A new design method of CDMA spreading codes based on multi-rate unitary filter bank

摘要

It is well-known that the multi-valued CDMA spreading codes can be designed by mans of a pair of mirror multi-rate filter banks based on some optimizing criterion. This paper indicates that there exists a theoretical bound in the performance of its circulating corre- lation property, which is given by an explicit expression. Based on this analysis, a criterion of maximizing entropy is proposed to design such codes. Computer simulation results suggests that the resulted codes outperform the conventional binary balaned Gold codes for an asynchronous CDMA system.