Study On Key Technologies Of IP-based Broadband Satellite Netwoks

With the development of satellite communication technologies,especially the improvement on the on-board digital processing technology,it begins to emerge a large amount of broadband communication satellites with the functions of on-board baseband data exchanging and processing.Communication satellites can provide not only the function of data transmitting,but also functions such as data multiplexing,switching,even routing.The IP protocol has become the key technology of terrestrial networks convergence,in order to implement the broadband transmission and distribution systems based on the integration of satellites and terrestrial networks,the ideal broadband satellite communication systems should access to the IP-based terrestrial networks seamlessly.Compared with the transparent transmitting communication satellites,on-board transmitting satellite communication is prone to construct high-capacity,high-speed broadband satellite communication systems because of their advantages,such as one hop connection,low power consumption,small noise accumulation,flexible channel change,low cost of terrestrial devices,etc.However,some intrinsic characteristics,including long propagation delay,large delay jitter,link bandwidth asymmetry,high bit error rate,and large bandwidth-delay product,make the mature technologies in terrestrial networks not to be applied to satellite networks without adaption.In this dissertation,according to the requirements and characteristics of IP technology in broadband satellite communication networks,the IP packet switch technologies and the integration technologies of satellite and terrestrial networks which suite for space environments,as well as the building of a packet network architecture based on IP technology,are studied.The main contributions of this dissertation are summarized as follows:(1)The baseband processing techniques used in current broadband communication satellites are studied,and two kinds of packet switching techniques in satellite,ATM and IP,are analyzed and simulated.Consequently,IP protocol is chosen as the exchange platform of broadband satellite communication networks.At the same time,in view of the trend of broadband satellite communication networks and the requirement of future battlefield,a hybrid multi-layer network architecture is designed which consist of the satellite core backbone networks and satellite space simulation networks.(2)According to the on-board baseband data exchange characteristics of broadband satellite communication networks,an improvement of TCP protocol,TCP-ISSAT,which is based on the improved Snoop,is proposed to improve the performance of satellite network transmission control.Then,a new TCP protocol,TCP-Satellite+,with the improvement of link connection and data transition to focus on those characteristics of high bit error rate and large propagation delay,is also presented.Simulation results show that file transmission time are sharply reduced with the TP-Satellite+ protocol to avoid the disadvantage of limit of reverse link resources with improvement of high bit error rate in the cannel and saving the bandwidth resource of reverse link.(3)With disturbing the QoS guarantees of broadband satellite communication networks to end users because of the characteristics of satellite channels,a static queue scheduling algorithm,crossover weighted poll algorithm basing on the ideal time interval-TIIWRR,is presented.It can sharply reduce the delay jitter in the same queue by introducing the conception,the ideal time interval and was proved the algorithm have magnificent effectiveness in the simulation verification.A new active queue management algorithm-satellite dynamic random early detective with IN/OUT-BIT,S-DRIO basing on bit error rate of channel was proposed to satisfy the need of satellite communication networks with the characteristics of high bit error rate in networks.No matter theoretical analysis or simulation experiments show that a better guarantee for the fairness among flows can be archived with the algorithm in the high bit error rate of the satellite link channels.(4)Based on the analysis of the current status of signaling system in the broadband satellite communication networks,several problems of signaling are also resolved,including defining syntax rules SSD,two encoding rules GER and IER,and analyzing coding efficiency;defining the interactive processing of typical protocol to standardize the signaling framework and format of the message;designing security mechanisms of signaling system.Focusing on security features of satellite communication networks,we analyze and design security solution loaded in the signaling system,and use the improved inductive protocol verification method to formalized analyze the security of signaling system.Signaling system can be used to detect those attacking actions such as counterfeit,replaying,falsifying in attack modules of the simulation systems and experiments show signaling system can be used to resist attack actions.