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: Computationally Efficient Blind Code Synchronization for Asynchronous DS-CDMA Systems with Adaptive | EURASIP Journal on Applied Signal Processing 2005 5 683-697 2005 Hindawi Publishing Corporation Computationally Efficient Blind Code Synchronization for Asynchronous DS-CDMA Systems with Adaptive Antenna Arrays Chia-Chang Hu Department of Electrical Engineering National Chung Cheng University Min-Hsiung Chia-Yi 621 Taiwan Email ieecch@ Received 28 July 2003 Revised 18 February 2004 A novel space-time adaptive near-far robust code-synchronization array detector for asynchronous DS-CDMA systems is developed in this paper. There are the same basic requirements that are needed by the conventional matched filter of an asynchronous DS-CDMA system. For the real-time applicability a computationally efficient architecture of the proposed detector is developed that is based on the concept of the multistage Wiener filter MWF of Goldstein and Reed. This multistage technique results in a self-synchronizing detection criterion that requires no inversion or eigendecomposition of a covariance matrix. As a consequence this detector achieves a complexity that is only a linear function of the size of antenna array J the rank of the MWF M the system processing gain N and the number of samples in a chip interval S that is O JMNS . The complexity of the equivalent detector based on the minimum mean-squared error MMSE or the subspace-based eigenstructure analysis is a function of Ỡ JNS 3 . Moreover this multistage scheme provides a rapid adaptive convergence under limited observation-data support. Simulations are conducted to evaluate the performance and convergence behavior of the proposed detector with the size of the J-element antenna array the amount of the L-sample support and the rank of the M-stage MWF. The performance advantage of the proposed detector over other DS-CDMA detectors is investigated as well. Keywords and phrases code-timing acquisition rank reduction smart antennas adaptive interference suppression generalized likelihood ratio test. 1. INTRODUCTION .
