Title :
Soft decision directed MAP estimate of fast Rayleigh flat fading channels
Author_Institution :
Center for Wireless Commun., California Univ., San Diego, La Jolla, CA
Abstract :
An iterative receiver with soft decision feedback is derived to yield a maximum a posteriori (MAP) estimate of fast Rayleigh flat fading channels. The derivation is based on the expectation-maximization (EM) algorithm. Simulation results indicate that the derived receiver performs better than an iterative receiver with hard decision feedback, for both uncoded data and convolutionally coded data. The combination with turbo codes is also investigated. Three kinds of decision feedback are proposed and compared namely, re-encoder, soft decision feedback and quantizer. It is shown via simulation that soft decision feedback is the best while the quantizer has similar performance. The re-encoder, on the other hand has performance degradation
Keywords :
Rayleigh channels; concatenated codes; convolutional codes; feedback; iterative decoding; maximum likelihood estimation; optimisation; quantisation (signal); receivers; turbo codes; EM algorithm; MLE; convolutionally coded data; decision feedback; expectation-maximization algorithm; fast Rayleigh flat fading channels; iterative decoder; iterative receiver; maximum a posteriori estimate; parallel concatenated convolutional codes; quantizer; re-encoder; simulation results; soft decision directed MAP estimate; soft decision feedback; turbo codes; uncoded data; Channel estimation; Convolutional codes; Degradation; Fading; Feedback; Iterative decoding; Maximum likelihood estimation; Rayleigh channels; Wireless communication; Yield estimation;
Conference_Titel :
MILCOM 2000. 21st Century Military Communications Conference Proceedings
Conference_Location :
Los Angeles, CA
Print_ISBN :
0-7803-6521-6
DOI :
10.1109/MILCOM.2000.904977
