卫星移动通信中准恒包络可重构多载波技术研究

Mobile satellite communication is a power-limited and band-limited system, and the communication links suffer from large-scale frequency offset. Therefore, multicarrier signal transmission with low Peak to Average Power Ratio (PAPR) and the capability to resist frequency offset is one of the key issues for next generation mobile satellite communication systems. However, the existed multicarrier waveform cannot satisfy the requirement of high spectrum efficiency and low PAPR well, and the methods used to resist the frequency offset have high computational complexity. In this project, we aim to design a multicarrier waveform with high spectrum efficiency, low PAPR and high ability to resist frequency offset jointly, and propose re-configurable multi-carrier with quasi-constant envelope based on the idea of data streams multiplexing. The project focus on the research of multicarrier transmission, low PAPR waveform optimization, and frequency offset estimation and complementation for the re-configurable multi-carrier with quasi-constant envelope. For the multicarrier transmission, phase shifting and adding at the transmitter and data streams de-multiplexing at the receiver are used to get the low complexity architecture. Moreover, the phase modulation indices for multiple data streams are optimized jointly to decrease the PAPR of the waveform further. At last, the null subcarrier in the waveform is used to estimate the frequency offset that used to be complemented with low complexity. The performance of the re-configurable multi-carrier with quasi-constant envelope has been verified initially. The evaluation results of the proposed waveform have shown its significance in science and application to increase the power efficiency of next generation mobile satellite communication systems.

卫星移动通信功率受限、带宽受限，通信链路具有大尺度频偏。因此，低峰均比多载波信号抗大尺度频偏传输是下一代卫星移动通信系统需要解决的关键问题之一。然而，现有多载波波形设计不能同时满足高谱效、低峰均比的要求，抗大尺度频偏信号检测算法复杂度高。本课题联合考虑高谱效、低峰均比波形设计和抗频偏信号检测，基于“数据流复用”思路提出准恒包络可重构多载波技术。课题组重点针对多流准恒包络可重构多载波传输、低峰均比波形优化，以及频偏估计与补偿技术展开研究。其中，课题组拟通过发送端移相叠加和接收端数据流解复用实现低复杂度准恒包络可重构多载波传输；通过多数据流调相指数联合优化进一步降低准恒包络可重构多载波的峰均比；通过空闲子载波频偏估计和补偿，实现低复杂度、抗大尺度频偏信号检测。课题组对准恒包络可重构多载波的性能进行了初步验证，该技术对于提升下一代卫星移动通信系统能效具有较大的科学意义和应用前景。

卫星移动通信系统中多载波传输所面临的核心科学问题是高谱效、低PAPR（Peak to Average Power Ratio，峰值平均功率比）多载波波形设计问题和低复杂度、抗大尺度频偏多载波信号检测问题。针对这一问题，课题组基于“数据流复用”思想，提出准恒包络可重构多载波及其信号检测技术，并重点从三个方面开展关键技术研究：.（1）多流准恒包络可重构多载波传输技术研究。课题组基于可变子载波带宽提出多流准恒包络可重构多载波设计框架，并提出适用于准恒包络多载波的收发信机实现方案。此外，课题组提出基于幅-相解调器的迭代接收机方案，可有效增强准恒包络多载波解调性能。.（2）准恒包络可重构多载波低PAPR波形优化技术研究。课题组分析了准恒包络多载波中数据流的调相指数、过采样因子等参数对波形PAPR的影响，并结合波形PAPR和信号检测性能需求，提出波形PAPR优化方法，可有效提升准恒包络多载波的能量效率。.（3）准恒包络可重构多载波频偏估计与补偿技术研究。课题组分析了载波频率偏移和载波相位偏移对准恒包络多载波的影响，提出了载波频率偏移和载波相位偏移联合估计方法，并同时提出最优的导频结构，可有效提升准恒包络多载波系统频偏估计与补偿精度。此外，课题组提出频偏和频偏变化率联合估计方案等，以进一步增强准恒包络多载波在大尺度频偏下的信号检测性能。.在项目执行期间，课题组共发表学术论文16篇（SCI论文5篇，EI论文11篇），申请国家发明专利4项。研究结果表明，本课题所提出的准恒包络可重构多载波及其信号检测技术可有效提升系统频谱利用率、降低波形PAPR，并可有效降低大尺度时变频偏及相位噪声对信号解调的影响，为下一代卫星移动通信系统的研究和建设提供了理论依据和数据参考。