A Novel Strategy for Proficient Channel Limitation Equalizer

Abstract

A time-domain equalizer (TEQ) employed in cascade with the channel yields an actual impulse response that is squatter than the channel impulse response. Time-domain equalization is critical in reducing channel state dimension in maximum likelihood sequence approximation, and inter-carrier and inter-symbol interference in multicarrier systems. This project evaluates two TEQ design methods docile to cost-effective real-time implementation: least mean squared error (LMSE) and extreme shortening SNR (ESSNR) methods. We condense the complexity of computing the matrices in the ESSNR and LMSE designs by a factor of 140 and a factor of 16 (respectively) relative to existing approaches, without degrading performance. We prove that an infinite length ESSNR TEQ with unit norm TEQ constraint is symmetric. A symmetric TEQ halves FIR implementation density, enables parallel training of the frequency-domain equalizer and TEQ, reduces TEQ training complexity by a factor of 4 and doubles the length of the TEQ that can be designed using fixed-point arithmetic, with only a small loss in bit rate. Simulations are presented for designs with a symmetric TEQ or target impulse response.