Partially-blind Estimation of Reciprocal Channels for AF Two-Way Relay Networks Employing M-PSK Modulation

TL;DR

This paper introduces a new consistent channel estimation method for AF two-way relay networks with M-PSK, improving accuracy at high SNR while analyzing the limitations of previous estimators.

Contribution

It proposes a novel consistent estimator for reciprocal channels in AF two-way relay networks with M-PSK, addressing limitations of earlier approaches.

Findings

The new estimator is consistent and performs well at high SNR.

The previous estimator is not consistent but approaches the true channel at high SNR.

The Cramer-Rao bound for unbiased estimators is derived.

Abstract

We consider the problem of channel estimation for amplify-and-forward two-way relays assuming channel reciprocity and M-PSK modulation. In an earlier work, a partially-blind maximum-likelihood estimator was derived by treating the data as deterministic unknowns. We prove that this estimator approaches the true channel with high probability at high signal-to-noise ratio (SNR) but is not consistent. We then propose an alternative estimator which is consistent and has similarly favorable high SNR performance. We also derive the Cramer-Rao bound on the variance of unbiased estimators.