Receiver diversity with blind and semi-blind FIR SIMO channel estimates

Abstract

Traditionally, the performance of blind SIMO channel estimates has been characterized in a deterministic fashion, by identifying those channel realizations that are not blindly identifiable. In this paper, we focus instead on the performance of Zero-Forcing (ZF) Linear Equalizers (LEs) or Decision-Feedback Equalizers (DFEs) for fading channels when they are based on (semi-)blind channel estimates. Although it has been known that various (semi-)blind channel estimation techniques have a receiver counterpart that is matched in terms of symbol knowledge hypotheses, we show here that these (semi-)blind techniques and corresponding receivers also match in terms of diversity order: the channel becomes (semi-)blindly unidentifiable whenever its corresponding receiver structure goes in outage. In the case of mismatched receiver and (semi-blind) channel estimation technique, the lower diversity order dominates. Various cases of (semi-)blind channel estimation and corresponding receivers are considered in detail. To be complete however, the actual combination of receiver and (semi-)blind channel estimation lowers somewhat the diversity order w.r.t. the ideal picture.