Achievable Sum Rates of Half- and Full-Duplex Bidirectional OFDM Communication Links

TL;DR

This paper analyzes the achievable sum rates of half- and full-duplex OFDM communication links considering practical non-idealities, proposing optimized strategies and comparing their performance across various channel conditions.

Contribution

It introduces optimized transmission strategies for HD and FD OFDM links that account for practical non-idealities and provides low-complexity solutions with near-optimal performance.

Findings

FD can nearly double capacity under ideal conditions

Optimized strategies outperform uniform power allocation

Performance varies with channel type and asymmetry

Abstract

While full-duplex (FD) transmission has the potential to double the system capacity, its substantial benefit can be offset by the self-interference (SI) and non-ideality of practical transceivers. In this paper, we investigate the achievable sum rates (ASRs) of half-duplex (HD) and FD transmissions with orthogonal frequency division multiplexing (OFDM), where the non-ideality is taken into consideration. Four transmission strategies are considered, namely HD with uniform power allocation (UPA), HD with non-UPA (NUPA), FD with UPA, and FD with NUPA. For each of the four transmission strategies, an optimization problem is formulated to maximize its ASR, and a (suboptimal/optimal) solution with low complexity is accordingly derived. Performance evaluations and comparisons are conducted for three typical channels, namely symmetric frequency-flat/selective and asymmetric frequency-selective channels. Results show that the proposed solutions for both HD and FD transmissions can achieve near optimal performances. For FD transmissions, the optimal solution can be obtained under typical conditions. In addition, several observations are made on the ASR performances of HD and FD transmissions.