, different transmission modes of the Radio-Frequency (RF) signals are available, allowing a variety of mechanism evaluation possibilities. Based on this platform, physical resource sharing mechanisms can be efficiently implemented and tested. First test results are shown in this paper

Capacity Regions of Wireless Network Coding with Hierarchical Decode & Forward Strategy Applied on Impulse Radio UWB Technology

  • Autoři: Hynek, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2011 IEEE International Conference on Ultra-Wideband. Piscataway: IEEE, 2011. pp. 298-302. ISSN 2162-6588. ISBN 978-1-4577-1764-2.
  • Rok: 2011
  • DOI: 10.1109/ICUWB.2011.6058849
  • Odkaz: https://doi.org/10.1109/ICUWB.2011.6058849
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses a cooperative communication scheme in a simple multi-node network of two mutually independent sources communicating over a common shared relay. We assume an Impulse Radio Ultra-Wideband (UWB) communication technique employed by all network nodes which influences used model of a channel impulse response. The signal received at the relay is processed by a Hierarchical Decode & Forward (HDF) strategy. Due to properties of a Hierarchical eXclusive Code (HXC) it is sufficient for the relay to fully decode only hierarchical symbols. The capacity region of the HDF strategy has a rectangular shape and exceeds the capacity region of a Joint Decode & Forward (JDF) concept. We assume a projection to given subspace at the input of the relay receiver to reduce the dimensionality of the signal. Impact of the choice of the subspace is analyzed in this paper. Various subspaces with different level of the knowledge of a Channel State Estimation (CSE) are considered.

Cooperative Communication in Wireless Relay Networks

  • Autoři: Hekrdla, M., Uřičář, T., Procházka, P., Mašek, M., Hynek, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Workshop 2011. Praha: České vysoké učení technické v Praze, 2011. pp. 1-18.
  • Rok: 2011
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The communication strategies based on the principles of network coding and relaying possess a great potential to increase data throughput in the future wireless mobile networks. Idea of hierarchical data processing was introduced in the Hierarchical Decode and Forward (HDF) strategy. A sophisticated design of modulation/coding for HDF is necessary to avoid detrimental effects of wireless channel parameterization. Extension of the HDF principle to the perspective Ultra-Wide Band (UWB) systems was also found to be non-trivial. A stand-alone research area is represented by the issues related to the cooperative relay/destination processing. In this paper we introduce an example of latency-reducing Compress and Forward (CF) strategy and a systematic design of continuous message representation for Sum-Product Algorithm on Factor Graphs (FG), suitable for an iterative receiver in a general multi-node network.

Design of Uniformly Most Powerful Alphabets for HDF 2-Way Relaying Employing Non-Linear Frequency Modulations

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: EURASIP Journal on Wireless Communications and Networking. 2011, 2011 1-18. ISSN 1687-1499.
  • Rok: 2011
  • DOI: 10.1186/1687-1499-2011-128
  • Odkaz: https://doi.org/10.1186/1687-1499-2011-128
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Hierarchical-Decode-and-Forward (HDF) is a promising wireless-network-coding-based 2-way relaying strategy due to its potential to operate outside the classical multiple access capacity region. Assuming a practical scenario with channel state information at the receiver and no channel adaptation, there exist modulations and exclusive codes for which even non-zero channel parameters (denoted as catastrophic) cause zero hierarchical minimal distance - significantly degrading its performance. In this work, we state that non-binary linear alphabets cannot avoid these parameters and some exclusive codes even imply them; contrary XOR does not. We define alphabets avoiding all catastrophic parameters and reaching its upper-bound on minimal distance for all parameter values (denoted Uniformly Most Powerful (UMP)). We find that binary, non-binary orthogonal and bi-orthogonal modulations are UMP.

Extended Mappings for Wireless Network Coded Butterfly Network

  • Autoři: Burr, A., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of European Wireless Conference 2011. Berlin: VDE VERLAG GMBH Berlin, 2011. pp. 240-246. ISBN 978-3-8007-3343-9.
  • Rok: 2011
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We consider the application of wireless network coding to a "butterfly" wireless network, comprising two sources and two destinations sharing a single relay. We obtain upper bounds on the end to end capacity of the network in terms of the codebook cardinalities, allowing the use of an extended rather than a minimal hierarchical mapping at the relay and assuming that partial complementary side information is available at each destination directly from its complementary source. We further show that this bound may be achieved using a linear mapping at the relay. We obtain numerical results for the mutual information on the links of the network, and hence show that the extended mapping may provide increased capacity compared to the minimal for some values of channel fading parameters.

Hierarchical Decode & Forward Strategy in IR-UWB Communication Systems

  • Autoři: Hynek, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Future Network and MobileSummit 2011 Conference Proceedings. Dublin: IIMC International Information Management Corporation Ltd, 2011. pp. 1-8. ISBN 978-1-905824-23-6.
  • Rok: 2011
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper investigates multinode networks based on a Ultra Wideband (UWB) technology. The presence of several simultaneously communicating nodes in the network is not handled by ``classical'' -- orthogonal separation -- methods but is based on a novel approach based on information theory. Relay nodes inside the network utilize Hierarchical Decode & Forward (HDF) strategy which is promising to substantially increase the overall throughput of the network. We develop a coding scheme which is aware of the surrounding network structure hence multiuser interferences can be handled in codebooks design procedure. Performance of the proposed coding schemes is verified on the simplest multinode network topologies. A channel capacity was chosen as the performance metric. The capacity is numerically evaluated for real UWB propagation behavior simulated by appropriate channel models.

Layered Design of Hierarchical Exclusive Codebook and Its Capacity Regions for HDF Strategy in Parametric Wireless 2-WRC

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.
  • Publikace: IEEE Transactions on Vehicular Technology. 2011, 60(7), 3241-3252. ISSN 0018-9545.
  • Rok: 2011
  • DOI: 10.1109/TVT.2011.2160105
  • Odkaz: https://doi.org/10.1109/TVT.2011.2160105
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper addresses a hierarchical decode-and-forward (HDF) strategy in the wireless two-way relay channel (2-WRC). This strategy uses a Hierarchical eXclusive Code (HXC) that allows full decoding of the hierarchical symbols at the relay. The HXC represents two data sources only through the exclusive law and requires side information on the complementary data at the destination (which naturally holds for the 2-WRC). The HDF strategy has the advantage over classical medium-access control (MAC) stage relaying with joint decoding in that its rate region extends beyond the classical MAC region. We present a layered design of the HXC codebook, which uses an arbitrary outer state-of-the-art capacity-approaching code [e.g., low density parity check (LDPC)] and an inner layer with an exclusive symbol alphabet. We provide basic theorems, showing that this scheme forms an HXC, and we also evaluate its alphabet-constrained rate regions.

