Performance Analysis of Subspace Based Synchronization Algorithms for Multi-rate DS-CDMA Systems

The performance of subspace based delay estimation algorithms for multi-rate asynchronous DS-CDMA systems is investigated. Two multi-rate access schemes, multi-code (MC) access and variable-spreading-length (VSL) access, are considered. A subspace based algorithm that can explicitly exploit the redundant information introduced by the multi-rate nature of the signal is proposed. A two stage algorithm with reduced complexity and strong performance is proposed for the VSL case. Performance is analyzed through Taylor series expansion of the cost function and asymptotic distribution of the sample correlation matrix and its eigenvectors, and compared with the Cram er-Rao Bounds. In addition, simulation results are also presented.