Improvement And Simulation Research On S-MAC Protocol In Wireless Sensor Network

Wireless sensor networks is an emerging research field integrates a variety of disciplines.It is widely used in the exploration of outer space, military monitoring, environmental Monitoring, health care etc. Sensor nodes in wireless sensor network use batteries for power supply, so they are power limited, thus the research of extending the network life cycle seems very important. Media Access Control(MAC) protocol is responsible for channel resource allocation and sharing communication medium. It is in the underlying part of network protocols stack and plays an important role in the energy consumption, throughput and time delay. The S-MAC is the most basic MAC protocol for wireless sensor network, and is widely used. But it also has many deficiencies. There is the contradiction between energy consumption and delay while loading changes. The BEB algorithm easily leads prone capture effect on backoff process after post-conflict, and it is not fairly. The S-MAC also does not consider the load balance of the network. In the article we focus on the problems of above,analyze and improve the S-MAC protocol.Firstly,by the derivation and analyzing of the listening/sleeping mechanism's average delay in S-MAC protocol, we can get that the transmission delay increases and appears idle listen when the load changes quickly. We analyze the duty cycle adjustment mechanism under the D-MAC(Data-gathering MAC) and DS-MAC(Dynamic Sensor MAC protocol), then use the node's current transmission rate to determine the duty cycle adjustment, which can adapt the changes of load and reduce the idle listening and transmission delay. Secondly, we use the Markov Chain model to analyze the S-MAC protocol's avoiding mechanism. Then, we can get that the throughput and fairness of wireless sensor network will have better performance with a right CW. By analyzing the use of MIMLD (Multiplicative Increase Multiplicative Decrease and Linear Decrease) algorithm in the Ad Hoc network, we apply this algorithm to wireless sensor network to reduce the transmission delay and the retransmission of packet collisions. Thirdly, to extend the life of network, we limit the range of the backoff time of the nodes with different energy, and balance the load between the nodes for avoiding some nodes consuming all the energy which will impact the lifetime of network. Finally, according to all the works that we talked above, we propose the Adaptive Duty Cycle and Dynamic Backoff S-MAC based on Load Balance, (ADBS-MAC). The ADBS-MAC protocol can adapt the changes of load better, improve the throughput of the network, avoid conflicts between nodes effectively, reduce energy consumption or data latency, and prolong the lifetime of the network. Meanwhile, the fairness of the communication channel has been proved.We use NS2 simulation platform for the simulation of the ADBS-MAC and the S-MAC.By analyzing and comparing the data of simulation, the three aspects in ADBS-MAC we talked above are improved. The results show the new method not only reduces energy consumption, but also has a better performance than S-MAC protocol in throughout capacity and time delay...