针对OFDM的低轨卫星资源动态分配算法

LEO satellite resource dynamic allocation algorithm based on OFDM

摘要:

在天地一体化信息网络场景下，卫星通信与地面5G的融合是大势所趋。因此，正交频分复用(OFDM)作为5G空口协议的关键技术，如何高效服务于频带资源受限的低轨卫星通信系统成为研究热点。针对低轨卫星高动态性、系统信道特征、业务时变性以及大多普勒频移等特点，提出一种针对OFDM的低轨卫星资源动态分配策略。首先根据3GPP标准规定和最大化频谱效率选择载波间隔，子载波分配前通过剔除劣子信道保证信道的传输性能，通过分簇成倍级减少分配时的循环次数；随后依据用户需求及信道特征对子载波进行贪婪分配；最后对单用户按照比例所分到的功率应用注水原理。仿真结果表明，该算法能有效适应低轨卫星场景，降低算法的复杂度，提高系统容量的同时仍可保证用户需求与传输速率的公平性。

Abstract:

In the scenario of integrated terrestrial and space information networks, the integration of satellite communication with terrestrial 5G is an inevitable trend. For Orthogonal Frequency Division Multiplexing(OFDM), a key technology of the 5G air-interface protocol, how to efficiently serve the Low Earth Orbit(LEO) satellite communication systems with limited frequency band resources has become a hotspot. In view of the high dynamics of LEO satellites, system channel characteristics, service variability, and most Doppler frequency shifts, a dynamic resource allocation strategy for OFDM in LEO satellite communication is proposed. Firstly, based on the 3GPP standard and the maximization of spectral efficiency, the subcarrier spacing is selected, and the transmission performance of the channel is ensured by eliminating inferior sub-channels before subcarrier allocation, and the number of cycles during allocation is reduced by clustering in multiples; then, the subcarriers are greedily allocated according to user demand and channel characteristics; finally, the power allocated to a single user is applied according to the proportional water-filling principle. Simulation results show that the algorithm can effectively adapt to the LEO satellite scenario, reduce the complexity of the algorithm, and improve the system capacity while still ensuring the fairness of user demand and transmission rate.