This study investigated the effectiveness of spatio-temporal scheduling in coordinated multi-transmitter WPT systems and demonstrated the potential of the proposed scheme for robust and efficient power supply, even under shadowing conditions.
Abstract
In multi-user wireless power transfer (WPT), scheduling schemes that determine the allocation of transmission resources among receivers play a crucial role in improving power transfer efficiency. Scheduling can be classified into time-division (TD) and space-division (SD) schemes, with the transmission order and direction designed to control when and to whom power is delivered. TD-WPT can exploit the nonlinear characteristics of rectennas by concentrating power in time; however, a system relying on highly directional transmission from a single location reduces robustness under time-varying channel conditions. This study investigated the effectiveness of spatio-temporal scheduling in coordinated multi-transmitter WPT systems. By employing multiple transmitters, the proposed method is robust against channel variations in delivering power. Moreover, coordinated beamforming among transmitters exploits inter-cluster interference. Simulation results demonstrate the potential of the proposed scheme for robust and efficient power supply, even under shadowing conditions.
Simulation results demonstrate that the APS NOMA scheme outperforms both the FPS NOMA and Orthogonal Multiple Access schemes, reducing OP significantly across a range of SNRs, making it highly effective for reliable and energy-efficient communication in future wireless networks.
S. Ajibowu, O. Adeleke, M. Asafa et al.· Nigerian Journal of Technolo...· 0 citations
With the increasing demand for efficient wireless communication services, researchers are actively seeking innovative solutions to optimize spectrum utilization. Two promising technologies, cognitive radio and non-orthogonal multiple access (CR-NOMA), have emerged as key enablers for next-generation wireless communication. By harnessing the available radio frequency spectrum, devices can cooperatively connect and communicate more efficiently, while also gathering energy to support green communication.
This study investigates the uplink simultaneous wireless power and information transfer (SWIPT) using a CR-NOMA system over Rayleigh fading channel, focusing on energy harvesting at the secondary transmitter (ST) as a cooperation node. Here, primary/secondary receivers (PR/SR) communicate with the ST, during first phase, which then utilizes the harvested power to transmit the primary data to the primary transmitter. This paper enhances the proposed system cell-edge user performance and derives analytical frameworks for outage probability, throughput, and ergodic capacity of PR, SR, respectively. Additionally, our results determine the optimal power allocation scheme to enhance the performance of PR/SR signals.
Rate-Splitting Multiple Access (RSMA) has emerged as a robust interference management strategy for future wireless networks. This paper investigates the performance of a hierarchical RSMA scheme in the downlink of a multi-antenna system, designed to efficiently serve clustered user deployments. We derive exact and asymptotic closed-form expressions for the outage probability of users under Nakagami- $m$ fading channels, considering a two-layer message splitting architecture (systemcommon, group-common, and private streams). Furthermore, to ensure fairness and reliability, we formulate a min-max power allocation problem to minimize the worst-case outage probability among users. A Geometric Programming-based algorithm is proposed to solve the resulting non-convex optimization problem. The numerical results validate the theoretical analysis and demonstrate the impact of different strategies for using this model, such as the number of users per group, user allocation strategies, and the number of base station transmit antennas.
R. P. De Souza, E. Olivo· International Mediterranean...· 0 citations
Network-level integrated sensing and communication (ISAC) is recognized as a transformative technology for next-generation mobile radio systems. By enabling collaboration among multiple transceivers, network-level ISAC can significantly enhance both communication and sensing performance through spatial diversity. However, existing resource allocation strategies typically overlook the impact of spatial geometry, where identical time-frequency resources contribute differently to sensing accuracy depending on the transceiver's location. This leaves the fundamental coupling between spatial topology and resource efficacy unclear, rendering optimal resource allocation a critical challenge for unlocking the full potential of network-level ISAC.To address this challenge, this paper investigates the optimal distribution of time-frequency resources across spatially distributed transceivers through a theoretically grounded two-stage framework. First, we analytically derive the optimal time and frequency aperture distributions for sensing, defined as the variances of the allocated symbol and subcarrier indices, respectively, under both two-transmitter and multi-transmitter scenarios. By exploiting the mathematical isomorphism between delay and Doppler estimation, we prove that the optimal resource allocation strategy follows the gradient direction of the Cramer-Rao Lower Bound (CRLB) with respect to the apertures. Second, to bridge the gap between theoretical aperture values and practical OFDMA constraints, such as the minimized communication rate of each user equipment (UE), we formulate the resource allocation as a combinatorial integer partitioning problem. To tackle the NP-hard nature of the formulated problem, a low-complexity Variance-Guided Partitioning Algorithm (VGPA) is proposed to jointly optimize the subcarrier and symbol patterns for communication and sensing.
Xiao-Yang Wang, Luting Kong, Lei Cao et al.· 0 citations
This work theoretically proves that TSDM achieves the desired mean and temporal variance for each flow, and conducts extensive simulations on two open joint throughput-AoI optimization problems, finding that TSDM significantly outperforms existing scheduling policies.
This paper investigates joint subcarrier and power allocation for a multi-user Orthogonal Frequency Division Multiplexing (OFDM)-based Integrated Sensing and Communication (ISAC) system in Vehicle-to-Everything (V2X) environments. The goal is to maximize a weighted sum of the capped effective radar Signal-to-Noise Ratio (SNR) and aggregate communication rate, under per-user constraints on minimum effective radar SNR, communication rate, and range resolution. The problem is formulated as a Mixed-Integer Nonlinear Programming (MINLP) model. To address its non-convexity, we develop a Block Coordinate Descent–based Joint Resource Allocation (BCD-JRA) algorithm that alternates between nonlinear power allocation and mixed-integer subcarrier assignment and is used as a benchmark in our study. To support real-time V2X operation, we further propose a low-complexity two-stage heuristic, termed Phased Constraint Satisfaction and Greedy Allocation (PSGA). PSGA first allocates the minimum resources needed to satisfy the Quality of Service (QoS) constraints, and then greedily assigns remaining resources based on marginal utility gains while accounting for effective radar SNR capping. The simulation results show that PSGA attains utility close to the BCD-JRA benchmark with millisecond-level latency and satisfies all QoS constraints in the reported experiments.
Jiahao Zheng, Xinhao Chen, Linyu Huang et al.· IEEE Transactions on Wireles...· 0 citations