摘要
Low earth orbit(LEO)mega-constellations can provide global low-latency high bandwidth coverage compared to the terrestrial network.The time-varying topology of satellite networks and the uneven traffic distribution lead to the mismatch between satellites and users,resulting in the waste of satellite resources and the degradation of user performance.Through negotiation with neighbors,the traditional terrestrial cell breathing continuously converges to the optimal cell size in the face of user tides,but this method is difficult to converge timely when facing rapid and extreme flow changes caused by the rapid movement of satellites.This paper presents a fast adaptive cell breathing scheme(Fa B)through sub-block division and satellite cell initialization and adjustment.Fa B divides the ground into sub-blocks according to the user density.When the satellite moves in the same sub-block,the step size of breathing is adjusted according to the cell size difference between the previous satellite and the current satellite.When the satellite switches between different sub-blocks,the initial value of the cell is determined according to the density of the new sub-block.In addition to negotiating with neighboring satellites,this scheme also introduces location information to directly adjust the parameters of cell breathing and decrease the time of cell breathing convergence.From the real constellation data-driven simulation,we conclude that Fa B can quickly adjust the size of the cell with the location changing,and the utilization rate is increased by 2.66 times compared to the method with no cell breathing,and by2.37 times compared to the method with cell breathing without location information.
相较于地面网络,低轨巨型星座可以提供覆盖全球的低延迟高带宽互联网服务。卫星网络的时变拓扑和不均匀的用户分布导致了卫星与用户之间的不匹配,进而造成卫星资源的浪费和用户性能的下降。传统地面的小区呼吸在面对用户潮汐时,一般通过与邻居不断协商收敛到最优小区大小,然而这种方法在面对卫星快速移动引起的快速极端流量变化时难以及时收敛。本文提出了一种新的小区呼吸方案Fa B,通过子块划分和卫星小区的自适应初始化和调整来应对这种变化。Fa B根据用户密度将地面划分为子块。当卫星在同一个子块中移动时,根据前一卫星与当前卫星的小区大小差异调整呼吸的步长。当卫星在不同子块之间切换时,根据新子块的密度确定小区的初始值。除了与相邻卫星协商外,Fa B还引入位置信息直接调整小区呼吸参数,从而减少了小区呼吸收敛时间。从真实星座数据驱动的仿真可以看出,Fa B可以随着位置变化快速调整小区大小,相较于没有使用小区呼吸前,卫星的利用率提升至2.66倍;相较于地面没有使用位置信息的小区呼吸,Fa B将利用率提高到2.37倍。
基金
the National Key Research and Development Plan of China(No.2018YFB1800301)
the National Natural Science Foundation of China(No.62132009)
the Youth Fund of National Natural Science Foundation of China(No.61902214)
the Tsinghua University-China Mobile Communications Group Co.,Ltd.Joint Institute。
作者简介
Corresponding author:LIU Jun,E-mail address:juneliu@tsinghua.edu.cn.
