Fast convergence signaling for adaptive linear interference canceller in DS-CDMA mobile communications

This paper analyzes the start-up characteristics of the optimal linear interference canceller for DS-CDMA mobile communication systems. The coefficient vector for the optimal combining depends on the correlation matrix of the despreading circuit outputs. Error of the actual correlation matrix is theoretically derived. The equation of the error shows that insertion of a training signal makes the startup fast. It should be noted that the training sequence is not required to be a priori for receivers, and blind processing can be carried out. Ideal conditions for the training signal are theoretically derived. Computer simulation demonstrates improvement of the start-up performance by several training sequences, among which the orthogonal Gold code training symbol sequence shows the best performance.