tailieunhanh - 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 Armin Dammann Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email Stephan Sand Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email Stefan Kaiser Research Group for Mobile Radio Transmission Institute of Communications and Navigation German Aerospace Center DLR Oberpfaffenhofen 82234 Wessling Germany Email Gunther Auer NTT DoCoMo Euro-Labs 80687 Munich Germany Email auer@ 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