A regional communication satellite system is being planned for Europe to satisfy the future needs of the European Conference of Post and Telecommunication Administration (CEPT) and the European Broadcasting Union (EBU). A model of the mission for the satellite system, based on the estimated future traffic requirements of the potential customers, has been defined to serve as a basis for system design. Starting with the postulated traffic model and with a review of the various system constraints, the present paper defines the parameters and the tradeoffs leading to the choice of the communication techniques fulfilling the requirements of the mission model. The resulting baseline communication system and its major characteristics are described. Alternate system design options are presented and commented upon. Some of these options would enhance the performance of the system but would generally involve more advanced techniques and would represent a larger technological risk. Finally, research and development topics in the field of communication technology are identified. Some of these topics are being investigated and some of the results are described in other papers.