Abstract— Wireless Sensor Networks (WSNs) are multihop wireless networks in which all nodes cooperatively maintain the connectivity of the network. In this paper, a new reliable multicast routing Protocol called “Fault Tolerant Adaptive Demand-Driven Multicast Routing” (FTADMR), is proposed for WSNs. The proposed protocol increases transmission range to send lost packet when a break occurs. Two mechanisms are applied to reduce the overall overhead in the network. Therefore, by this protocol, packets are routed in a reliable manner while consuming energy efficiently. The proposed protocol is compared with Adaptive Demand Driven Multicast Routing Protocol (ADMR) in terms of Packet Delivery Ratio (PDR), overhead packet, Normalized Packet Overhead, energy consumption and delivery delay. The simulation results show that proposed protocol achieved better results. Index Terms— multicast, wireless sensor network, fault tolerant, adaptive-demand. I. INTRODUCTION W ireless Sensor Networks (WSNs) have been considered as one of the most important technologies for the twenty first century [1]. A WSN typically consists of a large number of low-cost, low-power, sub-miniature and multi- functional sensor nodes that are able to sense its environment. These smart, tiny and cheap nodes are deployed in a physical area and communicate via wireless interfaces. In most sensor network scenarios, when sensors receive a query from sink or Base Station (BS), they sense the surrounding environment due to that query. The time nodes finish their missions, results will be sent back to sinks/BSs and sinks/BSs will process results or forward it to appropriate operators [2]. Processing such a signal reveals some properties about objects located and/or events happening in the vicinity of the sensor. With these networks, the Internet can be used to provide unprecedented opportunities for a variety of military and civilian applications like wild life observation, environmental monitoring and battle field surveillance [3]. Wireless sensor network and Adhoc network are similar to each other but there are some basic differences like: 1 Computer Science Department, University of Essex, Colchester, United Kingdom, mabbasb@essex.ac.uk. 2 Computer Science Department, University of Warwick, Coventry, United Kingdom, a.fadavinia@warwick.ac.uk. • Nodes in Adhoc network may not have memory, power and processing constraints as much as sensor network. • In WSN density of nodes is higher than Adhoc network. • Sensor nodes are more prone to failure than nodes in an Adhoc network. • Sensors transmit their collected data to the base station or sink, but Adhoc networks are typically used where there is no fixed infrastructure like base station. In every kind of network, to send a message from source to destination, routing protocol is used. One classification for routing protocols is unicast, broadcast and multicast. Unicast routing is used when a sensor node wants to send a message to a single sink. Broadcasting is used when it is necessary to send a message from a sensor node to all of the nodes in the network, this kind of routing protocol is usually used when the route is needed to be discovered. Multicasting in WSN is used to deliver messages from a source or sources to a set of sinks. As [4,6] indicate, multicasting is different from sending a copy of message to each sink separately. The aim of this kind of routing is to decrease the consumption of resources especially energy. There are many scenarios in which the use of multicasting is the best option for routing. In such scenarios, it is vital to design an efficient multicasting mechanism for decreasing the overall consumption of resources in the network. Several multicast routing protocols have been proposed for Adhoc and sensor networks. Battery drainage might make some routes invalid. In previous sensor network protocols such as [4]–[6], no route maintenance and update mechanisms are proposed. In ERUP [8] and RRASS [9] the route repair problem is solved with different extents but none of them have a procedure to send data when repair mechanism is running. RMRP [10] has some procedures in the case of packet loss that maintain additional route to destination. When a break occurs, the packet will be sent via alternative route. For sensors with constrain memory, it is not a good option to save a back up route. Moreover in some situations it is possible node loses its both routes to destination, so still they may have problem in reliability. The routing protocol also needs to minimize the number and size of control messages it transmits to conserve bandwidth and battery resources [2]. In [4]–[6], [8], [10] each node uses periodic hello messages for knowing its neighbours and updates its routing tables with these control packets which causes increasing traffic of site. For implementing new routing protocols for WSN, it is important that the new FTADMR: A Fault Tolerant Adaptive-Demand Multicast Routing Protocol in Wireless Sensor Networks Mahin Abbasipour 1 , and Ali Fadavinia 2 Proceedings of the World Congress on Engineering and Computer Science 2011 Vol II WCECS 2011, October 19-21, 2011, San Francisco, USA ISBN: 978-988-19251-7-6 ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online) WCECS 2011