Research On Wireless Sensor Network MAC Protocol Based On Improved Exhaustive Service Polling System

The purpose of the Internet of things(Io Ts)is to achieve the interconnection of everything.According to the prescribed protocol,it connects objects that need to communicate with the network through various information collection devices,to achieve the purpose of interaction between things and things,people and things.As an indispensable infrastructure of the perception layer of the Io Ts,wireless sensor network(WSN)is mainly used to collect and transmit physical information,and have many applications in urban construction,agricultural production,health care and many other areas.With the continuous improvement and application of WSN,some shortcomings of it are gradually exposed,such as network structure,energy efficiency,security,differences and quality of service.There are usually two solutions to solve these defects,the first one is to updating the sensor technology,and another one is to improving the network protocol.However,due to the great limitations in the update of sensor technology,the problems faced by WSN are generally solved by improving network protocols.The MAC protocol in WSN decides how nodes occupy the wireless channel to send and receive data,which affects the performance of the network.Aiming at the limitations of the current MAC protocol,this paper improves and implements the polling access MAC protocol in WSN with the goal of low delay,high energy efficiency and high service quality.First of all,to solve the problem of high network delay caused by high-density access sites and massive data collection,an exhaustive polling control model with multi-server access is proposed to realize load balancing.Based on the single server exhaustive polling system,a mathematical model is constructed to calculate the characteristic parameters such as the queue length and delay of the system,and a new method for calculating the polling period is proposed.The experiments were performed on MATLAB 2018 a to simulate the operation of the system.Simulation experiments and theoretical calculations indicate that the delay and queue length of the system are lower under different network size and traffic.Next,to fulfill the requirements of priority service and real-time performance,a twolevel polling control model is proposed,in which both the ordinary sites and priority site use exhaustive service mode.Using the continuous time analysis method and combined with the probability generating function,the first order characteristics of the system such as queue length and period,and the second order characteristics such as delay,are calculated accurately.Then through the simulation experiment to simulate the operation of the system,the results show that the system can not only distinguish the business priority,but also optimize the performance of the ordinary sites.Furthermore,the model is applied to clustered WSN,and a better energy efficiency is obtained.Then,the variables of each site are asymmetrically processed for different nodes and users in large-scale WSN.An asymmetric two-level exhaustive polling system model is proposed,and the mathematical model is established to derive the characteristic parameters of the system.And the BP neural network is used to predict and evaluate the performance of polling system.Finally,aiming at realizing the application of polling system in WSN,the two-level exhaustive polling model is implemented in Tiny OS system,and a WSN environment monitoring system using polling mechanism is built on One NET cloud platform,which realizes the visual management and monitoring of environmental information.