Data Flow Faster to Cars

As drivers and passengers expect more and more infotainment data in a vehicle, the challenge for information providers is to get this data to the vehicle efficiently. XM Satellite Radio and Honda Motor Co. are backing a communications technique that can reliably deliver maps, radio shows, movies, and other material to cars in far less time than existing broadcasts.

XM Radio (Washington, DC) just announced that it will use technology developed by Digital Fountain, while Honda recently was part of a $5 million capital investment for the six-year-old Fremont, CA, company (http://rbi.ims.ca/3850-511)

Next year, XM plans to begin using Digital Fountain's communication scheme to send navigation map and software updates, book-of-the-month selections, music videos, and other material to its subscribers. "It will be ubiquitous on XM receivers that have large memories, either hard drives or flash memory," says Neil Eastman, senior vice president for advanced applications at XM (http://rbi.ims.ca/3850-512). Disk drives can be used to store favorite shows, much like a Tivo stores TV programs, he adds.

The Digital Fountain scheme reduces the broadcasting time needed to get this material to cars, which often operate for short periods of time and may not receive data for hours or even days. It might take more than seven days to reach all vehicles using a revolving carousel technique now employed, while sending the same data via the Digital Fountain scheme takes less than one day.

The scheme splits data into so-called meta-content packets, which provide a mathematical recipe for the original data. "It's like simultaneous linear equations. If you have three simultaneous equations with three variables, you can choose any three of four to get the variables," says Charlie Oppenheimer, CEO at Digital Fountain.

These packets are transmitted for about the same time it takes to broadcast the original material. These transmissions can be spread out to accommodate the different times a car is driven.

"Using the Digital Fountain technology, all concerns about these disparate duty cycles disappear," Eastman says. Every car that is on and receiving data for a specified cumulative amount of time is guaranteed to receive the file.

Though automotive is a key target, the technology is also being used by corporations and the U.S. military. "The Jessica Lynch rescue was supported by data we helped move into the battlefield," says Oppenheimer.

Convert, Transmit: Digital Fountain converts broadcast data into meta-content packets that precisely describe the data, which are transmitted to targets that can decode them, all in about the same time it takes to broadcast the original material.

Quick Time: Only a few meta-content packets need to be received to build a complete data file, so transmission time is far shorter than those using carousels to repeatedly send files.