An effective CDMA multi-user detection schemeorthogonal decision-feedback detection and its performance analysis

Abstract

A novel CDMA multi-user detection scheme orthogonal decision-feedback detector (ODFD) is proposed for a synchronous CDMA system in this paper. It is robust for its near-far resistance and high multi-user detection efficiency with a performance similar to that of decorrelating decision-feedback detector (DDFD) but with a reduced complexity. The ODFD scheme employs a match-filter bank that matches a set of orthonormal sequences. The ortho-normal sequences are generated by the Gram-Schmidt orthogonalisation procedure based on the spreading codes. The ODFD algorithm involves only with the ortho-normal coefficient-matrix which requires no frequent recalculations even when system parameters change. Successive decision-feedback detection is carried out immediately at the output of the ODFD match-filter bank without matrix inversion operations resulting in a much simplified structure.