Load-Aware Dynamic Mode Selection for Network-Assisted Full-Duplex Cell-Free Large-Scale Distributed MIMO Systems

Yue Zhu,Jiamin Li,Heng Ye,Xiaohu You,Dongming Wang,Pengcheng Zhu

doi:10.1109/access.2022.3152545

Yue Zhu, Jiamin Li + Show 4 more

Open Access

https://doi.org/10.1109/access.2022.3152545

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Journal: IEEE Access	Publication Date: Jan 1, 2022
Citations: 4	License type: CC BY 4.0

Affiliation: Southeast University, Purple Mountain Laboratories

Abstract

The network-assisted full-duplex (NAFD) system realizes flexible duplex in the spatial domain within the same time-frequency resource. With the explosive growth of the number of users and remote antenna units (RAUs) under 6G scenario, the resource utilization of the system is lower. When the resource of users is selected by the RAUs to send or receive, collisions or congestion may occur due to mechanisms such as grant-free. Aiming at making better use of system resources, a load-aware dynamic mode selection scheme with NAFD scheme is proposed to improve the access efficiency and resource utility of the system. This paper first propose a centralized Q-learning algorithm which determines a clever strategy to approach the ultimate goal by itself and excels in environment dynamics. However, the size of the Q-table used in the centralized Q-learning algorithm for storage is huge. Further, a distributed multi-agent Q-learning algorithm is proposed which has a smaller size of Q-table and lower complexity to suit for actual scenarios. The simulation results showed that the proposed load-aware dynamic mode selection scheme can significantly improve resource utility and throughput performance than other traditional schemes.

Highlights

Ultra-reliable and low-latency communication (URLLC) related theories and technologies in 6G are in urgent need of breakthrough
Active and passive Self interference (SI) suppression techniques have been studied in [2] - [3], which makes full duplex (FD) a realistic technology for modern wireless systems. [4] studied a FD cell-free massive multiple-input multiple-output (MIMO) network, where the APs employ a simple conjugate beamforming/matched filtering scheme with the channel state information acquired through the uplink training with orthogonal pilots transmitted from the users
Algorithm 1 Proposed load-aware dynamic mode selection algorithm based on centralized Q-learning

Summary

Introduction

Ultra-reliable and low-latency communication (URLLC) related theories and technologies in 6G are in urgent need of breakthrough. [4] studied a FD cell-free massive multiple-input multiple-output (MIMO) network, where the APs employ a simple conjugate beamforming/matched filtering scheme with the channel state information acquired through the uplink training with orthogonal pilots transmitted from the users It provided a simple power control method to mitigate residual self-interference. Network-assisted full-duplex (NAFD) under cell-free massive MIMO network was proposed in [8], which does not have SI at the remote antenna unit (RAU) level and can solve the cross-link interference (CLI) problem by using joint processing [9] reducing the latency of interference cancellation It realizes flexible duplex transmission by selecting the uplink and downlink working modes of the RAUs in the spatial domain within the same time-frequency resource block at the network level, reducing the delay of the time division duplex (TDD) system and improving the

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