Over wireless, we stream movies, pictures and other highly compressed packets of data. Radio, in fact, is the underlying technology for the world's most sophisticated devices, from smartphones to weather satellites, from Mars rovers to stealth battlefield communicators.

Preston Marshall, project manager for Defense Advanced Research Projects Agency (DARPA) cognitive radio development, said that the basic functionality tests of the beta hardware was a success. This is a major step forward for all types of mobile radio handset users.

In most of the world, radio spectrum is used very inefficiently. Big chunks of spectrum remain silent while a small part of the spectrum is literally overloaded. By changing the RF spectrum reuse matrix, a cognitive radio could, for example, intelligently switch from a crowded part of the spectrum to a more open region. It could also ramp up its error correction capabilities in the face of interference - all the while tracking the user's actions and location, and making decisions based on predictive analysis.

We saw the limits of today's spectrum allocation as the Washington DC mobile phone system was overloaded during the American presidential inauguration. Mobile providers planned to mitigate this problem by bringing in COWS (Cell-site On Wheels) and COLT (Cell on Light Truck) parked near the Capitol Building, the Lincoln Memorial, along the inauguration parade route, and near the White House.

Dr Joseph Mitola is the father of cognitive radio, a term he coined in 1990. Mitola's advanced ideas helped mobile phones shrink from brick-sized to today's multifunction devices, blending computer functions with radio functionality.

The March 2006 Scientific American magazine called SDR (Software Defined Radios) "next-generation wireless technology" - a software-driven advance "that will produce a seismic shift in radio design." With SDR, the same device can be modified to perform different functions at different times. The same handheld thus can be used as both a mobile phone and a computer.

The military and public safety use old style LMR (land mobile radio) based push-to-talk technology that requires an operator to change radio channels. With a cognitive radio, the radio is aware of its environment and location, then alters its power, frequency, modulation, and other parameters so it dynamically reuses available radio spectrum.

Nextel is presently the technology which does some of what a true cognitive radio will do. If you are carrying a Nextel push-to-talk radio handset in the field, you can reach a nearby mobile radio tower. The mobile system telephone-based backbone will haul your conversation to another Nextel mobile radio base station and deliver the voice call to another Nextel user.

With a cognitive radio system, if your handset is within range of several similar radios, it finds one that has access to the internet. The cognitive radio handset with IP access to the internet will jump on board, carry your voice conversation over the internet, and finally deliver your conversation at the far end to another set of radios. They will then participate in relaying your voice to the ultimate radio handset. Marshall said that instead of having discrete - public safety - trunking systems like we think of them now, any IP based network becomes a trunking system.

Marshall said that today, we think of push-to-talk radios as having only the range of the handheld radio to another radio or base station on a tower. With a cognitive radio system, the first step is that it actually has the range of any connected node to any connected node, which is in turn connected to any connected node, through intermediate relay - an IP network like the internet. He said further that with IP, users would have the ability to contact anyone, anyplace in the world, using IP to forward to the cognitive radios, and the systems would be completely interoperable.

This would really reduce the public safety problems encountered with tall buildings or hills that block the radio signals. To assist in overcoming the problems of blocked radio signals, each radio handset is expected to include several gigabytes of memory so it can store all information it may need to relay and complete the transmission.

For voice communications, this system is effective because the DARPA tests demonstrated that using a cognitive radio, push-to-talk voice can be transmitted over three intermediate "hops" before reaching an IP network, while adding less than 100 milliseconds of latency to the transmission.

In addition, the cognitive radio tests demonstrated the ability to form an infrastructureless network automatically and without preplanned spectrum coordination that limits the present LMR based public safety networks. This is critical for the military and public safety during a major disaster.

Marshall said that one of the things they wanted to avoid was having a network fail because of human planning error. He added that the test cognitive network had no planning before it was deployed. All of its planning was based on what the cognitive radio handsets perceives.

Marshall believes DARPA is on track to meet the project goal of developing a cognitive radio by late 2010 that will benefit vendors. Vendors can profitably sell the radio for less than $500, if the vendor is confident the market will buy at least 100,000 units. DARPA is hopeful that public safety entities will adopt the technology, which would increase the size of the market and lead to a decrease in the cost of the equipment.

There are several homebrew SDR systems available including Flexradio for techie types to experiment with the ideas behind cognitive radios. X