低轨小卫星网络中基于编码缓存的协同传输机制研究

Research on Coded Caching-Enabled Cooperative Transmission Mechanism in LEO Small Satellite Network

随着低轨小卫星网络的快速发展,地面用户将可以借助密集部署的低轨卫星网络享受到全球覆盖的内容传输服务。由于星地通信链路往往具有长时延特性,再加上星上有限的通信和能量资源,卫星在提供内容传输服务的同时面临着传输开销的压力。因此,针对低轨小卫星网络,提出一种基于编码缓存的协同传输机制以实现高效的内容分发。通过采用细粒度的编码缓存方案,可以使得地面用户在请求内容数据时,同时接收来自多个低轨卫星节点缓存的编码数据,实现回程链路开销的降低与缓存效率的提升。仿真结果表明,在部署星上缓存后,可以降低39%以上的传输开销;当采用基于编码缓存的传输方案时,随着协同卫星数量的增加,可以进一步降低9%~42%的传输开销。

Along with the rapid development of low earth orbit(LEO)small satellite network,users can access content retrieval service through dense-deployed LEO satellite networks in the future.Due to the long propagation delay of satellite-to-terrestrial link,and also the constraint of limited communication resource and energy resource,it is diffi cult for satellites to provide effi cient content transmission service when facing the pressure of onboard overhead.A coded caching-based cooperative transmission mechanism was proposed in dense-deployed LEO small satellite network to achieve effi cient content distribution.By adopting fi ne-grained coded caching scheme,users could simultaneously receive cached packets from multiple LEO satellites to mitigated the cost of satellite backhaul link and improved the caching effi ciency.The simulation results showed that,after deploying onboard caching,the cost of content transmission could be reduced at least 39%.When coded caching-based transmission scheme was adopted,the cost of content transmission could be further reduced by 9%-42%with the increase of satellites providing cooperative transmission.