ADAPTIVE MAPSD ALGORITHMS FOR SYMBOL AND TIMING RECOVERY OF MOBILE RADIO TDMA SIGNALS

Dual-mode adaptive algorithms with rapid convergence properties are pr esented for the equalization of frequency selective fading channels an d the recovery of time-division multiple access (TDMA) mobile radio si gnals, The dual-mode structure consists of an auxiliary adaptive filte r that estimates the channel during the training cycle, The converged filter weights are used to initialize a parallel bank of filters that are adapted blindly during the data cycle, When the symbol timing is k nown, this filter bank generates error residuals that are used to perf orm approximate maximum a posteriori symbol detection (MAPSD) and prov ide reliable decisions of the transmitted signal, For channels with ti ming jitter, joint estimation of the channel parameters and the symbol timing using an extended Kalman filter algorithm is proposed. Various methods are described to reduce the computational complexity of the M AP detector, usually at the cost of some performance degradation, Also , a blind MAPSD algorithm for combining signals from spatially diverse receivers is derived. This diversity MAPSD (MAPSD) algorithm, which c an be easily modified for the dual-mode TDMA application, maintains a global set of MAP metrics even while blindly tracking the individual s patial channels using local error estimates, The performance of these single-channel and diversity MAPSD dual-mode algorithms are studied vi a computer simulations for various channel models, including a mobile radio channel simulator for the IS-54 digital cellular TDMA standard.