A new multiuser detector for synchronous DS/CDMA system

Several multiuser detectors for code-division multiple-access (CDMA) system have been studied previously. In this paper, we propose the orthogonal decision-feedback detector. It combines the decorrelating decision-feedback detector with the orthogonal detector, and has the merit of the good performance of the decorrelating decision-feedback detector and the simple structure of the orthogonal detector. The performance of the new multiuser detector is close to the decorrelating decision-feedback detector, but its construction is simpler. Because of the similarities between the multiuser detection problem and the decoding of the convolutional code, a tree search algorithm is taken on the detector, which makes its performance improved, and approaches the single user bound