Approximate Maximum Likelihood Approach for Code Acquisition in DS-CDMA Systems with Multiple Antennas

Sangchoon KIM

doi:10.1093/ietcom/e88-b.3.1054

Approximate Maximum Likelihood Approach for Code Acquisition in DS-CDMA Systems with Multiple Antennas

Sangchoon KIM

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The problem of estimating code timings in DS-CDMA systems with multiple antennas is considered in the presence of multipath time-varying fading channels and near-far environments. We present an efficient algorithm for an approximate maximum likelihood approach of jointly estimating the multipath timings of a desired user for DS-CDMA systems that consist of multiple antennas either uncorrelated or fully correlated in space. The procedures of the algorithm to estimate code-timings are developed in order to better exploit the time-varying characteristics of the fading process. In the multipath fading channels, the solution of the proposed algorithms is based on successively optimizing the criterion for increasing numbers of multipath delays. It is shown via simulation results that the modified approaches of the approximate maximum likelihood algorithm much more improve its acquisition performance in the time-varying fading channels. It is seen that the acquisition performance of multiple antennas based acquisition scheme is much better than that of a single antenna based timing estimator in the presence of multipath fading channels and the near-far problem. Furthermore, it is observed that the proposed algorithms outperform the correlator and MUSIC estimator in the multiuser environments with near-far situation on time-varying Rayleigh fading channels.

Publication: IEICE TRANSACTIONS on Communications Vol.E88-B No.3 pp.1054-1065

Publication Date: 2005/03/01

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DOI: 10.1093/ietcom/e88-b.3.1054

Type of Manuscript: PAPER

Category: Transmission Systems and Transmission Equipment for Communications

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Sangchoon KIM, "Approximate Maximum Likelihood Approach for Code Acquisition in DS-CDMA Systems with Multiple Antennas" in IEICE TRANSACTIONS on Communications, vol. E88-B, no. 3, pp. 1054-1065, March 2005, doi: 10.1093/ietcom/e88-b.3.1054.
Abstract: The problem of estimating code timings in DS-CDMA systems with multiple antennas is considered in the presence of multipath time-varying fading channels and near-far environments. We present an efficient algorithm for an approximate maximum likelihood approach of jointly estimating the multipath timings of a desired user for DS-CDMA systems that consist of multiple antennas either uncorrelated or fully correlated in space. The procedures of the algorithm to estimate code-timings are developed in order to better exploit the time-varying characteristics of the fading process. In the multipath fading channels, the solution of the proposed algorithms is based on successively optimizing the criterion for increasing numbers of multipath delays. It is shown via simulation results that the modified approaches of the approximate maximum likelihood algorithm much more improve its acquisition performance in the time-varying fading channels. It is seen that the acquisition performance of multiple antennas based acquisition scheme is much better than that of a single antenna based timing estimator in the presence of multipath fading channels and the near-far problem. Furthermore, it is observed that the proposed algorithms outperform the correlator and MUSIC estimator in the multiuser environments with near-far situation on time-varying Rayleigh fading channels.
URL: https://globals.ieice.org/en_transactions/communications/10.1093/ietcom/e88-b.3.1054/_p

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@ARTICLE{e88-b_3_1054,
author={Sangchoon KIM, },
journal={IEICE TRANSACTIONS on Communications},
title={Approximate Maximum Likelihood Approach for Code Acquisition in DS-CDMA Systems with Multiple Antennas},
year={2005},
volume={E88-B},
number={3},
pages={1054-1065},
abstract={The problem of estimating code timings in DS-CDMA systems with multiple antennas is considered in the presence of multipath time-varying fading channels and near-far environments. We present an efficient algorithm for an approximate maximum likelihood approach of jointly estimating the multipath timings of a desired user for DS-CDMA systems that consist of multiple antennas either uncorrelated or fully correlated in space. The procedures of the algorithm to estimate code-timings are developed in order to better exploit the time-varying characteristics of the fading process. In the multipath fading channels, the solution of the proposed algorithms is based on successively optimizing the criterion for increasing numbers of multipath delays. It is shown via simulation results that the modified approaches of the approximate maximum likelihood algorithm much more improve its acquisition performance in the time-varying fading channels. It is seen that the acquisition performance of multiple antennas based acquisition scheme is much better than that of a single antenna based timing estimator in the presence of multipath fading channels and the near-far problem. Furthermore, it is observed that the proposed algorithms outperform the correlator and MUSIC estimator in the multiuser environments with near-far situation on time-varying Rayleigh fading channels.},
keywords={},
doi={10.1093/ietcom/e88-b.3.1054},
ISSN={},
month={March},}

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TY - JOUR
TI - Approximate Maximum Likelihood Approach for Code Acquisition in DS-CDMA Systems with Multiple Antennas
T2 - IEICE TRANSACTIONS on Communications
SP - 1054
EP - 1065
AU - Sangchoon KIM
PY - 2005
DO - 10.1093/ietcom/e88-b.3.1054
JO - IEICE TRANSACTIONS on Communications
SN -
VL - E88-B
IS - 3
JA - IEICE TRANSACTIONS on Communications
Y1 - March 2005
AB - The problem of estimating code timings in DS-CDMA systems with multiple antennas is considered in the presence of multipath time-varying fading channels and near-far environments. We present an efficient algorithm for an approximate maximum likelihood approach of jointly estimating the multipath timings of a desired user for DS-CDMA systems that consist of multiple antennas either uncorrelated or fully correlated in space. The procedures of the algorithm to estimate code-timings are developed in order to better exploit the time-varying characteristics of the fading process. In the multipath fading channels, the solution of the proposed algorithms is based on successively optimizing the criterion for increasing numbers of multipath delays. It is shown via simulation results that the modified approaches of the approximate maximum likelihood algorithm much more improve its acquisition performance in the time-varying fading channels. It is seen that the acquisition performance of multiple antennas based acquisition scheme is much better than that of a single antenna based timing estimator in the presence of multipath fading channels and the near-far problem. Furthermore, it is observed that the proposed algorithms outperform the correlator and MUSIC estimator in the multiuser environments with near-far situation on time-varying Rayleigh fading channels.
ER -