Principle and performance of variable rate multi-code CDMA method

A variable data rate multi-code CDMA method is proposed. It can be applied to a future variable rate CDMA system, a spread spectrum multimedia system, and a personal interactive system. This method, which can select a set of spreading codes for the transmitted information data rate and map them into a binary sequence by orthogonal spreading codes for every user, can be used in such a way that a user send only a sequence in the transmitting channel irrespective of the data rate of the user information. Therefore, the proposed method may be used for variable data rate CDMA communication, and can so improve the transmitting properties and spectral efficiency of CDMA technology. The fundamental principle, code design and performance of this method are discussed.