This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks （MANET）. The class of networks generally lacks end-to-end connectivity. In order to improve t...This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks （MANET）. The class of networks generally lacks end-to-end connectivity. In order to improve the efficiency that messages are delivered successfully, multiple message copies routing protocols are usually used, but the network load is increased due to a large number of message redundancies. In the study, by using counter method, every node adds an encounter counter based on epidemic routing scheme. The counter records the number which the node encounters other nodes with the same message copy. If the counter of a node reaches tbe installed threshold, the node removes the copy. Theoretical analysis gives a lower bound of threshold in delay tolerant MANET. According to the lower bound of threshold, a rational threshold is installed in real environment. With proposed scheme message copies decrease obviously and are removed completely finally. The successful delivery efficiency is still the same as epidemic routing and the redundant copies are efficiently controlled to a relatively low level Computer simulations give the variation of message copies concerning different thresholds in fast and slow mobility scenes.展开更多
In this paper, an improved NHPP model is proposed by replacing constant fault removal time with time-varying fault removal delay in NHPP model, proposed by Daniel R Jeske. In our model, a time-dependent delay function...In this paper, an improved NHPP model is proposed by replacing constant fault removal time with time-varying fault removal delay in NHPP model, proposed by Daniel R Jeske. In our model, a time-dependent delay function is established to fit the fault removal process. By using two sets of practical data, the descriptive and predictive abilities of the improved NHPP model are compared with those of the NHPP model, G-O model, and delayed S-shape model. The results show that the improved model can fit and predict the data better.展开更多
基金supported by the Hi-Tech Research and Development Program of China (2007AA01Z429,2007AA01Z405)the National Natural Science Foundation of China (60702059,60872041,11061035)
文摘This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks （MANET）. The class of networks generally lacks end-to-end connectivity. In order to improve the efficiency that messages are delivered successfully, multiple message copies routing protocols are usually used, but the network load is increased due to a large number of message redundancies. In the study, by using counter method, every node adds an encounter counter based on epidemic routing scheme. The counter records the number which the node encounters other nodes with the same message copy. If the counter of a node reaches tbe installed threshold, the node removes the copy. Theoretical analysis gives a lower bound of threshold in delay tolerant MANET. According to the lower bound of threshold, a rational threshold is installed in real environment. With proposed scheme message copies decrease obviously and are removed completely finally. The successful delivery efficiency is still the same as epidemic routing and the redundant copies are efficiently controlled to a relatively low level Computer simulations give the variation of message copies concerning different thresholds in fast and slow mobility scenes.
基金the National High Technology Research and Development Program of China (863 Program) under Grant No. 2006AA01Z173.
文摘In this paper, an improved NHPP model is proposed by replacing constant fault removal time with time-varying fault removal delay in NHPP model, proposed by Daniel R Jeske. In our model, a time-dependent delay function is established to fit the fault removal process. By using two sets of practical data, the descriptive and predictive abilities of the improved NHPP model are compared with those of the NHPP model, G-O model, and delayed S-shape model. The results show that the improved model can fit and predict the data better.
