Iterative Joint Channel Estimation and Multiuser Detection for DS-CDMA in Frequency-Selective Fading Channels

• Published in: IEEE transactions on signal processing Vol. 56; no. 7; pp. 3261 - 3277
• Main Authors: Sau-Hsuan Wu, Mitra, U., Kuo, C.-C.J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ambiguity; Applied sciences; Cancellation; Channel estimation; Channels; Detection, estimation, filtering, equalization, prediction; DS-CDMA; Estimators; Exact sciences and technology; expectation maximization (EM); Fading; Frequency-selective fading channels; Information, signal and communications theory; Interference cancellation; Iterative methods; joint estimation and detection; Miscellaneous; Multiaccess communication; Multiuser detection; noncoherent detection; Phase detection; Phase estimation; Phase frequency detector; Recursive estimation; Signal and communications theory; Signal processing; Signal processing algorithms; Signal, noise; Symbols; Telecommunications and information theory; Parameter estimation; Noise reduction; Iterative method; Stochastic method; expectation maximization (EM); DS-CDMA; Frequency selection; noncoherent detection; Channel estimation; Stochastic signal; Direct sequence; Signal detection; Fading channels; Multiuser detection; Fading; Multiple access; joint estimation and detection; Joint detection; Interference suppression; Symbol detection; Signal interference; Posterior probability; Code division multiple access; Signal processing; EM algorithm; Phase reconstruction; Recursive estimation
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2008.920146

An iterative joint channel estimation, symbol detection, phase recovery and interference cancellation structure is proposed for asynchronous code-division multiple-access systems over frequency-selective fading channels. Based on the expectation maximization (EM) algorithm, a recursive channel estimator is developed for blind channel tracking, using a novel stochastic signal processing technique. To perform symbol detection given the phase ambiguities of the resultant EM channel estimates, a noncoherent scheme is developed to compute the a posteriori probabilities (APPs) of data symbols. Moreover, by incorporating the APPs into the proposed recursive channel estimator, phase ambiguity due to the EM channel estimation can be resolved, which enables soft multiple access interference cancellation for multiuser detection. Based on these new signal processing schemes, an iterative structure is proposed for joint channel estimation and multiuser detection over fast fading channels.