Ali Y. Al-Zahrani

Introduction: User data traffic—particularly video traffic and small IoT packets—has surged in recent years due to the proliferation of intelligent devices, sensors, and innovative applications like virtual reality and autonomous driving. These bandwidth-intensive applications place higher demands on user access and network capacity. Methods: To achieve faster data rates, increased throughput, and reduced latency, 6G networks may transition from orthogonal multiple access (OMA) to non-orthogonal multiple access (NOMA), which enhances spectral efficiency. Through a combination of analytical framework and intensive simulations, this paper examines the effects of admitting low-data- rate IoT devices into NOMA-based clusters of high-data-rate cellular users (CUs). Results: The simulation results indicate that admitting IoT devices with favorable locations can increase the total achievable rate of the cluster by about 30%, while maintaining each CU's target rate. Discussion: Spatial-based recommendations for establishing an effective device admission strategy are provided. The results pave the way for device scheduling and association with the objective of maximizing the network utilization Conclusion: Admitting IoT devices into a NOMA cluster of cellular users is achievable without compromising the CUs target rates, a result that render NOMA techniques to play an important role in the 6G future deployments.

Mobile Ad hoc Networks (MANETs) are emerging wireless networks with many distinct characteristics. MANET has the potential to be useful in many different commercial applications. However, before using MANET in commercial application, it is necessary to address different security issues related to MANET. Data routing is one of the fundamental operations in the MANET. This research work addresses security issues related to MANET routing protocols. In this paper, we consider the performance of MANETs routing protocols subject to black hole attacks. Trust management techniques aim to protect a network from the malicious behaviour of the participating nodes. This research work proposed a novel trust-based routing protocol for MANET called ITAODV, which is derived from regular AODV protocol. The proposed protocol uses an indirect trust mechanism, which takes into account the reliability of the nodes while forwarding the packets. The performance evaluation of AODV and ITAODV was carried out using Network Simulator 3 (NS-3). The experimental results demonstrate effectiveness of the ITAODV protocol against black hole attacks.

The domain of Robotics is a good partner of renewable energy and is becoming critical to the sustainability and survival of the energy industry. The multi-disciplinary nature of robots offers precision, repeatability, reliability, productivity and intelligence, thus rendering their services in diversified tasks ranging from manufacturing, assembling, and installation to inspection and maintenance of renewable resources. This paper explores applications of real robots in four feasible renewable energy domains; solar, wind, hydro, and biological setups. In each case, existing state-of-the-art innovative robotic systems are investigated that have the potential to create a difference in the corresponding renewable sector in terms of reduced set-up time, lesser cost, improved quality, enhanced productivity and exceptional competitiveness in the global market. Instrumental opportunities and challenges of robot deployment in the renewable sector are also discussed with a brief case study of Saudi Arabia. It is expected that the wider dissemination of the instrumental role of robotics in renewable energy will contribute to further developments and stimulate more collaborations and partnerships between professionals of robotics and energy communities.

A cellular communication system is divided into two main parts, core network, and radio access network. This research is concerned with the radio access network part which consists of multiple-cells, each served by a central located base station. Furthermore, the users in each cell are considered to be uniformly distributed inside the cell. In the downlink context, the users’ packets usually arrive at the base station via fiber optic and then are relayed to the users via radio waves of certain frequency/ies. The speeds of delivering users’ packets vary, depending on the users’ location. In this paper, the actual distribution of the service time over different users whose locations are uniformly distributed in a cell served by one base station is analytically found. Simulation results are presented to validate the derived model.

Several emerging mobile applications and services (e.g., autonomous cars) require higher wireless throughput than ever before. This demand stresses the need for investigating novel methods that have the potential to dramatically increase the spectral efficiency (SE) of wireless systems. An evolving approach is the Single-channel full duplex (SCFD) communication where each node may simultaneously receive and transmit over the same frequency channel, and, hence, this could potentially double the current SE figures. In an earlier research work, we derived a model of the signal to interference plus noise ratio (SINR) in an SCFD-based cellular system with imperfect self interference cancellation, and investigated interference management under feasible QoS requirements. In this paper, game theoretic results are exploited to investigate the intercell interference management in SCFD-based cellular networks under infeasible QoS requirements. The investigation starts with a game formulation that captures two different cases. Then, the existence and uniqueness of the Nash equilibrium point are established. After that, a computationally efficient distributed algorithm, which realizes best effort and fair wireless services, is designed. The merit of this scheme is that, when the QoS requirements are feasible, they will be achieved with minimum energy consumption. Results of extensive simulation experiments are presented to show the effectiveness of the proposed schemes.

Oxides of chromium (Cr), molybdenum (Mo), or tungsten (W) were supported on mixed oxides of cerium and zirconium (CeO2-ZrO2) by an incipient wetness impregnation process, and used to investigate their activities for partial oxidation of methanol. High Resolusion Transmission Electron Microscope (HR-TEM) revealed that nanoparticles of Cr2O3, MoO3 or WO3 were formed on the CeO2-ZrO2 support. The particle sizes of Cr2O3, MoO3 and WO3 were 2-4, 3-6 and 4-5 nm, respectively. As a result of partial oxidation of methanol at 275-450 C, formaldehyde (CH2O) was obtained as the major product over all these catalysts. Cr2O3 supported on CeO2-ZrO2 produced both CO and CO2 along with H2 production, while MoO3 and WO3 on CeO2-ZrO2 support generated only CO as a by-product. It was found that MoO3 supported on CeO2-ZrO2 showed the highest methanol conversion and CH2O yield among these three catalysts.

In heterogeneous networks (HetNets), energy-efficient resource allocation and intercell-interference management are important issues. In this paper, we address these issues using a two-level dynamic scheme. First, we assign the MUs with the optimum number of subchannels that achieves an operator's required balance between macro users' satisfaction and maximization of network efficiency. Then, the remaining subchannels are left to be shared by a number of small cells. In the latter step, a transmit power adaptation method using a noncooperative game-theoretic approach is developed to reduce cochannel interference in the whole network. The problem is formulated by allowing multiple neighboring small cells to share each subchannel (i.e., universal frequency reuse in the small cell level). We fully characterize the pricing factor in the penalty part of the utility function. The existence and uniqueness of the Nash equilibrium (NE) are analyzed and proved. Then, a distributed iterative algorithm based on the fixed-point theorem is proposed to attain the equilibrium of the game. Simulation results are presented to show the effectiveness of the proposed scheme in different network topologies.

In hyperdense heterogeneous networks (HetNets), efficient intercell interference management is an important issue. In this paper, using recent advances in mean-field game (MFG) theory, we propose a novel game-theoretic approach for interference management in HetNets. The intercell interference management issue in HetNets is formulated as two nested problems: an overlay problem at the macrocell base station (MBS) level and an underlay problem at the small-cell base station (SBS) level. In the overlay problem, the MBS selects the optimal action first, which satisfies its associated users with a minimum amount of cross-layer interference, taking into account the reaction of the SBSs. The underlay problem is then formulated as a noncooperative game among the SBSs. The mean-field theory is exploited to help decouple a complex large-scale optimization problem into a family of localized optimization problems. Thus, each SBS can implement its policy by using only its local information and some macroscopic information. In addition to the achieved tradeoff between spectral efficiency (SE) and energy efficiency (EE), our approach can substantially reduce the communication overhead and convergence time of interference management in hyperdense HetNets. Simulation results are presented to show the effectiveness of the proposed scheme.