Blind Multiuser Recursive Constant Modulus Detectors for DS/CDMA Signals with QPSK Modulation

H.M. Al-Neyadi and C.G. Guy (UK)


--DS/CDMA, Multiuser, CMA, RCMA andSC.


A successive detection technique using multi-stages of finite impulse response filter, controlled by the constant modulus algorithm (CMA), and a signal canceller (SC) was presented for blind detection of DS-CDMA signals. The CMA/SC multi-stages system shows robustness of detection of different users in dense environments, it is easy implemented by simple gradient algorithms, and it requires lower computational cost. Further CMA/SC does not require the knowledge of the spreading codes of the different users. The drawback of the multi-stage CMA/SC system is the relative slow convergence of the CMA algorithm, which may not be suitable for some applications. This paper provides a recursive constant modulus filter/ signal canceller (RCMA/SC) for blind detection of DS/CDMA signals over additive white Gaussian noise (AWGN) channel. The RCMA is derived by analogy to the recursive least squares algorithm (RLS) as a fast version of the CMA. The convergence properties of the algorithms are analyzed and compared with the conventional CMA. Simulation examples, for both the CMA and the RCMA, are given to demonstrate the robustness of the proposed algorithm and its superiority from the point of view of fast convergence.

Important Links:

Go Back