Low-Latency Multiuser Two-Way Wireless Relaying for Spectral and Energy Efficiencies

TL;DR

This paper explores low-latency multiuser two-way wireless relaying using full-duplex and time-split approaches, proposing optimization algorithms to enhance spectral and energy efficiencies in multi-antenna relay networks.

Contribution

It introduces a novel time-split relaying approach that avoids self-interference, along with path-following algorithms for joint power and beamformer optimization.

Findings

The second approach outperforms the first in numerical simulations.

Optimization algorithms effectively improve energy and spectral efficiencies.

The proposed methods handle complex nonconvex problems in relay networks.

Abstract

The paper considers two possible approaches, which enable multiple pairs of users to exchange information via multiple multi-antenna relays within one time-slot to save the communication bandwidth in low-latency communications. The first approach is to deploy full-duplexes for both users and relays to make their simultaneous signal transmission and reception possible. In the second approach the users use a fraction of a time slot to send their information to the relays and the relays use the remaining complementary fraction of the time slot to send the beamformed signals to the users. The inherent loop self-interference in the duplexes and inter-full-duplexing-user interference in the first approach are absent in the second approach. Under both these approaches, the joint users' power allocation and relays' beamformers to either optimize the users' exchange of information or maximize the energy-efficiency subject to user quality-of-service (QoS) in terms of the exchanging information throughput thresholds lead to complex nonconvex optimization problems. Path-following algorithms are developed for their computational solutions. The provided numerical examples show the advantages of the second approach over the first approach.