| Wireless sensor network is a distributed sensor network which is composed of a large number of devices that can sense and detect the external data. In WSN, each sensor communicates with each other through wireless and multi-hop, its configuration is very flexible and can change the position of sensors arbitrarily. But sensor device general powered by battery, and its capacity of data processing and storage is limited. Traditional routing algorithm of WSN is not conducive to the management and topology maintenance, and the interoperability with other networks is poor. Therefore, the Ro LL work group successively completed a standard formulation for a routing protocol which is suitable for working in low power and lossy networks. RPL protocol can effectively make up the shortcomings of traditional wireless sensor network routing method, which is based on topology construction and data routing, so it has a wide range of application prospect, which has attracted great attention, and has important research and application value.Firstly, this thesis summarizes the concept, characteristics and the research status at home and abroad of wireless sensor networks and low power and lossy networks. Then, the RPL routing protocol was detailed analyzed and classified by the key problems according to the difference of routing strategy for topology construction, data forwarding and routing repair. Lastly, several representative algorithms are introduced, and their characteristics are analyzed and compared.Then, aiming at the problems that the existing energy balanced RPL(EB-RPL) algorithm which select the best parent node according to the expected survival time of bottleneck node in each path, the joining node do not consider all flow through bottleneck node, and not take into account the number of control packet which is used to construct and maintain the topology, and without considering the change of bottleneck node after node joining in the network, node can not select the best parent node accurately. We proposed an Energy Balanced and High Efficiency Routing Protocol for Low Power and Lossy Networks(EBHE-RPL). It first uses the classify sending mechanism for DAO-ACK messages firstly to reduce the number of control packets sent by the parent node. Secondly, using a traffic accumulation mechanism to calculate expected lifetime of bottleneck on each path, so that the lifetime calculated of bottleneck is closer to the actual value. Thirdly, it uses a control packet accumulation mechanism to calculate expected lifetime of the joining node, so that the expected lifetime of node is more accurate and is good for selecting the best parent node. Lastly, it uses a bottleneck re-estimating mechanism after node's joining to avoid the wrong choice of bottleneck node. Simulation results show that, compared with the existing protocols such as RPL and EB-RPL, the performance of EB-RPL is improved in the extension of network lifetime and the balance of network energy.Next, the thesis analysis the reason of owning big energy consumption and delay as well as small delivery rate in another classic algorithm named cluster-parent based RPL for low power and lossy networks(CRPL). And on this basis, this thesis proposed an opportunistic and best forward set based routing for low power and lossy networks(OBFSB-RPL). The algorithm optimizes the cluster-parent set selection mechanism, and increases the opportunities of data to successfully forward to the next hop. And the algorithm changes the calculation process of each cost value in the selection of cluster-parent set according to the queuing model, makes the data forward with the accurate order in the best forward set, so that reducing the delay. The simulation results show that the performance of OBFSB-RPL algorithm is better than the CRPL algorithm and RPL protocol in terms of delay, success rate and so on.Finally, we summarizethe work of the whole thesis, and gives the future research direction of RPL routing. |
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