Cognitive wireless network infrastructure and restoration activities for the earthquake disaster

Cognitive radio is a key technology for optimized and efficient radio resource utilization. However, cognitive radio systems achieve most performance not as individual radio devices, but as a wireless network infrastructure comprising a number of radio devices deployed over geographically wide area. This paper describes a world first trial of cognitive wireless network infrastructure with about 500 cognitive wireless routers, which have been originally developed by the authors, throughout a city cooperatively managed from an operation center. Part of the design has been contributed and adopted by IEEE 1900.4. The test-bed was partly reinstalled in North-east area of Japan for the restoration of the Internet access after the earthquake disaster occurred in March 11, 2011, where stability and applicability of the system is verified by analysis of obtained measurements. Tendency of internet access in terms of traffic amount and user connections is also analyzed as well as raising requirements for wireless network infrastructure in disaster cases.