Vertical Handover Strategy in Satellite-Aerial Based Emergency Communication Networks

After a disaster, a network of unmanned aerial vehicles (UAVs) and low Earth orbit (LEO) satellites can provide communication services rapidly to the affected area. In this emergency communication system, UAVs frequently encounter network handover (HO) issues while conducting post-disaster situational awareness (SA) tasks such as searching and monitoring during their flight. Due to the high demand for uplink data rates and the time-sensitive nature of sensing data, transmission disconnections are prone to occur if UAVs connect to an inappropriate network, potentially affecting subsequent rescue operations. To tackle this problem, a vertical HO scheme based on the Analytic Hierarch Process-Entropy (AHP-Entropy) weighting and Technique for Order Preference by Similarity to Idea Solution (TOPSIS) is proposed. In this work, received signal strength, data rate, and latency are taken into account. The comprehensive attribute weights are obtained by the AHPEntropy weighting method, and then TOPSIS is applied to rank the candidates to select the best network. Moreover, the satelliteground distance is obtained by the Mean Value Theorem for Integrals and the maximum and minimum elevation angles during the movement of LEO satellite. Meanwhile, mobile edge computing (MEC) is introduced on LEO satellite for data compression to further reduce the feeder link delay of LEO satellite. The simulation results show that, compared with the benchmark method, the proposed scheme can significantly improve throughput and reduce disconnections without increasing delay excessively. This ensures the stability and reliability of real-time post-disaster SA.