Distributed Satellite-Terrestrial Cooperative Routing Strategy Based on Minimum Hop-Count Analysis in Mega LEO Satellite Constellation

Mega low earth orbit (LEO) satellite constellation is promising in achievingglobal coverage with high capacity. However, forwarding packets in megaconstellation faces long end-to-end delay caused by multi-hop routing andhigh-complexity routing table construction, which will detrimentally impair thenetwork transmission efficiency. To overcome this issue, a distributedlow-complexity satellite-terrestrial cooperative routing approach is proposedin this paper, and its core idea is that each node forwards packets to next-hopnode under the constraints of minimum end-to-end hop-count and queuing delay.Particularly, to achieve an accurate and low-complexity minimum end-to-endhop-count estimation in satellite-terrestrial cooperative routing scenario, wefirst introduce a satellite real-time position based graph (RTPG) to simplifythe description of three-dimensional constellation, and further abstract RTPGinto a key node based graph (KNBG). Considering the frequent regeneration ofKNBG due to satellite movement, a low complexity generation method of KNBG isstudied as well. Finally, utilizing KNBG as input, we design the minimumend-to-end hop-count estimation method (KNBG-MHCE). Meanwhile, thecomputational complexity, routing path survival probability and practicalimplementation of our proposal are all deeply discussed. Extensive simulationsare also conducted in systems with Ka and laser band inter-satellite links toverify the superiority of our proposal.