A Bioinspired Adaptive Congestion-Avoidance Routing for Mobile Ad Hoc Networks

Traditional mobile Ad Hoc network routing protocols are mainly based on the Shortest Path, which possibly results in many congestion nodes that incur routing instability and rerouting. To mitigate the side-efforts, this paper proposed a new bioinspired adaptive routing protocol (ATAR) based on a mathematics biology model ARAS. This paper improved the ARAS by reducing the randomness and by introducing a new routing-decision metric "the next-hop fitness" which was denoted as the congestion level of node and the length of routing path. In the route maintenance, the nodes decide to forward the data to next node according to a threshold value of the fitness. In the recovery phase, the node will adopt random manner to select the neighbor as the next hop by calculation of the improved ARAS. With this route mechanism, the ATAR could adaptively circumvent the congestion nodes and the rerouting action is taken in advance. Theoretical analysis and numerical simulation results show that the ATAR protocol outperforms AODV and MARAS in terms of delivery ratio, ETE delay, and the complexity. In particular, ATAR can efficiently mitigate the congestion

Effects of Unstable Links on AODV Performance in Real Testbeds

<p/> <p>A link between a pair of nodes is defined <it>unstable</it> if it is characterized by a packet loss which is not negligible in one or both directions. The presence of unstable links in multihop ad hoc networks is very likely and it depends on several factors (e.g., different transmission capabilities of the devices, interferences caused by additional wireless devices). Their management by the routing protocols is of paramount importance since they negatively affect applications performance. In our previous experimental studies, we found that AODV is characterized by very low performance in some specific situations and, in this work, we demonstrate that it mainly depends on the wrong management of unstable links as valid routes. We present some policies that have been proposed in literature to avoid this problem, and we validate two of them through experimental results, exploiting also a direct comparison with the proactive routing protocol OLSR. Our results show that AODV is not able to avoid the use of unstable links, even when an alternative stable route exists. In the same conditions, OLSR outperforms AODV by correctly managing unstable links. In fact, it is able to guarantee a higher packet delivery ratio to the application by using the most stable path to reach the destination.</p