Abstract:

In some scenarios, Epidemic algorithm has high delivery ratio, small delivery delay, but poor adaptabilityd. Moreover, the performance of the algorithm will significantly degrade in other scenarios. On the basis of analysis of the factors affecting the algorithm performance, CrowdingOut effect is considered as the main reason leading to negative performance. In this paper, the performance of Epidemic algorithm with immune mechanism is analyzed and some defects of the immune mechanism are indicated. Therefore, an improved algorithm is formulated with a kind of Backoff mechanism, so that the node will no longer receive packets from meeting nodes when its buffer is close to saturation. The promising results on the ONE simulation platform show that the proposed algorithm can effectively suppress CrowdingOut effect and greatly improve the delivery ratio and  reduce the routing overhead to some extend under various scenarios.  

Key words: opportunistic network；routing algorithm；epidemic；crowdingout effect；backoff mechanism