An Adaptive Broadcasting Scheme in Mobile Ad Hoc Networks

Mobile and static nodes in battlefields or within the vicinity of disaster areas may not depend on fixed infrastructure for communication. To rapidly provide the required communication between the nodes in such environments, a Mobile Ad hoc Network (MANET) is the only available platform. With no fixed infrastructure, the efficient use of MANETs resources is highly crucial for the successful communication between mobile nodes. In situations where both the transmitting and the receiving nodes are placed within the transmission range of each other, communication is possible through a single-hop connection. In all other scenarios where the nodes are distanced, the exchange of packets is possible as long as a multi-hop path is available between them. Despite the unique characteristics of MANETs, they share many attributes and operations with other traditional networks. DNS lookups, exchange of control packets for management purposes and routing discovery requests are some examples of common operations, which all require broadcasting pieces of information across the network. However, due to lack of a centralised administrative and hardware, some modification is required to adopt broadcast operation for MANET environment. The most straightforward broadcast mechanism used in MANETs is Simple Flooding (SF). The algorithmic procedure followed in SF is very simple, thus making its implementation and integration inside more complex operations fairly undiscomforting. In SF, upon reception of a broadcast packet the receiver will check whether or not this is a duplicate packet. If it is a new packet it will immediately retransmit it to all of its neighbouring nodes. Simply flooding the entire network may be the fastest and easiest way for a node to broadcast information over the network but it has been found to be a very unreliable and resource inefficient mechanism leading to the Broadcast Storm Problem (Ni et al., 1999) especially in highly populated and dense networks. Over the past few years many studies (Leng et al., 2004), (Zhu et al., 2004), (Qayyum et al., 2002), (Hsu et al., 2005), (Purtoosi et al., 2006), (Barrit et al., 2006), (Bauer et al., 2005) have proposed novel broadcast mechanisms to alleviate the effects of SF. Early works were focused on developing schemes where the rebroadcast decision is made based on fixed and pre-determined threshold values. Probability-Based (PB), Counter-Based (CB) and DistanceBased (DB) are three schemes which have been proposed based on the concept of introducing a threshold value. PB bases it rebroadcasting decision on a fixed probability value, CB decides it by counting the number of received duplicate packets and finally the