Smart antenna based interference-blocking RAKE receiver for CDMA systems over multipath fading channel

In this paper, a space-time RAKE (ST-RAKE) receiver with enhanced interference rejection is proposed for CDMA communications systems over a multipath fading channel. The proposed scheme involves three stages. An interference-blocking (IB) transformation is first developed based on the received data (undespread data) for suppressing the strong interference. Optimum beamforming is then performed on the IB transformed despread data, consisting only of signal-of-interest (SOI) data and noise, to produce reception of SOI and rejection of strong interference. Finally, a RAKE receiver with maximum ratio combining technique employed is used to constructively collect the SOI energy. Since strong interference has been removed, RAKE receiver can effectively combine the SOI's, leading to performance enhancement as compared with the conventional RAKE receiver. Numerical results are given to demonstrate that the proposed IB-RAKE receiver exhibits robustness against strong interference.