Virtually Full-duplex Cell-Free Massive MIMO with Access Point Mode Assignment

TL;DR

This paper introduces a virtually full-duplex cell-free massive MIMO system that optimizes access point mode assignment and power control to significantly enhance spectral efficiency over traditional schemes.

Contribution

It proposes a novel joint optimization framework for AP mode assignment and power control in vFD cell-free MIMO, employing successive convex approximation for solution.

Findings

vFD approach achieves 2.5 times higher sum SE than half-duplex.

Proposed algorithm effectively maximizes spectral efficiency.

Numerical results validate the superiority of the vFD scheme.

Abstract

We consider a cell-free massive multiple-input multiple-output (MIMO) network utilizing a virtually full-duplex (vFD) mode, where access points (APs) with a downlink (DL) mode and those with an uplink (UL) mode simultaneously serve DL and UL users (UEs). In order to maximize the sum spectral efficiency (SE) of the DL and UL transmissions, we formulate a mixed-integer optimization problem to jointly design the AP mode assignment and power control. This problem is subject to minimum per-UE SE requirements, per-AP power control, and per-UL UE power constraints. By employing the successive convex approximation technique, we propose an algorithm to obtain a stationary solution of the formulated problem. Numerical results show that the proposed vFD approach can provide a sum SE that is $2.5$ and $1.5$ times larger than the traditional half-duplex and heuristic baseline schemes, respectively, in terms of $95\%$-likely sum SE.