A multistage multi-carrier CDMA receiver with enhanced interference suppression

A multistage multi-carrier CDMA (MSMC-CDMA) receiver with enhanced multiple access interference (MAI) suppression is proposed. MC-CDMA is based on a combination of CDMA and orthogonal frequency division multiplexing (OFDM) techniques. The design of the receiver involves the following procedure. First, a set of adaptive matched filters (MF) is constructed to collect multipath signals with different time delays. The tap weights of each MF are determined in accordance with the linearly constrained minimum variance (LCMV) criterion so that strong MAI can be effectively suppressed. Second, channel estimation and signal reconstruction are accomplished by exploiting pilot symbols, decision-directed symbols and the signal's signature. Finally, a decision-directed RAKE receiver gives the estimate of the signal, which is then subtracted from the data sent to the next stage. The proposed receiver can be used in a reverse link system with time-multiplexed pilot symbols, and achieves nearly the performance of the optimal maximum SINR (MSINR) receiver.