基于IIVSSLMS低轨卫星导航增强系统数字域自干扰对消算法研究

Research on Digital-domain Self-interference Cancellation Algorithm of LEO Satellite Navigation Augmentation System Based on IIVSSLMS

低轨卫星导航增强系统在实现高精度定位时,导航增强信号和低轨导航增强载荷正常接收信号会产生自干扰,针对此问题,提出了一种基于改进的迭代变步长最小均方(Improved Iterative Variable Step-size Least Mean Square,IIVSSLMS)的数字域自干扰对消算法。在初始阶段设置较大的步长因子以提高收敛速度,并基于箕舌线函数建立步长因子和迭代次数之间的非线性关系,同时利用当前误差信号和上一步误差信号之间的自相关估计协同控制步长因子。利用步长因子、误差信号和发射信号得到估计的自干扰信道冲激响应,并根据已知的发射信号重构自干扰信号。从接收信号中去除重构的自干扰信号,实现数字域自干扰对消。仿真结果表明,该算法与已有变步长最小均方(Least Mean Square,LMS)算法相比,收敛速度提高2.5倍,干扰对消比提高7.4 dB,性能提升显著。

When an LEO satellite navigation augmentation system realizes high-precision positioning,the navigation enhancement signal and the normal received signal of LEO navigation enhancement payload will produce self-interference.In order to solve this problem,a digital-domain self-interference cancellation algorithm based on IIVSSLMS is proposed.A larger step factor is set in the initial stage to improve the convergence speed,and the nonlinear relationship between the step factor and the number of iterations is established based on the Versoria function.At the same time,the autocorrelation between the current error signal and the previous error signal is used to collaboratively control the step factor.The estimated self-interference channel impulse response is obtained by using the step factor,error signal and transmission signal,and the self-interference signal is reconstructed according to the known transmission signal.The reconstructed self-interference signal is removed from the received signal to realize self-interference cancellation in digital-domain.Simulation results show that compared with the existing Least Mean Square(LMS)algorithm with variable step size,the convergence speed of the proposed algorithm is improved by 2.5 times,the interference cancellation ratio is improved by 7.4 dB,and the performance is significantly improved.