Exploiting the Structure of the Joint Detection Problem with Decision Feedback

Performing joint detection in a TD-CDMA system corresponds to the solution of a large system of linear equations, whose matrix exhibits a strong band and Toeplitz structure. Taking advantage of the structure allows a cheap solution by standard algorithms (Cholesky, QR-decomposition). Including decision feedback into the solution process improves the performance of the system. This, however, leads to a loss of the beneecial band structure. Furthermore, the known approximation schemes can no longer be applied. In this paper, we present a Schur-type algorithm that is able to exploit the remaining Toeplitz structure of the decision feedback system. A new approximation scheme is developed that can successfully reduce the computational complexity of this algorithm.