Pilot-aided adaptive MMSE receivers for DS/CDMA

A weighted recursive least-squares algorithm for pilot-signal aided channel estimation in direct-sequence/code-division multiple-access (DS/CDMA) is proposed. Centralized and decentralized versions of the basic algorithm are considered. Since the algorithm tracks both the channel of the user of interest and the inverse covariance matrix of interference, it can be coupled with an adaptive linear MMSE receiver without additional complexity. The resulting receiver automatically performs the cancellation of the pilot-signals before data detection. Therefore, fairly significant power can be devoted to the pilot signals without affecting the overall interference level and without increasing the dimensionality of the desired signal space.