The Effect of Platform Instability on the User Terminal and Backhaul Link Performance of HAPS-UMTS

High Altitude Platform Stations (HAPS) are a new, promising means of providing Third Generation (3G) mobile services, broadband services and TV broadcasting. One of the potential problems of the system, where aircraft technology is used, is the platform positional instability due to rotation and stratospheric winds. This may produce fluctuations in the signal level and thus degrading the performance level. In this work, a study of the effect of positional instability of HAPS (aircraft category) on the link level performance of an International Mobile Telecommunications (UMTS) served by HAPS is presented. The analysis is performed in three different climatic conditions of Malaysia, which is a tropical country. Then two types of radio links have been analyzed – firstly, the end user link which connects aerial station and end user and then, backhaul link that establishes communication between HAPS and Ground Transmission Gateway (GTG). A platform instability model obtained through measurements of rotation and stratospheric winds. Finally, the effect of instability was given in received signal level variation and link availability or percentage outage of the link. Obtained results showed that, the link availability of the backhaul link meets the ITU-R recommendations. Lately, it can be said that, the results of the service obtained can be used to design the communication network with higher level of user satisfaction.