Linear diversity precoding design criterion for finite block-fading parallel MIMO channels

  • Autoři: prof. Ing. Jan Sýkora, CSc., Kníže, M.
  • Publikace: Wireless Communications and Mobile Computing. 2011, 11(11), 1463-1472. ISSN 1530-8669.
  • Rok: 2011
  • DOI: 10.1002/wcm.943
  • Odkaz: https://doi.org/10.1002/wcm.943
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A novel optimal two stage coding for finite set of parallel flat-fading MIMO channels with single common information source with specific constant rate requirement is derived. The optimality of suggested coding is achieved in terms of the capacity versus outage performance. The well-known optimal coding rule relies on Gaussian codewords spanned over the whole available finite set of parallel channels. We prove that the equivalent preprocessing to the ideal interleaving is to re-code independent parallel channels codewords by a linear inner precoder from a special class of unitary precoders complying with the optimality criterion derived in the paper. Performing such linear mixture of codewords sharing common Gaussian block-wise codebook, the same capacity versus the outage is guaranteed without any interleaving over parallel channels.We utilize a virtual multiple access (VMA) channel approach to derive the optimality criterion.

Network Coded Modulation with HDF Strategy and Optimized Beam-Forming in 2-Source 2-Relay Network

  • Autoři: prof. Ing. Jan Sýkora, CSc., Jorswieck, E. A.
  • Publikace: 2011 IEEE 74th Vehicular Technology Conference (VTC Fall) Proceedings. Piscataway: IEEE, 2011. pp. 1-6. ISSN 1550-2252. ISBN 978-1-4244-8327-3.
  • Rok: 2011
  • DOI: 10.1109/VETECF.2011.6093013
  • Odkaz: https://doi.org/10.1109/VETECF.2011.6093013
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper address the Network Coded Modulation (NCM) with Hierarchical Decode and Forward (HDF) strategy in the 2-source 2-relay scenario with SIMO (Single-Input Multiple-Output) fading channels. The NCM/HDF technique is known to be vulnerable to the mutual phase rotations of the signals from the sources. We use additional degrees of freedom in SIMO channels and create a specific receiver beam-forming tailored for given NCM/HDF strategy. We derive a closed form solution of the NCM/HDF specific beam-former and apply it on example NCMs. We evaluate the performance in terms of the mean and the outage hierarchical rates. It is shown that these rates significantly benefit from the beam-forming and that the resulting rate significantly outperforms classical (non WNC (Wireless Network Coding)) channel sharing techniques.

Non-Uniform 2-Slot Constellations for Bidirectional Relaying in Fading Channels

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: IEEE Communications Letters. 2011, 15(8), 795-797. ISSN 1089-7798.
  • Rok: 2011
  • DOI: 10.1109/LCOMM.2011.060811.110962
  • Odkaz: https://doi.org/10.1109/LCOMM.2011.060811.110962
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper we introduce the constellation alphabets suitable for bidirectional relaying in parametric wireless channels. Based on the analysis of hierarchical minimum distance, we present a simple design algorithm for the non-uniform 2-slot constellation alphabets. These novel constellation alphabets outperform traditional linear modulation schemes in Hierarchical-Decode-and-Forward and Denoise-and-Forward relaying strategies in fading channels without sacrificing the overall system throughput.

Optimized Beam-Forming and Achievable Rates of Network Coded Modulation with HDF Strategy in 2-Source 2-Relay Network

  • Autoři: prof. Ing. Jan Sýkora, CSc., Jorswieck, E. A.
  • Publikace: COST IC1004 - 1st Scientific Meeting. Brussels: COST Office, 2011. pp. 1-7.
  • Rok: 2011
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper address the Network Coded Modulation (NCM) with Hierarchical Decode and Forward (HDF) strategy in the 2‐source 2‐relay scenario with SIMO fading channels. The NCM/HDF technique is known to be vulnerable to the mutual phase rotations of the signals from the sources. We use additional degrees of freedom in SIMO channels and create a specific receiver beam‐forming tailored for given NCM/HDF strategy. We derive a closed form solution of the NCM/HDF specific beamformer and apply it on example NCMs. We evaluate the performance in terms of the mean and the outage hierarchical rates. It is shown that these rates significantly benefit from the beamforming and that the resulting rate significantly outperforms classical (non WNC) channel sharing techniques.

Symbol-Wise Processing Implementation of Semi-Iterative Turbo Principle in Multi-Hop Relay Networks

  • Autoři: Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 19th European Signal Processing Conference (EUSIPCO 2011). Herent: EURASIP, 2011. pp. 186-190. ISSN 2219-5491.
  • Rok: 2011
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The latency presents one of the major problem in communication systems. The seriousness increases in more complex physical scenarios, where the latency is accumulated in sequent nodes. We propose a novel concept of a latency re- duced distributed iterative decoder design in a multi-node wireless network. The concept is based on the traditional turbo decoder, where we exploit the topology of the network to decompose the iterative decoder among more physically separated nodes. In this concept, the relay-part of the decoder computes symbol-wisely a soft metric, which is then transmitted through a wireless link into the destination-part of the decoder. The iterative process in the destination-part of the decoder has therefore only limited capabilities for it- erations via the relay-part of the decoder. We formulate an optimization task for the proposed concept, design an initial (add-hoc) decoder decomposition and evaluate its properties.

Uniformly Most Powerful Alphabet for HDF Two-Way Relaying Designed by Non-linear Optimization Tools

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: 2011 8th International Symposium on Wireless Communication Systems. Aachen: RWTH Aachen University, 2011. pp. 594-598. ISSN 2154-0217. ISBN 978-1-61284-401-5.
  • Rok: 2011
  • DOI: 10.1109/ISWCS.2011.6125425
  • Odkaz: https://doi.org/10.1109/ISWCS.2011.6125425
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Hierarchical-Decode-and-Forward (HDF) strategy, representing wireless/physical-layer network coding, is a promising 2-way relay strategy due to its potential to operate outside the classical multiple access capacity region. We consider a practical scenario assuming channel state information at the receiver side and no channel-adaptation, then HDF performance is unavoidably parametrized by channel fading coefficients. While some modulations have hierarchical minimal distance reaching its upper-bound for all parameter values (e.g. BPSK), some other modulations have the distance much lower (e.g. QPSK), which appears as it undergoes considerably stronger fading. Design of modulations with performance similar to BPSK (denoted Uniformly Most Powerful (UMP)) have already been investigated restricting on non-linear frequency modulations. In this paper, we formulate UMP alphabet design as a bi-quadratically-constrained linear-program on which non-linear optimization methods are applied.

Channel Parameter Invariant Network Coded FSK Modulation for Hierarchical Decode and Forward Strategy in Wireless 2-Way Relay Channel

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 2100 - 11th MCM Aalborg. Brussels: COST Office, 2010. pp. 1-8.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper presents channel parameter invariant network coded FSK modulation for hierarchical decode and forward strategy in wireless 2-way relay channel.

Design Criteria for Hierarchical Exclusive Code with Parameter-Invariant Decision Regions for Wireless 2-Way Relay Channel

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: EURASIP Journal on Wireless Communications and Networking. 2010, 2010(si9), 1-14. ISSN 1687-1499.
  • Rok: 2010
  • DOI: 10.1155/2010/921427
  • Odkaz: https://doi.org/10.1155/2010/921427
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The unavoidable parametrization of the wireless link represents a major problem of the network-coded modulation synthesis in a 2-way relay channel. Composite (hierarchical) codeword received at the relay is generally parametrized by the channel gain, forcing any processing on the relay to be dependent on channel parameters. In this paper, we introduce the codebook design criteria, which ensure that all permissible hierarchical codewords have decision regions invariant to the channel parameters as seen by the relay). We utilize the criterion for parameter-invariant constellation space boundary to obtain the codebooks with channel parameter-invariant decision regions at the relay. Since the requirements on such codebooks are relatively strict, the construction of higher-order codebooks will require a slightly simplified design criteria.

