基于插值的多普勒频偏和频率斜升联合估计算法
doi: 10.3724/SP.J.1146.2012.00716
Joint Estimation of Doppler Frequency Shift and Doppler Frequency Rate Based on Interpolation
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摘要: 为解决卫星移动通信系统中突发传输在低信噪比条件下的载波快速同步问题,该文提出一种基于插值的频偏和频率斜升联合估计算法。先通过对多普勒斜升搜索结合低复杂度频偏估计获得频偏和频率斜升的粗估计结果,再以频率斜升粗估计结果为中心、计算3个频率斜升值所对应的对数似然函数并据此对频率斜升进行二次插值以获得频率斜升估计值,最后在该估计值下计算出对应的频偏估计值,完成频偏和频率斜升的联合估计。仿真结果表明,该文算法的信噪比门限较低,估计性能接近克拉美罗下界(CRLB),而且计算复杂度远低于最大似然估计算法,非常适于实际应用。
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关键词:
- 卫星移动通信 /
- 载波同步 /
- 联合估计 /
- 多普勒频偏和频率斜升 /
- 克拉美罗下界
Abstract: A joint estimation method of Doppler frequency shift and Doppler frequency rate based on interpolation is proposed for achieving fast carrier synchronization of burst in mobile satellite communication system under the circumstance of low Signal-to-Noise Ratio (SNR). In the proposed method, a coarse estimation of Doppler frequency shift and Doppler frequency rate is achieved first by a Doppler frequency rate searching combined with a traditional low-complexity frequency-estimating algorithm. The log-likelihood function of three Doppler frequency rate testing values, with the coarse estimation result as the center, is calculated and then an interpolation is taken to decide the final estimation of Doppler frequency rate. Finally, the frequency-estimating algorithm is used again to get the final estimation of Doppler frequency shift. Simulation results show that the proposed method has a low SNR threshold and an estimation performance close to Cramer-Rao Low Bound (CRLB). And it has a complexity by far the less than the max-likelihood algorithm and so is very applicable.
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