Using Stratospheric Platforms

R&D for wireless communication systems using aircraft called high altitude platform keeping at an altitude of about 20 km has been made progress as a national project in Japan since 1998. In order to realize such novel wireless communication systems, allocation and maintenance of available frequency bands are the key issues. At this stage, following three frequency bands are allocated for the communication systems using stratospheric platforms; 2 GHz bands for IMT-2000, 31/28 GHz bands for fixed service and 47/48 GHz bands for fixed service. Among these frequency bands, 31/28 GHz bands were proposed by Japan and the use of the bands was allowed in WRC-2000 as the results of the frequency sharing and compatibility studies with the other services in ITU-R. On the allocation, however, stringent conditions are imposed and there still remain a lot of further studies in order to deregulate these conditions. This paper describes the current status of the frequency sharing and compatibility studies between the stratospheric platform communication systems and other radio systems in the 31/28GHz bands in the International Telecommunication Union (ITU).