Real-time design of a smart antenna system utilizing a modified conjugate gradient method for CDMA-based mobile communications

摘要

A beamforming module is implemented with a general-purpose DSP (digital signal processor). The proposed beamforming module utilizes a linearized CGM (conjugate gradient method) for finding the suboptimal weight vector in an adaptive manner. Each module of the receiving antenna system at the cell site provides the beam-pattern having its maximum gain along the direction of the corresponding target mobile subscriber. The computational load of the the conventional CGM, i.e., O(3N/sup 2/+12N), has been significantly reduced to the order of O(16N) for tracking the target subscriber in real-time where N denotes the number of antenna elements in the array. The performance of the proposed system is given in terms of the tracking speed, BER (bit error rate), and achievable capacity of the cell.