A scheduling algorithm based on downlink performance for full‐duplex MU‐MIMO systems

Abstract

A full-duplex (FD) multiuser multiple-input multiple-output (MU-MIMO) system, where a FD base station (BS) with multiple antennas serves multiple half-duplex (HD) user equipments (UEs) in both uplink (UL) and downlink (DL) via the same time-frequency resources, is considered. UE scheduling is in demand to manage the UL-to-DL interference (UDI) incurred by the FD operation. Existing scheduling algorithms require UDI channel state information between each pair of the candidate UEs, which incurs a significant amount of overhead as the number of UEs grows. To reduce the overhead, a new UE scheduling algorithm that uses channel reciprocity and UL-DL duality to design a scheduling algorithm based on downlink performance was designed. By selecting UEs only based on their DL channels and received UDI strength, the proposed scheme no longer requires the massive UDI channel state information (CSI). Numerical results demonstrate the proposed algorithm can achieve a near optimal performance without knowing any UDI CSI. 1 INTRODUCTION Full-duplex (FD) wireless communication has come closer to reality, thanks to development of self-interference cancellation and suppression techniques [1-5]. Recent research interest focuses on application of FD techniques in cellular networks [6-8]. However, FD operation in the cellular system incurs uplink-to-downlink interference (UDI), which may reduce the FD gain if not properly managed [9]. Papers [10] and [11] studied UDI management in FD networks, and proposed UDI management schemes based on interference alignment and wireless side-channels respectively. However, these two complex management schemes require communication nodes to cooperate closely with each other and a large amount of UDI channel estimation and feedback overhead, so their feasibility is very low for larger networks [12]. UE scheduling is an effective way to suppress the UDI by selecting the UL and the DL UEs that least interfere with each other [9, 13, 14]. The paper [9] proposed a two-step UE scheduling algorithm. The first step is to select some downlink UEs with the highest sum rate under the assumption of ignoring the influence of UDI. In the second step, when selecting an uplink UEs, we comprehensively consider the uplink sum rate This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.