Synergy Between Satellite Land Mobile and Terrestrial Cellular Systems - Towards a Personal Communication System M.Richharia and Professor B.G.Evans Department of Electronic and Electrical Engineering.University of Surrey.Gui1dford.U.K. Abstract The current scenario in Europe is of a well defined Pan European digital cellu- lar system together with several proposals for land-mobile satellite systems.The integration of a satellite system with the terrestrial system has obvious advantages.This paper investigates the possible synergy of a land mobile satellite system with the Pan European terrestrial digital cellular system.A possible integrated system architecture using the main functional blocks of the terrestrial system is proposed.Alternative satellite systems have been examined and a likely implementation scenario. based on the foreseeable development in the region,has been suggested. 1. Introduction At present there are several opera- tional terrestrial land mobile communica- tion systems for public use in Europe. The demand in the region has increased by over six and a half times in the past few years and the growth continues to accelerate. Most of these systems are .however.incompatible with each other. To harmonise the development and to tap the potential large scale econ0my.a pan European system - also called the GSM system (after Group Special Mobile-A CEPT group responsible for the system definition) - has been defined.The GSM system is planned to be operational in 1991.However it has been established that even after the full deployment of the sys- tem .sometime in the late 1990s.large geo- graphical areas will remain uncovered by the terrestrial cellular network.Recent surveys indicate that there is a substantial tr&c demand in such areas - enough to make a satellite system viable (l).Such a satellite system .if integrated with the GSM system.can provide an elegant solu- tion to the needs of the European mobile communication (2.3.4). One constraint in such an integration process arises due to the necessity of adapting the satellite sys- tem to the GSM definitions-In addition such an integration involves not only technical but also institutional problems .In this paper the technical issues involved in the integration of a satellite system with the GSM system are addressed. 2. Rationale On a close scrutiny the following features related to the integration process emerge. (i) The structure of the GSM network is such that it permits roaming of mobiles between several public land mobile networks.Hence it should be possible to incorporate a satellite network as a sub- set. (ii) The deployment of the GSM system is expected to take several years.During this period a satellite system can provide ser- vices in all uncovered areas,parts of which may later be covered by the GSM system. (iii) In the initial stages a satellite system can provide only certain supplementary services due to the low bit rate transmis- sions possible with the present satellite systems.Voice and higher data rates ( 10 kb/s ) can be added subsequently as the techno logy develops. Copyright @ 1990 American Institute of Aeronautics and Astronautics, lnc. All rights reserved.