| 摘要: |
| 针对卫星移动通信低信噪比条件下快变多普勒频偏捕获提出了一种新的算法即基于搜索空间压缩的谱线循环平移算法。首先，介绍了现有的载波频偏捕获技术，分析其不能适应快变多普勒频偏条件的原因；其次，分析了多普勒变化率对载波频偏捕获的影响，主要考虑一次变化率与二次变化率将严重限制低信噪比情况下对载波频偏估计时非相干累加的有效性；最后，在此基础上，提出了低信噪比条件下快变多普勒频偏捕获的基于搜索空间压缩的谱线循环平移算法。对算法进行的Matlab仿真结果表明，其具有2~3 dB的改善增益，与最大似然算法相比，在性能仅有0.2 dB损失的情况下运算量大大减少。 |
| 关键词: 低地球轨道星座 卫星移动通信 高动态信号 载波捕获 快变多普勒频偏 低信噪比 |
| DOI： |
|
| 基金项目: |
|
| A fast changing Doppler frequency offset acquisition algorithm under low SNR |
| ZHAO Rui,WANG Yan-wen |
| () |
| Abstract: |
| A new algorithm or the spectrum line circle shift algorithm based on compressed searching space is proposed for fast changing Doppler frequency offset acquisition under low signal-to-noise ratio （SNR） for satellite mobile communication. Firstly,current carrier frequency offset acquisition technologies are introduced,and the reason why these technologies can not adapt to fast changing Doppler frequency offset acquisition is analyzed.Then,the effect of changing rate of Doppler frequency offset on
carrier frequency offset acquisition is analyzed. The situation that the first order changing rate and second order changing rate affect carrier acquisition is considered emphatically. The changing rate of Doppler frequency offset seriously reduces the effectiveness of non-coherent accumulation during carrier frequency offset estimation at low SNR. Finally,on this base,the spectrum line circle shift algorithm based on the compressed searching space is provided and simulated with Matlab.The result shows that the algorithm has gain improvement of 2~3 dB. Compared with maximum likelihood（ML）,the proposed algorithm losses 0.2 dB performance，however，amount of calculation is greatly reduced. |
| Key words: low earth orbit constellation satellite mobile communication high dynamic signal carrier frequency offset acquisition fast changing Doppler frequency offset low SNR |
《电讯技术》编辑部 