Example Design of Multi-Dimensional Parameter-Invariant Hierarchical Exclusive Alphabet for Layered HXC Design in 2-WRC

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc., Hekrdla, M.
  • Publikace: COST 2100 - 10th MCM Athens. Brussels: COST Office, 2010. pp. 1-8.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper we propose a new design method, which request only the HDM itself to be invariant to channel parametrization (contrary to E-PHXC). The example HXA design based on this new approach have the hierarchicalMAC capacity region extended beyond the classicalMAC region regardless to the channel parametrization.

Hierarchical Alphabet and Parametric Channel Constrained Capacity Regions for HDF Strategy in Parametric Wireless 2-WRC

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.
  • Publikace: Proceedings of IEEE Wireless Communications and Networking Conference. Piscataway: IEEE, 2010. pp. 1-6. ISSN 1525-3511. ISBN 978-1-4244-6398-5.
  • Rok: 2010
  • DOI: 10.1109/WCNC.2010.5506416
  • Odkaz: https://doi.org/10.1109/WCNC.2010.5506416
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses wireless the 2-Way Relay Channel (2-WRC) system with a Hierarchical Decode and Forward strategy. This strategy uses a Hierarchical eXclusive Code (HXC) that allows full decoding of the hierarchical symbols at the relay. The HXC represents two data sources only through the exclusive law and requires side information on the complementary data at the destination (which naturally holds for the 2-WRC). The HDF strategy has the advantage over classical MAC stage relaying with joint decoding that its rate region extends beyond the classical MAC region. We evaluate the hierarchical MAC capacity regions for various alphabets, constellation point indexing and various channel parametrization and compare that to the alphabet limited and unconstrained cut-set bounds.

Hierarchical eXclusive Alphabet in Parametric 2-WRC - Euclidean Distance Analysis and Alphabet Construction Algorithm

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 2100 - 11th MCM Aalborg. Brussels: COST Office, 2010. pp. 1-9.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper, we introduce the euclidean distance analysis and alphabet construction algorithm for hierarchical exclusive alphabet in parametric 2-WRC.

Karhunen-Loeve-Based Reduced-Complexity Representation of the Mixed-Density Messages in SPA on Factor Graph and Its Impact on BER

  • Autoři: Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: EURASIP Journal on Wireless Communications and Networking. 2010, 2010 1-11. ISSN 1687-1499.
  • Rok: 2010
  • DOI: 10.1155/2010/574607
  • Odkaz: https://doi.org/10.1155/2010/574607
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The sum product algorithm on factor graphs (FG/SPA) is a widely used tool to solve various problems in a wide area of fields. A representation of generally-shaped continuously valued messages in the FG/SPA is commonly solved by a proper parameterization of the messages. Obtaining such a proper parameterization is, however, a crucial problem in general. The paper introduces a systematic procedure for obtaining a scalar message representation with well-defined fidelity criterion in a general FG/SPA. The procedure utilizes a stochastic nature of the messages as they evolve during the FG/SPA processing. A Karhunen-Loeve Transform (KLT) is used to find a generic canonical message representation which exploits the message stochastic behavior with mean square error (MSE) fidelity criterion. We demonstrate the procedure on a range of scenarios including mixture-messages (a digital modulation in phase parametric channel).

Network Coded Modulation with partial side-information and hierarchical decode and forward relay sharing in multi-source wireless network

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.
  • Publikace: Proceedings of European Wireless Conference. Piscataway: IEEE, 2010. pp. 639-645. ISBN 978-1-4244-5999-5.
  • Rok: 2010
  • DOI: 10.1109/EW.2010.5483476
  • Odkaz: https://doi.org/10.1109/EW.2010.5483476
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We present a strategy for the relay sharing in the 2-source relay wireless network with the hierarchical decode and forward relaying. It processes both incoming coded symbols through the minimal hierarchical symbol mapping of the same cardinality as the two individual symbol streams and requires a full (perfect) Complementary Side-Information (C-SI) on the other stream available at the destination. This scheme is known to have an advantage in a rectangular shape capacity region which provides higher sum-capacity than the classical MAC. We investigate the capacity region of the case where the destination has only partial C-SI available through a wireless link. We conclude that the overall finite alphabet constrained capacity region including both MAC and BC phase remains rectangular.

Per-symbol representation of sufficient statistics for FSM decoder metric used in BC phase of 2WRC with HDF strategy

  • Autoři: Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 2100 - 10th MCM Athens. Brussels: COST Office, 2010. pp. 1-8.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We introduce a novel special class of Per-Symbol Decoding Metric Sufficient Statistics (PSyDMSS) for an arbitrary FSM.We call the proposed class a Surviving Set (SuS). The PSyDMSS is usable with advantage in all distributed broadcasting systems including the 2-Way Relay Channel (2-WRC) with HDF strategy. The PSyDMSS allows the symbol-wise processing of the coded sequence instead of the full hierarchical decoding at the relay. The latency of the transmission from the source to the destination might be thus considerably decreased. We evaluate the per-symbol metric representation entropy of SuS to consider the possibility of the source coding in relay. The entropy of the SuS is a crucial measure for the potential efficiency of the BC-phase per-symbol forwarding. We thus outline some possible ways to minimize the entropy and show one optimum entropy-achieving model situated in 2-WRC with HDF strategy.

Physical Network Coding with Partial Side-Information and Hierarchical Decode and Forward Relay Sharing in Multi-Source Wireless Network

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We present a strategy for the relay sharing in the 2-source relay wireless network with the hierarchical decode and forward relaying. It processes both incoming coded symbols through the minimal hierarchical symbol mapping of the same cardinality as the two individual symbol streams and requires a full (perfect) Complementary Side-Information (C-SI) on the other stream available at the destination. This scheme is known to have an advantage in a rectangular shape capacity region which provides higher sum-capacity than the classical MAC. We investigate the capacity region of the case where the destination has only partial CSI available through a wireless link. We conclude that the overall finite alphabet constrained capacity region including both MAC and BC phase remains rectangular. The BC phase region is limited by the C-SI link capacity and we conjecture that it obeys the capacity product law of the individual relay to destination and C-SI links.

Resource sharing in wireless networks: The SAPHYRE approach

  • Autoři: Jorswieck, E.A., Badia, L., Fahldieck, T., Gesbert, D., Gustafsson, S., Haardt, M., Ho, K.M., Karipidis, E., Kortke, A., Larsson, E.G., Mark, H., Nawrocki, M., Piesiewicz, R., Römer, F., Schubert, M., prof. Ing. Jan Sýkora, CSc., Trommelen, P., Van Ende, B.D., Zorzi, M.
  • Publikace: Future Network & MobileSummit 2010 Conference Proceedings. Dublin: IIMC International Information Management Corporation Ltd, 2010. pp. 1-8. ISBN 978-1-905824-18-2.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Physical resource sharing between wireless operators and service providers is necessary in order to support efficient, competitive, and innovative wireless communication markets. By sharing resources, such as spectrum or infrastructure, which are usually exclusively allocated interference is created on the physical layer. Therefore, the economic gains, regulatory overhead, and engineering efforts need to be addressed by a consolidated cross-layer approach. This paper describes briefly the approach taken by the EU FP7 project SAPHYRE.

