Blind adaptive decorrelating decision-feedback multiuser detection for multirate synchronous DS/CDMA communications

A three-rate synchronous DS/CDMA system provides service to low, medium and high bit rate users, and all kinds of user have the same chip rate. Previously, two types of decorrelators have been proposed: a high-rate decorrelator (HRD), and a low-rate decorrelator (LRD). It has been observed that the LRD provides better performance than the HRD for all users at the expense of higher complexity and longer demodulation delay for high-rate users. To improve the performance and reduce the demodulation delay, a decorrelating decision feedback detector (DF) has been proposed. Although the DF has less complexity than that of the LRD, the complexity of DF is still high. This paper presents a blind adaptive decorrelating decision-feedback detector (BADF) which uses a bootstrap algorithm to decrease the complexity of DF and eliminates the singular-matrix problem of the decorrelator.