Software on tap to ease cell congestion

AT&T Wireless Chief Technology Officer Rob Nelson said at the CTIA Wireless 2002 trade show here that the company will use the software, known as AMR, to help find paths for voice calls through areas of overworked spectrum.

The software will be installed on the new network that AT&T Wireless began building last year, which uses the cell phone standard known as GSM(Global System for Mobile Communications). The handsets that contain AMR will be available by the end of the year, Nelson said, and will be manufactured by most of the leading handset suppliers the carrier uses.

"We don't have a lot of GSM customers at the moment, but we're preparing for it now," Nelson said at the show, which is being hosted by Washington-based lobbyist group Cellular Telecommunications & Internet Association.

European carriers have been using the AMR software for about 6 months. And although phones containing the software are few and far between at this point, the technology is expected to grow.

Congestion is a call killer. If a network is crowded with calls, like it was in the hours after the Sept. 11 terrorist attacks, it literally comes to a standstill with no calls going through.

One of the problems has to do with a piece of the cell phone called a "vocoder," which translates voices into digital signals to send over a cellular network. It also translates the digital pulses back into voices once the call reaches the cell phone.

Vocoders send and receive information at 12kbps, a rate that never varies. Comparatively, the new software lets a vocoder vary the speeds.

Sometimes a faster speed is needed to fight through an area filled with base stations sending out competing signals, for instance, Nelson said. The vocoders sense the conditions themselves and make the adjustments automatically.

AMR is in the small family of software that tries to help carriers address capacity problems. It has also gotten some positive feedback from some industry analysts, with Gartner's Bryan Prohm calling it "a big deal."

"Every carrier is going to use it," he said.

However, other techniques are being used to battle network congestion. For instance, Verizon Wireless is using a technique known as "compression," which shrinks the size of a file to help speed its route through the new, next generation network it launched in January.

AT&T Wireless also plans to attack capacity problems by borrowing a technique made famous by Qualcomm, which holds most of the patents for a cell phone standard known as CDMA (code division multiple access), Nelson said. Cell phone calls on some phone networks not using CDMA travel along one path, never varying.

AT&T Wireless plans to adopt "frequency hopping," which will vary the paths the signals take on its way to a cell phone. The signal is then spread around, cutting down on possible interference issues, he said.