Analysis of Key Generation Rate from Wireless Channel in In-Band Full-Duplex Communications

TL;DR

This paper investigates how in-band full-duplex wireless devices can enhance secret key generation rates by utilizing simultaneous channel sensing, overcoming half-duplex limitations, and analyzing the impact of self-interference cancellation.

Contribution

It proposes a key generation strategy for IBFD devices, analyzing the effects of self-interference and showing conditions where IBFD outperforms half-duplex in key rate.

Findings

IBFD can achieve higher key rates than HD with effective SI cancellation.

In high SNR, IBFD significantly outperforms HD in key generation.

Key rate loss occurs due to SI channel estimation overhead.

Abstract

In this paper, the impact of in-band full-duplex (IBFD) wireless communications on secret key generation via physical layer channel state information is investigated. A key generation strategy for IBFD wireless devices to increase the rate of generated secret keys over multipath fading channels is proposed. Conventionally, due to the half-duplex (HD) constraint on wireless transmissions, sensing simultaneous reciprocal channel measurements is not possible, which leads to a degraded key generation rate. However, with the advent of IBFD wireless devices, the legitimate nodes can sense the shared wireless link simultaneously at the possible cost of a self-interference (SI) channel estimation and some residual self-interference (RSI). As we demonstrate, with HD correlated observations the key rate is upper bounded by a constant, while with IBFD the key rate is only limited by the SI cancellation performance and is in general greater than that of its HD counterpart. Our analysis shows that with reasonable levels of SI cancellation, in the high SNR regime the key rate of IBFD is much higher, while in low SNRs, the HD system performs better. Finally, the key rate loss due to the overhead imposed by the SI channel estimation phase is discussed.