INTRODUCTIONWireless mesh networks (WMNs) are a very promising technology to provide an easily deployable and cost-efficient solution for access to packet-based services for metropolitan areas with high population densities. Thus, WMNs may be a key technology in future 4G wireless networks and are currently becoming attractive in situations where it is not convenient to deploy wired backhaul connectivity. For example, it is often impractical to deploy wired infrastructure cost effectively or under tight time constraints. This is particularly true if the deployment is only transient in nature. Another key feature of WMNs is that unlike wireless multihop relay networks, WMNs are not restricted to tree-shaped topologies rooted at the gateway to the wired network and hence do not suffer from the same performance bottlenecks. Instead, any mesh node may communicate with any other one over multiple paths, allowing more efficient utilization of network resources. In contrast to ad hoc networks, WMNs are operated by a single entity, and their components have far fewer restrictions in terms of energy, resilience, and processing power.The main aim of the Carrier Grade Mesh Networks (CARMEN) project is to design WMN architecture capable of delivering carrier grade triple-play services at significantly lower capital and operational expenditures than comparable wired backhaul networks. There is a particular emphasis on providing a solution for both fast deployment and transient usage scenarios. This goal presents a number of significant research challenges. One key challenge is to reduce the investment required to deploy and operate WMNs. This will be achieved by applying advanced self-configuration and management techniques in all stages from planning to deployment and operation. Currently neither coordinated (e.g., WiMAX-like) nor uncoordinated (e.g., WiFi-like) medium access control (MAC) technologies use wireless resources efficiently for multihop mesh scenarios, making it difficult to provide any guaranteed quality of service (QoS) levels. Therefore, methods for provisioning the QoS required by carrier grade services over coordinated or uncoordinated wireless MAC protocols are a further research topic. In order to develop a robust and long lasting solution, the CARMEN architecture will not be bound to a specific radio technology. Rather, an abstract interface will be defined that can support heterogeneous radio technologies within CARMEN systems.Although WMNs have been the subject of several research initiatives (e.g., [2][3][4]) over the last few years, some of which have been developed into products, current WMN solutions fail to meet the stringent quality and reliability requirements of service providers. THE CARMEN PROJECTThe CARMEN Project is a three-year project partially funded by the EU's 7th Research Framework Program and has a total budget of approximately 6 million. The CARMEN project focuses on developing a heterogeneous mesh backhaul solution to provide carrier grade services with greater flexibility and at...