User recognition and time delay estimation with near far robust in asynchronous bandlimited DS-CDMA system

摘要

An algorithm for user recognition and time delay estimation (UR/TDE) in an asynchronous band-limited DS-CDMA system in a near far scenario is presented. The algorithm, which is based on subspace concept, consists of preprocessing (UR) and post-processing (TDE). In the preprocessing, by estimating the noise subspace, we propose a method to determine whether a user transmits signal while requiring only a priori knowledge of the user's signature coldes. If a user is active, an initial and coarse TDE is available, and the following postprocessing is needed, which is designed to get fine estimation by an efficient search strategy for active users. Simulations are carried out. It's strategy for active users. Simulations are carried out. It's shown that the algorithm is near far resistant, the accuracy of TDE with noise-subspace estimator outperforms without it.