Handover Procedure Design and Performance Optimization Strategy in LEO-HAP System

Abstract

High altitude platform (HAP) is an important supplement facility for low earth orbit mobile satellite system (LEO-MSS) to increase the capacity in hot-spot regions beyond the coverage of terrestrial networks. Because of the large propagation delay and the frequent passive handover caused by the quick movement of LEO satelliets, handover protocols and strategies should be studied and improved. In this paper, we design different handover procedures suitable for LEO-HAP system based on 5G protocol and analyze the performance on delay and signalling cost. And we propose a dynamic handover strategy to optimize the handover moment and resource allocation. Lagrange duality is used and a sub-gradient algorithm is presented to solve this problem. Simulation results show that the proposed handover processes provide better performance on delay and signalling cost compared with the traditional protocol. And the proposed strategy has an excellent performance on drop rate and power consumption.