Research On QoS Guarantee For IP Double-layered Satellite Networks

As multimedia services in IP satellite networks communication have been greatly growing, the transmission for satellite networksis required to have high reliability, have a global reach for mobile terminal, possess high-quality access services and offer efficient QoS guarantee. In internet on the ground, QoS issue has not been satisfactorily resolved. Satellite networks not only faces original QoS issue of internet on the ground, but also faces a series of issues in the context of satellite networks. For example, routing problems in high-speed movement of satellite and topology dynamic changes, bit error rate of high channel and transport protocol of high transmission distance, and mobile management technique in the frequent shift of ISLs and inter-satellite links have a direct influence on ensuring the quality of IP networks services.QoS includes the quantitative QoS indicators such as bandwidth, delay, delay jitter and throughput. Aiming at demand of every QoS indicator and starting from the design goal of double-layered LEO/MEO satellite networks, this dissertation designs and optimizes the structure of double-layered satellite networks, and on the basis of it expands the research about the routing algorithms and transport algorithm to match and adapt into different business needs so as to realize the goal of QoS guarantee.First, design a stale, strong structure of LEO/MEO double-layerednetworks. Double-layerednetworks system is represented by Kimura's DLSC model. But DLSC model rely heavily on redundant connection to strengthen networks stabilities so as to make complexity of satellite networks system too high. Based on the limitation of DLSC model, structure of LEO/MEO double-layerednetworks system employs backbone networks/accesss networks model and appropriate connection inter-satellite links to ensure stability of networks. Meanwhile, it makes us of management rules and gap partitioning strategy to reduce the complexity of the satellite Networks.Second, the design supports LEO/MEO double-layeredNetworks structure. Based on the structure of stable and strong LEO/MEO double-layered system, combining QoS indicators such as coverage total, bandwidth, delay, delay jitter, loss rate and throughput, we design the double-layerednetworks from constellatioin design and inter-satellite link design. Constellation design take the parameters into consideration such as constellation type, orbital altitude, orbital inclination, the number of orbital planes and the number of satellites each orbital plane has. Inter-satellite link design take into account inner layer link design of LEO, inner layer link design of MEO and inter layer link design of LEO/MEO. From the perspective of QoS guarantee, networks design meet the need of QoS routing and QoS transmission.Third, the design considers routing strategy of multi QoS guarantee. First, based on the asymmetry of LEO/MEO to the business requirements in the delay and bandwidth, in the time and location, we have designed QoS consuming integrated weighted model which tradeoffs QoS consuming information of delay and bandwidth; proposed an algorithms of QoS consuming collection and caculating separatioin, which simplifies route calculation, reduces the convergence time of route calculation; analyzed the strategy of routing caculating in the context of slot switching, satellite failure and link congestion and put forword the optimization plans such as jitter optimization algorithms and priority transmission backbone networks optimization algorithm according to routing recaculating strategy in different situations. Tradeoff QoS guarantee routing strategies consider QoS indicators such as the demand of QoS guarantee, delay and delay jitter, bandwidth in order to meet the needs of QoS routing in case of asymmetric traffic.Fourth, we proposed improved transmission algorithm of TCPQ based on the QoS indicatorsguarantee. Satellite protocol of TCP on the ground cannot be directly applied to the satellite networks with high transmission delay and high bit error rate, while congestion control is the core mechanism of the TCP protocol, which has a direct impact on the overall performance of the QoS transmission. TCPQ designed the algorithm to accelerate the start, nonlinear congestion avoidance algorithm and self-adaptive threshold error discriminant algorithm in order to guarantee the requirement of the QoS transmission requirements from the throughput, bandwidth utilization, error rate and other indicators.