A Novel Reliable Transmission Protocol for Urgent Information in Wireless Sensor Networks

In monitoring wireless sensor networks (WSNs), the occurrence of an emergency will generate a large amount of data in a very short time. Among them, some urgent information is more critical and needs to be transmitted out reliably as soon as possible. In this scenario, congestion is inevitable due to the limited resources, especially near the sink. To address this problem, we propose a novel reliable transmission protocol for urgent information (RETP-UI) in WSNs. In RETP-UI, not only the current queue length but also the ratio of queue length´s fluctuation is adopted as indication of congestion. Each sensor node evaluates its congestion level locally and determines its congestion state with a state machine. Furthermore, we use a multistage rate adjustment mechanism to adjust each node´s sending rate cooperatively according to different congestion states. Finally, with extensive simulation results we illustrate that the performance of RETP-UI is significantly improved over traditional protocols.