Wireless network coding

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.
  • Publikace: Invited research talk. London: Imperial College Press, 2010. pp. 1-140.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    It is becoming widely accepted that the most significant future developments in the physical layer of wireless communication systems will not take place in the PHY layer of individual communication links, but rather in the context of complete wireless networks. Over the past decade or so there have been significant developments in network information theory which have shown that very significant overall performance gains are available compared to the conventional paradigm in which PHY techniques are applied to individual links only, leaving network aspects to be dealt with only at higher layers of the protocol stack.

Wireless network coding: the network aware PHY layer

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.
  • Publikace: Proceedings of the Seventh International Symposium on Wireless Communication Systems - Tutorials. York: University of York, 2010. pp. 1-128.
  • Rok: 2010
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    One such new research field is network coding, in which coding techniques are applied to multiple data streams at intermediate nodes in a network, rather than only to individual streams on single links. This can exploit network topology to significantly improve throughput in multiuser networks. However in its original form it operates at the level of data streams, rather than signal waveforms, and hence is not well suited to the inherently broadcast nature of wireless networks. Physical layer or wireless network coding (WNC)allows it to be applied directly to wireless networks, with a further significant improvement in efficiency. The key advance on conventional PHY techniques is that both signalling waveforms and node signal processing is aware of the network topology and exploits it to improve overall network throughput.

CPM Constellation Subspace Projection Maximizing Average Minimal Distance - Sufficiency Condition and Comparison to PC Analysis

  • Autoři: Hekrdla, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 2100 - 8th MCM Valencia. Brussels: COST Office, 2009. pp. 1-8.
  • Rok: 2009
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We consider the problem of optimal low-dimensional approximation of generally high multidimensional CPM signal. The optimal receiver must perform a multidimensional matched filtering (MF) on its front-end to provide sufficient statistics. This operation is highly demanding on the processing computational resources and increase the overall receiver complexity. We focus on the optimal arbitrary dimensional constellation subspace with the lowest degradation performance of bit-error-rate (BER) measure. It is well tight with the minimum Euclidean distance for medium to high signal-to-noise ratio (SNR).

Design Criteria for Parametric Hierarchical Exclusive Constellation Space Code for Wireless 2-Way Relay Channel

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A hierarchical exlusive code allows us to design the 2-way relay channel communication where the destination uses the knowledge of its own data to create source-relaydestination link working as if there was no other link. It uses similar principles as the network coding for discrete alphabet channels. The wireless communication links are unavodably parametric (e.g. the complex channel gain). Generally, the composite codeword received in relay is parametrized by channel gains. The decoding or any other processing on the relay is thus dependent on the channel parameters. This significantly affects the codeword (as visible by relay) structure and properties. We present the source node codebook design that the received codeword at relay have structure (decision regions) invariant to the channel parameters. The relay can then perform the decoding over the composite codeword regardless of the channel parameters.

Determinant Criterion Optimizing Linear Subspace Projector for Burst Orthogonal STC CPM Modulation in MIMO Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc., Hekrdla, M.
  • Publikace: IEEE 69th Vehicular Technology Conference (VTC 2009-Spring). Piscataway: IEEE, 2009. pp. 846-851. ISSN 1550-2252. ISBN 978-1-4244-2516-7.
  • Rok: 2009
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We consider a general burst block orthogonal space- time coded CPM modulation in MIMO slowly fading Rayleigh channel. The modulated signal has multidimensional constellation waveforms. The optimal receiver must perform a multidimensional matched filtering on its front-end. This operation is highly demanding on the processing computational resources. We derive sub-optimal complexity reducing receiver linear preprocessor which reduces the dimensionality of the signal. We analytically derive the optimal linear projector matrix for several cases of the free trellis path and its termination.

Extended Design Criteria for Hierarchical Exclusive Code with Pairwise Parameter-Invariant Boundaries for Wireless 2-Way Relay Channel

  • Autoři: Uřičář, T., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 2100 - 9th MCM Wien. Brussels: COST Office, 2009. pp. 1-8.
  • Rok: 2009
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The unavoidable parametrization of the wireless link represents a major problem of the network coded modulation synthesis in a 2-way relay channel. Composite codeword received at the relay is generally parametrized by the channel gains, forcing any processing on the relay to be dependent on the channel parameters. Design criteria for parametric hierarchical exclusive code (PHXC) introduce a set of conditions for terminal (individual) codebook selection, which guarantees that the received composite codeword at the relay has the structure invariant to the channel parameters. Although this requirement could be relatively strict, it allows us to express the design criteria in a compact se t of required conditions. We present this extended criteria for the parametric hierarchical exclusive codebook design and show that all requirements of the extended design criteria can be satisfied at once only if the terminals use different individual codebooks.

Hierarchical Exclusive Codebook Design Using Exclusive Alphabet and its Capacity Regions for HDF Strategy in Parametric Wireless 2-WRC

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses a Hierarchical Decode and Forward strategy in the wireless 2-Way Relay Channel (2-WRC). This strategy uses Hierarchical eXclusive Code (HXC) that allows full decoding of the hierarchical symbol at the relay. The HXC represents two data sources only through the exclusive law and requires side information on the complementary data at the destination (which naturally holds for 2-WRC). There is an advantage of the HDF strategy over the classical MAC stage relaying with joint decoding. It's rate region can go outside the classical MAC region. We present a layered design of the HXC codebook which uses an outer arbitrary state-of-the-art capacity approaching code (e.g. LDPC) and an inner layer with exclusive symbol alphabet. We provide basic theorems showing that this scheme forms a HXC and we also evaluate its alphabet constrained rate regions.

Karhunen-Loeve based reduced-complexity representation of the mixed-density messages in SPA on Factor Graph

  • Autoři: Procházka, P., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 2100 - 9th MCM Wien. Brussels: COST Office, 2009. pp. 1-6.
  • Rok: 2009
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses a stochastic analysis of the messages in sum-product algorithm on factor graphs. The Karhunen Lo`eve Transform is used as a tool for systematic synthesis of a canonical representation of the mixed-density messages on FG-SPA. Finally, an impact of an imperfectly transformed message to BER is investigated in a concrete FG-SPA containing the mixture densities.

Space-Waveform Coded CPFSK with Full Rank Optimized Waveforms

  • Autoři: prof. Ing. Jan Sýkora, CSc., Anis, K.
  • Publikace: COST 2100 - 7th MCM Braunschweig. Brussels: COST Office, 2009. pp. 1-6.
  • Rok: 2009
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A nonlinear modulation, the constant envelope CPM class being of particular interest, has multi-dimensional signal waveforms. We introduce a spatial code for multi-antenna CPFSK system using a different waveform (constellation) space on each antenna. The 2-dimensional space-waveform codeword spans an antenna (spatial) and constellation (waveform) dimensions. We optimize the waveforms for rank and determinant criterion. The resulting space-waveform code exhibits a full rank without any need of temporal domain encoding. Numerical results are presented for a selected set of CPFSK class of signals and 2- antenna transmitter. In this particular case, the procedure leads to an elegant implementation by SpatiallyMirrored Tilted Phase CPFSK. The presented scheme is well suited for the concatenation with outer scalar temporal domain code.

