移动通信中适用于高车速环境的精确Doppler频移与信噪比联合估计算法

Accurate joint estimation of Doppler shift and SNR in mobile communications with high vehicle speed

车载移动通信中信噪比与Doppler频移对通信质量有重要影响.本文探究了基于迭代自相关函数的Doppler频移估计算法,指出其在高车速环境下估计误差较大,提出了一种插值改进方法以改善高车速时的Doppler频移估计.最后根据迭代Doppler频移估计在不同迭代环节具有不同估计误差这一特性,提出了基于Doppler频移估计误差比的信噪比估计算法.计算机仿真结果表明,所提出的算法在一般通信系统的工作信噪比与车速范围内均有较好的估计性能,最高仿真车速达到了300 km/h.

The signal-to-noise ratio（SNR） and Doppler shift significantly affect vehicular communication.Therefore, we investigate the biases of an iterative Doppler shift estimator by addressing the approximation of the autocorrelation function（ACF）, and then explicitly view the estimation errors occurring at high vehicle speeds. Accordingly, a refined process by exploiting the interpolation operation is proposed to reduce the estimation bias at high moving speeds. Subsequently, an SNR estimator is presented by utilizing the bias variation in different iterations, where the estimates of the Doppler shift in the first and final rounds of iterations are combined to construct a bias ratio, and this ratio is then employed to derive an SNR estimator. Computer simulations have shown that our proposed algorithm achieves accurate estimates for both the SNR and Doppler shift in wide ranges of working SNRs and mobile speeds, i.e., at a simulated velocity approaching 300 km/h.