An algebraic technique for the blind separation of DS-CDMA signals

In this paper, we propose a new deterministic technique for the blind separation of DS-CDMA signals received on an antenna array. We start from the observation made by Sidiropoulos et al. that the received data exhibit the structure of a Canonical Decomposition in multilinear algebra. We provide a new condition for the uniqueness of this decomposition and we present a new algorithm in which the solution is obtained by means of a simultaneous matrix diagonalization. Next, we consider the special case in which the transmitted signals have constant modulus. In the Analytical Constant Modulus Algorithm by van der Veen and Paulraj the constant modulus constraint leads to an other simultaneous matrix diagonalization. The CDMA structure constraint and the constant modulus constraint can be combined. We derive an alternating least squares algorithm that solves both sets of matrix equations simultaneously.