SATELLITE-ENHANCED PERSONAL COMMUNICATIONS EXPERIMENTS

Users of future generation wireless information services will have div erse needs for voice, data, and potentially even video communications in a wide variety of circumstances. For users in dense, inner-city are as, low power personal communications services (PCS) technology should be ideal. Vehicular-based users travelling at high speeds will need h igh-power cellular technology. For users in remote or inaccessible loc ations, or for applications that are broadcast over a wide geographic area, a satellite technology would be the best choice. Packet data net works provide an excellent solution for users requiring occasional sma ll messages, whereas circuit switched networks provide more economical solutions for larger messages. To provide ubiquitous personal communi cations service, it is necessary to capitalize on the strength of each wireless technology and network to create one seamless internetwork i ncluding both current and future wired and wireless networks. As an in itial step in exploring the opportunities afforded by the merging of s atellite and terrestrial networks, Bellcore and JPL conducted several experiments. These experiments utilized Bellcore's experimental person al communications system (including several messaging applications wit h adaptations to wireless networks), NASA's advanced communications te chnology satellite (ACTS), JPL's ACTS mobile terminal, and various com mercial data networks (such as the wireline Internet and the RAM wirel ess packet data network). Looking at loss of bits, packets and higher layer blocks (over the satellite-terrestrial internetworks with mobile and stationary users under various conditions) our initial results in dicate that the communication channel can vary dramatically, even with in a single network. We show that these conditions necessitate powerfu l and adaptive protocols if we are to achieve a seamless internetworki ng of satellite and terrestrial networks.