Blind joint iterative optimization reduced-rank adaptive receiver for DS-UWB systems based on constrained constant modulus criterion

A novel linear blind reduced-rank scheme based on the constrained constant modulus (CCM) design criterion is proposed for interference suppression in direct-sequence ultra-wideband (DS-UWB) systems. The proposed two-stage blind receiver consists of a projection matrix that performs dimensionality reduction and is followed by a reduced-rank filter that produces the output. The projection matrix and the reduced-rank filter are obtained with a joint-iterative optimization (JIO) that minimize the constant modulus (CM) cost function subject to a constraint. Low complexity adaptive implementation is achieved by developing normalized stochastic gradient (NSG) algorithms. Simulation results show that the proposed scheme has excellent performance in suppressing the inter-symbol interference (ISI) and multiple access interference (MAI) with low complexity.