Dynamic Bandwidth Allocation and Precoding Design for Highly-Loaded Multiuser MISO in Beyond 5G Networks

Abstract

Multiuser techniques play a central role in the fifthgeneration (5G) and beyond 5G (B5G) wireless networks that exploit spatial diversity to serve multiple users simultaneously in the same frequency resource. It is well known that a multi-antenna base station (BS) can efficiently serve a number of users not exceeding the number of antennas at the BS via precoding design. However, when there are more users than the number of antennas at the BS, conventional precoding design methods perform poorly because inter-user interference cannot be efficiently eliminated. In this paper, we investigate the performance of a highly-loaded multiuser system in which a BS simultaneously serves a number of users that is larger than the number of antennas. We propose a dynamic bandwidth allocation and precoding design framework and apply it to two important problems in multiuser systems: i) User fairness maximization and ii) Transmit power minimization, both subject to predefined quality of service (QoS) requirements. The premise of the proposed framework is to dynamically assign orthogonal frequency channels to different user groups and carefully design the precoding vectors within every user group. Since the formulated problems are non-convex, we propose two iterative algorithms based on successive convex approximations (SCA), whose convergence is theoretically guaranteed. Furthermore, we propose a low-complexity user grouping policy based on the singular value decomposition (SVD) to further improve the system performance. Finally, we demonstrate via numerical results that the proposed framework significantly outperforms existing designs in the literature.

Efficient Content Caching for Delivery Time Minimization in the LEO Satellite Networks

“…Although the impact of the bandwidth is numerically evaluated, these works do not exploit the flexible payload capability. It has been shown in our recent work [10], that joint bandwidth and transmit power design is beneficial in highly-loaded terrestrial systems. Furthermore, the authors of [11] showed that satellite communications can be improved by using geographical user demands.…”

User-Centric Flexible Resource Management Framework for LEO Satellites With Fully Regenerative Payload

“…Since the LEO satellites can only provide uninterrupted service to the particular area in the earth fixed beam scenario for about 10 to 15 minutes during one orbital, it is crucial to consider the HO scenario via inter-satellite link (ISL) [20]. Unfortunately, the existing literature lacks proper algorithm designs for HO duration involving multiple LEOs.…”

“…‚ We formulate a joint design of spot beam coverage, operating bandwidth, and multi-user precoding vectors to minimize the average delivery time in LEO-assisted caching networks, including HO scenarios. Although flexible bandwidth has been considered in satellite communications, to the best of our knowledge, this is the first work exploiting spatial multiplexing [20] technique within each spot beam in LEO-enabled caching systems thanks to fully flexible regenerative payload and electronically steered phased array antennas capabilities. ‚ We propose to solve the joint optimization problem via two sub-problems: beam coverage design and radio resource allocations.…”

Joint Optimization of 3D Placement and Radio Resource Allocation for Per-UAV Sum Rate Maximization

“…3 (8N KL+5N L+KL+L)) [28], [29]. Furthermore, assuming that t m are a total number of iterations, the overall complexity of Algorithm 2 is O t m (3N KL+N L) 3 (8N KL+5N L+KL+L) .…”