Fuzzy blind adaptive minimum output energy multiuser detector

In this paper, we introduce a novel fuzzy adaptive algorithm for blind detection of direct sequence code division multiple access (DS-CDMA) signals in a multiuser communication scenario. We make use of fuzzy control systems to wisely determine the appropriate step size of the adaptive algorithm based on the quality of the received signal. We have used the popular minimum output energy (MOE) blind detector proposed by Honig et al. as our blind adaptive detector whose step size is to be determined by the fuzzy control system. This blind detector requires no more knowledge than does the conventional single-user receiver, i.e. the desired user´s signature waveform and its timing. We have proposed to use signal to interference ratio (SIR) and its variations as the key inputs to our fuzzy algorithm. By simulation, we show the competency of our algorithm in terms of the convergence characteristics of the adaptive algorithm. Likewise, by simulation results we show that these convergence improvements yield to a lower bit error rate (BER) for the demodulation process in the receiver.