Data dissemination solutions for wireless ad hoc network

Abstract

Wireless ad hoc networks have gained a lot of momentum in the last few years due to their ability to enable spontaneous networking. In those networks, nodes cooperate in a distributed fashion way to spontaneously establish a communication environment independently of a centralized management infrastructure. Examples of wireless ad hoc network are mobile ad hoc networks (MANETs), wireless sensor networks (WSNs) and vehicular ad hoc networks (VANETs), which have distinct characteristics. Network wide broadcasting or data dissemination is a very common procedure employed in different tasks in wireless ad hoc networks. For instance, such technique has been used as a control mechanism in route establishment of unicast and multicast protocols, as a method to create data replication and storage protocols, or simply as a data comunication procedure. The main goals of any data dissemination solution are to minimize the number of packet retransmissions and to deliver as many packets as possible to the intended recipients. Given the importance of the data dissemination procedure for wireless ad hoc networks, this thesis investigates how data dissemination may be used to build a data replication and storage machanism for WSns. Therefore, we propose a data dissemination solution that relies on a small subset of powerful nodes to create replication structures and dissemante the sensed data to the nodes in the network. In this scheme, the sensed data is intelligently replicated and disseminated to sensor nodes in such a way that a mobile sink can later visit a small subset of nodes to collect the sensed data produced by the whole network. Simulation results show that such solution has the lowest overhead when compared to existing approaches, however is possesses a slightly worse dissemination and collection efficiency. Nevertheless, we also show that by taking advantage of the data redundancy and correlation inherent to WSNs, it is possible to decrease the overhead of the proposed protocol and attain a dissemination and collection efficiency similar to existing approaches. Thereafter, we investigate how data dissemination may be used as a data communication procedure to report events to drives who are inside a region of interest in VANETs. Hence, we proposed a data dissemination protocol for highway VANETs that can seamlessly adapt to the perceived road traffic conditions to deliver messages to intended recipients. Simulation results show that when compared to existing solutions, our approach has the best delivery ratio under sparse traffic, and has both the lowest delay and the lowest overhead under dense traffic. Moreover, we also show tht our solution is robust to GPS erros. A limitation of the previous solution is that it is confined to highway scenarios. Therefore, we propose a new data dissemination protocol that can also seamlessly adapt to the perceived road traffic condition in urban environments. Furthermore, such solution avoids the synchronization effects introduced by the new data communication standard for vehicular networks. In order to enable fair use of the available bandwidth and avoid channel overloading, the protocol adapts the rate at which vehicles insert data into the channel. Simulation results show that when compared to existing solutions, our approach provides the best delivery, the lowest delay and the lowest overhead.