MANETs consist of mobile wireless devices communicating through relatively unreliable wireless connections. This unreliability is mainly caused by device mobility and signal interference, both can degrade networking performance significantly.
2.1 Single-Path Routing
In order to achieve better reliability in MANETs, (Ye, Krishnamurthy, & Tripathi, 2003) introduced a reliable routing framework in which some reliable R-nodes are manually inserted into the MANETs and play a role of supporting the network as backbones. This idea could be practical in some metropolitan areas where advanced network infrastructures are available, but it is not suitable for other improvisational situations such as disaster rescue.
Noticing that information exchange is important among neighbor nodes, in (Joe & Batsell, 2002) Joe and Batsell introduced MPR-based hybrid routing which makes use of the multipoint relaying based on the information exchange among neighbor nodes. Nevertheless, this routing algorithm does not involve any memory of the relationship among neighbor nodes. Thus all nodes are treated the same no matter they are stable in terms of mobility or not.
Some other researchers have suggested that routing can be done by collecting and aggregating relative information among neighbor nodes from the source to the destination. For example, ABR in (Toh, 1997; Toh, Delwar, & Allen, 2002) makes use of the Associativity Ticks among neighbor nodes. The Associativity Ticks show a mobile node’s dormant time, in which the node is in a stable status. However, these Associativity Ticks are not able to show the long term accumulated relationship among neighbors.