A Novel Precoder Design for OFDM Receivers in Unknown Fading Channels

This paper presents a novel precoder design for an orthogonal frequency division multiplexing (OFDM) system using a channel estimator. First, an asymptotically tight approximation of the pairwise error probability (PEP) error with channel estimation error is presented and is shown to improve the existing upper bound of the PEP. Using the proposed approximation, a near-optimal power allocation scheme is derived and investigated and a new precoding scheme is introduced to improve the bit error rate (BER) performance of the receiver assisted by a minimum mean square error (MMSE) channel estimator. Both experimental and theoretical results included in this paper show improvement in the BER performance of a receiver with channel estimators utilizing the introduced precoder and power allocation scheme.