Research On And Implementation Of Accessing A Network And Discovery Of Resource Directory For Iot Node

The Internet of Things(IoT)contains a wide variety of items and devices in people's life and production.These devices have poor processing capacity,are battery-powered,and their storage space is small.These limited characteristics of the nodes lead to we can't give the nodes the same tasks.Therefore,how to apply the traditional Internet node access and management mechanism to the constrained network will be a big problem.In addition,direct resource discovery is not feasible in the IoT.The IETF CoRE working group proposed a resource directory mechanism for resource discovery in the IoT,the primary problem of the mechanism facing is how to find the location of the resource directory server.Based on the constrained environment,this paper proposes and verifies the solutions for how to implement the access network mechanism and resource directory discovery mechanism of the constrained node.The work of this paper is divided into two parts:the optimization and implementation of the IoT node access network and management mechanism,and the proposal and verification of the resource directory discovery mechanism.Aiming at the problem the existing node access network and management mechanism is not suitable for constrained nodes and constrained networks,this paper analyses the network aceess and management mechanism,uses the stateless address automatic allocation mechanism to allocate node addresses.Based on the work of the IETF working group,this paper optimizes the neighbor discovery protocol which the stateless mechanism relies on,making it suitable for constrained networks,and it can supports node mobility and multi-hop networks.This paper analyzes the resource directory discovery mechanism envisioned by the IETF CoRE working group in the resource directory draft,including the mechanism based on pre-configuration and the mechanism based on multicast,analyzes its feasibility,analyzes and optimizes the trickle algorithm,and introduces it into the mechanism based on multicast to adapt to the constrained network.Finally,based on the Contiki system and the libcoap open source framework,this paper implements the proposed node access and management mechanism and resource directory discovery mechanism.The Cooja simulator is used to verify the proposed mechanism.The experimental results show that the optimized node access and management mechanism is more suitable for the constrained network with limited node resources than the traditional mechanism,and it saves resources such as energy consumption of the network and supports the constrained nodes better.The optimization mechanism enables the router to recognize the movement of the node and the repeated registration through optirmization work such as introducing TID identification,and it can update the cache in time;By combining with the RPL protocol,the optimization mechanism performs better in the evaluation of important indicators such as network convergence time,number of control messages,and average network delay,it can save energy consumption in a multi-hop network and is adapted to dynamic changes of the network.For the resource directory discovery mechanism,coupled with the address allocation mechanism,the pre-configured mechanism is simple to implement,and is suitable for the case where the resource directory information is relatively constant;the mechanism based on multicast with trickle optimization has more advantages in message number,reliability,energy consumption and average discovery time than the mechanism based on traditional multicast.