Minimum conditional probability of error detection for MC-CDMA

Multi-carrier code division multiple access (MC-CDMA) is an attractive choice for high speed wireless communication as it mitigates the problem of intersymbol interference (ISI) and also exploits frequency diversity. The data stream in MC-CDMA is spread using a user specific spreading sequence in the frequency domain and every chip travels on a different sub-carrier. At the receiver, the different sub-carriers have to be combined properly to form the decision variable. Minimum mean square error (MMSE) detection is a popular choice for this, but as it tries to minimize the mean square error (MSE) and not the bit error rate (BER), the BER it attains is not optimum. We propose a minimum probability of error (MPOE) based linear multiuser detector, which tries to minimize the probability of error. A minimum conditional probability of error (MCPOE) detector is introduced for reducing the computational complexity of the MPOE detector. Theoretical and simulation results are presented for the MCPOE and MPOE detector and it can be seen that the MPOE detector outperforms the MMSE detector.