ADAPTIVE SYMBOL AND PARAMETER-ESTIMATION IN ASYNCHRONOUS MULTIUSER CDMA DETECTORS

Existing multiuser code-division multiple-access (CDMA) detectors eith er have to rely on strict power control or near-perfect parameter esti mation for reliable operation, In this paper, a novel adaptive multius er CDMA detector structure is introduced, Using either an extended Kal man filter (EKF) or a recursive least squares (RUS) formulation, adapt ive algorithms which jointly estimate the transmitted bits of each use r and individual amplitudes and time delays may be derived, The propos ed detectors work in a tracking mode after initial delay acquisition i s accomplished using other techniques not discussed here, Through comp uter simulations, we show that the algorithms perform better than a ba nk of single-user (SU) receivers in terms of near-far resistance. Prac tical issues such as the selection of adaptation parameters are also d iscussed in some detail.