Optimal user ordering and time labeling for ideal decision feedback detection in asynchronous CDMA

A strategy of user ordering and time labeling for a decision feedback (DF) detector in asynchronous code-division multiple-access communications is proposed and is proved to be optimal for the ideal DF detector. The proposed algorithm requires O(K⁴) offline operations, where K is the number of users. Although error propagation complicates the analysis of the actual DF detector, computer simulations show that, with the proposed user ordering and time labeling, the performance of an actual DF detector overlays the theoretical bound in most cases.