Design of Binary Multi-code CDMA System with Constant Amplitude

High PAPR (peak to average power ratio) happens because of the summation of Walsh codes in the multicode CDMA (code division multiple access) communication system. In this paper, we propose a binary CA-MC-CDMA (constant amplitude multicode code division multiple access) system to solve the high PAPR problem. Unlike the conventional pre-coding method, there is no loss of bandwidth efficiency in the proposed system because the code rate is always 1. The proposed system always generates output signal with 0 dB PAPR. The proposed binary CA-MC-CDMA system is based on the 2/2 and 4/4 binary CA-MC-CDMA systems. The proposed system can be easily extended into a large number of parallel multi-code branches by multiple combinations of these two systems. From the computer simulation results, it can be seen that the proposed binary CA-MC-CDMA system always produces binary constant amplitude output data without any loss of code rate, which cannot be found in the conventional MC-CDMA using a pre-coding method. Therefore, it can prevent the nonlinear distortion in the HPA and maximization of HPA power efficiency can be available in the data transmission using multi-code