Cognitive Radio

As you read about unlicensed use of spectrum for wireless broadband services, it's helpful to consider developments in radio technology that are enabling such use.  Steven Ashley has a good overview of "smart radios" in the March edition of Scientific American.  He writes:  "Your favorite radio station transmits on a specific frequency. When you set your receiver to so many cycles per second, you tune the antenna circuit to pluck that station's frequency out of the ether. If other transmitters interfere with your reception, your only real option is to wait out the problem. In the best of all worlds, though, your receiver would respond by switching immediately to an open backup frequency that carries your station's broadcast. Such a solution is beyond today's radio technology, and perhaps that example makes the problem seem trivial. But now imagine that interference is interrupting an urgent, emergency cell-phone call. In that case, rapid transfer of the call to a clear cell channel would be more than merely convenient--it might save a life.  ¶  Engineers are now working to bring that kind of flexible operating intelligence to future radios, cell phones and other wireless communications devices. During the coming decade, cognitive radio technology should enable nearly any wireless system to locate and link to any locally available unused radio spectrum to best serve the consumer. Employing adaptive software, these smart devices could reconfigure their communications functions to meet the demands of the transmission network or the user. ..."  Link:  Scientific American.  --Dennis