In the present paper we analyze the problem of multi-user detection for multitone CDMA systems in the presence of multipath and multiple access interferences. Two types of decision feedback structures are derived for an MSE criterion. In order to understand the potential of these detectors we study their steady-state behaviors. The investigation is carried out for devices following a receiver made of a bank of matched filters and assuming perfect carrier phase and timing recovery. An exact expression of the bit error probability for BPSK symbols after joint detection is obtained by means of the characteristic function method. The performance of the two DF multi-user detectors is obtained for a constrained comparison and their near-far resistance is demonstrated in asynchronous scenarios for two types of channels.
Vandendorpe, L., & vandeWiel, O. (1997). Decision feedback multi-user detection for multitone CDMA. European Transactions on Telecommunications and Related Technologies, 8(1), 67-78. https://doi.org/10.1002/ett.4460080109 (Original work published 1997)