Design And Implementation Of Traffic Adaptive MAC Protocol For Wireless Sensor Networks

Wireless sensor networks are comprised of a large number of energy-constrained sensors that self-organization into a multi-hop wireless network, each node perform data transmitting cooperatively. But the nodes are the size-constrained and the cost-constrained, the sensor nodes are normally serious influence on the computing capacity, the communications capacity and energy, the consumption energy of the sensor nodes come from the limited battery. Due to the limit of cubage and cost, reducing energy consumption to extend network lifetime is one of the most important requirements in designing wireless sensor networks. Recently, there has been many theses to prolong the lifetime of wireless sensor networks by many ways. And in this thesis, the MAC protocol of the link layer is studied to save energy.According to the shifty traffic, this thesis propose a kind of adaptive traffic MAC protocol with common active periods to accommodate the shifty of the traffic. The proposed MAC protocol introduces the global synchronization, the same schedule is used by all of the sensors on the wireless sensor networks, so all the sensors of the network are at the beginning of active periods or at the beginning of sleep periods on the same time, reduce the idle time which be resulted by the similar MAC protocol adopt the virtual cluster mechanism; According to the number of data packet in the transmit queue, nodes adaptively adjust the duty cycle, so that increase the nodes’transmitting time, decrease the data packets’end-to-end delay and improve the network’s throughput; A new backoff strategy also be adopted by the proposed MAC protocol, this strategy adjust the Contention Window based on the number of the backoff and the collision in the five recent duty, on the high traffic network this strategy could increase the backoff time, then decrease the collisions’probability of the data packet, on the low traffic network this strategy could decrease data packet’s backoff time and also decrease the nodes’idle time, then decrease the packets’end-to-end delay.On the NS2simulation platform, this thesis establishes the experiment of no traffic network, the experiment of a single traffic network, the experiment of a convergence traffic network and the experiment of a randomly deployed network. The proposed MAC protocol, IEEE802.11and SMAC protocol are operated on the four simulation experiment, then analyse the performance of three protocol based on the trace file. The analytical results indicate that on the wireless sensor network of the different traffic and the different topology, the proposed MAC protocol of this thesis has a good performance on the network’s throughput and the end -to-end delay, and prolong the life time of the wireless sensor networks.In this thesis, the method of designing MAC protocol for wireless sensor networks is provided. Future work will focus on fluctuation problem of the proposed MAC in complex environment.