Rapid acquisition schemes for CDMA systems in a multipath delay and fading environment

The speed of acquisition is one of the major factors that limits the performance of CDMA receivers. The search rate of direct sequence acquisition schemes can be significantly increased by replacing the multiply and integrate operation with a passive correlation device such as a matched filter (MF). The problems of acquisition using the matched filter have attracted considerable interest. Many results were derived assuming a single user in a fading and multipath delay mobile environment or multi-users in the additive white Gaussian noise channel. In the present paper a numerical method and computer simulation have been developed to simulate the acquisition. The acquisition performance using a matched filter with different numbers of parallel processors is investigated in the multipath delay and fading channel for a CDMA system. The results show that the acquisition performance is significantly degraded in this channel, even when large values of correlation length, which require fewer parallel processors, are used, The performance of a proposed new channel filter placed before the correlator is examined using a Monte Carlo method. Comparison or results of the performance of the correlator using the matched filter with different numbers of parallel processors, with and without the proposed channel filter, shows that the normalized mean acquisition time can be reduced by a factor of 10 when the new channel filter is used.<
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