A detector based on optimal estimator for asynchronous CDMA systems

Although the maximum likelihood sequence detector can provide optimal detection for code division multiple access (CDMA) systems, it has a complexity growing exponentially with the number of users. To reduce the complexity, a detector is proposed that is based on an optimal estimator derived by maximizing the likelihood (ML) function. Computer simulation indicates that the number of users can reach 90% of the processing gain when the signal is 20-dB stronger than the white noise, and when the bit error rate objective is less than 0.1%.