In recent years, the wireless communication technique has gained a rapid development. The wireless ad hoc network is applied to various fields because of its advantages of needing no preset network facility, fast automatic networking or the like.
Routing protocols are focus in the ad hoc network research. Presently, researchers have proposed several protocols applicable for routing in the ad hoc network. According to mechanisms for obtaining routing information in the protocols, these protocols are generally divided into initiative routing protocols and on-demand routing protocols. The route discovery policy of the initiative routing protocols is similar to that of conventional routing protocols. In the initiative routing protocols, each node in the network should transmit the latest routing information periodically to other nodes, and each node should save one or more routing tables to store the routing information. As compared with the initiative routing protocols, in the on-demand routing protocols, a source node initiates operations for establishing a route only when the source node needs to transmit data to a destination node. Therefore, contents of the routing tables are established on-demand, and after completing the data transmission, it is possible to terminate the route maintenance.
According to existing on-demand routing protocols, implementing communication mainly comprises two processes of route establishment and data transmission. The route establishment may be further divided into two phases of route discovery and route selection. In the route discovery phase, a data source node searches for routes by broadcasting route request messages to neighbor nodes. If the destination node receives the route request messages transmitted in multiple paths, in the route selection phase, the path where the route request message with the minimum hops originates is selected to establish the route for subsequent data transmission.
The above manner of selecting the route having the minimum hops cannot ensure the latency performance of data in the network transmission, although it is able to complete the data transmission with less overhead. In transmission processes such as voice service, video service or the like, there is higher requirement on data latency performance. If latency jitter of data packets to a destination node is too significant, the service may be not continuous, thereby badly influencing the service quality.
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