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Báo cáo hóa học: " Rotated Walsh-Hadamard Spreading with Robust Channel Estimation for a Coded MC-CDMA System"

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: Rotated Walsh-Hadamard Spreading with Robust Channel Estimation for a Coded MC-CDMA System | EURASIP Journal on Wireless Communications and Networking 2004 1 74-83 2004 Hindawi Publishing Corporation Rotated Walsh-Hadamard Spreading with Robust Channel Estimation for a Coded MC-CDMA System Ronald Raulefs Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email ronald.raulefs@dlr.de Armin Dammann Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email armin.dammann@dlr.de Stephan Sand Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email stephan.sand@dlr.de Stefan Kaiser Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email stefan.kaiser@dlr.de Gunther Auer NTT DoCoMo Euro-Labs 80687 Munich Germany Email auer@docomolab-euro.com Received 1 November 2003 Revised 2 April 2004 We investigate rotated Walsh-Hadamard spreading matrices for a broadband MC-CDMA system with robust channel estimation in the synchronous downlink. The similarities between rotated spreading and signal space diversity are outlined. In a multiuser MC-CDMA system possible performance improvements are based on the chosen detector the channel code and its Hamming distance. By applying rotated spreading in comparison to a standard Walsh-Hadamard spreading code a higher throughput can be achieved. As combining the channel code and the spreading code forms a concatenated code the overall minimum Hamming distance of the concatenated code increases. This asymptotically results in an improvement of the bit error rate for high signal-to-noise ratio. Higher convolutional channel code rates are mostly generated by puncturing good low-rate channel codes. The overall Hamming distance