Research And Implementation Of The RPL-based Herarchical Routing Protocol In Wireless Sensor Networks

Wireless sensor networks (WSNs) are consist of a large number of low-cost and low-power sensor nodes. Sensor nodes with computing, sensing and communicating capabilities collaborate in monitoring and collection, and the information is transmitted by multi-hop self-organizing to user terminals. With the large-scale deployment of WSNs and the application scenarios becoming more complex, storage capacity and energy constrained severely restricted the expansion of WSNs. The ROLL Working Group of IETF investigated a routing porotcol so-called RPL which meets the requirements of low-power and lossy networks. RPL routing protocol can support large-scale deployment of WSNs in resource-constrained environments. This thesis proposes an RPL-based herarchical routing protocol, and carries out the implementation and verification.In this thesis, firstly, we analyze the characteristics of the routing protocols for WSNs, and then deeply study the RPL routing protocol on route building process, routing policy and repair mechanism in detail.Then, on the basic of analysis of requirements of large-scale WSNs, this thesis proposes an RPL-based herarchical routing protocol. After building route according RPL, we divide the network topology into different tiers, and then select several sink nodes in every tier called csink nodes which are responsible for data fusion in a tier. In this mechanism, the desired number of retransmissions and residual energy are considered, in order to select high-performance nodes as csink nodes. In each tier, unfused data is sent to a csink node which fuse the data and then send to its parent node while fused data is sent to the RPL parent node via original path. The proposed protocol also designs csink node rotation mechanism to balance the energy consumption and prolong the lifetime of the network. This paper describes the design ideas, the route building process, routing repair mechanism and message format related.Subsequently, we implement the routing protocol on micro sensor nodes MSN-213 and MSHPN-06 successfully. We also build an actual network environment to verify the function of the routing protocol, such as the route building process, packet routing and the repair process when a node failure happens. Through a series of testing, the RPL-based herarchical routing protocol can be verified effective and stable. Finally, we summarize the thesis and point out the work of future.