多天线时变信道频偏的估计下界

Estimation Lower Bound of Time-varying Channel Frequency Offset for Multiple Antenna

针对多天线信道频偏参数的随机时变特点,建立参数化的观测模型,根据时变参数估计的克拉美-罗下界求取原理,在非线性的观测模型和序贯的观测值下,利用参数真值推导频偏估计的克拉美-罗下界。由于特征参数的真值不可知,因此将观测模型在估计值处进行二阶泰勒级数展开,通过参数估计值获得频偏参数估计的近似下界。仿真结果表明,基于参数真值和估计值的频偏估计下界具有渐近收敛性,且随信噪比和观测值个数的增加均能达到稳态。

According to the characteristics of random time-varying frequency offsets parameters of multiple antenna channel, this paper establishes the parametric observation model. It depends on time-varying estimation Cramer-Rao Lower Bound（CRLB） calculation principal, derives the CRLB of frequency offsets characteristics parameters under nonlinear observation model and sequential observations. The value of characteristics parameters is unknown, the observation equation is linearized at estimated values by using Taylor series expansion and then it gets the approximate CRLB of frequency offsets. Simulation results show that the method can achieve good asymptotic convergence of varying parameters＇ CRLB whether the true value of the parameters are known or not. The two estimation lower bounds can reach steady state with the increment of signal to noise ratio and the number of observation value.