RPL Wireless Sensor Network Routing Protocol Optimization And Design

The rapid development of wireless communication technology and integration of electronic technology has enabled the development of wireless sensor networks (WSN).Wireless sensor network is composed of a large number of low-cost,low-power sensor nodes deployed in the monitoring area, the monitoring area of monitoring environment for data collection and transmission. 'They transmit the test data of detected area to monitoring system through wireless link and the self-organization communication. Nowadays,wireless sensor network has been used in every corner of people's life, such as environment monitoring,health care, traffic regulation, etc, the vigorous development of the WSN brings great benefits to people's lives.For the aspects of some key techniques used in wireless communication, for example,routing protocol, power management and node localization, the most important is the routing technique. Routing protocol is the base of operation of sensor network as it's compatibility with different application impact the efficiency and effectiveness of the network directly.IETF working group find that there is no routing protocol specialized for the low-power and lossy networks after they have investigated the existing routing protocol for wireless sensor network. So they have proposed a new routing protocol—RPL (Routing for low-Power and Lossy networks) routing protocol which is fit for the low-power and lossy networks.Considering that communication nodes deployed in the network, which has unstable transmission link and frequently mutated topology, need to adapt themselves to some incidences, such as increasing dramatically data traffic, mutated quality of the link and inconsistent network, this paper focused on network congestion and latency phenomenon of mass data traffic, optimized the RPL routing protocol from two aspects, multi-routing dynamic payload balance optimization and cross level minimum latency optimization.Based on single routing RPL, this paper optimized the multi-routing RPL,making sure the link stability. Besides, the paper proposed a dynamic payload balance method based on routing weight. This optimization enabled mass traffic to be transmitted through the better quality link and not-busy multi-routing. The testing result showed that it would mitigate the network congestion effectively and efficiently when it was applied to mass data communication, and it would bring a better network service when the network communication link suffered worse quality.Further more, based on the analyses to ContikiMAC layer mechanism, the paper optimized the cross-level minimum latency for multi-routing RPL. It proposed a routing metric based on average latency, and then designed a novel object function focusing on latency optimization with the new routing metric. This novel function utilized the wake cycle of the nodes in MAC layer to get the minimized latency. The testing result verified that the improved algorithm can mitigate the network congestion and make the average latency of the whole RPL network.