<p class="MsoNormal" style="margin: 0cm 0cm 0pt; layout-grid-mode: char;"><span style="mso-bidi-font-weight: bold;"><span style="font-size: x-small;"><span style="font-family: Times New Roman;">Broadcasting is an essential operation for Wireless Ad Hoc Networks to perform routing path discovery, and it has become the predominant technology for message dissemination in Vehicular Ad Hoc Networks (VANETs). In the reactive routing schemes of wireless ad hoc network, Routing Request (RREQ) packets are broadcast from the source, and once received the destination traces back the broadcasting path to build an on-demand route. In VANETs, different broadcasting schemes have been proposed for safety, comfort, and commercial applications. However, broadcasting usually generates a lot of redundant messages which would cause excessive channel contention and packet collisions, especially when the density of the network becomes higher. In this survey article, we first introduce the most common data dissemination techniques used in wireless ad hoc networks. After that, we discuss techniques that have been proposed to mitigate the broadcast storm problem. Finally, we introduce an effective model for analyzing the broadcasting schemes, and based on the model we propose an adaptively adjusted probabilistic scheme that highly improves the reliability of broadcasting in dense ad hoc networks.</span></span></span></p>

No abstract

No abstract

No abstract

In this paper, we investigate and propose a latency minimized CSMA variation to enhance the performance of event-driven wireless ad hoc network applications. By first analyzing latency performance based on p-Persistence CSMA, we show that the optimal transmission probability for latency minimized p-Persistent CSMA (LMPP) in an event-driven scenario equals to the optimal transmission probability for throughput maximization in a saturated wireless local area network when the number of competing nodes is much larger than the number of messages a node intends to receive and the packet length is a lot longer than the slot time. The proposed Latency Minimized Probabilistic CSMA/CA (LaMP) is a multiple access scheme with constant contention window size built atop standard 802.11 CSMA/CA, to approach the performance of LMPP. To deal with the critical contender estimation problem in LaMP, we also propose an Exponentially Decreased Matching (EDeM) strategy to approximate the number of contenders. Simulation results show that the proposed method consistently outperforms existing methods in latency performance.