I. Introduction
Spread spectrum communication is a widely used communication mode, of which Direct Sequence Spread Spectrum is the most widely used. In the Direct Sequence Spread Spectrum, the nature of spreading sequences is very important, which need good autocorrelation and cross-correlation properties [1]. The traditional spreading sequences, such as m sequences, Gold sequences and so on, have the limited set of available codes and low linear complexity, which greatly affect the capacity and security performance of the system [2]. In addition, the period of m and Gold sequence is generally _, and the choice of period is limited. People have always been looking for the spreading sequences which have better performance, larger number.