System capacity optimization in time and frequency for multibeam multi-media satellite systems

Current Ka-band, multi-media satellite systems employ spot beam technology to accommodate a wide range of multi-media type services. These satellites typically employ uniform allocation of RF power and bandwidth to spot beams. Since the traffic distribution tends to be highly asymmetrical and with a high degree of uncertainty, the satellite does not have sufficient flexibility to satisfy the traffic request on a beam per beam basis in an efficient manner. This paper investigates two new candidate multibeam system transmission schemes, namely, the Flexible and Beam-Hoping (BH) scheme, focusing on the forward link. We formulate the system-level optimization and propose an iterative algorithm that always converges given the constraints posed by the payload. The algorithm feeds a detailed system-level simulator which takes into account Ka-band channel and physical layer statistics. Our results show that both candidates outperform the conventional system in terms of both adaptation throughput matching to traffic demands and a more efficient use of available resources. The results were obtained during a project funded by the European Space Agency, with title “Beam Hopping techniques for multibeam satellite systems”.