Providing Emergency Services in Public Cellular Networks

Abstract

When emergency situations like natural disasters or terrorist attacks happen, demand in telecommunication networks will go up drastically, causing congestion in the networks. Due to the local nature of most disaster events, this kind of congestion is usually most serious at access networks, which is of special concern for cellular networks. With serious congestion in the cellular networks, it is very difficult for customers to obtain access to services. It might be possible to use reserved spectrum for national security and emergency preparedness (NS/EP) customers, such as with police and fire radio systems. However, capacity may be limited. Also, the deployment of additional equipment takes time and could not address the urgent need for communications quick enough. On the other hand, publicly available wireless communication capabilities are pervasive and always ready to use. It would be very beneficial if NS/EP customers could use the commercially available wireless systems to respond to natural and man-made disasters (Carlberg et. al., 2005). For several years, but especially in response to the events of September 11, 2001, the U.S. government and the wireless telecommunications industry have worked together to specify a technically and politically feasible solution to the needs of homeland security for priority access and enhanced session completion. This has resulted in definition of an end-to-end solution for national security and emergency preparedness sessions called the Wireless Priority Service (WPS) defined in the Wireless Priority Service Full Operating Capability (WPS FOC) by the FCC (FCC, 2000), (National Communications System, 2002), (National Communications System, 2003). First-responders, NS/EP leadership, and key staff are able to use this capability in public cellular networks. To support emergency services in public cellular networks, NS/EP users should be identified and provided better guaranteed services than general customers. When NS/EP customers present access codes and have been authorized to use the emergency service, special admission control policies are employed in the base station to make sure their session requests get better admission. Proper methods are also deployed in the core network to provide end-to-end service for NS/EP users. 1