Blind channel estimation for CDMA systems: An induced cyclostationarity approach

In this paper, the recently introduced Transmitter Induced Cyclostationarity (TIC) techniques are applied to the CDMA uplink blind identification problem. In the proposed transmission model, the spreading code vectors are periodic, each user having a period of his own. As a consequence, a cyclic covariance function is associated to each user. This function generates a structured signal subspace which depends only on the transfer function of this user. The approach leads to clear and mild identifiability conditions. An identification algorithm is described and its theoretical asymptotic performance is presented. Simulations and comparisons with the existing stationary subspace techniques are provided. The algorithm is particularly adapted to systems where the number of users is close to the spreading factor.