Simulation And Analysis Of MAC Protocol Based On OPNET

With the rapid development of industrial control technology, demand of intelligent industrial control deployed network for real-time is higher and higher, the delay of network has become the focus of the present research. Although cable network transmission technology is relatively mature, energy consumption of wireless sensor network technology has been continually improved, but limited network resources has not been fully used yet, how to further reduce the network delay and jitter, increase throughput of network, and indirectly improve limited bandwidth utilization of wired and wireless network, and the efficiency of energy consumption of wireless sensor network (WSN) still is a hot spot in the field of transmission control.Paper first relates and analyses the characteristics of MAC protocols in Ethernet and wireless sensor network (WSN), the system structure and energy management method; Then based on the network delay model, analysis the key factors influencing the Ethernet and wireless sensor network, comparisons are made between the existing improved algorithms of MAC protocol. Based on the above theoretical basis, it can be found that the selection of appropriate sending probability p is the key to improve the performance of CSMA/CD protocol. Aimed at this problem, this paper puts forward a kind of thought that dynamic adjustment can be made to probability p based on network environment and request of performance, the idea was applied to Ethernet and wireless sensor network, two kinds of MAC protocol algorithm is designed with adaptive changing probability p and maximum back-off limit. Based on OPNET simulation software, simulation research is done on the delay, the end-to-end delay and queuing delay, throughput and utilization rate of the bus of the above two protocols. The simulation results show that compared with the present new proposed protocol, the two protocol algorithms can effectively reduce delay, eliminate jitter. Paper’s main work and innovations are as follows:1. Firstly, the paper demonstrates the feasibility of using the markov theory, and then based on the theory of discrete time markov chain model, the relationship between the sending probability p and the network status is established, the factors that affect sending probability p and throughput are obtained, map the impacting factor into four network status monitoring variables, through the joint judgment of status monitoring variables to adjust the value of p and the maximum back-off limit, the theoretical basis is built for the following simulation research of the protocol.2. The theoretical basis of the first point is applied to wired Ethernet MAC protocol, a new adaptive algorithm of CSMA/CD protocol is proposed. According to the characteristics of the Ethernet channel and data distribution probability, the algorithm sets up threshold value for four network status monitoring variables. According to joint judgment of the monitoring variables, adjustment is made to the value of p and maximum back-off limit. Then based on OPNET simulation platform, delay, the end-to-end delay and queuing delay, throughput and utilization rate of bus simulation of the protocol is simulated. Finally compare the simulation results with the simulation results of the classical CSMA/CD protocol and the latest adaptive CSMA/CD protocol. The simulation results show that in the scenarios with same network structure but different number of nodes, the new adaptive CSMA/CD protocol put forward by this paper has smaller delay, higher channel utilization.3. Reduce the delay is one of the effective ways to improve the energy consumption of wireless sensor network. This paper puts forward a kind of MAC layer protocol RCA-CSMA/CA suitable for ZigBee network. After compare the differences of wired and wireless environment, the thread value of the four monitoring variables are set according to the characteristics of the channel of wireless sensor network and data distribution probability. Then, based on the OPNET simulation platform, simulations are performed for the delay, end to end delay, queuing delay and throughput of three different topology including the star, cluster, Mesh networks. The simulation results are compared with the classical method, in scenarios of the same topology with different nodes, RCA-CSMA/CA protocol can effectively reduce delay, enhance throughput and embodies good scalability and adaption.