  To achieve ubiquitous wireless connectivity, low earth orbit (LEO) satellite
networks have drawn much attention. However, effective beam management is
challenging due to time-varying cell load, high dynamic network topology, and
complex interference situations. In this paper, under inter-satellite handover
frequency and satellite-terrestrial/inter-beam interference constraints, we
formulate a practical beam management problem, aiming to maximize the long-term
service satisfaction of cells. Particularly, Lyapunov framework is leveraged to
equivalently transform the primal problem into multiple single epoch
optimization problems, where virtual queue stability constraints replace
inter-satellite handover frequency constraints. Since each single epoch problem
is NP-hard, we further decompose it into three subproblems, including
inter-satellite handover decision, beam hopping design and
satellite-terrestrial spectrum sharing. First, a proactive inter-satellite
handover mechanism is developed to balance handover frequency and satellite
loads. Subsequently, a beam hopping design algorithm is presented based on
conflict graphs to achieve interference mitigation among beams, and then a
flexible satellite-terrestrial spectrum sharing algorithm is designed to
satisfy the demands of beam cells and improve spectral efficiency. Simulation
results show that our proposal significantly improves service satisfaction
compared with baselines, where the average data queue length of beam cells is
reduced by over 50% with affordable handover frequency.
