Blind adaptive decision feedback CDMA receivers for dispersive channels - Electronics Letters

Introduction: Blind adaptive linear receivers for DS-CDMA have been proposed in recent years to supress multiple acess interference (MAI) [1–4]. Blind solutions for flat channels based on the minimum variance (MV) and the constant modulus (CM) criterion have been reported in [1] and [2]. Recently, constrained minimum variance (CMV) and constrained constant modulus (CCM) adaptive linear receivers [3, 4] were proposed in order to operate in dispersive channels. Although relatively simple, decision feedback (DF) structures can perform significantly better than linear systems [5,6] and the work on blind adaptive DF receivers offers only single-path channel solutions [7]. In this Letter we propose blind adaptive stochastic gradient (SG) algorithms for frequency selective channels in DSCDMA systems based on constrained optimisation techniques using the MV and CM criteria.