基于用户分组的低轨卫星动态跳波束算法

Dynamic Beam Hopping Algorithm for LEO Satellite Systems Based on User Grouping

在部署了大规模MIMO的卫星通信系统中,当用户数量远超卫星的波束数时,即便增加射频链的数量,即增加同时服务用户的数量,仍然难以满足卫星通信系统的时延要求。针对以上问题,提出一种基于用户分组的动态跳波束方案,根据用户组进行通信服务覆盖。所提方法利用信道角域分布的稀疏性,根据用户能量最大的波束方向自适应划分用户分组。由于卫星上功率限制使得射频链数量受限,且增加同时服务的用户组会增加用户组间的干扰,因此共信道用户组的数量受到功率和干扰约束,限制了通信业务服务时延减小。于是进一步提出波束簇分组的跳波束方案,此时波束簇通过增加同一时刻服务用户的数量,来减小用户的时延。由于以上问题是非凸的,采用数据驱动的行列式点过程方法简化跳波束方案中的波束调度。仿真结果表明,基于用户分组的动态跳波束算法能够有效减小用户的平均时延,与单波束方案相比,平均时延减少超过52%。同时在仿真结果中也验证了行列式点过程模型的泛用性。

In a satellite communication system deployed with massive MIMO,when the number of users far exceeds the number of beams of the satellite,it is still difficult to satisfy the delay requirements of the satellite communication system even if the number of RF chains is increased,i.e.,the number of concurrently serving users is increased.To address the above problems,it proposed a dynamic beam hopping(BH)scheme based on user grouping for communication service coverage.The proposed method utilized the sparsity of the angular domain channel distribution to adaptively divide user groups accorded to the beam direction where the user energy is maxi-mum.The number of co-channel user groups was constrained by power and interference constraints,limiting the reduction of commu-nication traffic delay,as power limitations on the satellite make the number of RF chains limited and increased the number of simulta-neously served user groups increased the interference between user groups.So the BH scheme with beam cluster grouping was further proposed,when the beam clusters reduced the user delay by increased the number of users served at the same moment.Since the above problem was non-convex,it adopt a data-driven determinantal point process(DPP)learning method to simplify the beam scheduling in BH scheme.Simulation results showed that the dynamic BH algorithm based on user grouping could effectively reduce the average user delay by more than 52%compared with the single-beam scheme,also verifies the versatility of the DPP learning.