Rate Gain Region and Design Tradeoffs for Full-Duplex Wireless Communications

TL;DR

This paper analytically characterizes the conditions under which practical full-duplex wireless systems outperform half-duplex systems, considering hardware impairments and providing a detailed rate gain region analysis.

Contribution

It introduces a comprehensive signal model accounting for hardware impairments and derives a piece-wise linear approximation of the rate gain region for full-duplex systems.

Findings

Full-duplex can outperform half-duplex in certain regimes with hardware impairments.

Phase noise significantly impacts the rate gain region.

Active analog or digital cancellation can achieve similar performance when phase noise dominates.

Abstract

In this paper, we analytically study the regime in which practical full-duplex systems can achieve larger rates than an equivalent half-duplex systems. The key challenge in practical full-duplex systems is uncancelled self-interference signal, which is caused by a combination of hardware and implementation imperfections. Thus, we first present a signal model which captures the effect of significant impairments such as oscillator phase noise, low-noise amplifier noise figure, mixer noise, and analog-to-digital converter quantization noise. Using the detailed signal model, we study the rate gain region, which is defined as the region of received signal-of-interest strength where full-duplex systems outperform half-duplex systems in terms of achievable rate. The rate gain region is derived as a piece-wise linear approximation in log-domain, and numerical results show that the approximation closely matches the exact region. Our analysis shows that when phase noise dominates mixer and quantization noise, full-duplex systems can use either active analog cancellation or base-band digital cancellation to achieve near-identical rate gain regions. Finally, as a design example, we numerically investigate the full-duplex system performance and rate gain region in typical indoor environments for practical wireless applications.