Traffice Adaptive Energy Efficient MAC Protocol For Wireless Sensor Network

The research for Wireless sensor networks is a hot spot field of information technology in recent years, which integrates wireless communications, sensing, embedded computing, grid computing and other technologies, and it is a typical non-infrastructure communication network. As an emerging technology, wireless sensor networks can be widely used in environmental testing, smart space, medical systems, as well as machine learning, which is composed of many distributed nodes forming a multi-hop network. Each sensor node is usually by the battery-powered. These nodes coordinate to complete a task.Since the energy of sensor is limited, therefore, the protocol running on sensor networks must have energy efficiency for a longer life cycle. Medium access control sublayer is the main energy consumption. Therefore, the key issue of the design is medium access control for wireless sensor networks.This paper proposes a traffic adaptive energy efficient MAC protocol for wireless sensor networks, TAEE-MAC protocol. According to successive failure number of channels competition, the size of contention window is dynamically adjusted in order to adapt to network traffic load, thereby reducing transmission collision and energy consumption caused by the collision. As to the rapid backoff mechanism, when the nodes in the backoff process detect a certain successive idle time slots, they can jump the conclusion that there are no other nodes to complete the channel. At this time, backoff process can be accelerated in order to speed up backoff timer to reduce to zero, and start data transmission without having to wait for the entire backoff time. The backoff stage is divided into linear and exponential backoff phases. When the network traffice load is high, with certain mechanisms, linear backoff is mainly used to reduce the conflict and packet retransmission. When the network load is relatively light, the exponential backoff accounts for the major part. That is, the backoff stage can be accelerated to reduce the idle listening energy consumption.In order to minimize energy consumption, this paper presents adaptive algorithm to adjust the duty cycle. Based on the traffic information for nodes, adaptively coordinate the listen/sleep period, at the same time, piggyback SYNC packet with RTS, not only to reduce the idle listening time to reach the purpose of saving energy, but also to reduce the control packet overhead.The simulation results show that energy consumption for the TAEE-MAC protocol is lower than S-MAC protocol, which meets energy efficient requirements for wireless sensor networks. Also, The TAEE-MAC protocol surpasses S-MAC in delay and throughout performances during the light traffic load.