Book excerpt: Mobile satellite services are set to change with the imminent launch of satellite personal communication services (S-PCS), through the use of non-geostationary satellites. This new generation of satellites will be placed in low earth orbit or medium earth orbit, hence, introducing new satellite design concepts. One of the first texts to cover this rapidly evolving field, this text provides the reader with an overview of mobile satellite systems, from their initial introduction (Inmarsat), current satellite-PCS (referring to such systems as Globalstar), through to Satellite-UMTS and an understanding of the following: * The design concepts associated with non-geostationary satellite systems (constellation, link budgets, Doppler) * The concepts of UMTS (network architecture, aims, in the context of IMT-2000) and the role foreseen for the satellite component (complementary to terrestrial network, network extension, global availability) * Inter-working between satellite and terrestrial networks (network architecture, ATM Adaptation Layer) * Radio interface technologies (WB-CDMA, TDMA, transmission environment) * Regulatory issues * Future services and applications * Potential satellite markets (prediction techniques, effect of tariffing policies on potential market) With leading edge information, this valuable resource will be indispensable to researchers, engineers, operators and market evaluators in satellite service industries and research institutions, as well as postgraduates and research students in the field.