Limiting Performance of Conventional and Widely Linear DFT-precoded-OFDM Receivers in Wideband Frequency Selective Channels

TL;DR

This paper analyzes the limiting behavior of linear and decision feedback equalizers in wideband frequency selective channels, showing they achieve near-optimal post-SNR and BER performance in Rayleigh fading environments.

Contribution

It provides analytical expressions for post-SNR in conventional and widely linear DFT-precoded-OFDM receivers under wideband fading conditions.

Findings

Equalizers reach a fixed post-SNR close to the matched filter bound.

Receivers effectively mitigate fading and ISI in frequency selective channels.

Simulation confirms near-optimal BER performance of the considered receivers.

Abstract

This paper describes the limiting behavior of linear and decision feedback equalizers (DFEs) in single/multiple antenna systems employing real/complex-valued modulation alphabets. The wideband frequency selective channel is modeled using a Rayleigh fading channel model with infinite number of time domain channel taps. Using this model, we show that the considered equalizers offer a fixed post signal-to-noise-ratio (post-SNR) at the equalizer output that is close to the matched filter bound (MFB). General expressions for the post-SNR are obtained for zero-forcing (ZF) based conventional receivers as well as for the case of receivers employing widely linear (WL) processing. Simulation is used to study the bit error rate (BER) performance of both MMSE and ZF based receivers. Results show that the considered receivers advantageously exploit the rich frequency selective channel to mitigate both fading and inter-symbol-interference (ISI) while offering a performance comparable to the MFB.