一种新的抗转发干扰直接序列扩频系统的性能分析

在直接序列扩频通信系统中，假设敌方能够逐个比特地检测到整个PN序列，并产生一个调制的转发干扰。当干扰信号的PN序列与原始信号的PN序列具有一致的相位时，这种转发干扰将对普通DS扩频系统产生严重威胁。针对这一问题，本文基于PSK和FSK调制的组合提出了一种新的抗转发干扰DS扩频结构，称之为抗干扰增强型系统。根据所提出的信号解调结构，本文推夺出最佳干扰情况下系统误比特率的解折表达式。最后，对误比特率的数值结果进行了分折，并提出了采用纠错编码的方法来改善AJES系统的可靠性。

Performance Analysis of a New Retransmitted Interference Resistant DS Spread Spectrum System

In direct sequence spread spectrum communication system, enemy is assumed to detect whole PN sequence chip by chip and a modulated retransmitted interference is created. When the PN sequence for the interference signal has the same phase shifts as that of an original signal,the retransmitted interference produces a serious threat against the conventional DS spread spectrum communication system. To prevent this attack, a new retransmitted interference resistant DS spread spectrum structure is proposed based on combined phase shift-keyed and frequency shift-keyed (PSK-FSK) modulation. The constructure is called the anti-jamming enhanced system (AJES). According to the posed signal demodulation structure, analytical expression of system bit error rate (BER) for optimized interference is also deduced. Finally, numerical results of BER are analysed and implementation of error correcting coding is presented to improve the reliability of the AJES system.