Channel coding, multiuser detection, and space-time diversity for multicarrier CDMA systems.

摘要

Multicarrier code division multiple access (MC-CDMA) is a promising multiuser modulation scheme for enabling high-speed wireless transmission capabilities. In this dissertation, we investigate various advanced coding and receiver signal processing techniques for MC-CDMA systems.; The initial study focuses on the performance analysis of MC-CDMA systems with two powerful coding techniques, turbo codes and serial concatenated convolutional codes (SCCC). Analytical bounds on bit error rate performance are derived for fully interleaved Rayleigh fading channels. Performance analysis with turbo and SCCC coding is also carried out for high-rate data transmission over wideband Rayleigh fading channels.; The next part of the dissertation deals with multiuser detection techniques for coded MC-CDMA systems. First, a combination of SCCC coding and successive interference cancellation is investigated for high-rate data transmission over Rayleigh fading channels. Next, we discuss various iterative multiuser detection schemes for MC-CDMA uplink systems. Iterative multiuser detection looks into the problem of multiuser detection and channel decoding jointly, which provides improved performance through iterative processing between the detector and the channel decoders. A novel low complexity iterative receiver structure is proposed, which is based on groupwise multiuser detection, interference cancellation and iterative processing with the decoders. The receiver performs very close to the optimum MAP-based iterative receiver, with much lower computational requirements.; In addition, design of iterative multiuser receivers for MC-CDMA uplink transmission systems in the presence of unknown interference is investigated. We derive various iterative multiuser receivers using a subspace based semi-blind approach. These receivers are based on linear multiuser detection and interference cancellation, which suppress both intracell and intercell interferences.; To further improve the system capacity and performance, we investigate the application of space-time diversity techniques in MC-CDMA systems. A group-based low-complexity iterative multiuser receiver is proposed for space-time coded MC-CDMA system over frequency selective Rayleigh fading channels. In addition, various semi-blind space-time iterative multiuser receivers are developed for multiple transmit and receive antenna MC-CDMA systems. The combination of channel decoding, space-time processing and semi-blind multiuser detection provides a very attractive and robust receiver structure that can exploit efficient diversity reception as well as cope with both the known and unknown interferences.