| 摘要: |
| 与地面蜂窝网络相比，非地面通信网络如低轨卫星通信场景下往往存在更高的多普勒频偏和较低的接收信噪比等问题，严重影响系统性能。为了提高同步性能，提出了一种多级频偏估计方法，以补偿由星地之间相对运动引起的多普勒频偏。首先，星历频偏预估计利用终端位置和星历信息进行粗略估计。其次，对于剩余频偏估计问题，将其等效地转化为离散傅里叶变换（Discrete Fourier Transform，DFT）插值迭代频率估计问题，并通过残余频偏粗估计和精估计分别完成。仿真结果表明，与传统的互相关方法及其他几种典型改进方法相比，所提方法具有更高的多普勒频偏估计精度，在归一化频偏为4.487、信噪比为0 dB时，频偏估计的均方根误差可达到10-2，有助于提高接入成功率和通信质量。 |
| 关键词: 非地面通信网络 同步性能 多普勒频偏估计 插值迭代 |
| DOI：10.20079/j.issn.1001-893x.231208003 |
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| 基金项目:国家自然科学基金资助项目（62371082） |
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| A High-precision Doppler Frequency Offset Estimation Method for Non-terrestrial Networks |
| LI Changmiao,SHEN Bin,HUANG Xiaoge |
| (1.School of Communications and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China;2.Chongqing Key Laboratory of Mobile Communications Technology,Chongqing 400065,China) |
| Abstract: |
| Compared with terrestrial cellular networks,non-terrestrial network(NTN) communication systems,for instance in the low Earth orbit satellite communication scenario,often have higher Doppler frequency shifts and lower signal-to-noise ratios,which seriously affect the system performance.To improve the synchronization performance,a frequency shift estimation method is proposed to compensate for the Doppler frequency induced by the relative motion between the satellite and the ground.Firstly,the pre-estimation of ephemeris shift uses the terminal position and ephemeris information for rough frequency compensation.Then,the residual frequency shift estimation problem is equivalently transformed into the discrete Fourier transform(DFT) iterative interpolation-based frequency estimation problem,which is completed by the coarse and fine estimation of the residual frequency shift,respectively.Simulation results show that compared with traditional cross-correlation methods and other typical methods,the proposed method has higher Doppler frequency offset estimation accuracy.When the normalized frequency offset is 4.487 and the signal-to-noise ratio is 0 dB,the root mean square error of frequency offset estimation can reach 10-2,which helps to improve the user access success rate and the communication quality. |
| Key words: non-terrestrial networks synchronization performance Doppler frequency offset estimation iterative interpolation |
