基于QBOC码的BOC信号码跟踪环路的性能分析

Analysis for Performance of Code Tracking Loop for BOC Signals Using QBOC Code

在Galileo系统建设和GPS现代化的进程中,为实现与BPSK(Bi-phase Shift Keying)的频谱分离,采用了BOC(Binary Offset Carrier)调制。BOC调制在码跟踪精度、多径抑制等方面比BPSK调制具有更好的性能,但其自相关函数的多相关峰特性使得在测距中可能产生偏差,因此,消除相关峰的模糊度是BOC信号接收中非常关键的问题。介绍了一种基于QBOC码的BOC信号码跟踪环路("BOC+QBOC-BOC"),并推导出该环路码跟踪性能的解析表达式,最后的仿真结果验证了理论推导的正确性,可为BOC信号接收机的设计提供参考。

In the implementation of Galileo and GPS modernization, binary offset carrier （BOC）modulation has been selected to obtain a higher spectral separation from the bi-phase shift keying （BPSK） signals. The BOC modulation has better performance than BPSK modulation in many aspects, such as code tracking performance and multipath mitigation. However, its multi-peak autocorrelation function can possibly result in biased measurements. Therefore, it is quite critical to remove the ambiguity of correlation peaks while receiving BOC signals. The code tracking loop （＂BOC＋QBOC-BOC＂） for BOC signals which uses QBOC code is introduced. To the best of the author＇s knowledge, its theoretic performance is derived for the first time, which is well supported by the simulation results. The conclusion can be used to compare theoretical performance between different code tracking loops and guide the design of BOC signal receivers.