Communicating in disaster
Currently, the only failsafe communications technology is satellite telephony, which uses either geostationary (positioned at 35,000 km) or low-Earth-orbit (positioned at 640 to 1120 km) satellites instead of terrestrial cell base stations. Satellite communication networks are unaffected by natural disasters. Using a network of 66 low-Earth-orbit satellites, it is possible to cover the entire planet, and one commercial satellite system (Iridium) offers 100% global coverage. In contrast, less than 1% of the Earth’s surface has mobile phone coverage.
With satellite systems being unaffected by disasters here on Earth, the simple solution for improving disaster recovery communications is to increase the number of handsets available for emergency and aid services. The problem is that the cost of broadband global area network (BGAN) terminals (see figure 2) makes wide scale deployment impractical for emergency services & aid charities. The challenge is finding a way to make it financially viable on a larger scale for civil support workers.
Figure 2: Broadband global area network (BGAN) satellite phones are reliable but too expensive for wide-scale deployment.
Portable base stations
Increasing levels of technology integration allow us to build smaller and smaller base stations that enable temporary networks to be established on the fly. With these networks, aid workers can now use normal cellular handsets to communicate. Local infrastructure might be destroyed but these base stations allow both local emergency services and traveling aid relief organizations to coordinate efforts by inexpensive, often donated, handsets. Key to delivering this is both portability and flexibility.
Figure 3: Powered by the LimeLMS6002D flexible radio transceiver, the 9-cm x 8-cm Sidewinder base station reference design from Cambridge Consultants can be powered from a battery or from an adaptor that plugs into the socket of a vehicle cigarette lighter.
An ideal portable base station consists of a software defined radio that can be configured to connect any handset within a few hundred meters. A flexible radio transceiver enables the user to operate across a broad band of carrier frequencies, allowing handsets from the widest possible variety of countries and years to be used. The Sidewinder’s range of 300 MHz to 3.8 GHz, with a 28-MHz channel bandwidth allows it to support a Nokia 2110 from 1995, for example. Such systems can alter standards and frequency bands to work with the available handsets and avoid interference from other wireless networks.
With these types of units, local communication networks could be established within minutes of emergency services and relief teams entering the disaster zone, enabling better management of search and medical assistance teams. By combining the base station with a satellite network back haul, emergency services could also rapidly deploy a network to remote teams and headquarters to optimize the aid effort.
From Haitian earthquakes to Ugandan landslides, disasters often strike in the most inconvenient of locations. However difficult the situation, emergency service workers need ubiquitous communications. Satellite communications seems like a good fit but the costs is prohibitive. By using technological advances to create affordable, portable, low-power, and flexible cellular base stations, coupled with a low scale satellite back-haul, we can sidestep one of the major preventable causes for loss of life—the failure of telecommunications infrastructure.
1. A. Townsend and M. Moss, "Telecommunications Infrastructure In Disasters
," Robert F. Wagner Graduate School of Public Service, New York University (2005).
About the authors
Tim Phipps works in wireless business development for Cambridge Consultants. Throughout his career he has been involved in the development of leading-edge wireless technologies including cellular, wi-fi and Bluetooth.
Ebrahim Bushehri has over 15 years in directing and managing IC design teams within the wireless communication market. Prior to founding Lime, Ebrahim was with Middlesex University Microelectronics Centre (MUMEC), collaborating with top tier organizations such as Nokia, Qinetiq (formerly Defence Evaluation Research Agency) and Fraunhofer IAF.