Space-time adaptive acquisition and demodulation in mobile cellular

A “smart” antenna receiver (receiving antenna array) that uses adaptive spatial-temporal signal processing is being made available to a future generation of mobile radio and phone systems. The spatial locations of the system users can be exploited by an adaptive array receiver that is capable of spacially suppressing multiple-access interference (MAI) that occurs in mobile communications. As a consequence adaptive antenna arrays can be made to achieve a better quality of service and a significant increase of capacity.; In this thesis adaptive self-synchronizing receivers are developed for asynchronous DS-CDMA (direct-sequence code-division multiple-access) systems and cochannel TDMA (time-division multiple-access) systems with such a smart J-element antenna array. In this new approach a generalized maximum likelihood ratio test (GLRT) is formulated to automatically adaptively acquire both synchronization and direction-of-arrival (DOA) in both asynchronous DS-CDMA systems and cochannel TDMA systems. The primary requirement is knowledge of the desired signature code sequences. However, its full direct realization and implementation is not feasible at the present due to both a computationally intensive matrix-inversion and an eigen-decomposition operation.; A considerably lower complexity version of such an asynchronous DS-CDMA receiver is developed here that utilizes the concept of the multistage reduced-rank Wiener filter system, introduced recently by Goldstein and Reed. This new technique results in a self-synchronizing detection criterion that requires no matrix inversions or eigen-decomposition of a covariance matrix. Also this multistage adaptive filtering scheme achieves a rapid adaptive convergence under limited observation-data support. These important features contribute significantly to a reduction of the computational cost and the amount of data sample support needed to accurately obtain the required estimates of the problem.