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

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 (underspread 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 the SOI and rejection of strong interference. Finally, a RAKE receiver employing the maximum ratio combining technique is used to collect the SOI energy constructively. Since strong interference has been removed, the RAKE receiver can effectively combine the SOIs, 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.