Performance analysis of RAKE receivers with maximum a posteriori channel state estimation over time varying frequency selective finite state Markov fading channels

Time varying channels have memory due to the correlation between successive channel impulse responses. By using finite state Markov chains, this memory can be exploited to improve the receiver performance. A channel estimation scheme for time varying frequency selective fading channel is developed and used in a maximum ratio combining RAKE receiver for a QPSK WCDMA downlink. The receiver only requires a sequence of pilot symbols to start. The channel estimation algorithm models the amplitude as well as the phase of the recombined paths of the RAKE receiver and makes use of maximum a posteriori metrics and an efficient arrangement of Viterbi algorithms.