An efficient implementation for MMSE based MIMO time domain equalizer

A time domain equalizer is a finite impulse response filter that shortens the channel impulse response to mitigate inter-symbol interference (ISI). Al-Dhahir and Cioffi proposed a design criteria for single input single output TEQ based on designing a MMSE decision feedback equalizer. They also extended this method to MIMO channels. In this paper, we propose a simple implementation of time domain equalizer for MIMO channels also based on the MMSE criteria. The solution is simplified compared to the above solution by eliminating the cross channel linear equalizers. This results in a set of M independent equalizers, each designed to meet a multi-objective channel shortening MMSE criterion. The new method is simple and provides good results for the MIMO problem. Finally we demonstrate the efficiency of the proposed approach compared to the Al-Dhahir's on measured channels, where the NEXT channels are simultaneously shortened with the direct channels. These are the first published results demonstrating MIMO-TEQ design on real life measured DSL channels.