Semiblind Multiuser Detection for MC-CDMA

Download or read book Semiblind Multiuser Detection for MC-CDMA written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The code-division multiple-access (CDMA) technique has emerged in recent years as the preferred multiple access technique for providing voice and multimedia services in modern mobile communications. However, the traditional use of the DS-CDMA technology does not appear realistic for very high data-rate multimedia services due to the severe multipath-induced intersymbol interference as well as multiple access interference. To mitigate the interchip and intersymbol interferences, multicarrier CDMA (MC-CDMA) communication systems, which integrate the advantages of multicarrier transmission systems with those of CDMA, has attracted much attention over the last several years. Traditional multiuser detection techniques for MC-CDMA require either prior knowledge, such as spreading sequences, amplitudes and/or timing, regarding all active users or some explicit estimation procedures for this information. It makes such technology difficult for practical implementation for high data rate multiuser receivers. In this thesis, a different approach for MC-CDMA multiuser receiver design is proposed. Instead of the traditional multiuser vector channel model, a new semiblind multiuser vector channel model and a new semiblind multiuser detection framework are proposed. With this semiblind multiuser detection framework, several group-based semiblind multiuser detectors, which can detect the information bits of more than one spreading channel or user, are proposed for MC-CDMA wireless communication systems. These multiuser detectors are based on a semiblind signature matrix and least squares criterion. The proposed algorithms are simple and direct. Differing from other blind or semiblind multiuser detection algorithms, no search or pairing procedure is required but only the amplitude of the desired user. Besides the derived relationship between the proposed algorithms and the conventional decorrelating detector, a geometric interpretation and the criteria of choosing the size of the semiblind spreading matrix are discussed. Computer simulations are finally provided to demonstrate the performance of the algorithms.