Full-Duplex Relaying over Block Fading Channel: A Diversity Perspective

TLDR

The study investigates full‑duplex relaying protocols that extract diversity gains over block‑fading channels. The authors propose a block‑by‑block transmission scheme that spans multiple fading realizations, guaranteeing at least one diversity order, and analyze its diversity‑multiplexing trade‑off for AF and DF relays with or without imperfect loop‑interference cancellation, presenting universal codes that achieve the trade‑off. AF relaying without loop‑interference cancellation achieves full time diversity regardless of interference statistics, whereas imperfect cancellation limits diversity to one under strong residual interference.

Abstract

In this paper, we study full-duplex (FD) operation from a diversity perspective and investigate several protocols that extract diversity gains over a block fading channel. The investigated approach introduces a block-by-block transmission and requires data codewords that span several independent realizations of channel fading. This fundamental approach ensures a diversity gain at least equal to one (i.e., it does not suffer from error floors) and is employed to different relaying strategies without loop interference cancellation (LIC) and with imperfect LIC: a) Amplify-and-Forward (AF) without LIC, b) AF with imperfect LIC and c) Decode-and-Forward with imperfect LIC. The proposed protocols are analyzed from a diversity-multiplexing tradeoff (DMT) standpoint and practical universal codes that achieve the DMT of the proposed schemes are also presented. We show that AF without LIC ensures a full time diversity independently on the statistics of the loop interference, and it is introduced as a general FD-based relaying scheme. In addition, we demonstrate that imperfect LIC is not efficient for cases with strong residual loop interference and limits the diversity gain to one.