Design of an adaptive antenna array for tracking the source of maximum power and its application to CDMA mobile communications

TLDR

In CDMA mobile communications, the proposed adaptive beamforming technique assumes a dominant desired signal and yields a suboptimal beam pattern that improves SNR/SIR and channel capacity while reducing computational load from O(3N²+12N) to O(11N). The paper proposes an alternative adaptive beamforming method. The method constructs a suboptimal beam pattern in real time by updating weights based on the autocovariance matrix, avoiding reference signals and training periods. The technique achieves real‑time beamforming without reference signals or training, is insensitive to signal intercoherency, and dramatically reduces computation compared to conventional methods.

Abstract

This paper presents an alternative method of adaptive beamforming. Under an assumption that the desired signal is large enough compared to each of interfering signals at the receiver, which is preconditionally achieved in code division multiple access (CDMA) mobile communications by the chip correlator, the proposed technique provides for a suboptimal beam pattern that increases the signal-to-noise/signal-to-interference ratio (SNR/SIR) and eventually increases the capacity of the communication channel. The main advantages of the new technique are: (1) the procedure requires neither reference signals nor a training period; (2) the signal intercoherency does not affect the performance or complexity of the entire procedure; and (3) the total amount of computation is tremendously reduced compared to that of most conventional beamforming techniques such that the suboptimal beam pattern is produced at every snapshot on a real-time basis. In fact, the total computational load for generating a new set of weights including the update of an N-by-N autocovariance matrix is O(3N/sup 2/+12N). It can further be reduced down to O(11N) by approximating the matrix with the instantaneous signal vector.