Towards High Energy Efficiency Contact Plan Design in Collaborative Data Offloading in Space Information Network

Space information network (SIN) consisting of communication satellites plays an important role in information acquisition and transmission. An increasing volume of data produced by different space missions is forwarded by satellites to ground stations (GSs), which leads to satellites that are responsible for forwarding being overload and data cannot be timely downloaded to GS. Moreover the dynamic and complex SIN operating environment deteriorates the performance of data downloading. Thus, for improving data downloading, it is a key to realize data load balance. That means extra data is offloaded to other satellites having extra downloading capacity with an effective scheduling method. To this end, we modeled collaborative data offloading problem as multi-objective mixed integer nonlinear programming (MOMINLP) problems based on developing time-evolving graph (TEG) and contact plan. Due to its computational complexity, we proposed a heuristic approach with phasing based on contact plan, i.e., phased offloading algorithm (POA) operating on a slot-by-slot basis, to jointly schedule data offloading among the satellites and data downloading from satellites to the GS. Simulation results demonstrate that, in many cases, the proposed algorithms can guarantee relatively high data downloading throughput and low energy consumption produced by data offloading.