tailieunhanh - Báo cáo sinh học: " Research Article Low Complexity MLSE Equalization in Highly Dispersive Rayleigh Fading Channels"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Research Article Low Complexity MLSE Equalization in Highly Dispersive Rayleigh Fading Channels | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 874874 16 pages doi 2010 874874 Research Article Low Complexity MLSE Equalization in Highly Dispersive Rayleigh Fading Channels H. C. Myburgh1 and J. C. Olivier1 2 1 Department of Electrical Electronic and Computer Engineering University of Pretoria Lynnwood Road 0002 Pretoria South Africa 2Defence Research Unit CSIR Meiring Naude Road 0184 Pretoria South Africa Correspondence should be addressed to H. C. Myburgh Received 1 October 2009 Revised 29 March 2010 Accepted 30 June 2010 Academic Editor Xiaoli Ma Copyright 2010 H. C. Myburgh and J. C. Olivier. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. A soft output low complexity maximum likelihood sequence estimation MLSE equalizer is proposed to equalize M-QAM signals in systems with extremely long memory. The computational complexity of the proposed equalizer is quadratic in the data block length and approximately independent of the channel memory length due to high parallelism of its underlying Hopfield neural network structure. The superior complexity of the proposed equalizer allows it to equalize signals with hundreds of memory elements at a fraction of the computational cost of conventional optimal equalizer which has complexity linear in the data block length but exponential in die channel memory length. The proposed equalizer is evaluated in extremely long sparse and dense Rayleigh fading channels for uncoded BPSK and 16-QAM-modulated systems and remarkable performance gains are achieved. 1. Introduction Multipath propagation in wireless communication systems is a challenge that has enjoyed much attention over the last few decades. This phenomenon caused by the arrival of multiple delayed copies of the transmitted