Research Article Fault Tolerant Mechanism for Multimedia Flows in Wireless Ad Hoc Networks Based on Fast Switching Paths Juan R. Diaz, 1 Jaime Lloret, 1 Jose M. Jimenez, 1 Sandra Sendra, 1,2 and Joel J. P. C. Rodrigues 2 1 Instituto de Investigaci´ on para la Gesti´ on Integrada de Zonas Costeras (IGIC), Universidad Polit´ ecnica de Valencia, Camino Vera s/n, 46022 Valencia, Spain 2 Instituto de Telecomunicac ¸˜ oes, Universidade da Beira Interior, Rua Marquˆ es de ´ Avila e Bolama, 6201-001 Covilh˜ a, Portugal Correspondence should be addressed to Jaime Lloret; jlloret@dcom.upv.es Received 14 July 2014; Accepted 21 July 2014; Published 2 September 2014 Academic Editor: Jingjing Zhou Copyright © 2014 Juan R. Diaz et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Multimedia trafc can be forwarded through a wireless ad hoc network using the available resources of the nodes. Several models and protocols have been designed in order to organize and arrange the nodes to improve transmissions along the network. We use a cluster-based framework, called MWAHCA architecture, which optimizes multimedia transmissions over a wireless ad hoc network. It was proposed by us in a previous research work. Tis architecture is focused on decreasing quality of service (QoS) parameters like latency, jitter, and packet loss, but other network features were not developed, like load balance or fault tolerance. In this paper, we propose a new fault tolerance mechanism, using as a base the MWAHCA architecture, in order to recover any multimedia fow crossing the wireless ad hoc network when there is a node failure. Te algorithm can run independently for each multimedia fow. Te main objective is to keep the QoS parameters as low as possible. To achieve this goal, the convergence time must be controlled and reduced. Tis paper provides the designed protocol, the analytical model of the algorithm, and a sofware application developed to test its performance in a real laboratory. 1. Introduction A wireless ad hoc network is a decentralized structure by nature. Tis type of network does not depend on a preexisting infrastructure such as wireless routers or access points in managed wireless networks. Instead of this, each node par- ticipates in routing tasks by forwarding data to other nodes. Te purpose of these nodes is determined dynamically based on the network connectivity. An ad hoc network typically refers to any set of nodes where all of them have the same status within the network and are free to associate with any other node in the radio coverage [1]. An ad hoc network is composed of several nodes connected by radio links. Tese links are limited by the resources of each node such as its power consumption, transmission power, computing power, memory, performance properties, and radio link properties (e.g., the duration of the connection, signal loss, interference, and noise). As radio links can be connected or disconnected at any time, a functioning network must be able to cope this dynamic restructuring, preferably in a timely, efcient, reliable, robust, and scalable way [2]. Ad hoc networks are suitable for a variety of applications such as emergency situations, armed conficts, natural disas- ters [3], or environmental monitoring [4], where nodes are not dependent on a central node. Tis feature can improve the scalability of these networks compared to managed wireless networks. Furthermore, we can fnd lots of hardware available for their implementation [5]. Among lots of applications that can be implemented by the ad hoc networks, we can fnd the multimedia content distribution. Design of a multimedia ad hoc network for a certain application is infuenced by several factors, such as fault tolerance [6], scalability, production costs, operating environment, network topology, hardware constraints, transmission media, and power consumption [7]. Moreover, there exist additional factors which afect the efciency of multimedia communication in ad hoc networks such as high bandwidth demand, multimedia cod- ing techniques, application-specifc quality of service (QoS) Hindawi Publishing Corporation Mathematical Problems in Engineering Volume 2014, Article ID 361543, 12 pages http://dx.doi.org/10.1155/2014/361543