Dynamic Handover in Satellite-Terrestrial Integrated Networks

Abstract

The satellite-terrestrial integrated networks (STIN) can obtain wider coverage area and flexible connectivity to deal with the increasing traffic demands of the users. However, the dynamic mobility of nodes in STIN gives rise to the frequent link switching between low earth orbit (LEO) satellites and mobile terminals, which leads to the poor quality of service (QoS). As an effort to address the above problems, a novel handover scheme with multi-attribute dynamic graph (MADG) is proposed to reduce handover delay, as well as the unnecessary handover. Firstly, the link connectivity is analyzed to obtain the available switching path information after constructing a STIN model, which consists of LEO satellites and mobile terminals with different mobility features. Since the handover process can be modeled as finding an optimal path from the available switching paths, a dynamic graph named MADG is given to represent all the possible handover paths via considering the elevation angle, coverage time, and free channel state. Meanwhile, the multi-service data transmission problem for STIN is analyzed to fulfill the different service requirements with multiple attribute decision making (MADM). Afterwards, a dynamic handover scheme with MADG and MADM is proposed, in which an optimal handover path can be selected by Floyd algorithm according to the edge weights. The simulation results show that the proposed handover scheme can effectively minimize the total handover latency and reduce unnecessary handovers.