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Báo cáo hóa học: " Super-Orthogonal Space-Time Turbo Transmit Diversity for CDMA"
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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Super-Orthogonal Space-Time Turbo Transmit Diversity for CDMA | EURASIP Journal on Applied Signal Processing 2005 6 861-871 2005 Daniel J. van Wyk et al. Super-Orthogonal Space-Time Turbo Transmit Diversity for CDMA Daniel J. van Wyk RapidMobile Pty Ltd Persequor Park Pretoria 0020 South Africa Email danie@rapidm.co.za Louis P. Linde Department of Electrical Electronic and Computer Engineering University of Pretoria Pretoria 0002 South Africa Email llinde@postino.up.ac.za Pieter G. W. van Rooyen Broadcom 15435 Innovation Drive San Diego CA 92128 USA Email pieter@broadcom.com Received 8 September 2003 Revised 30 July 2004 Studies have shown that transmit and receive diversity employing a combination of multiple transmit-receive antennas given ideal channel state information CSI and independent fading between antenna pairs will potentially yield maximum achievable system capacity. In this paper the concept of a layered super-orthogonal turbo transmit diversity SOTTD for downlink direct-sequence code-division multiple-access CDMA systems is explored. This open-loop transmit diversity technique improves the downlink performance by using a small number of antenna elements at the base station and a single antenna at the handset. In the proposed technique low-rate super-orthogonal code-spread CDMA is married with code-division transmit diversity CDTD . At the mobile receiver space-time ST RAKE CDTD processing is combined with iterative turbo code-spread decoding to yield large ST gains. The performance of the SOTTD system is compared with single- and multiantenna turbo-coded TC CDTD systems evaluated over a frequency-selective Rayleigh fading channel. The evaluation is done both by means of analysis and computer simulations. The performance results illustrate the superior performance of SOTTD compared to TC CDTD systems over practically the complete useful capacity range of CDMA. It is shown that the performance degradation characteristic of TC CDTD at low system loads due to the inherent TC error floor is alleviated by the SOTTD .