Schur algorithms for joint-detection in TD-CDMA based mobile radio systems

Third generation mobile radio systems will employ TD-CDMA in their TDD mode. In a TD-CDMA mobile radio system, joint-detection is equivalent to solving a least squares problem with a system matrix that exhibits some form of block-Toeplitz structure. This structure can be successfully exploited by using variations of the Schur algorithm for computing the QR decomposition of this system matrix. Together with a displacement representation, the Schur algorithm can be straightforwardly adapted to a wide variety of matrix structures. In this paper we show this approach for two concrete manifestations of the TD-CDMA system matrix: first for a very compact, block-Toeplitz structure; and second for the less favorable Toeplitz-block structure that arises when decision feedback is added to the data process.