Research And Optimization For WSN Based On Software Defined Network

Wireless sensor network(WSN)is a distributed network system with perceptive ability,which is usually composed of a large number of low cost nodes.As an effective medium connecting the information world and the physical world,WSN has been widely concerned by academia and industry and has shown great potential in military defense,intelligent transportation,environmental monitoring,intelligent medical treatment and other fields.Along with the emergence of concepts such as intelligence and Internet of Things,WSN technology is facing new challenges:diversification of application scenarios requires higher network scalability and the increase of network scale aggravates the burden of network management and maintenance.The emergence of software defined network(SDN)provides an effective way to solve the problems mentioned above.SDN is a new network architecture,whose core idea is to separate the forwarding plane and the control plane of the network.By guaranteeing the programmability of the control plane,the manager can manage and control the network flexibly.In view of the good performance of SDN's south interface protocol represented by OpenFlow in the field of wired,many scholars have tried to introduce SDN technology to WSN field,so as to simplify the network management.However,as a centralized architecture,SDN will bring huge control overhead when applied to WSN.Excessive control overhead will become one of the most important factors that affect network performance.In order to make full use of the advantages of SDN while taking into account the control overhead introduced from SDN,this paper studies and analyzes the technology of SDN and WSN.Meanwhile,this paper presents an efficient software defined wireless sensor network architecture which is called ESD-WSN(Efficient Software Defined Wireless Sensor Network).In ESD-WSN,the controller node has a global network view and it is responsible for implementing the packet processing policy.The rest nodes only perform simple flow table matching behavior.To this end,ESD-WSN covers an efficient topology discovery process and an efficient flow table matching mechanism.Based on the above design,the control plane of the network is completely removed to the controller node,so the network manager can flexibly deploy the global optimized network strategy according to the business needs.For the control overhead problem,by analyzing the energy and load of the network nodes,the controller will dynamically assign some nodes as proxies to aggregate and process the control traffic in the network.Since proxy nodes are greatly related to the stability of the control plane and the effect of control traffic aggregation,this paper proposes a dynamic proxy management(DPM)strategy under our architecture with the objective of minimizing control overhead and prolonging the network lifetime.Finally,this paper builds an experimental environment based on the Contiki operating system and the Cooja network simulator.We have implemented the proposed ESD-WSN architecture in the experimental environment.By setting up parameters of different network size and data rate,the performance of ESD-WSN is tested and evaluated in this paper.Compared with SDN-WISE which is a mature software defined wireless sensor network architecture,ESD-WSN achieves considerable performance improvement in terms of control overhead,end to end delay and network lifetime.