全双工射频自干扰改进时变步长NLMS对消算法

针对现有基于最小均方误差准则的全双工射频域自干扰对消算法存在收敛速度与干扰对消比相互制约的矛盾，提出一种改进时变步长归一化最小均方算法。该算法通过建立最小均方误差步长因子与改进时变sigmod函数的非线性关系，利用实时误差信号自相关和时间参量t协同控制步长因子μ(t)，较好的兼顾了收敛速度与干扰对消比。分析与仿真表明:在干信比为80dB、步进间隔Δt=1/32ms、信噪比Eb/N0=10 dB的2FSK全双工系统模型下，该算法能够实现88dB的自干扰消除高出同类算法至少1.5dB且收敛速度和抗突发干扰能力提升显著。 

Improved Time-Varying Step-Size NLMS Algorithm for RF Self-Interference Cancellation in Full-Duplex

Aiming at the conflict between convergence speed and interference cancellation ratio(ICR) of radio frequency(RF) domain self-interference cancellation algorithm which based on the minimum mean square error (MMSE) criterion in full-duplex systems, proposing an improved time-varying step-size normal least mean square algorithm. This method on the basis of the self-interference cancellation construction, building nonlinear relationship between time varying step-size and modified sigmod function, the autocorrelation of real-time error signal and time parameter t are utilized to vary step-size in order to better convergence speed and ICR. Analysis and simulation show that RF domain ICR of proposed method reached to 88 dB higher than similar algorithms at least 1.5 dB and the convergence speed and the ability to resist sudden interference are significantly improved on the full-duplex 2FSK systems model which interference to signal ratio(ISR) is 80 dB, step interval Δt=1/32 ms, signal to noise ratio Eb/N0=10 dB.