Ishtiaq Ahmad, Ph.D.

Efficient radio resource management for Device-to-Device (D2D) communication is challenging due to the need to satisfy diverse Quality of Service (QoS) requirements for various applications. While machine learning techniques have gained attention for addressing these issues, joint prediction of multiple radio resource parameters, such as transmission power, or bandwidth allocation, often leads to suboptimal performance. Thus, in this paper, we propose a coordinated multi-task learning approach based on deep neural networks for joint prediction of channel quality, power, and bandwidth allocation for D2D communication. Then, we design task-specific loss functions and their mutual coordination to maximize sum capacity, ensure QoS, and satisfy task-specific constraints, such as limits on transmission power and bandwidth. Simulation results demonstrate that the coordinated multi-task learning improves the sum capacity and the ratio of devices satisfied with capacity by up to 54% and 30%, respectively, compared to state-of-the-art techniques.

In this paper, a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted uplink non-orthogonal multiple access (NOMA) system with semi-grant-free (SGF) transmission in the presence of the illegal user is investigated. Particularly, with the help of SGF transmission, grant-free (GF) users omit the tedious process of requesting authorization from the base station and are able to transmit signals by sharing the resource blocks reserved for grant-based (GB) user. Among the K GF users, the one with the best channel conditions is eligible to share the resource block for GB user, which ensures the quality of service for the GB user and avoids collisions due to too many GF users. For this setup, we consider the covert performance and secrecy performance. Particularly, expressions for the outage probability (OP), detection error probability (DEP), optimal detection threshold, and secrecy outage probability (SOP) are derived to assess the system performance. In addition, we present many special cases to get more intuitive insights. Finally, the simulation results verify the correctness and validity of the theoretical calculations, and the effect of each parameter on the system performance is also investigated.

Vehicle Edge Computing (VEC) assists vehicles in performing latency-sensitive tasks by deploying resources near the vehicle. Designing an incentive mechanism for vehicles and VEC is crucial for realizing an intelligent transmission system. Considering the rationality of resource allocation, we model the utility functions of the VEC and the vehicle, which are used as optimization objectives. Specifically, the VEC allocates resources through pricing to maximize revenue under resource-constrained conditions, and the vehicle weighs payments against energy consumption to determine offloading and resource allocation. Given the vehicle movement and the variable channel state, we use the Deep Reinforcement Learning (DRL) algorithm to solve these optimization problems. To reduce the learning difficulty of the DRL algorithm in complex VEC scenarios with multiple optimization variables, we propose a Pricing-Driven Resource Allocation (PDRA) algorithm that performs mobility-aware task offloading and calculates the optimal values of the optimization variables in the utility function of the vehicle to reduce the decision dimension. Furthermore, we also propose a DRL-based Pricing-Driven Dynamic Resource Allocation (DPDDRA) algorithm to achieve efficient resource allocation. Extensive experimental results show that the proposed algorithms can reduce the learning difficulty while maximizing VEC and vehicle revenue in complex VEC scenarios.

The rapid advancement of consumer connected and autonomous vehicle (CAV) technologies offers significant improvements in transportation efficiency, safety, and user convenience. However, these benefits come with substantial cybersecurity risks, as in-vehicle networks and cloud connectivity expose CAVs to increasingly sophisticated cyberattacks. Conventional intrusion detection systems (IDS) often fall short in this domain, as they are not adaptive and struggle to handle the dynamic and stealthy nature of modern attacks. To address these limitations, we propose a novel IDS framework based on a stacking ensemble architecture that integrates multiple machine learning algorithms, Random Forest (RF), Support Vector Machine (SVM), Adaptive Boosting (AdaBoost), and Extreme Gradient Boosting (XGBoost), as base learners. A Long Short-Term Memory Recurrent Neural Network (LSTM-RNN) serves as the meta-learner to capture temporal dependencies and sequential patterns in network traffic. To enhance the model's generalization capability, we incorporate a model-agnostic meta-learning (MAML) approach into the LSTM-RNN meta-learner. The MAML-enhanced set of capabilities enables more effective detection of evolving and previously unseen attack scenarios. Simulation results demonstrate that the proposed framework consistently outperforms standalone LSTM-RNN models, traditional ensemble methods, and individual base learners in detecting complex cyberattack patterns in consumer CAV environments. These findings highlight the potential of meta-learning-driven ensemble IDS frameworks for securing next-generation intelligent transportation systems.

