Iterative Multiuser Detection for Single Carrier Space-Time Block-Coded CDMA transmission Over Frequency-Selective Fading Channel.

• Main Authors: Wei-yu Lai, 賴威諭
• Other Authors: Der-feng Tseng
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/qks43r

碩士 === 國立臺灣科技大學 === 電機工程系 === 94 === In this thesis, we combine single carrier space-time blocked transmission with multi-user CDMA system, in the meanwhile, we adopt low complexity iterative multi-user detection and consider frequency selective fading channel. Besides, in order to increase data rate, we use super-orthogonal codes to extension. In transmitter, for combination of super-orthogonal codes, CDMA system and single carrier transmission, we propose a new space-time block codes structure. Take two transmitter antennas as an example, this structure need to have two spreading sequence to distinguish different user. Utilization of MTCM, we can increase data rate and apply this structure to multi-user system. The receiver, based on these user-specific sequences, intends to differentiate the active users by invoking the “turbo principle” decoding due to the serially concatenated framework. A soft-input soft-output (SISO) interference suppressor for each user is first derived by minimum mean-square error sense to provide the reliability estimates of coded bits, assuming the channel state information is known precisely at the receiver. The resulting extrinsic information for coded bit streams is passed through a bank of single-user decoders after being de-interleaved. Simulation results demonstrate system performance in terms of bit error probability with variant ratio of the number of users to spreading length for the receiver equipped with multi-antennas. Besides, the performance comparison with conventional coded DS-CDMA systems is also manifested under the constraint of identical power and bandwidth efficiencies.