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Dileep George Proceedings of the IEEE International Conference on 3G Wireless -2000 June-2000, San Francisco. Abstract Performance of Maximal Ratio Combining (MRC) as a multi-path diversity combining technique in WCDMA downlink reception depends on the reliability of obtained channel estimates. With increase in downlink interference the channel estimates become less reliable, thereby degrading the performance of MRC. Simulation results are used to show that when interference is high, Equal Gain Combining (EGC) performs better than Maximal Ratio Combining with non-ideal channel estimates. It is possible to remove hte effect of multi-path interference from the received pilot symbols to obtain better channel estimates. It is shown analytically that for a single user case, the interference on pilot symbols can be deteremined exactly with the knowldege of mutli-path profile and transmission characteristics. This is further developed into an iterative technique to improve the channel estimates even when unknown interferers are present. Finally, an algorithm is presented which will adaptively use MRC or
EGC depending on the accuracy of the obtained channel estimates.
Simulation results are provided to show the improvement obtained above
conventional methods of using only EGC or MRC exclusively.
The capacity of a CDMA system is interference limited. Interfernce
cancellation techniques exploit the determinitic structure of the
interference to cancel their contribution from the wanted signal.
Interfernce Cancellation schemes are analysed from the view point of
implementation on a W-CDMA mobile terminal . Simulation results are used
to quantify the parameters that affect the performance of the interference
cancellation schemes.
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