A NOMA-Combined Hybrid Approach for SDMA Improvement in Wireless Powered Communication Networks

Abstract

Wireless Powered Communication Network (WPCN) consists of Hybrid Access Point (HAP) that performs power transmission and data collection at the same time, and multiple nodes that can transmit data. In WPCN, depending on the wireless communication environment, the nodes cannot be able to transmit data because they can fail to receive power. Hence, increasing the transmission rate under a given resource is one of the very important issues. In ordinary mobile communications, a cell is divided into several sectors and the data is collected through multiple antennas to increase the transmission rate using SDMA. As a result, if the number of nodes in the one sector increases, the interference between nodes increases, and the transmission rate may decrease. Accordingly, in order to maximize performance, the number of nodes that can exist in a sector must be limited. The transmission rate between nodes according to the distance difference may not be fair because the nodes far from the HAP charge a small amount of power by attenuation of the signal, and the nodes close to the HAP charge a relatively large amount of power. Therefore, we propose Hybrid SDMA and Non-Orthogonal Multiple Access (NOMA) as a way to maximize the performance in term of both Sum-Throughput and Fairness. Also, we prove that there is a tradeoff between Sum-Throughput and Fairness according to the number of sectors. The simulation results show that the Hybrid SDMA and NOMA improves the performance substantially compared to the conventional SDMA.

Optimal Power Allocation with Sectored Cells for Sum-Throughput Maximization in Wireless-Powered Communication Networks Based on Hybrid SDMA/NOMA

“…SDMA techniques were studied in [27][28][29][30][31][32], and SDMA increases the available spectral efficiency, range, and bandwidth to moving wireless devices. In [33], the author proposed a hybrid approach based on multiuser multi-input single-output (MU-MISO) to improve the existing SDMA. As the interference between multiple WDs is reduced through spatial multiplexing and NOMA, sum throughput is improved.…”

An effective combination of terahertz band NOMA and MIMO system for power efficiency enhancement

“…In order to deal with the non-convexity issue, the second-order cone and sequential convex approximation were jointly utilized. Maeng et al 22 implemented multiple user-multiple input single output (MU-MISO)-based hybrid space division multiple access (SDMA) and NOMA to enhance the wireless powered communication network (WPCN) performance. SDMA and spatial multiplexing with multiple antennas could enhance the throughput.…”