接触图路由利用空间DTN节点运动轨迹可以预知的特点,将节点间通信的开始与截止时间、速率等信息配置在接触图中,以此为依据计算路由,但这也带来了对接触图准确性要求极高的问题.在复杂的空间环境中,短时的电磁干扰或能量过低等原因可能导致接触意外失效,此时按照原始配置计算的路径将无法使用,另外接触图路由未考虑排队时延对低生存时间束(Bundle)的影响,导致这些束可能会在排队中过期.针对上述问题,提出一种接触图路由精确性提高方法,包括接触失效发现机制、接触恢复探测机制、接触失效及恢复通告机制、接触图更新机制和考虑接触失效的路由计算机制,同时使用基于效用函数的转发策略优先发送生存时间低的束.实验表明接触图路由精确性提高方法在链路意外失效的情况下能够提高束的传递率、降低传递时延.%Using the preconfigured contact information of space nodes such as the start time,end time and communication rate,CGR (contact graph routing) can calculate a delivery path from the source to destination conveniently.However,this requires high accuracy of contact graph.Due to the complexity of the space network,satellite may suffer node failure and its associated links suffer from the electromagnetic interference frequently and this may lead to unpredictable contact disruption.Bundles sent by the source using the initially configured contact information cannot be transmitted successfully.Furthermore,CGR''s failure to consider the impact of queuing delay on the bundles with low TTL may lead to expiration of these bundles in intermediary nodes.To address these issues,proposed a scheme to improve the accuracy of contact graph routing,including contact failure discovery mechanism,contact recovery detection mechanism,contact failure and recovery notification mechanism,contact graph updating mechanism and routing computing mechanism that considers contact failure.At the same time,a utility function based bundle forwarding mechanism was used.Experiments showed that the accuracy enhancement scheme could improve the delivery ratio and reduce delivery delay in the case of unexpected contact disruption.
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