Research On CSMA Based On Priority Grouping In M2M Communications

With the continuous development of Internet of Things(IoT)technology,a variety of intelligent hardware gradually into our lives.At present,such concepts as smart home and smart city are endless.However,with the development of the IoT,the most important communication methods in the IoT,Machine-to-Machine(M2M)communications are also facing more and more challenges.This is because as the number of intelligent nodes shows an explosive growth trend,a large number of Nodes need efficient access to the network,and has brought unprecedented challenges to the traditional random access.This dissertation will focus on the random access process in M2 M communication.And the research focuses on how to reduce the access collision probability,reduce the access delay and improve the network energy efficiency when a large number of nodes exist in the network.First of all,aiming at the problem that large-scale node access in machine communication can easily lead to network congestion and reduce transmission efficiency,the single-channel carrier sense multiple access(CSMA)protocol is analyzed.Based on this,to improve the access efficiency and probability,a multi-channel frequency division multiplexing CSMA protocol is proposed.By dividing the channel into multiple subchannels,the nodes are also divided into multiple groups,and each group of nodes corresponds to a subchannel,thereby reducing the number of participating nodes in each subband,thereby reducing the probability of collision.Then can reduce latency and increase energy efficiency.It is also verified that when the load exceeds a certain delay threshold or energy efficiency threshold,the application of more subchannels will help reduce access delay and improve energy efficiency.Secondly,in view of the diversity of nodes in different IoT environments and the different requirements of networks for different applications,based on the idea that important nodes can access the network in time,a CSMA protocol based on priority grouping is proposed.By dividing different priority nodes into different groups and using different frequency band resources for transmission,besides through two kinds of bandwidth allocation strategy for different priority nodes.The differentiated transmission of data is realized to ensure that data packets of high-priority nodes can meet specific delay requirements in any case and are superior to data packets of low-priority nodes in terms of delay and energy efficiency.Finally,through MATLAB simulation experiments,we verify the two aspects of access delay and energy.The results show that the proposed two methods can achieve the desired goal,and prove that the two proposed methods are effective.