The Research Of AODV-ETT Routing Protocol Based On Location Prediction

A Mobile Ad Hoc network is a distributed wireless multi-hop network, and which doesn’t depend on any fixed infrastructure. It has many advantages, such as flexible networking, quick deployment so that Ad Hoc network has wide application in the military and civilian fields. So far, many routing protocols have been proposed, for example, typical AODV and DSR routing protocols choose shortest path as routing metric. But the complexity of wireless link makes the protocols hardly acquire the actual condition of the physical link. So far, various route metrics are proposed to choose the best link such as ETX、ETT、WCETT and so on. ETT is the expansion of ETX, which takes into account the link bandwidth as well as the size of packet, while ETX only considers network loss ratio. ETT can choose a high throughput path.The ETT of a link is the predicted delay of a successful wireless data transmissions required to send a packet over that link. The ETT of a route is the sum of the ETT for each link in the route. Each node broadcasts periodically link probe packet in the network. The two nodes of a link remember the number of probes they received to calculate the link loss rate, which is used to calculate the value of ETX. Each node broadcasts periodically two back-to-back probe packets, and its adjacent nodes calculate the difference of time they received to calculate link bandwidth. Therefore, AODV-ETT routing protocol is proposed, and its implementation is described in the QualNet Simulator. But evaluation of the quality of the link by ETT metric used can only reflect the loss rate of the network in the past period. The ETT value isn’t able to reflect real status of the network. In order to solve this problem, a grey prediction algorithm is proposed and which can predict the node’s location during next interval. In this way, we can judge that whether the nodes will still be in each other’s communication coverage during next interval. Thus, the predicted result will act as the pre-condition of the ETT.The simulation and performance analysis of AODV-ETT routing protocol based on location prediction (AODV-LP-ETT) are described in QualNet simulation platform. Then compare the performance of AODV-LP-ETT and AODV by changing node’s pause time and speed. Simulation results show that AODV-LP-ETT improves throughput and delivery ratio, reduces average end to end delay and average jitter, and then the network performance is improved.