Ing. Peter Macejko

In this article, we would like to deal with challenges and analysis approaches in the area of narrow band communication networks. Especially those networks which use TCP/IP protocol family. We also present a new universal data generator for OMNeT++ simulation environment. We created this generator to satisfy the evaluation, stress testing and benchmarking demands of more and more complex industrial and the Internet of Things networks. We also present the methods for evaluation and comparison of results obtained from simulated and real TCP/IP based networks in this article.

The paper deals with a measurement of single-hop one way packet delay on embedded systems used for networking. The single-hop one way packet delay is essential parameter when we need to process packets with strict delivery time constrains. Comparison of different approaches to single-hop one way packet delay measurements is presented in this work along with discussion about strong and weak points in specific measurement approach. The impact of different types of system load and number of CPU cores are also covered by presented results. The presented results of measurement single-hop one way packet delay in embedded Linux system show that for the specific system configuration the packet processing delay depends (in different ways) on system load and network stack load.

The paper presents a methodology proposal for testing and evaluation of communication systems in Smart Grids, especially for Power Line Communication (PLC) systems. The PLC technology is widely used in power grid as a part of Advanced Metering Infrastructure (AMI) allowing mainly data transfers between a management system at utility and customer-premises smart meters. However, the PLC technology on medium voltage (MV) lines is often used for remote control and monitoring of distribution transformers as well. Since power grid and consequently power lines have different transmission parameters affected by their placement and potentially burdened by interferences, the PLC systems have to be evaluated on site before placed to production. In this paper, authors propose a methodology for long-term benchmarking of the PLC systems using newly developed testing tools. The methodology is subsequently tested on real power grid and a selection of results is presented.

This article presents new metric for TCP connection robustness evaluation and comparison. This metric is focused on TCP connection and transmission continuity rather then on maximal throughput or minimal RTT. This metric is developed especially for evaluation of narrow band networks. That is why it is very convenient to use this metric for networks such as Internet of Things networks or industrial sensor networks. Our metric is based on observing if connections or transmissions are successfully finished or not. It is possible to optimize this metric for specific situations. This metric can be used in both the real networks and in discrete simulation environments.

Heterogeneous computational platform offers a great ratio between the computational power and the price of the system. Static and dynamic scheduling methods offer a good way of how to use these systems efficiently and therefore many algorithms were proposed in the literature in past years. The aim of this article is to present the dynamic (on-line) algorithm which schedules multiple DAG applications without any central node and the schedule is created only with the knowledge of node’s network neigbourhood. The algorithm achieves great level of fairness for more DAGs and total computation time is close to the standard and well known competitors.

This article presents a new tool for network throughput and stress testing. The FlowPing tool is easy to use, and its basic output is very similar to standard Linux ping application. The FlowPing tool is not limited to reach-ability or round trip time testing but is capable of complex UDP based throughput stress testing with rich reporting capabilities on client and server sides. Our new tool implements features, which allow the user to perform tests with variable packet size and traffic rate. All these features can be used in one single test run. This allows the user to use and develop new methodologies for network throughput and stress testing. With the FlowPing tool, it is easy to perform the test with the slowly increasing the amount of network traffic and monitor the behavior of network when the congestion occurs.

here is a great diversity in the transmission technologies in current data networks. Individual technologies are in most cases incompatible at physical and partially also at the link layer of the reference ISO/OSI model. Network compatibility, as the ability to transmit data, is realizable through the third layer, which is able to guarantee the operation of the different devices across their technological differences. The proposed inverse packet multiplexer addresses increase of the speed and reliability of packet transmission to the third layer, and at the same time it increases the stability of the data communication by the regulation of the delay value during the transmission. This article presents implementation of a communication system and its verification in real conditions. The conclusion compares the strengths and weaknesses of the proposed control system.

The results of experiments with Multipath TCP (Multipath Transmission Control Protocol) in LTE (3GPP Long Term Evolution) networks are presented. Our results show increased resiliency and availability of network Multipath TCP connection. Using multiple sub-flows over diverse network paths inside Multipath TCP session results in greatly increased bandwidth and availability. When Multipath TCP is used the behavior of this protocol is consistent in situation of adding new sub-flow or removing flow on a faulty line. Different strategies for path selection are possible with great impact on Multipath TCP session performance. Network structure consisting of few connections with similar parameters is optimal for full mesh Multipath TCP path topology. In this case the behavior of Multipath TCP predictable.

Paper describes results from the measurement of the transmission system that is designed for active backup of transmission lines through mobile networks. Measurements have been designed and implemented to verify the ability of uninterruptible data transfer during train movement in places with different quality of mobile networks. Testing was realized on the Small test ring of the Railway Research Institute in Velim. We present the results of the measurement on the physical, link and network layer of the reference model ISO / OSI, including results evaluation.

Task scheduling is a way of how to run ``any'' application in a distributed computation system. Traditional attitude is loosely coupled with the well known structure of the application and all the data this application needs to work with is already known when the computation begins. Similarly, these data are available to all of the computation nodes. In this article we modified this model by adding constraints that some data are available only after a specific time and at a specific place. We present a modified HEFT, CPOP and DLMDAG algorithms so that they are able to take this modification into account.

Heterogeneous computational platform offers a great ratio between the computational power and the price of the system. Research in static and dynamic scheduling has been done and many algorithms were proposed in the literature. The aim of this article is to present the dynamic (on-line) algorithm which schedules multiple DAG applications dynamically without any central node and the schedule is created only with the local knowledge of the network. This algorithm does not beat the minimal makespan but offers good ratio of fairness for multiple DAGs and usage of computational resources.

Contemporary Next Generation Networks (NGN) are mainly built on the Internet Protocol (IP) and Ethernet. Major challenge for emerging types of wired and wireless IP-based networks is to provide an adequate Quality of Service (QoS) for different services. The quality of evaluation requires a detailed knowledge of the performance requirements for particular services and applications. The paper is primarily oriented to the end-to-end testing for the Ethernet-based terminal equipment. The extension for emulation network with the E1 interfaces and TDM over IP transmission can be used with external converters.

Modification of the task duplication scheduling mechanism for machines with more computing cores that avoids some schedule anomalies.