Space-time adaptive reduced-rank multistage receiver for asynchronous CDMA

We develop an adaptive near-far resistant self-synchronizing receiver for asynchronous CDMA systems with a J-element antenna array. The primary requirement is knowledge of the desired user´s signature sequence. Also, a low-complexity version of the proposed receiver is developed that utilizes the concept of the reduced-rank multistage Wiener filter (MWF) introduced by J.S. Goldstein et al. (see IEEE Trans. Inform. Theory, vol.44, p.2943-59, 1998). This technique obviates the necessity of either a covariance matrix inversion or an eigen-decomposition. Moreover, this multistage scheme achieves a rapid adaptive convergence under limited observation-data support. These features contribute significantly to the reduction of the computational cost and the amount of sample support.