A Hybrid Adaptive Diversity Combining Receiver Over Rayleigh Fading Channels

A. El-Sayed El-Mahdy (Egypt)


Diversity, fading, and channel estimation


This paper introduces an adaptive diversity combining receiver over a flat time varying Rayleigh fading channel. The receiver uses a hybrid selection/maximal ratio combining of the diversity branches. At every time instant, the diversity branches to be combined are selected based on comparing the maximum likelihood (ML) metric of each branch with a threshold. The branches that are lower than the threshold are selected. Therefore, the number of combined branches is a random variable rather than a fixed number. The threshold is chosen as the average value of the ML metrics of all the branches. The selected branches are combined and used to obtain the received data symbol at that time instant. The receiver continuously estimates the time variant fading channel parameters directly within the ML metric at every time instant. The recursive least square (RLS) algorithm is used for this estimation. At the start up phase a training sequence is used in the channel estimation algorithm and then the extracted data symbol is used to update the estimate. Computer simulations are performed to evaluate the performance of the receiver. Moreover, the performance of the receiver is compared with the other diversity receivers.

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