Experiment-driven Characterization of Full-Duplex Wireless Systems

TL;DR

This paper provides an experimental analysis of passive and active self-interference cancellation techniques in full-duplex wireless systems, revealing how cancellation effectiveness varies with interference power and the importance of selective digital cancellation.

Contribution

It offers a detailed experimental characterization of passive suppression and active cancellation, including their dependence on interference power and the distribution of the interference channel.

Findings

Active cancellation effectiveness increases with interference power.

Digital cancellation can sometimes worsen interference, requiring selective application.

Self-interference channel distribution changes after cancellation.

Abstract

We present an experiment-based characterization of passive suppression and active self-interference cancellation mechanisms in full-duplex wireless communication systems. In particular, we consider passive suppression due to antenna separation at the same node, and active cancellation in analog and/or digital domain. First, we show that the average amount of cancellation increases for active cancellation techniques as the received self-interference power increases. Our characterization of the average cancellation as a function of the self-interference power allows us to show that for a constant signal-to-interference ratio at the receiver antenna (before any active cancellation is applied), the rate of a full-duplex link increases as the self-interference power increases. Second, we show that applying digital cancellation after analog cancellation can sometimes increase the self-interference, and thus digital cancellation is more effective when applied selectively based on measured suppression values. Third, we complete our study of the impact of self-interference cancellation mechanisms by characterizing the probability distribution of the self-interference channel before and after cancellation.