<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

With the growth of multimedia traffic over mobile networks, multicast becomes one of more effective transmission approaches to be widely considered. The Multimedia Broadcast multicast service Single Frequency Network (MBSFN) has been introduced for long term evolution to improve signal-to-interference-plus-noise ratio at the cell edges, while selecting efficient modulation and coding schemes (MCS) for transmission is still an open issue. Unlike existing solutions in literature, the opportunistic multicasting concept is adopted in this work to aggressively enhance the spectrum efficiency (SE) of single frequency networks. Based on the derived model of effective SE in extended MCS adaptation intervals, we propose a statistical feedback-based approach to achieve opportunistic multicasting in MBSFN. The algorithm carefully selects the MCS complying with the adaptation need for channel quality changes and enabling high bottleneck user SE under reduced feedbacks. Comparing with other schemes for a single stream setup, the simulations show up to 340% higher SE over non-opportunistic method and 25% over the second best method maximizing the average SE. The number of successfully transmitted streams in a multi-stream scenario increased by 250% over the non-opportunistic approach and 40% over the average SE maximizing approach.