基于平均碰撞的伪随机异步FH-CDMA系统性能分析

Performance analysis for pseudo-random asynchronous FH-CDMA system based on average-hit method

跳频多址接入(FH-CDMA)系统采用具有伪随机特性的多进制序列(如RS序列、多项式序列和低碰撞区序列等)作为跳频码。目前,基于伪随机跳频码的FH-CDMA系统的误码率性能估计一般采用仿真方法得到,缺少有效的理论分析手段。提出了基于平均碰撞方法,对频点碰撞情况进行建模,简化了多用户的干扰分析过程,建立了伪随机跳频序列碰撞特性与系统理论误码率性能的数值关系。通过理论分析和MATLAB仿真测试可知,提出的伪随机跳频的平均碰撞分析是一种有效的多用户跳频频点碰撞和误码性能的估计方法;另外,给出了伪随机跳频序列可达到的最优误码率性能的下界。

The pseudo-random M-ary sequence （such as RS code, polynomial code and low-hit zone FH code and so forth） is widely adopted as FH code in FH-CDMA system. However, the performance of FH-CDMA system employing FH sequence is usually evaluated by simulation, and lack of substantial theoretical analysis. A systematic method for modeling the frequency-hit according to the pre-assigned FH code was proposed; then with the proposed model, the analysis for multi-access interference（MAI） was simplified. The numerical relation between the properties of pseudo-random FH code and the error-rate performance of FH-CDMA system was established. Theoretical and simulation results show that the proposed average-hit model is an efficient method to evaluate the frequency hit and the error-rate of pseudo-randomly FH-CDMA system. Meanwhile, the optimal error-rate low-bound of FH-CDMA system which can achieved by pseudo-random FH code is shown in the conclusion.