Performance of various multistage interference cancellation schemes for asynchronous QPSK/DS/CDMA over multipath Rayleigh fading channels

Performance of multistage interference cancellation (MIC) and three combini ng techniques, i.e., multipath decorrelating (MIC-DECO), optimum combining (MIC-OPTM), and RAKE combining (MIC-RAKE) for asynchronous quadrature phase -shift keying/direct-sequence code-division multiple access over frequency- selective multipath Rayleigh fading channels is studied. The analytical bit -error probabilities of the MIC-DECO and MIC-OPTM are derived and shown to be in a good agreement with simulation results, Both analytical and simulat ion results show that the MIC-DECO, MIC-OPTM, and MIC-RAKE in a multiuser e nvironment provide a good performance close to the ideal performance in a s ingle-user system even in the presence of channel estimation error.