Wireless sensor and actor networks (WSAN) is derived from wireless sensor networks (WSN), and is composed of a large number of resource-limited sensors and a small number of resource-rich actors to perform distributed sensing and acting tasks. Sensors gather north face jackets information about physical phenomenon and send collected data to actors, while actors take decisions and then perform appropriate actions upon the environment. WSAN is able to perform actions upon events as well as detect them, so it has great application prospect, and has received broad northface jackets attention.As is different from WSN at network structure and application background, WSAN has different requirements, it requires not just lower energy cost but also timely transmission and cheap womens nike shoes fault-tolerance. In WSAN, when sensors send the collected data to actors, Single-Actor model or Multi-Actor model is usually used. Every sensor sends data to only one actor in both models, once this actor is invalid, the collected data would not be properly received, which lead to the fault of the network. A new model named cheap men's nike shoesMulti-Actuator/Multi-Sensor is proposed recently, every sensor sends data to more actors, which improves the network's tolerence to fault through the nike running shoes redundance of data transmission.Based on deep research at the data transmission of MAMS model, an energy-efficient and fault-tolerant transmission algorithm, multicast greedy forward (MGF) algrithm, is presented in this paper. MGF algrithm contains actors selection, foundation of multicast routing tree and data transmission the three phases. Firstly, sensor selects nearest actors to receive their data; Then a multicast routing tree is founded; Lastly, sensor send its data to selected actors along this tree. Multicast routing tree is a tree structure with the sensor to be root node and the selected actors to be leaf nodes, the way to form the tree is to make the links of the tree as fewer as possible. As there is only one data packet on the link, fewer links lead to lower energy cost, and fewer links always lead to better real time performance.Simulation results show that MGF algrithm makes the network tolerant to fault, meanwhile, it has good performance at energy efficiency and real time transmission, so MGF algrithm meets the requirements of WSAN very well.
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