Performance analysis of joint EM/SAGE estimation and multistage detection in UTRA-WCDMA uplink

This paper deals with the performance evaluation of an asynchronous UTRA-WCDMA uplink using a sequential algorithm for channel estimation and multiuser detection. A multipath slowly Rayleigh fading channel is considered. Both perfect and non-perfect channel estimations are studied with the pilot-to-data amplitude ratio as a parameter, when pilot symbols are transmitted in parallel with data. For channel estimation we use expectation maximization (EM) and spaced alternating generalized expectation maximization (SAGE) algorithms; for symbol detection we use interference cancellation. Bit Error Probabilities (BER) are derived using Monte Carlo simulations for binary phase shift keying (BPSK). The users may have different bit rates. In addition the mean squared estimation error (MSEE) of channel gains is computed and compared to the classical Cramer-Rao lower bound (CRLB)