【作者】 刘炯；

【导师】 曹志刚；

【作者基本信息】 清华大学 ， 信息与通信工程， 2007， 博士

【摘要】 因特网的迅猛发展使得全球一体化的宽带因特网成为必然。另外,随着星上数字处理技术的不断提高,通信卫星将不仅仅实现数据的转发,还会实现数据的复用、交换,甚至是路由功能。本文以具有星上基带数据处理的新型卫星因特网为目标,研究此类卫星网络的传输控制协议。按照卫星数据处理能力,星上基带数据处理的卫星网络可以分为两种:1、星上实现基带数据的再生、复用和转发;2、星上实现基带数据的交换和路由。针对这两种卫星网络提出相应的数据传输控制的解决方案。本文的主要研究成果如下:1、针对星上实现基带数据再生、复用和转发的卫星网络,提出了一种数据传输控制解决方案。此方案的特点是地面网关配置TCP-Splitting代理的同时,在卫星上加载TCP-Spoofing代理。此方案不仅屏蔽了卫星链路的长延时和误码对地面接入部分的影响,而且缩短了丢失数据的重传等待时间,从而提高了卫星前向链路的资源利用。2、针对上述卫星网络,提出了数据传输和处理协议――NSTP。此协议利用了卫星网络中不存在拥塞的特点,提出了UDP的数据传输和主动周期应答策略。此协议能够迅速提升数据的发送速率,实现多个丢失数据的一次重传,以及降低反向链路带宽的占用,占用的带宽下降一个数量级。3、针对星上实现基带数据的交换或路由的卫星网络,提出了一种端到端数据传输控制协议――TP-Satellite。协议中提出了Super Start、Loss Distinc-tion、Congestion Recovery、Congestion Avoidance和主动周期应答等新的策略。其特点是将发送数据分为高、低两种优先级,并交替发送。此协议能够在极短的时间内实现数据发送速率的迅速提升,有效区分链路误码和网络拥塞造成的数据丢失,并且占用极少的反向链路带宽,不论在随机误码还是在突发误码情况下,都能够充分利用卫星前向链路资源,表现出良好的传输性能。本论文充分考虑了卫星网络的特点,提出了卫星网络数据传输和控制的改进方案,有助于卫星网络中数据和多媒体通信的系统性能。更多还原

【Abstract】 As a result of the exponential growth of the networks, the global broad band In-ternet will become true. In addition, with the continuous development of the on-boardsatellite digital processing technology, the signal will not only be relayed like in thebent-pipe transponder, but also be regenerated, multiplexed, switched, and routed on-board satellite. This paper studies transport control protocols for the new generationsatellite networks with on-board digital processors. Based on the ability of the on-boardprocessing, the new generation satellite networks can be classified into two types. Oneis that data is only regenerated, multiplexed, and transmitted by on-board processors.The other is that data is switched or routed on board. In the paper, three solutionsare proposed for these two types of the new generation satellite networks. The maincontributions of our work are as follows:1. A new solution for the satellite networks is proposed. The characteristic ofthe solution is that an on-board TCP-Spoofing proxy is placed in satellite, while TCP-Splitting proxies is placed at gateway stations. The advantages provided by this so-lution are as follows: terrestrial accessing segments can be shielded from the impactof transmission errors and propagation delay over satellite links; the waiting time forthe retransmitted data is reduced; the resource utilization over the satellite links areimproved.2. A new transport control protocol called NSTP is proposed. UDP strategy andperiodical ACK sending strategy are proposed in the protocol. The advantages of theprotocol are: the data rate can be speeded up rapidly, the bandwidth used in reversepath is sharply reduced, and the waiting time for the multiple retransmitted packets isreduced.3. A new end-to-end transport control protocol called TP-Satellite, is proposed.The novel strategies including Super Start, Loss Distinction, Congestion Recovery,Congestion Avoidance and periodical ACK sending strategy, are proposed in it. The exclusive feature of the protocol is that different class priority IP packets are sent alter-nately. TP-Satellite can speed up the data rate quickly, separate packets loss caused bycongestion from link errors effectively, reduce the bandwidth used in the reverse path,fully utilize the resource in the forward path, and exhibit the outstanding performanceover the links with sporadic or burst errors.The features of the new generation satellite networks are considered sufficientlyin the above researches, and the solutions proposed in the paper can improve the per-formance of satellite networks in data and multimedia communication.更多还原