Mobile devices integrating wireless short-range communication technologies make possible new applications for spontaneous communication, interaction and collaboration. An interesting approach is to use collaboration to facilitate communication when mobile devices are not able to establish direct communication paths. Opportunistic networks, formed when mobile devices communicate with each other while users are in close proximity, can help applications still exchange data in such cases. In opportunistic networks routes are built dynamically, as each mobile device acts according to the store-carry-and-forward paradigm. Thus, contacts between mobile devices are seen as opportunities to move data towards destination. In such networks data dissemination is done using forwarding and is usually based on a publish subscribe model. Opportunistic data dissemination also raises questions concerning user privacy and incentives. Such problems are addressed dierently by various opportunistic data dissemination techniques. In this we analyze existing relevant work in the area of data dissemination in opportunistic networks. We present the categories of a proposed taxonomy that capture the capabilities of data dissemination techniques used in such networks. Moreover, we survey relevant data dissemination techniques and analyze them using the proposed taxonomy. In this we analyze existing work in the area of data dissemination in opportunistic networks. We analyze dif- ferent collaboration-based communication solutions, em- phasizing their capabilities to opportunistically dissemi- nate data. We present the advantages and disadvantages of the analyzed solutions. Furthermore, we propose the categories of a taxonomy that captures the capabilities of data dissemination techniques used in opportunistic net- works. Using the categories of the proposed taxonomy, we also present a critical analysis of four opportunistic data dissemination solutions. To our knowledge, a classication of data dissemination techniques has never been previously proposed.
Authors of @cite_9 previously proposed a taxonomy for analyzing forwarding techniques. It separates them between algorithms without infrastructure (designed for completely flat ad-hoc networks) and algorithms with infrastructure (in which the ad-hoc networks exploit some form of infrastructure to opportunistically forward messages). Algorithms without infrastructure can be further divided into algorithms based on dissemination (like Epidemic, MV and Networking Coding), that are forms of controlled flooding, and algorithms based on context (like CAR and MobySpace), that use knowledge of the context that nodes are operating in to identify the best next hop at each forwarding step. Algorithms that exploit a form of infrastructure can also be divided into fixed infrastructure and mobile infrastructure algorithms. These algorithms have special nodes that are more powerful than the normal nodes. In case of fixed infrastructure algorithms (like Infostations and SWIM), special nodes are located at specific geographical points, whereas special nodes proposed in mobile infrastructure algorithms (like Ferries and DataMULEs) move around in the network randomly or follow predefined paths.
@cite_9
2030307498 2126003739 2120361596 2140000065
This paper proposes a novel network architecture based on content routing and dissemination techniques, expressly adapted for hybrid mobile and vehicular ad-hoc networks. Hybrid vehicular ad-hoc networks (VANETs) are a subclass of mobile ad-hoc networks (MANETs) where each node is a moving vehicle equipped with one or more communication devices, potentially having access to several different physical communication channels. This results in a partly decentralized, self-organizing mobile radio network with a fast changing topology. Applications designed for VANETs still require efficient mapping techniques to associate content to the host serving it, as well as centralized databases associating vehicles and mobile nodes to a persistent and unique identifier. They also assume that the content providers are located in the infrastructure, but nodes and vehicles can be equipped with sensors and as such produce information. This means that dissemination and retrieval algorithms have to take into account the distribution of the consumers, providers and forwarder all over the network. We propose an architecture based on Van Jacobson's Content Centric Networking, extended and modified to solve some of the issues related to content access and dissemination across hybrid VANETs. The implementation and simulation on a realistic platform are presented as well as an application to a real case scenario, demonstrating the efficiency of the approach. Since ad hoc and sensor networks can be composed of a very large number of devices, the scalability of network protocols is a major design concern. Furthermore, network protocols must be designed to prolong the battery lifetime of the devices. However, most existing routing techniques for ad hoc networks are known not to scale well. On the other hand, the so-called geographical routing algorithms are known to be scalable but their energy efficiency has never been extensively and comparatively studied. In a geographical routing algorithm, data packets are forwarded by a node to its neighbor based on their respective positions. The neighborhood of each node is constituted by the nodes that lie within a certain radio range. Thus, from the perspective of a node forwarding a packet, the next hop depends on the width of the neighborhood it perceives. The analytical framework proposed in this paper allows to analyze the relationship between the energy efficiency of the routing tasks and the extension of the range of the topology knowledge for each node. A wider topology knowledge may improve the energy efficiency of the routing tasks but increases the cost of topology information due to signaling packets needed to acquire this information. The problem of determining the optimal topology knowledge range for each node to make energy efficient geographical routing decisions is tackled by integer linear programming. It is shown that the problem is intrinsically localized, i.e., a limited topology knowledge is sufficient to make energy efficient forwarding decisions. The leading forwarding rules for geographical routing are compared in this framework, and the energy efficiency of each of them is studied. Moreover, a new forwarding scheme, partial topology knowledge forwarding (PTKF), is introduced, and shown to outperform other existing schemes in typical application scenarios. A probe-based distributed protocol for knowledge range adjustment (PRADA) is finally introduced that allows each node to efficiently select online its topology knowledge range. PRADA is shown to rapidly converge to a near-optimal solution. We consider a routing problem in the context of large scale networks with uncontrolled dynamics. A case of uncontrolled dynamics that has been studied extensively is that of mobile nodes, as this is typically the case in cellular and mobile ad-hoc networks. In this paper however we study routing in the presence of a different type of dynamics: nodes do not move, but instead switch between active and inactive states at random times. Our interest in this case is motivated by the behavior of sensor nodes powered by renewable sources, such as solar cells or ambient vibrations. In this paper we formalize the corresponding routing problem as a problem of constructing suitably constrained random walks on random dynamic graphs. We argue that these random walks should be designed so that their resulting invariant distribution achieves a certain load balancing property, and we give simple distributed algorithms to compute the local parameters for the random walks that achieve the sought behavior. A truly novel feature of our formulation is that the algorithms we obtain are able to route messages along all possible routes between a source and a destination node, without performing explicit route discovery repair computations, and without maintaining explicit state information about available routes at the nodes. To the best of our knowledge, these are the first algorithms that achieve true multipath routing (in a statistical sense), at the complexity of simple stateless operations. Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. A class of routing protocols called on-demand protocols has recently attracted attention because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particular on-demand protocol, called dynamic source routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. We develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. Results show that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long path lengths. It also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths.