Two-stage multiuser detection for asynchronous CDMA using DPSK signalling

In this paper, a two-stage multiuser detector for asynchronous code division multiple access (CDMA) using differential phase shift keying (DPSK) is proposed and analyzed. The detector operates using tentative bit decisions of the bilinear decorrelating detector to estimate the multiple access interference corrupting the desired signal. The two-stage detector subsequently subtracts the reconstructed interference from the received signal, and then forms final bit estimates using a bank of conventional differential phase shift keying (DPSK) detectors. Numerical examples indicate that the two-stage detector may offer a significant performance advantage over the bilinear decorrelator with little added complexity.