WIRELESS MESH NETWORKS FOR PUBLIC SAFETY AND DISASTER RECOVERY APPLICATIONS

Abstract

Reliable and efficient communication is absolutely crucial for public safety in general, and emergency response and disaster recovery operations in particular. Recent events such as 9/11 and Hurricane Katrina have dramatically demonstrated that there exist significant inadequacies in current first responder communications. One of the main problems that plagued rescue teams and emergency services during these disasters was the lack of interoperability between communications equipment used by different public safety agencies and jurisdictions. The 9/11 commission report [1] noted that a patchwork of incompatible technology and the uncoordinated use of frequency bands were the main reasons for nonexisting or poor interagency communication during emergency response and recovery operations. Shouting, waving signs, and runners with handwritten messages often had to be used as a primitive alternative. Another problem of public safety and disaster recovery (PSDR) communication is the strong reliance on terrestrial communications infrastructure such as traditional landline and cellular telephony as well as infrastructure-based land mobile radio (LMR). Hurricane Katrina uprooted hundreds of wireless base stations, disconnected numerous vital communications cables, and flooded central offices. The remaining functional parts of the network were often completely overloaded and unable to provide adequate services in the aftermath of the disaster. First responders were surprised and severely hampered by a near-complete breakdown of the fixed terrestrial communications infrastructure. In a number of recent major disasters, communication systems relying on fixedterrestrial infrastructure have proven to be rather unreliable. A strong dependence on point-to-point communication links and a limited degree of redundancy give these systems an insufficient level of resilience and robustness in disaster scenarios. A further shortcoming of current PSDR communications is the lack of support for broadband data rates. It is widely recognized that data-intensive multimedia applications have a great potential to improve the efficiency of disaster recovery operations. Real-time access to critical data such as highresolution maps or floor plans can be extremely valuable for frontline first responders. Being able to send a live video stream from the incident site back to the command post would greatly increase the situational awareness and would allow more efficient decision-making. The need for broadband communication capabilities for PSDR agencies is also pointed out in a report by the SAFECOM program of the US Department of Homeland Security [2,28]. The document states that ‘‘voice communications are critical, but voice communications requirements are not the only issue . . . public safety agencies are increasingly dependent on sharing of data, images, and video.’’ Unfortunately, current PSDR communication systems do not provide the necessary broadband capabilities for bandwidth-intensive multimedia applications. Given the shortcomings of current PSDR communications mentioned earlier, Wireless mesh networks (WMNs) provide an interesting alternative technology. The key features of WMNs such as broadband support, fault tolerance, and a high level of interoperability provide them with a great potential as a platform for PSDR communication. The aim of this chapter is to discuss the suitability of WMN technology for PSDR applications. Section 16.2 gives a brief overview of WMN technology and highlights its key characteristics and features. Section 16.3 provides a background on PSDR communications and discusses some of the key technologies and standards. It also specifies the key requirements of PSDR communication systems in terms of functionality and performance. In Section 16.4, we investigate to what extent WMNs are able to meet these requirements, and highlight areas of strength as well as those of weakness, in which further research is required. Section 16.5 gives an overview of the key research activities that are underway to address the main limitations and shortcomings of current WMNs. Finally, Section 16.6 concludes the chapter.