Title :
Joint estimation of time delays and DOAs for DS-CDMA system over multipath Rayleigh fading channels
Author :
Wang, Kun ; Ge, Hongya
Author_Institution :
Dept. of Electr. & Comput. Eng., New Jersey Inst. of Technol., Newark, NJ, USA
Abstract :
An approximate maximum likelihood (ML) method for joint estimation of time delays and directions-of-arrivals (DOAs) for the direct-sequence code-division multiple-access (DS-CDMA) systems over the multipath Rayleigh fading channels is developed. The proposed estimation scheme is developed by modeling the known training sequence of the desired user as the desired signal and the multiple access interference (MAI)-plus-AWGN as unknown colored Gaussian noise uncorrelated with the desired signal. An efficient iterative algorithm for estimating channel parameters (the time delays and DOAs of multipath signals) is proposed to reduce the computational complexity. The algorithm transforms the multi-dimensional maximization problem into two simple one-dimensional (1-D) maximization problems based on an iterative scheme. Analytical and simulation results are presented to illustrate the performance in comparison with the Cramer-Rao bounds (CRBs). It is shown that the proposed algorithm is near-far resistant for both time delay and DOA estimation and little performance loss is observed in comparison with the CRBs at reasonable SNRs
Keywords :
AWGN; Rayleigh channels; code division multiple access; computational complexity; delay estimation; direction-of-arrival estimation; iterative methods; maximum likelihood estimation; multipath channels; multiuser channels; optimisation; radiofrequency interference; spread spectrum communication; 1D maximization problems; AWGN; Cramer-Rao bounds; DOA estimation; DS-CDMA system; MLE; SNR; approximate maximum likelihood method; channel parameters estimation; colored Gaussian noise; computational complexity reduction; direct-sequence code-division multiple-access; directions-of-arrivals; efficient iterative algorithm; joint estimation; multipath Rayleigh fading channels; multipath signals; multiple access interference; near-far resistant algorithm; simulation results; time delay estimation; training sequence; Delay effects; Delay estimation; Direction of arrival estimation; Fading; Gaussian noise; Iterative algorithms; Maximum likelihood estimation; Multiaccess communication; Multiple access interference; Parameter estimation;
Conference_Titel :
Communications, 2001. ICC 2001. IEEE International Conference on
Conference_Location :
Helsinki
Print_ISBN :
0-7803-7097-1
DOI :
10.1109/ICC.2001.937158
