Push-based information delivery in two stage satellite-terrestrial wireless systems

One of the prominent objectives of National/Global Information Infrastructure is to provide all types of users global access to information. Satellite broadcast data delivery has inherent advantages, such as scalability and location independent availability, in achieving this objective. However, users need expensive and cumbersome equipment to receive and transmit satellite signals. Furthermore, as the amount of information being broadcast increases, average user latency increases as well. Often, users in a geographical locality have similar interests, which can be better served by employing a local broadcast schedule. In this context, a two stage satellite terrestrial wireless broadcast system can provide more efficient service in terms of lower average user latency and cheaper and more convenient user equipment. In such a system, the main server broadcasts information via satellite to the geographically distributed local ground stations. Every ground station has limited buffer capacity to store the data broadcast by the satellite. According to their buffer content, and the interests of their users, local stations deliver the information to their users via terrestrial wireless channel. We develop novel methods for the joint cache management and scheduling problem encountered in these systems. Our results demonstrate that such two stage systems are feasible and they can provide more efficient data delivery compared to the single stage systems.