Low earth orbit (LEO) satellite communication has been seen as a promising solution for achieving global ubiquitous connectivity and high data rates. However, the propagation delays between satellites and cells are time-varying and significantly different, resulting in asynchronous inter-cell interference. Most existing research assume that the signals from all satellites are received simultaneously, which oversimplifies the interference situation and limits their applicability. To address this challenge, a beam management approach with asynchronous interference mitigation is proposed to improve network throughput. Firstly, a primary serving duration allocation method is developed based on convex optimization, while asynchronous interference is ignored. Subsequently, considering that inter-cell interference can be mitigated by appropriately setting guard periods, a beam scheduling with guard period selection method is designed under given service duration constraints, where conflict graphs are constructed to characterize interference situations. Extensive simulation results validate that our proposed scheme can effectively mitigate asynchronous inter-cell interference and significantly enhance network throughput. Specifically, the network through-put is increased by 20% compared with baselines that ignore asynchronous interference.

Mega low earth orbit (LEO) satellite constellation is promising in achieving global coverage with high capacity. However, forwarding packets in mega constellation faces long end-to-end delay caused by multi-hop routing and highcomplexity routing table construction, which will detrimentally impair the network transmission efficiency. To overcome this issue, a distributed low-complexity satellite-terrestrial cooperative routing approach is proposed in this paper, and its core idea is that each node forwards packets to next-hop node under the constraints of minimum end-to-end hop-count and queuing delay. Particularly, to achieve an accurate and low-complexity minimum end-to-end hop-count estimation in satellite-terrestrial cooperative routing scenario, we first introduce a satellite realtime position based graph (RTPG) to simplify the description of three-dimensional constellation, and further abstract RTPG into a key node based graph (KNBG). Considering the frequent regeneration of KNBG due to satellite movement, a low complexity generation method of KNBG is studied as well. Finally, utilizing KNBG as input, we design the minimum end-to-end hop-count estimation method (KNBG-MHCE). Meanwhile, the computational complexity, routing path survival probability and practical implementation of our proposal are all deeply discussed. Extensive simulations are also conducted in systems with Ka and laser band inter-satellite links to verify the superiority of our proposal