tailieunhanh - Báo cáo hóa học: " Adaptive Iterative Soft-Input Soft-Output Parallel Decision-Feedback Detectors for Asynchronous Coded "

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: Adaptive Iterative Soft-Input Soft-Output Parallel Decision-Feedback Detectors for Asynchronous Coded | EURASIP Journal on Wireless Communications and Networking 2005 2 155-162 2005 Hindawi Publishing Corporation Adaptive Iterative Soft-Input Soft-Output Parallel Decision-Feedback Detectors for Asynchronous Coded DS-CDMA Systems Wei Zhang School of Information Technology and Engineering SITE University of Ottawa 800 King Edward Avenue Ottawa ON Canada K1N 6N5 Email weizhang@ Claude D Amours School of Information Technology and Engineering SITE University of Ottawa 800 King Edward Avenue Ottawa ON Canada K1N 6N5 Email damours@ Abbas Yongacoglu School of Information Technology and Engineering SITE University of Ottawa 800 King Edward Avenue Ottawa Ontario Canada K1N 6N5 Email yongacog@ Received 29 April 2004 Revised 4 October 2004 The optimum and many suboptimum iterative soft-input soft-output SISO multiuser detectors require a priori information about the multiuser system such as the users transmitted signature waveforms relative delays as well as the channel impulse response. In this paper we employ adaptive algorithms in the SISO multiuser detector in order to avoid the need for this a priori information. First we derive the optimum SISO parallel decision-feedback detector for asynchronous coded DS-CDMA systems. Then we propose two adaptive versions of this SISO detector which are based on the normalized least mean square NLMS and recursive least squares RLS algorithms. Our SISO adaptive detectors effectively exploit the a priori information of coded symbols whose soft inputs are obtained from a bank of single-user decoders. Furthermore we consider how to select practical finite feedforward and feedback filter lengths to obtain a good tradeoff between the performance and computational complexity of the receiver. Keywords and phrases soft-input soft-output multiuser detection adaptive multiuser detection parallel decision-feedback detection adaptive soft-input soft-output parallel decision-feedback detection asynchronous