Code timing acquisition for DS-CDMA in fading channels by differential correlations

@article{citeulike:2802169, abstract = {We propose simple and efficient algorithms for the code timing acquisition in the direct-sequence code-division multiple-access communication system. The essential assumption is that a preamble or an unmodulated pilot channel is available for the desired user. Then the correlation matrix R(\τ) of the sampled data, where \τ is suitably chosen time lag, contains the timing information only of desired user, while the contributions of uncorrelated interferers and noise are suppressed out. Hence, compared to the conventional approach, more interference suppression is achieved. Coarse delay estimates are then obtained by a matched filter (MF) or multiple signal classification-type approaches. In the latter case, only L eigenvectors are computed, where L is the number of resolvable paths. If only one path exists, an additional procedure is proposed to both approaches, by which the estimation accuracy is greatly improved with negligible increase in computation. More precisely, the chip timing offset due to chip-asynchronous sampling can be determined by solving a system of two second-order polynomials for each chip interval. Therefore, only at most 2C hypotheses are needed, where C is the processing gain. All the proposed methods are computationally quite simple, containing mainly MF-operations, or at most computation of only few eigenvectors. Mean acquisition time analysis is carried out semi-analytically. Numerical experiments speaks for the possibility of achieving significant performance gains compared to conventional acquisition, especially in the presence of strong multiple-access interference, making them attractive options to be attached for the next generation mobile receivers}, author = {Ristaniemi, T. and Joutsensalo, J. }, booktitle = {Communications, IEEE Transactions on}, citeulike-article-id = {2802169}, doi = {10.1109/26.923813}, journal = {Communications, IEEE Transactions on}, keywords = {acquisition, cdma, channel, code, fading, spread-spectrum, time}, number = {5}, pages = {899--910}, posted-at = {2008-05-15 18:33:40}, priority = {2}, title = {Code timing acquisition for DS-CDMA in fading channels by differential correlations}, url = {http://dx.doi.org/10.1109/26.923813}, volume = {49}, year = {2001} }

TY - JOUR ID - citeulike:2802169 L3 - citeulike-article-id:2802169 TI - Code timing acquisition for DS-CDMA in fading channels by differential correlations T2 - Communications, IEEE Transactions on JF - Communications, IEEE Transactions on VL - 49 IS - 5 SP - 899 EP - 910 N2 - We propose simple and efficient algorithms for the code timing acquisition in the direct-sequence code-division multiple-access communication system. The essential assumption is that a preamble or an unmodulated pilot channel is available for the desired user. Then the correlation matrix R(τ) of the sampled data, where τ is suitably chosen time lag, contains the timing information only of desired user, while the contributions of uncorrelated interferers and noise are suppressed out. Hence, compared to the conventional approach, more interference suppression is achieved. Coarse delay estimates are then obtained by a matched filter (MF) or multiple signal classification-type approaches. In the latter case, only L eigenvectors are computed, where L is the number of resolvable paths. If only one path exists, an additional procedure is proposed to both approaches, by which the estimation accuracy is greatly improved with negligible increase in computation. More precisely, the chip timing offset due to chip-asynchronous sampling can be determined by solving a system of two second-order polynomials for each chip interval. Therefore, only at most 2C hypotheses are needed, where C is the processing gain. All the proposed methods are computationally quite simple, containing mainly MF-operations, or at most computation of only few eigenvectors. Mean acquisition time analysis is carried out semi-analytically. Numerical experiments speaks for the possibility of achieving significant performance gains compared to conventional acquisition, especially in the presence of strong multiple-access interference, making them attractive options to be attached for the next generation mobile receivers KW - acquisition KW - cdma KW - channel KW - code KW - fading KW - spread-spectrum KW - time AU - Ristaniemi, T AU - Joutsensalo, J PY - 2001/// UR - http://dx.doi.org/10.1109/26.923813 ER -