Performance Research Of Satellite System Based On DVB-S2/RCS

With the rapid development of terrestrial communication network, life become more and more convenient. However, there is no enough communication resources in some areas. Brandband multimedia satellite communication system has advantagy of large coverage area, small limitation from geographical conditions, which can meet people communication needs, thus, it is important to establish satellite communication system.Key technologies of satellite communication system contain signal transmission and processing, resource allocation, flow control. In the paper, a broadband multimedia satellite communication system based on DVB-S2/RCS is researched. In the system, forward link bases on DVB-S2, return link bases on DVB- RCS, and ground stations are connected by optical fiber. Research and results of system performance contain three parts:(1) Information efficiency, spectrum efficiency and bit error rate(BER) in channel were simulated and analyzed when different Coding and Modulation is employed in forward link. The results show that information efficiency and spectrum efficiency increase with code rate increasing, while symbol rate and BER decrease with code rate decreasing.(2)Frequency and time slots resources position allocation algorithms are researched in return link based on DVB-RCS. Return link resources allocation includes RCSTs access, resource request, resources number allocation and resources position allocation. The part has an emphasis on resources position allocation. Adaptive bandwidth RCP fit algorithm is proposed by improving RCP fit. Resource fragments and packet delay are compared between adaptive bandwidth RCP fit and RCP fit. The results show that, to real time traffic like video, adaptive bandwidth RCP fit decreases packet delay and improve QoS while it does not increase resource fragments compared to RCP fit, which proves adaptive bandwidth RCP fit is correct. In addition, jitter affects QoS to real time traffic, so voice packets jitter are compared between JRA or no JRA, which improves JRA is an effective algorithm decreasing packets jitter.(3)Flow control of ground station optical fiber network has an effect on service delay. A kind of flow control method based on link usage is proposed and simulated. The research results show that ground-station fiber network using star topology structure has better performance on management of the center node over other nodes. The network congestion of satellite communication scheme using the link usage-based flow control method is reduced without changing source rate, moreover, quality of service and the whole network performance are improved.