tailieunhanh - Báo cáo hóa học: " Soft-In Soft-Output Detection in the Presence of Parametric Uncertainty via the Bayesian EM Algorithm"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Soft-In Soft-Output Detection in the Presence of Parametric Uncertainty via the Bayesian EM Algorithm | EURASIP Journal on Wireless Communications and Networking 2005 2 100-116 2005 Hindawi Publishing Corporation Soft-In Soft-Output Detection in the Presence of Parametric Uncertainty via the Bayesian EM Algorithm A. S. Gallo Department of Information Engineering University of Modena and Reggio Emilia via Vignolese 905 41100 Modena Italy Email asgallo@ G. M. Vitetta Department of Information Engineering University of Modena and Reggio Emilia via Vignolese 905 41100 Modena Italy Email Received 30 April 2004 Revised 6 October 2004 We investigate the application of the Bayesian expectation-maximization BEM technique to the design of soft-in soft-out SISO detection algorithms for wireless communication systems operating over channels affected by parametric uncertainty. First the BEM algorithm is described in detail and its relationship with the well-known expectation-maximization EM technique is explained. Then some of its applications are illustrated. In particular the problems of SISO detection of spread spectrum singlecarrier and multicarrier space-time block coded signals are analyzed. Numerical results show that BEM-based detectors perform closely to the maximum likelihood ML receivers endowed with perfect channel state information as long as channel variations are not too fast. Keywords and phrases expectation-maximization algorithm soft-in soft-out detection fading channels space-time coding OFDM. I. INTRODUCTION In recent years many research efforts have been devoted to the study of detection algorithms for digital signals transmitted over channels affected by random parametric uncertainty like multipath fading channels and AWGN channels with phase jitter see . 1 2 3 4 5 6 7 8 9 10 II 12 13 and references therein . In this field the attention has been progressively shifting from maximum likelihood ML sequence detection 2 3 4 to maximum a posteriori MAP symbol detection techniques 5 6 7 8 9 10 11 12 13 producing a posteriori .