New-user identification in a CDMA system

We present three Detector/Estimators (DEs) which allow multiuser detection and parameter estimation without a side channel in a dynamic asynchronous CDMA system in which users are entering and leaving the system. These DEs optimally detect a new user given only the chip rate and the spreading factor of the new user. Two of these DEs, the Maximum Likelihood Detector/Estimator (MLDE) and Generalized Maximum Likelihood Detector/Estimator (GMLDE), produce maximum likelihood estimates of the new user's signature sequence, delay and amplitude which are then incorporated into a multiuser detector. The third DE, the Cyclic Detector/Estimator (CDE), is the most computationally eecient of the three processors. This DE detects the new user by testing for cyclostationar-ity and then uses suboptimal schemes to estimate the new user's signature sequence, delay and amplitude. Simulations indicate that all three DEs reliably detect a new user for an E s == 2 (symbol energy to noise ratio) of 5 dB. The MLDE and GMLDE produce signature sequence and delay estimates with probability of error less than 0.07 for an E s == 2 of 10 dB, and the CDE produces signature sequence and delay estimates with probability of error less than 0.13 for an E s == 2 of 15 dB.