Spatially Irregular Space-Waveform Coded CPFSK with Full Rank Optimized Waveforms

  • Autoři: prof. Ing. Jan Sýkora, CSc., Anis, K.
  • Publikace: Proceedings of the IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications. Piscataway: IEEE, 2009. pp. 152-156. ISBN 978-1-4244-5123-4.
  • Rok: 2009
  • DOI: 10.1109/PIMRC.2009.5450263
  • Odkaz: https://doi.org/10.1109/PIMRC.2009.5450263
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A nonlinear modulation, the constant envelope CPM class being of particular interest, has multi-dimensional signal waveforms.We introduce a spatial code for multi-antenna CPFSK system using a different waveform (constellation) space on each antenna. The 2-dimensional space-waveform codeword spans an antenna (spatial) and constellation (waveform) domains. We optimize the waveforms for rank and determinant criterion. The resulting space-waveform code exhibits a full rank without any need of temporal domain encoding. Numerical results are presented for a selected set of CPFSK class of signals and 2-antenna transmitter. In this particular case, the procedure leads to an elegant implementation by Spatially Mirrored Tilted Phase CPFSK. The presented scheme is well suited for the concatenation with outer scalar temporal domain code.

Determinant Maximizing and Rank Preserving Waveform Subspace Linear Projector for Burst Alamouti STC MSK Modulation

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We consider burst block Alamouti space-time coded MSK modulation in MIMO slowly fading Rayleigh channel. The modulated signal has multidimensional constellation waveforms. The optimal receiver must perform a multidimensional matched filtering on its front-end. This operation is highly demanding on the processing computational resources. We derive sub-optimal complexity reducing receiver linear preprocessor which reduces the dimensionality of the signal. We analytically derive the optimal linear projector matrix for several cases of the free trellis path and its termination. We apply the procedure for a particular case of one-dimensional subspace projector applied on a MSK modulation as a special case of CPM modulation.

Error Rate Performance of the Factor Graph Phase Space CPM Iterative Decoder with Modulo Mean Canonical Messages

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses the CPM class of the modulation passing through the parametric channel with the factor graph decoding inherently coping with the channel parameter. The combination of the discrete channel symbols with continuous valued channel parameter leads generally to complex mixture densities difficult to cope in the sum-product algorithm message updates in the factor graph. We attack the problem by, first, performing the factor graph operations in phasespace domain, and, second, by defining proper canonical densities described by a limited set of parameters. We derive proper factor and variable node update rules respecting the modulo 2*pi nature of the phase operations. We evaluate the error rate performance and compare it against the brute-force marginalization rules.

Multiplexing Precoding Scheme for STC-CPM with Parametric Phase Discriminator IWM Receiver

  • Autoři: prof. Ing. Jan Sýkora, CSc., Schober, R.
  • Publikace: Proceedings of the IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications. Piscataway: IEEE, 2008. pp. 1791-1796. ISBN 978-1-4244-2643-0.
  • Rok: 2008
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A constant envelope Continuous Phase Modulation (CPM) class of Multi-Channel (MC) modulations for multiantenna transmitters is considered. Each receive antenna receives a superposition of CPM waveforms. The useful signal at the receiver spans a curved space - the Information Waveform Manifold (IWM). Particularly it has the form of a cylinder on a cylinder for 2-component CPM signals. At the receiver, we use a nonlinear preprocessor consisting of a nonlinear projector on the IWM, optional processing on the curved space, and a decoding isomorphism. A particular form of the preprocessor, the 2-component IWM phase discriminator, is analyzed. We show that the discriminator can separate individual instantaneous phases of the component CPM modulations and therefore has multiplexing capabilities with respect to the individual transmitted components.

Performance Evaluation of the Factor Graph CPM Phase Discriminator Decoder with Canonical Messages and Modulo Mean Updates

  • Autoři: prof. Ing. Jan Sýkora, CSc., Procházka, P.
  • Publikace: Proceedings of the IEEE 14th Asia-Pacific Conference on Communications. Piscataway: IEEE, 2008. pp. 1-5. ISBN 978-4-8855-2232-1.
  • Rok: 2008
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses the CPM class of the modulation passing through the parametric channel with the factor graph decoding inherently coping with the channel parameter. The combination of the discrete channel symbols with continuous valued channel parameter leads generally to complex mixture densities difficult to cope in the sumproduct algorithm message updates in the factor graph.

Subspace Recursive Weighted LS Solution of Iterative Synchronization in Time-Variant Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc., Včelák, J.
  • Publikace: European Transactions on Telecommunications. 2008, 19(6), 681-696. ISSN 1124-318X.
  • Rok: 2008
  • DOI: 10.1002/ett.1225
  • Odkaz: https://doi.org/10.1002/ett.1225
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Expectation-Maximization (EM) based iterative synchronizer is a particular form of the Information Measure Directed (IMD) synchronizer using a posteriori soft-information from the iterative decoding network. We solve the problem of EM based IMD synchronization in the general fast time-variant channel. The channel coefficients are allowed to change arbitrarily up to the granularity of the symbol period. We have identified the correspondence between the EM iterator and the weighted least squares (LS) problem. Particularly interesting is the subspace order recursive form of the LS iterator which reduces the implementation complexity. The procedure is demonstrated on example systems with the estimation of phase and jointly amplitude and phase on serially concatenated coding scheme. We use realistic Jake's Doppler dynamics as an example for the true channel and variety of subspace models for the EM estimator.

Factor Graph Framework for Serially Concatenated Coded CPM with Limiter Phase Discriminator Receiver

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the IEEE 66th Vehicular Technology Conference. Piscataway: IEEE, 2007. pp. 1-6. ISSN 1090-3038. ISBN 978-1-4244-0263-2.
  • Rok: 2007
  • DOI: 10.1109/VETECF.2007.268
  • Odkaz: https://doi.org/10.1109/VETECF.2007.268
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses the system with the Serially Concatenated Coded CPM (SCCCPM) and the nonlinear limiter phase discriminator receiver. We develop the FG framework allowing the use of the SPA factor node marginalization rules involving canonical distributions with finite number of parameters. We show that the straightforward application of the traditional constellation space approach is intractable. We also show that the sampled signal space does not allow an application of the parametrized canonical distributions for the variable nodes densities. The solutions we suggest in the paper stands on using the sampled parametric (phase) space of the CPM for all SPA processing.

Factor Graph Sum-Product Algorithm Update Rules in Sampled Phase Space of Limiter Phase Discriminator Receiver

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A particular form of the preprocessor, the 2-component IWM phase discriminator, is analyzed. We show that the discriminator can separate individual instant phases of the component CPM modulations and therefore has multiplexing capabilities with respect to the individual transmitted components. It creates parallel eigen-space like virtual channels. No time domain processing is needed, the procedure fully relies on the curved space properties of the IWM and thus is applicable with arbitrary outer space-time coding of MC-CPM. Information theoretic analysis of the multiplexing properties based on capacity region is presented.