Unmanned aerial vehicles (UAVs) have become essential elements of non-terrestrial networks (NTNs) utilized in various sectors, including agriculture, public safety, surveillance, and critical military operations. However, in addition to the benefits of these NTNs, they are increasingly being exploited for malicious purposes, leading to a heightened need for timely detection and identification. Despite advances in UAV detection, challenges remain, particularly in dealing with different UAV types, the payloads they carry, and their flight characteristics. Relying on a single convolutional neural network (CNN) for UAV detection and identification presents difficulties in managing diverse datasets and capturing complex, interdependent relationships. To address this, we propose a novel approach that integrates the visual geometry group-based CNN for UAV detection and the mask region-based CNN for the identification of various traits of UAVs. Additionally, to overcome the computational complexity of deep convolutional layers, we introduce a quantum computation-based CNN (QCNN) instead of the conventional CNN, applied in both the visual geometry group-based detection and mask region-based identification processes, jointly termed VM-QCNN. To effectively deploy VM-QCNN, we enhance the dataset by applying data augmentation techniques, which add diversity to the training data. This ensures the model accurately detects various UAV types, payload categories, and flight characteristics. Performance evaluation through simulations demonstrates that the VM-QCNN approach significantly improves the detection of malicious UAVs compared to competitive algorithms.

We address the problem of a coordination among machine learning tools solving different problems of radio resource management. We focus on energy efficient device-to-device (D2D) communication in a scenario with many devices communicating adhoc directly with each other. In such scenario, deep neural network (DNN) is a convenient tool to predict the channel quality among devices and to control the transmission power. However, addressing both problems by a single DNN is not suitable due to a dependency of the power control on the predicted channel quality. Similarly, a simple concatenation of two DNNs leads to a high cumulative learning error and an inevitable performance degradation. Hence, we propose a mutual coordination of the DNNs for channel quality prediction and for power control via a feedback and a knowledge transfer to mitigate the accumulation of errors in individual learned models. The proposed coordination improves the energy efficiency by 10-69% compared to state-of-the-art works and reduces the training time of DNNs more than 3.5-times compared to DNNs without coordination.

User applications based on the deep neural networks (DNNs), such as object or anomaly detection, image recognition, or language processing, running on computation- and energy-constrained user equipment (UE) can be partially or fully processed in the edge computing servers to reduce a processing time and save an energy in the UE. To further reduce the processing time and the UE's energy consumption, DNN with multiple exit points can be incorporated. In this article, we address the problem of the decision on whether the computation should be offloaded from the UE to the edge computing server or processed locally by the UE and we solve this problem jointly and "on-the-fly" together with DNN exit selection. Since the formulated problem is very complex, we exploit the deep deterministic policy gradient for the exit selection and the offloading decisions (labeled DDPG-EOD) for the DNN-based applications. To this end, we first convert the problem into the Markov decision process, and then, we employ an end-to-end learning via DDPG with the actor-critic architecture. Second, we use a knowledge distillation-based technique to efficiently select the DNN's exit to minimize the delay and energy consumption. Simulation results show that the proposal is highly scalable, converges very quickly, and surpasses the best performing state-of-the-art approach by up to 120% and 100% in terms of the overall DNN processing delay and the energy consumption, respectively.

Multihop communication has gained prominence within the realm of the Internet of Underwater Things (IoUT) owing to its exceptional reliability amidst the challenges posed by the underwater acoustic environment. Despite this, the persistence of limitations caused by propagation delay, high collision rate, and limited energy in underwater communication remains, representing the most formidable hurdles in ensuring the successful transmission of data gathered by sensor nodes. To address these challenges, we employ a machine learning (ML)-based optimal cooperating node selection for each hop, considering the Shortest propagation delay, minimal residual Energy, and a low Collision rate (referred to as SEC). For this purpose, we initially assemble the sensor nodes to create a list of cooperative nodes, considering the aspect of SEC. Then, using an assembled list of cooperating sensor nodes, we employ ML-based algorithms, such as reinforcement learning (RL-SEC), deep Q-networks (DQN-SEC), and deep deterministic policy gradient (DDPG-SEC), to predict the optimal cooperating node for each hop. The simulation results of the DDPG-SEC demonstrate a significant improvement of approximately 56% when compared with RL-SEC, DQN-SEC, and other state-of-the-art techniques.

