Platform displacement impact on mobile WiMAX handover performance over HAPS cannel

High Altitude Platform Station (HAPS) is one of a new infrastructure in telecommunication, which is like airship or aircraft that is placed on the stratosphere. The distance of platform is about 17-22 km from the earth's surface. However, in its application HAPS that placed on the stratosphere layer of air is affected by the wind gusting. Position HAPS can change from the normal state that is called Platform Displacement. In this research discuss about platform displacement impact that experienced by the mobile station (MS) during the handover (HO) process. User is mobile WiMAX user who is using VoIP communications services. Performance of the system is calculated by some parameters value, there are throughput, data dropped, and HO (handover) delay. System will be simulated using simulator OPNET Modeler 14.5. In the simulation results can be seen the influence of platform displacement and speed of the user. When platform moves to the higher altitude will increase the area of cells coverage so that each cell can interfere its neighbor cells, especially in the transition region where MS do HO process. This condition can disturb HO process and increase data dropped during HO process.