Multiplexing Properties of 2-Component Information Waveform Manifold Phase Discriminator for Multichannel CPM Modulation in MIMO System

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A constant envelope CPM class of MultiChannel (MC) modulations at multi-antenna transmitter is considered. Each receive antenna in MIMO system receives a superposition of CPM waveforms. The useful signal at the receiver spans a curved - Information Waveform Manifold (IWM). Particularly it has a form of a cylinder on cylinder for 2-component CPM signal. At the receiver, we use a nonlinear preprocessor consisting of nonlinear projector on the IWM, optional processing on curved space and decoding isomorphism.

Receiver Constellation Waveform Subspace Preprocessing for Burst Alamouti Block STC CPM Modulation

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the 2007 IEEE Wireless Communications & Networking Conference. Piscataway: IEEE, 2007. pp. 1-5. ISSN 1525-3511. ISBN 1-4244-0658-7.
  • Rok: 2007
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We assume burst Alamouti coded STC CPM (MSK) modulation in MIMO channel as a particular example of Nonlinear Multichannel Modulation (NMM). The NMM has multidimensional constellation waveforms. The major goal is to find suboptimal receiver signal preprocessing that could substantially reduce receiver decoding metric computation complexity with minor degradation of the STC performance.

Adaptive Subspace Iterative Information Measure Directed Synchronization in MIMO Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc., Včelák, J.
  • Publikace: Proceedings of 2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications. Piscataway: IEEE, 2006. pp. 1-5. ISBN 1-4244-0329-4.
  • Rok: 2006
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper addresses the problem of iterative soft-information measure supported synchronization. We use a subspace based model for the arbitrarily time-variant MIMO channel. The channel subspace can have arbitrary dimension allowing to model also a fast time-variant channel. The equivalence between Expectation-Maximization based iterative synchronizer and weighted Least Squares problem is demonstrated to hold for general MIMO system. We introduce the idea of adaptive subspace control during the iterative synchronization iterations using the order recursive solver.

Mobile Broadband Multimedia Networks

  • Autoři: Correia, L. M., Aghvami, H., Bajic, D., Beach, M., Bolomey, J., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Oxford: Elsevier, 2006. ISBN 0-12-369422-1.
  • Rok: 2006

Nelineární zpracování signálu mnohokanálovych CPM modulací v MIMO kanálu

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Nelineární zpracování signálu mnohokanálovych CPM modulací v MIMO kanálu.

Signal processing

  • Autoři: Burr, A., Javornik, T., Matsumoto, T., prof. Ing. Jan Sýkora, CSc., Clavier, L., Oien, G.E.
  • Publikace: Mobile Broadband Multimedia Networks. Oxford: Elsevier, 2006. p. 35-118. ISBN 0-12-369422-1.
  • Rok: 2006

Achievable Rate Region of Linearly Precoded Multiple Access Block-Fading Delay Limited MIMO Channel

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST 273 MCM - Bologna. Brussels: COST Office, 2005. pp. 1-8.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper, the achievable rate region of multiple-access delay limited MIMO channel with user-wise independent linear precoding is investigated. No channel state information is assumed to be known at the transmitter and each user wants to communicate at the maximum but constant rate during the frame consisted of finite number of blocks of block-fading channel realizations. Each user employs the linear transmit energy preserving preprocessing. We aim at better performance in the terms of outage capacity compared with block-wise independent coding over the whole frame. There was found proper information-theoretical channel description. The behavior of the maximum achievable rate and entire rate region volume was evaluated so that there was proved that in the case of linear precoding the maximum achievable rate is stabilized and there exists the rate region achievable with lower guaranteed probability of outage.

Achievable Rate Region of Multiple Access with Linearly Precoded Parallel Block-Fading MIMO Channels

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of IEEE International Symposium on Wireless Communications Systems. Piscataway: IEEE, 2005. pp. 1-5. ISBN 0-7803-9207-8.
  • Rok: 2005
  • DOI: 10.1109/ISWCS.2005.1547643
  • Odkaz: https://doi.org/10.1109/ISWCS.2005.1547643
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The goal is to derive achievable rate region of multiple access MIMO channel with finite number of flat-fading parallel observations when novel user-wise independent linear precoding (pre-equalizing) is performed as the second level encoding procedure for each user separately.

Extended Transfer Bound Error Analysis for Parametric Channel with Continuous Valued Correlated Random Nuisance Parameter

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper we address the extended use of transfer bound analysis of bit error rate (BER) properties. In conjunction with proper parameter modeling, we offer a method to resolve the problem of transfer bound applicability on a system with random and possibly correlated continuous valued nuisance parameters.

Extended Transfer Bound Error Analysis in the Presence of Channel Random Nuisance Parameter

  • Autoři: Včelák, J., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of IEEE International Symposium on Personal Indoor and Mobile Radio Communications. Berlin: VDE Verlag, 2005. pp. 1-5. ISBN 3-8007-2909-1.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper, we present the extended transfer bound analysis for the error performance of a general trellis code in the channel with the overall correlated continuous valued nuisance parameters. Computer simulation results are presented for two different codes and various fading scenarios, and comparisons are made among analytical and measured system error performances.

General Framework and Advanced Information Theoretical Results on Eigenmode MIMO Channel Inversion

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    This paper provides general and deep investigation of adaptation strategies based on the channel inversion policy regarding wide variety of channel models. Our novel approach to the eigenmode space MIMO channel inversion policy relies on the eigenmode space reduction providing zero transmission outage probability regardless of the instantaneous channel fading realization.

Information Measure Directed Synchronization in MIMO Channel with Adaptive Parameter Subspace Dimension

  • Autoři: prof. Ing. Jan Sýkora, CSc., Včelák, J.
  • Publikace: Proceedings of the COST 273 MCM - Lisboa. Lisboa: COST273 Secretary, 2005. pp. 1-8.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Information measure directed synchronization in MIMO channel with adaptive parameter subspace dimension ...

Information Waveform Manifold Based Preprocessing for Nonlinear Multichannel Modulation in MIMO Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of IEEE Global Telecommunications Conference 2005. Piscataway: IEEE, 2005. pp. 2333-2338. ISBN 0-7803-9414-3.
  • Rok: 2005
  • DOI: 10.1109/GLOCOM.2005.1578080
  • Odkaz: https://doi.org/10.1109/GLOCOM.2005.1578080
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We present an Information Waveform Manifold (IWM) based preprocessing reducing the dimensionality of the problem. It is based on nonlinear projector, optional processing on IWM and decoding isomorphism with channel symbols expansion space. We show that the nonlinear projector is generally suboptimal, however the information loss comparing with optimal processing is negligible. The decoding isomorphism also directly separates the individual components of the received signal in MIMO channel.

Iterative EM Based IMD Synchronization for Fast Time-Variant Channel with Subspace Order Recursive LS Iterator

  • Autoři: prof. Ing. Jan Sýkora, CSc., Včelák, J.
  • Publikace: Proceedings of IEEE Asia-Pacific Conference on Communications. Piscataway: IEEE, 2005. pp. 1-5. ISBN 0-7803-9132-2.
  • Rok: 2005
  • DOI: 10.1109/APCC.2005.1554197
  • Odkaz: https://doi.org/10.1109/APCC.2005.1554197
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We solve the problem of iterative expectation-maximization (EM) based information measure directed (IMD) synchronization in fast time-variant environment. We identified correspondence between the EM iterator and the weighted least squares (LS) problem. An order recursive form of the LS iterator reduces the implementation complexity. The channel coefficients are allowed to change arbitrarily up to the granularity of the symbol period. The coefficients are modeled using parametric subspace providing a wide range of configuration for the channel dynamics while reducing the dimensionality of the problem substantially.