Unmanned aerial vehicles (UAVs) offer advantages in serving as aerial small cells (ASCs) to support public safety terrestrial cells (PSTCs) while providing pervasive coverage during disasters. To ensure reliable communications for long-term evolution-based public safety (PS-LTE) users, it is crucial to obtain an accurate understanding of network performance for practical cell association design and network stability. This comprehension is vital for the practical design of cell associations and for maintaining network stability in next-generation consumer wireless networks. For this purpose, we first employ a flexible biased cell association (FBCA) policy that optimally selects the bias factor where a PS-LTE user (PUE) connects to the eNodeB (eNB) giving the maximum power for the received signal. Then, we present a resource allocation and subframe-type selection by formulating stochastic optimization programming to resolve system stability issues in the coexisting PS-LTE andLTE-based high-speed railway (LTE-R) networks and PS-LTE and UAV networks. In addition to this, we employ the Lyapunov optimization technique to seek an optimal almost blank subframe (ABS) algorithm with dynamic delay-aware resource allocation (ADDRA) to resolve the problem of network stability. Using ADDRA, the PS-LTE eNodeB (PSeNB), the aerial eNodeBs (AeNBs), and the LTE-R eNodeBs (ReNBs) obtain up-to-date queues of attached users and accordingly compute a matrix for scheduling resources based on channel state information (CSI) feedback. The simulation results of the UAV-assisted networks using FBCA and ADDRA in coexisting PS-LTE/LTE-R and PS-LTE/UAV networks demonstrate a significant improvement when compared with other state-of-the-art techniques.

The co-channel interference for mobile users (MUs) of a public safety network (PSN) in the co-existence of heterogeneous networks such as unmanned aerial vehicles (UAVs) and LTE-based railway networks (LRNs) needs a thorough investigation, where UAVs are deployed as mobile base stations (BSs) for cell-edge coverage enhancement. Moreover, the LRN is employed for the train, and its control signal demands high reliability and low latency. It is necessary to provide higher priority to LRN users when allocating resources from shared radio access channels (RACs). By considering both sharing and non-sharing of RACs, co-channel interference was analyzed in the downlink network of the PSN, UAV, and LRN. By offloading more PSN MUs to the LRN or UAVs, the resource utilization of the LRN and UAV BSs was enhanced. In this paper, we aimed to adopt deep-learning (DL)-based enhanced inter-cell interference coordination (eICIC) and further enhanced ICIC (FeICIC) strategies to deal with the interference from the PSN to the LRN and UAVs. Moreover, a DL-based coordinated multipoint (CoMP) for coordinated scheduling technique was utilized along with FeICIC and eICIC to enhance the performance of PSN MUs. In the simulation results, the performance of DL-based interference management was compared with simple eICI, FeICIC, and coordinated scheduling CoMP. The DL-based FeICIC and CoMP for coordinated scheduling performed best with shared RACs.

Unmanned aerial vehicles (UAVs) equipped with reconfigurable intelligent surfaces (RISs) have emerged as a promising technology for numerous applications involving aerial networks. However, the UAV-RIS concept faces challenges related to the deployment of the UAV-RIS, especially in cases, where UAV-RIS is combined with emerging technologies, such as beamforming, sensitive to propagation channel variation. In this article, we first overview various use-cases of UAV-RIS beam-forming considering practical scenarios. Aiming to improve the performance of communication channels, we propose a machine learning-based beamforming policy for UAV-RIS by employing prioritized experience replay (PER) based deep Q-Network (DQN). Compared to traditional approaches, the proposed PER DQN-based beamforming for UAV-RIS communication provides significant enhancements in performance. Finally, we highlight some potential directions for future research.