一种新扩频码的性能分析

Performance analysis of a new spreading code

在码分多址(CDMA)的卫星导航定位系统中,采用扩频码进行测距,同时根据不同的扩频码来区分不同的卫星,因此,扩频码性能的优劣将直接影响导航系统定位精度、抗干扰、鲁棒性等核心性能。针对传统卫星导航信号扩频码在线性复杂度上存在的不足,给出了一种新扩频码,并对新扩频码的相关性、平衡性、游程性、线性复杂度以及在加性高斯白噪声信道(AWGN)和瑞利衰落信道(Rayleigh)下的误比特率(BER)进行了仿真分析。结果表明:新扩频码的相关性、平衡性、游程性三方面的性能与传统扩频码相当,能够满足卫星导航定位系统的应用需求;新扩频码的线性复杂度明显优于传统导航信号扩频码,能够极大增强系统的保密性;同时,新扩频码在两种信道下误比特率较低,具有优良的抗干扰性能。

The code division multiple access(CDMA), spread spectrum code is used for ranging in the satellite navigation and positioning system, and different satellites are distinguished according to different spread spectrum codes. Therefore, the performance of spread spectrum code will directly influences the core performance of the navigation system, such as positioning accuracy, anti-jamming and robustness. Aiming at the shortcomings of the linear complexity for the spread spectrum code of the traditional satellite navigation signal, a new spread spectrum code is presented in this study. The correlation, balance, run-length, linear complexity of the new spread spectrum code and the bit error rate(BER) under the additive white Gaussian noise channel(AWGN) and Rayleigh fading channel(Rayleigh) are simulated and analyzed. The results show that the correlation and flatness of the new spread spectrum code are good. The performances of balance and run-length are similar to the traditional spread spectrum codes, which can meet the application requirements of satellite navigation and positioning system. The linear complexity of the new spread spectrum codes is obviously better than the traditional spread spectrum codes, which can greatly enhance the confidentiality of the system. In addition, the new spread spectrum codes have low bit error rate and excellent anti-jamming performance under two channel conditions.