Iterative Synchronization on Time-variant Channel with Recursive Subspace Estimator

  • Autoři: prof. Ing. Jan Sýkora, CSc., Včelák, J.
  • Publikace: Proceedings of the COST 273 MCM - Leuven. Brussels: COST Office, 2005. pp. 1-5.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We solve the problem of iterative synchronization in fast time-variant environment. The iterative synchronizer is based on expectation-maximization (EM) information measure directed (IMD) algorithm. We identified correspondence between the EM iterator and the weighted least squares (LS) problem. An order recursive form of the LS iterator reduces the implementation complexity. The channel coefficients are allowed to change arbitrarily up to the granularity of the symbol period. The coefficients are modeled using parametric subspace providing a wide range of configuration for the channel dynamics while reducing the dimensionality of the problem substantially.

Linear Subspace Projection and Information Waveform Manifold Based Preprocessing for Nonlinear Multichannel Modulation in MIMO Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Conference Proceedings: ICT2005. Piscataway: IEEE, 2005. pp. 1-6. ISBN 0-9584901-3-9.
  • Rok: 2005

Multicomponent Phase Discriminator for Multichannel CPM Modulation in MIMO Channel Based on Nonlinear Geometric Approach

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST 273 MCM - Bologna. Brussels: COST Office, 2005. pp. 1-3.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Multicomponent phase discriminator for multichannel CPM modulation in MIMO channel based on nonlinear geometric approach ...

Sufficient Statistic and Reduced Dimensionality Equivalent Symbol Space Model for Frequency Flat MIMO Channel with Spatially Nonuniform Delay

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    We first derive an equivalent symbol space discrete channel model for frequency flat block fading MIMO spatial diversity channel with spatially nonuniform path delays. A general nonlinear modulation scheme is assumed by allowing channel symbols to be multidimensional per one antenna. The sufficient symbol spaced statistic dimensionality is shown to be a product of transmit, receive and symbol dimensions unlike for a traditional frequency flat MIMO model where the dimension is a product of receive and symbol dimensions. The traditional model is valid only for spatially uniform delays. We show that the spatially nonuniform path delays cause spatial Inter-Branch Interference (IBI).We introduce a reduced dimensionality equivalent system. The spatial IBI can be reduced using Linear Minimum Mean Square Error (LMMSE) spatial-temporal preprocessing (equalizer).

Synchronisation and Channel State Estimation for Digital Transmission Techniques

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST 273 MCM - Leuven. Brussels: COST Office, 2005. pp. 36-48.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Synchronisation and Channel State Estimation for Digital Transmission Techniques in Proceedings of the COST 273 MCM - Leuven

Two-Mode Limited Feedback Block-Fading Transmission with Minimum Guaranteed Rate in MIMO Channel

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST 273 MCM - Lisboa. Lisboa: COST273 Secretary, 2005. pp. 1-9.
  • Rok: 2005
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    In this paper ... two-mode limited feedback block-fading transmission with minimum guaranteed rate in MIMO channel ...

Adaptation in MIMO Rayleigh Channel Using Subspace Total Inversion with Zero Outage Probability

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST#273 MCM - Gothenburg. Brussels: COST Office, 2004. p. 1-5.
  • Rok: 2004

Analytical Error Performance Analysis for Reduced Complexity Detection of General Trellis Code with Parametric Uncertainty

  • Autoři: Včelák, J., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST#273 MCM - Gothenburg. Brussels: COST Office, 2004. p. 6-10.
  • Rok: 2004

Discrete Energy Allocation in MIMO Systems - Preliminary Results on Outage Capacity and Adaptation Algorithm

  • Autoři: Fišera, R., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the COST#273 MCM - Gothenburg. Brussels: COST Office, 2004. p. 1-6.
  • Rok: 2004

Iterative Decoding Networks with Iteratively Data Eliminating SDD and EM Based Channel State Estimator

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.G.
  • Publikace: Proceedings of the COST#273 MCM - Gothenburg. Brussels: COST Office, 2004. p. 1-6.
  • Rok: 2004

Iterative Decoding Networks with Iteratively Data Eliminating SDD and EM Based on Channel State Estimator

  • Autoři: prof. Ing. Jan Sýkora, CSc., Burr, A.G.
  • Publikace: Proceedings of the IEEE International Symposium on Personal, Indoor and Mobile Radio Communications Conference. Piscataway: IEEE, 2004. pp. 785-790.
  • Rok: 2004
  • DOI: 10.1109/PIMRC.2004.1373807
  • Odkaz: https://doi.org/10.1109/PIMRC.2004.1373807
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper establishes a general framework for iterative separate CSE in general iterative decoding networks. Two particular cases of CSE are examined-SDD (Soft-Decision Directed) and EM (Expectation-Maximization) based one. Both have capabilities for exploiting the iteratively improved backward measure from the decoding network, however both exhibit different properties and provide different possibilities for iteration scenarios.

Iterativní dekódovací sítě

  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Článek se zabývá teoretickými principy iterativních dekódovacích sítí v digitálních komunikačních systémech. Analyzujeme výchozí kritéria optimální detekce. Na jejich základ je navržen algoritmus asymptoticky optimálního iterativního dekódování obecné kódovací sítě. Základním prvkem takové sítě je SISO modul. Jsou odvozeny jeho vstupně-výstupní vztahy pro marginalizovanou iterativní dekódovací sít'.

Linear Diversity Precoding Design Criterion for Block-Fading Delay Limited MIMO Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc., Kníže, M.
  • Publikace: COST#273 Conference Proceedings. Brussels: COST Office, 2004. pp. 1-5.
  • Rok: 2004

Linear Diversity Precoding Design Criterion for Block-Fading Delay Limited MIMO Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc., Kníže, M.
  • Publikace: Proceedings of the IEEE Global Telecommunications Conference (GlobeCom). Piscataway: IEEE, 2004. pp. 3711-3715. ISBN 0-7803-8794-5.
  • Rok: 2004
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    A novel approach utilizing the virtual multipleaccess like capacity region with symmetry condition on rates is used to develop the design criterion of linear precoding (inner code) for the block-fading delay limited MIMO channel. The overall coding process is split into two parts-outer and inner code. The outer coders are supposed to work blockwise independently and the only joint processing is assumed inherently in the inner code. The motivation is to develop twolevel coding process having the same outage capacity performance but significantly lower complexity of the design compared with the information-theoretically optimal joint coding book.

