Measurement based performance evaluation of finite MMSE equalizers with and without time-reversal processing at the transmitter

Abstract

Time reversal (TR) is a transmission technique that relies on pre-processing the signal at the transmitter (TX) by filtering it through a filter, the impulse response of which is a time reversed and phase conjugated version of the channel impulse response (CIR) to the target receiver (RX). TR is known to have remarkable temporal and spatial focusing properties. Specifically temporal focusing indicates that the perceived channel delay spread is reduced, and therefore we expect a less complicated equalizer to be required at the RX side to guarantee successful signal detection. In this paper we investigate how TR preprocessing affects the performance of finite minimum mean square error (MMSE) equalizers. The results are based on wideband measurements taken in an urban environment. We show that the application of TR is beneficial in the case of low signal to noise ratio (SNR) and low equalizer complexity.