Modeling And Performance Simulation For High Altitude Platform Communication System Based On OPNET

High Altitude Platform Station (HAPS) based communication system provides communication service to fixed or mobile users on the ground using either an airship or an aircraft in the stratosphere. Compared with terrestrial cellular communication systems, HAPS has larger coverage area, better path loss characteristics, fewer infrastructure needs. Compared with satellite communication systems, HAPS has higher system capacity, lower propagation delay, lower configuration cost, and its terminal can be more portable. Flexible HAPS overcomes the deficiency of terrestrial cellular communication systems and satellite communication systems, and has wide application prospects in emergency communications and military communications. This paper studies the modeling and simulation of HAPS communication system, which provides a strong support for the theoretical research, and provides a useful reference for the system planning and construction.We introduce the architecture and the function of each segment for the HAPS communication system at first. We study the unstable characteristic of the platform and establish its mobility model. Geometry model of two kinds of multi-beam antenna are created. Radiation characteristic is analyzed. The results show that equal coverage area multi-beam antenna has better CIR then equal beam width multi-beam antenna.HAPS communication system simulation platform based on OPNET is established. Node models for the platform and users and the corresponding interior process models are built. Model process mechanisms are expatiated. We simulate unstable characteristic of HAPS by movement control module. Regular cellular coverage is realized by equal coverage area multi-beam antenna module. Connection admission control procedure is realized and different algorithms are implanted.We study and evaluate three kinds of connection admission control and handover scheme. We analyze call blocking probability and handover probability under two different load balancing rules. Results show that the second algorithm can reduce handover probability significantly while moderately increasing call blocking probability. Based on guard channel, we propose partial-area guard channel algorithm, which improves call blocking performance greatly while moderately reducing handover performance. Based on Time-based Channel Reservation Algorithm with Overbooking (TCRA-O), we propose overlap area assisting TCRA-O, which remarkably improves system handover performance.