Research Of The Routing Protocol For Low-Power And Lossy Networks In Wireless Sensor Networks

With the increasingly complex application scenarios of wireless sensor networks and the continuous expansion of the network scale,the nodes have the limited storage capacity,the limited energy,the unstable links and other features,which seriously restrict the largescale expansion of wireless sensor networks.Aiming at the low energy consumption and lossy characteristics of wireless sensor networks,the ROLL(Routing Over Low power and Lossy Networks)working group of the Internet Engineering Task Force(IETF)proposed an RPL routing protocol based on IPv6.Based on the RPL routing protocol,this paper studies the load imbalance and congestion problem of the RPL routing protocol.The specific research content is as follows:Using the single-path to transfer data for RPL routing protocol can cause load imbalance problem,this paper proposes a multi-path RPL routing algorithm based on dynamic weights.Firstly,the optimal multi-parent set of nodes are selected according to the data transmission cost in the process of network topology construction.Secondly,a data traffic distribution metric is proposed,and the weight of each path is calculated according to the data traffic distribution metric.The weights of the path are dynamically updated according to the changes of nodes and links status.The metric effectively combines the quality of the wireless links,the residual energy of the node,the buffer occupancy of the node,the number of child nodes of the relay nodes and so on.Finally,in order to effectively balance the network load,the node distributes different number of packets to each path according to the size of the weight of each path.The simulation results show that the proposed algorithm can not only increase the packet delivery rate,but also prolong the network lifetime.It can also reduce the average end-to-end delay and increase the average throughput of the root node.In view of the congestion problem in the network topology constructed by RPL routing protocols,the existing congestion control algorithms do not consider the problem of the expected lifetime of nodes,and congestion detection only considers the buffer occupancy or packet service rate and packet generation rate.This paper proposes a RPL Congestion Control Algorithm based on energy-balanced.Firstly,the buffer occupancy and the expected lifetime of the nodes are comprehensively considered in the process of selecting the optimal parent node.The fusion decision is performed using the triangular modular fusion operator to select the optimal parent node.Secondly,congestion detection is performed by taking into account the buffer occupancy and buffer change rate of nodes in the process of congestion detection,which can effectively avoid congestion.Finally,the node takes into account the buffer occupancy and the expected lifetime of the nodes to switch to the optimal parent node in the process of congestion mitigation and it can be switched to a node with lower congestion and a longer expected lifetime,so that the node can mitigate the congestion and energy consumption can be balanced.The simulation results show that the proposed algorithm can not only reduce the packet loss rate,but also increase the data packet receiving rate of the root node.It can also prolong the network lifetime and reduce the average power consumption.