Providing multimedia communications services from high altitude platforms

System level design considerations for high altitude platforms operating in the mm-wave bands are examined. Propagation effects in these bands are out lined, followed by a brief introduction to different platform scenarios. Gr ound-based and platform-based fixed wireless access scenarios are considere d. and it is shown that using a platform. a single base station can supply a much larger coverage area than a terrestrial base station. The effects on performance of platform displacement from its desired location with both f ixed and steerable antennas are also examined. It is shown that steerable a ntennas are of most use when fixed stations are immediately below the platf orm, with no benefit for fixed stations on the edge of coverage. The bandwi dths required to serve several traffic distributions (suburbs and city cent re based) are evaluated using the Shannon equation. It is shown that capaci ty can be constrained when users are located in the city centres, despite l onger line of sight paths to users out in the suburbs. The effects of tempo ral changes in the spatial traffic distribution are investigated. It is sho wn that bandwith requirements can be reduced if the platform moves to track these changes. Copyright (C). 2001 John Wiley & Sons, Ltd.