Outage Capacity and BER Performance Analysis of Linear Diversity Precoding in Block-Fading Delay Limited MIMO Channel

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST#273 Conference Proceedings. Brussels: COST Office, 2004. pp. 1-8.
  • Rok: 2004

Principy diversitní a adaptivní rádiové komunikace v mobilních kanálech

Subspace Inversion Symbol Energy Adaptation in MIMO Rayleigh Channel with Zero Outage Probability

  • Autoři: Kníže, M., prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the IEEE Vehicular Technology Conference (VTC). Piscataway: IEEE, 2004. pp. 1-5.
  • Rok: 2004

Symmetric Capacity of Nonlinearly Modulated Finite Alphabet Signals in MIMO Random Channel with Waveform and Memory Constraints

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the IEEE Global Telecommunications Conference (GlobeCom). Piscataway: IEEE, 2004. pp. 425-430. ISBN 0-7803-8794-5.
  • Rok: 2004
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    The paper shows a procedure for evaluating the symmetric ergodic capacity of nonlinearly modulated finite alphabet signals in MIMO random channel.

Adaptive State Partitioning Complexity Reduction of Viterbi Equalizer for MIMO Rayleigh Fading Channel

Information Capacity of Nonlinearly Modulated Finite Alphabet Signals in MIMO Channel

Lower-upper Energy Constrained Waterfilling in MIMO Channels with Delay Limited Transmission

Multiple-input Multiple-output Wireless Systems

  • Autoři: Včelák, J., Javornik, T., prof. Ing. Jan Sýkora, CSc., Kandus, G., Plevel, S.
  • Publikace: Electrotechnical Review. 2003, 70(4), 167-172. ISSN 0013-5852.
  • Rok: 2003

Optimal Energy Allocation and Outage Capacity for the Delay Limited Transmission Over MIMO Block-Fading Channel Under Specific Energy Constraints

Prostorově diversitní komunikační systémy

Spatial Inter-Branch Interference Equalization in MIMO Frequency Flat Fading Channel With Mutually Unequal Path Delays

Capacity Evaluation of Frequency Selective Rayleigh Block Fading Channel with Correlated Scattering

  • Autoři: prof. Ing. Jan Sýkora, CSc., Fišera, R.
  • Publikace: COST 273 - 4th Meeting of the Management Commitee. Brussels: EU, 2002. pp. 1-6.
  • Rok: 2002

MIMO Spatial Diversity Communications - Signal Processing and Channel Capacity

Principy digitálních modulací v komunikačních systémech

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Radiokomunikace 2002 - sborník přednášek. Pardubice: UNIT, 2002. pp. 5-13.
  • Rok: 2002

Prostorově diversitní digitální komunikační systémy

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Zpracování signálu. Praha: Česká elektrotechnická společnost, 2002. pp. 7-10.
  • Rok: 2002

Self-Noise in MIMO Space-Time Coded Systems with Imperfect Symbol Timing

Self-Noise in MIMO Space-Time Coded Systems with Imperfect Symbol Timing

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST 273 - 4th Meeting of the Management Commitee. Brussels: EU, 2002. pp. 1-6.
  • Rok: 2002

Spatial Diversity Communications - Signal Processing and Channel Capacity

Trellis Coded CPM Type Space-Time Modulation Design Rules for Rayleigh Flat Fading Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: COST - European Cooperation in the field of Scientific and Technical Research - 3rd Meeting. Brussels: EU, 2002. pp. 1-8.
  • Rok: 2002

Constant Envelope Space-Time Modulation Trellis Code Design for Rayleigh Flat Fading Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of GLOBECOM '01. Piscataway: IEEE, 2001. p. 1113-1117. ISBN 0-7803-7206-9.
  • Rok: 2001

Digital Signal Processing Application in Radioelectronics

Application of Digital Signal Processing in Radio Engineering

Tapped Delay Line Model of Linear Randomly Time-variant WSSUS Channel

Teorie digitální komunikace

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Radiokomunikace 2000. Praha: ČVUT FEL, Katedra radioelektroniky, 2000. p. 1-37. ISBN 80-01-02142-4.
  • Rok: 2000

Complete Receiver Signal Processing Algorithms Specification for Terrestrial Segment Part of the System

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: ATNMIS-TMS Cop708 SALMS PPR 004. Brussels: European Commission, 1998. pp. 1-55.
  • Rok: 1998

Design of An Experimental Integrated Satellite/Terrestrial Digital Mobile Communication System

  • Autoři: prof. Ing. Jan Sýkora, CSc., Ozimek, I., Kandus, G., Javornik, T.
  • Publikace: Vitel 1998. Ljubljana: Electrotechnical Society of Slovenia, 1998. pp. 11-18. ISBN 961-6187-08-2.
  • Rok: 1998

Teorie digitální komunikace

  • Autoři: prof. Ing. Jan Sýkora, CSc., Hrdina, Z.
  • Publikace: Radiokomunikace '98. Praha: ČVUT FEL, Katedra radioelektroniky, 1998, pp. 1-40. ISBN 80-01-01780-X.
  • Rok: 1998

A Systematic Approach to MAP Data Detection in Flat Fading Channel with Recursive Metric and Realizable Extreme Search Algorithms---Results for Constant Symbol Energy Modulation Schemes

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the 4th International Symposium on Communication Theory and Applications. Lake District: Charlotte Mason College, 1997, pp. 367-374.
  • Rok: 1997

A Systematically Built Optimal Data Detection Algorithm for Flat Fading Digital Communication Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Workshop 97. Praha: České vysoké učení technické v Praze, 1997. pp. 975-976.
  • Rok: 1997
  • Pracoviště: Katedra radioelektroniky
  • Anotace:
    Systematicky konstruovaný optimální detekční algoritmus pro digitální komunikační kanál s frekvenčně plochým únikem

Multidimensional MAP Data Detector for Flat Fading Channel With Recursive Metric and U-lag DD SBD Extreme Search

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: ATNMIS-TMS Cop708 SALMS PPR 003. Brussels: European Commission, 1997. pp. 1-5.
  • Rok: 1997

Self Noise of the General CPM Type Modulation With Distorted Frequency Impulse/Truncated Correlation Lenght

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: ATNMIS-TMS Cop708 SALMS PPR 003. Brussels: European Commission, 1997. pp. 1-2.
  • Rok: 1997

A Systematic Approach to MAP Data Detection In Flat Fading Channel With Recursive Metric and Realizable Extreme Search Algorithms - Preliminary Results for Constant Symbol Energy Modulation

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: ATNMIS-TMS Cop708 SALMS PPR 002. Brussels: European Commission, 1996. pp. 1-10.
  • Rok: 1996

Channel State Estimation

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of 3rd International Symposium on Communication Theory and Applications. Lake District: Charlotte Mason College, 1995. pp. 445-450.
  • Rok: 1995

Decision Directed and Non Decision Directed Channel State Estimators for Slowly Fading Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: Proceedings of the 2nd Joint COST 227/231 Workshop on mobile and personal communications. Amsterdam: Elsevier, 1995. pp. 327-341. ISBN 0-444-82328-X.
  • Rok: 1995

Decision Directed Channel State Estimator

Spectral Properties of Linear Modulations in Nonlinear Channel

  • Autoři: prof. Ing. Jan Sýkora, CSc.,
  • Publikace: ATNMIS-TMS Cop708 SALMS PPR 001. Brussels: European Commission, 1995. pp. 1-5.
  • Rok: 1995

Modernization of PhD. Studies in Radioelectronics

Za stránku zodpovídá: Ing. Mgr. Radovan Suk