The Research On Data Dissemination Scheme In Opportunistic Networks

The appearance of opportunistic networks offers communication solutions for delay tolerant networks. The main idea of opportunistic networks is "store, carry, forward", which means communication is completed by exploiting the meeting opportunity of mobile nodes. Opportunistic networks don’t require an entirely connected environment, which is more suitable for networking, playing an important role in the realization of future ubiquitous computing. However, for the resource limitation of nodes in opportunistic networks, when the scale or the traffic of the network increase, its performance may decline sharply. To solve this problem, researchers put forward many approaches, in which forming hierarchical opportunistic networks by setting cluster nodes in the network can effectively improve the network’s scalability and solve the bottleneck problems of opportunistic networks.This paper is aimed to research the data dissemination scheme in hierarchical opportunistic networks. The goal of data dissemination is to share resources between nodes. Nodes in opportunistic networks, such as smart phones, vehicles, usually carry lots of multi-media data, which may be produced by themselves or downloaded from the Internet. Sharing these data between users will become a demand. Data dissemination in opportunistic networks can provide users a convenient and cheap service of resource share without the support of communication infrastructures.The first section in the paper points out the background and significance of research for data dissemination in hierarchical opportunistic networks. Firstly the concept and application scenarios of opportunistic networks are introduced, and then we describe the usage of ONE simulator. Section two introduces movement models and network architecture of opportunistic networks. Section three gives a brief description of routing and data dissemination schemes in opportunistic networks.Section four describes how to set fixed cluster nodes in opportunistic networks. Two approaches are proposed and their performances are compared through simulations. A novel data dissemination scheme in hierarchical opportunistic networks is put forward in section five. In this scheme, nodes disseminate their interests in a controlled flooding way. After receiving subscription requests, publishers forward related data items to subscribers. To select relays, transmission delay and buffer consumption are taken into consideration. What’s more, because of its powerful computing and storage ability, cluster nodes are acted as complementary relay nodes. A simulation is represented to evaluate this scheme.This paper provides an effective solution for data dissemination scheme in hierarchical opportunistic networks. This scheme can effectively improve the delivery rates of requesting data items and achieve a trade-off between delay and overhead.