Multi-user Detection for Wideband CDMA based on the Conjugate Gradient Method

Multiple users communicate with individually assigned codes on a single radio carrier frequency in a DS-CDMA system. Mutual interference among codes limits the capacity of the system. Conventional detectors of receivers are for single-user, which are designed neglecting the mutual interference. Multi-user detection is expected to enhance the capacity. In this paper, a new scheme is proposed corresponding to solve a huge matrix equation under the multiple access interference (MAI) environments. This scheme is related to the mathematics; the Conjugate Gradient Method (CGM). The modeling of multi-user detection is shown, then the algorithm is given based on the mathematics; the Conjugate Gradient Method (CGM). The characteristics of the proposed scheme are evaluated with the comparison of the conventional single user detector. The proposed scheme is found to have reduced complexity comparing conventional technologies based on the serial and the parallel configurations. Key-Words: multiple access interference (MAI), multi-user detection, the conjugate gradient method (CGM)