基于劳伦多项式的LAS码构造及性能分析

对基于Hadamard矩阵的LA码和基于劳伦多项式（Laurent Polynomial）的LS码的生成及相关特性进行研究，从占空比、相关特性、零干扰窗长度、码字总数等方面仿真分析了LAS码的性能，并结合实际应用，理论分析了LAS-CDMA系统与传统CDMA系统的归一化容量，仿真比较了LAS码和Gold序列在准同步CDMA系统中的误码性能。仿真和理论分析表明：LAS码具有均匀的零干扰窗（Interference Free Window，IFW）特性；不同主码的互相关函数IFW附近存在较小的副峰，多址干扰较小；在准同步移动通信系统中，LAS-CDMA抗多址干扰性能明显优于传统CDMA系统，使用 LAS码比使用Gold序列有更好的误码性能。

Construction and performance analysis of large area synchronous code based on Laurent polynomial

Large area code(LAS) based on Hadamard Matrix and large loosely code based on Laurent Polynomial are firstly discussed, then the performance of LAS code is analysed, including duty ratio, correlation properties, the length of Interference Free Window(IFW) and total number. The normalized system capacity in LAS-CDMA system and traditional CDMA system is given by theoretical analysis, subsequently the BER performance of the LAS code and Gold code in quasi-synchronous CDMA systems is simulated. The simulations show that the LAS code has the characteristics of uniform IFW. The multiple access interference is smaller for the LAS code with different LA code. LAS-CDMA has advantages on normalized system capacity system over traditional CDMA system and BER performance is significantly better than that of application of Gold code.