Storage Management Of Network Node In Deep Space Communications

Delay/Disruption Tolerant Networking(DTN), as an end-to-end networking architecture, provides flexibility among heterogeneous network and reliable file delivery service in stressed communication environment. Thus, it is also considered as one of the very promising technology in further deep space network. Bundle protocol sits at the application layer of DTN, using custody transfer and store-and-forward mechanism to tolerant the long delay and interruption in deep space and achieve the reliability of data transmission. Therefore, it is necessary to research the technology on storage management.This paper studied the memory dynamics of BP in the nodes’ storage area. Based on a network consisted of multi-source nodes, one relay node and one destination node, firstly we proposed a threshold model of bundle size so as to avoid the congestion in uplink channel. Then we analysis the effect of bundle size on memory release, and build a model on single transmission effort. Finally, based on some researches about store-and-forward mechanism, responding scheme design, long link delay and flow control in deep space communications, we build a mathematic model of memory dynamics in the relay node.The proposed model was verified by the testbed that supports the space link simulator. The testbed is consisted of several PCs based on Linux, simulating source nodes, relay node, channel and destination node respectively. The results showed that the model was matched by the simulation data. We then conclude that small bundles lower than the threshold are practically preferred in order to achieve both optimal memory utilization and high data transmission performance. In addition, with the increasing of BER and file size, the more transmission rounds also result in the longer release time in total. In conclusion, it is recommended that small bundles are preferred in future deep space communications.