Analytical Results for BER Performance of MIMO-Rake Receiver in WCDMA System

Abstract – The use of Rake Receiver in Wideband Code Division Multiple Access (WCDMA) system provides a unique and valuable means of combating the adverse effects of short-term multipath fading in mobile radio propagation environments. The transmitted signal bandwidth in WCDMA system is much larger than the coherent bandwidth of the channel, in this case the channel is frequency selective channel. BER performance of Rake Receiver can improve by using Spatial Multiplexing (SM) in WCDMA systems. In general, the SM increases the data rate and the diversity order as well. The approximate maximum likelihood detector is derived in this paper and it shown that the diversity order is related to the product of the numbers of receives antennas and taps (the number of Resolvable Paths or the number of Rake Fingers). Spatial Multiplexing can be realized using multiple antennas at the base station and the mobile terminal i.e. Multiple Input Multiple Output (MIMO) system. In this paper BER performance of MIMO-Rake receiver is analysed and also compared with the generalized Rake Receiver system.