| Summary: | The broadcast operation is perhaps one of the most fundamental services utilized frequently by other communication mechanisms in MANETs. It is the key element for exchanging control packets to support some services such as those provided by management and routing protocols. The dynamic nature of such network topologies and also the limited resources available, introduce a wide range of challenges when trying to design and implement a broadcast scheme that would function adequately in MANETs. Simple Flooding (FL) is a basic approach to broadcasting without global information; in which a broadcast packet is forwarded exactly once by every node in the network. in FL, the broadcast packet is guaranteed to be received by every node in the network given that there is no packet loss caused by collision and also there is no high-speed movement of nodes during the broadcast process. However, due to the broadcast nature of this environment, redundant transmissions in FL may cause the broadcast storm problem, in which redundant packets cause contention and collisions. Over the past years many studies have been conducted to develop broadcast mechanisms to alleviate the effects of FL. The focus of the early works was on the schemes where the mobile nodes make the rebroadcast decision based on fixed and preconfigured thresholds. The most common thresholds relate to the distance between sender and receiver (Distance Based scheme - DB), the number of duplicate packets received (Counter Based scheme - CB), and a fixed probability for rebroadcast (Probability Based scheme - PB). Despite the fact that these schemes have been shown to considerably improve the overall performance of the network, they have been found to depend highly on the combination of threshold selected, traffic load and level of population. The degree of dependency is such that in certain network topologies FL performs better than these schemes.
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