Use of highly elliptic orbits for new communication services

The use of highly elliptic orbits for communication services can be analyzed according to several parameters, but the final parameter which will determine the adoption of a system instead of another one is the cost of the space infrastructure, when deployed into the selected orbit. Thus, the selection of mission parameters has to be made by comparing their impact on overall system costs. The major parameters concern with: coverage; number of satellites; and orbit altitude, inclination, ellipticity. In general, the above parameters have to be selected according to the service requirements, but from their choice will derive the system complexity and the cost, including also the launch cost. Thus, the definition of a convenient space infrastructure for new services has to be assessed through extended trade-offs of above elements, at least. The purpose of this paper is to identify major rules capable to help and simplify the system definition process. Several architectures are analyzed and compared with many orbit periods. The following topics are considered: coverage requirements and mask angle selection; radiation environment typical of the selected orbit; and orbit acquisition and orbit control strategies. The paper addresses the above matters and attempts to identify the solutions and the rules applicable to similar cases.