New DSL technology designed for video, voice

On Monday, the chipmaker announced Uni-DSL, or UDSL, which raises the bandwidth of digital subscriber line technology to the level necessary to deliver high-definition television (HD-TV) signals and other advanced video services, as well as voice and data.

The Uni-DSL technology, which is backward-compatible with standardized variations of DSL, including asynchronous DSL (ADSL) and very high-speed DSL (VDSL), will allow carriers to boost their bandwidth to 200mbps (megabits per second), said Pete Chow, Texas Instruments' chief technology officer for DSL technology.

DSL deployments are growing at a fast pace, as telephone companies struggle to keep up with competition from cable companies. Most DSL customers today use the service to surf the Web rather than to access voice or video applications. But in order for phone companies to compete with cable companies, they will have to offer new higher-speed services that support applications like voice and video over their broadband connections, requiring upgrades to their infrastructure.

The two biggest problems with today's DSL service have to do with distance and speed. The further a subscriber is from the central office where the DSL equipment provides the service, the slower the data rate.

According to the DSL Forum, there are roughly 73.4 million DSL subscribers worldwide. Most of them use ADSL services, which typically offer 8mbps of downstream bandwidth at distances of up to 5 or 6 kilometers.

VDSL, a newer kind of DSL, provides much higher speeds, of up to 52mbps. But it can only transmit signals up to 800 meters, making it useful only in very densely populated areas, such as high-rise apartment buildings. VDSL services are popular in large cities in Asia but are not viable for most markets in the United States.

UDSL provides a middle ground, according to Chow. Because the technology is compatible with both ADSL and VDSL standards, it adheres to requirements of both technologies. For example, at distances greater than 1 kilometer, it provides an ADSL-like service with ADSL data rates. But at shorter distances, it can provide VDSL-like service with data rates that match or exceed VDSL. In some instances, Chow claims, a UDSL service could provide up to 200mbps of bandwidth. This is four times as much bandwidth as is currently available through VDSL services.

UDSL-based equipment will allow operators to deploy a flexible menu of services based on ADSL and VDSL standards using common equipment, Chow said. Today, operators who want to offer both ADSL and VDSL services must buy separate equipment. By allowing ADSL and VDSL services to be deployed from the same networking products, carriers can more affordably offer high-data rate services.

Texas Instruments is working with standards bodies to make this technology standard. It's also working with them to include features from emerging technologies, including VDSL2, into its chip design. Standards for VDSL2, the next generation of VDSL, are still being hammered out by the International Telecommunications Union.

"We'd like our version of the technology to become a standard," Chow said. "And we're working with people developing the VDSL2 standards to make sure that we will support that technology too, when it becomes a standard."

Texas Instruments expects to have samples of these new chips available in the second half of next year. The first generation of products using Texas Instruments' chips will likely be introduced sometime in 2006.