Blind Adaptive Constrained Reduced-Rank Estimation Algorithms for Constant Modulus Signals Applied to CDMA Interference Suppression

This work proposes a multistage decomposition for blind adaptive parameter estimation in the Krylov subspace with the code-constrained constant modulus (CCM) design criterion. Based on constrained optimization of the constant modulus cost function and utilizing the Lanczos algorithm and Arnoldi-like iterations, a multistage decomposition is developed for blind parameter estimation. A family of computationally efficient blind adaptive reduced-rank stochastic gradient (SG) and recursive least squares (RLS) type algorithms is also devised and evaluated against existing methods. Simulation results consider the application of the proposed techniques to the suppression of multi-access and intersymbol interference in DS-CDMA systems.