The XG1™ cognitive radio uses advanced signal processing techniques to identify unused bandwidth, normally licensed to others, and creates a selection of channels available for use by the XG1 network. Individual XG1 sites detect non XG1 radio users and relays this information to the central radio. This information is processed by the central radio to create a "composite" usage map covering the entire XG1 network (Networks with XG1 cognitive radios can span a radius of over 50 miles).
This map is continuously updated and distributed throughout the network. Using a spectrum usage policy in accordance with FCC and network operator guidelines, the XG1 cognitive radio determines opportunities to use these channels on a shared, non-interfering basis. When any XG1 adaptive radio in the network recognizes the presence of another licensed user within the specified band, that frequency is immediately removed from the selection of available channels until the network again determines that it is not being used. The network also employs a programmable "keep away" feature that allows the operator to determine the amount of "white space" buffer to maintain around other primary users.
