Waste not
A true broadband wireless system will demand much more efficient use of radio spectrum than any existing approach.
Marty Cooper, ArrayComm

For example, consider a wireless MP3 player that can download a 5-minute song in 20 seconds, or a real-time multiplayer-capable GameBoy-like device. Applications like these demand always-on connections, broadband data rates, and the freedom to move.

Unfortunately, no wireless service today offers anywhere near that much bandwidth. Even highly touted future services such as third-generation cellular don't come close. Realistically, 3G won't deliver data rates above 100 kbits/sec/subscriber. And if today's oversubscribed services are any indication, rates could be much lower. The MP3 application described above would require burst rates of 1 Mbit/sec/subscriber. The 3G hype suggests rates as high as 2 Mbits/sec, but that refers to a raw data pipe that's shared by all users connected in a cell to a single 10-MHz radio channel.

Cellular and PCS are fundamentally voice-centric systems that are being tortuously adapted to data communications. A true broadband wireless system will demand much more efficient use of the radio spectrum than any existing approach.

This battle for spectral efficiently isn't new. In 1901, the first transatlantic transmission blanketed an area of millions of square miles and sent a pitifully small amount of information. In fact, that technology could have accommodated only about six separate "conversations" on the entire surface of the earth. Today's technology allows us to accommodate about 100 million conversations in the same area.

If we include all of the factors that improve spectral efficiency (that is, the number of conversations—voice, data, or a combination—that can theoretically be conducted in all the useful spectrum in a given area), we find that the number has increased a trillion times in 100 years. Put another way, our ability to use the radio spectrum for personal communication has doubled every two and a half years for the past 104 years. I modestly refer to this observation as "Cooper's Law."

These gains have come from modulation improvements and channel-division schemes, but we've tapped most of the advances possible from such techniques. While most of our historical gains have come from reusing spectrum, virtually all future gains will result from more geographic reuse—spatial division.

Rather than broadcasting a signal in all directions and wasting most of that signal energy, we can direct a "cloud" of RF energy to a specific person or device. The ultimate promise is the ability to deliver the entire spectrum to each individual.

Just a pipe dream? ArrayComm's spatial technology is now deployed in some 30,000 base stations serving millions of subscribers. ArrayComm has developed

i-BURST, a wireless broadband system that uses this technology, and will begin a commercial trial next year in San Diego. You'll see spatial technology in 3G systems as well.

Author information

Marty Cooper is Chairman and CEO of ArrayComm.