CableLabs chooses Broadcom, GIPS codecs for PacketCable systems

WAYNE, N.J. — CableLabs confirmed Tuesday (Aug. 2) that it has chosen Broadcom Corp. and Global IP Sound (GIPS) to provide royalty-free voice codecs for future PacketCable 1.1 and 1.0 embedded multimedia terminal adapters (EMTAs) and media gateways.

CableLabs' PacketCable specification serves as the de-facto standard for delivering voice-over-IP (VoIP) services over a cable modem link. However, when defining the specification, CableLabs left the codecs as an optional part of the specification.

"CableLabs left the codecs as an optional part of the specification," said John Gleiter, director of business development at Broadcom. "They left it up to the operators to choose the codec scheme."

But, the optional nature of the codecs left operators and equipment vendors wondering what codec to implement and created potential interoperability issues. It also forced chip vendors to support multiple codec schemes, which Gleiter said added processing complexity to a VoIP design.

To solve this issue and eliminate carrier confusion, CableLabs issued a request for proposal in early 2003 for a new codec option. After more than a year of work, CableLabs has tapped low-bit-rate codec schemes from both Broadcom and GIPS.

On the Broadcom side, CableLabs has selected the BroadVoice16 16-bit narrowband codec that supports a frame rate down to 5 ms, which Broadcom uses for the development of its VoIP processors. On the GIPS front, CableLabs has tapped the iLBC codec, a 15-kbit codec with a 20-ms frame rate.

The benefits of the codecs chosen are three fold. First, the codecs chosen bring more efficiency than existing codecs, like G.711 andG.729, to PacketCable designs, according to Gary Hermansen, president and CEO of Global IP Sound. "The new codecs allow you to handle more calls," Hermansen said.

Second, the new codec approach will enable easier interoperability between cable networks. "The new specification eliminates interoperability issues between carriers," Gleiter said.

One of the reasons that interoperability becomes less of an issue is because CableLabs has mandated that both codecs be supported in media gateway designs as well as in EMTAs residing in the customer premise. "This is not an optional requirement," Gleiter said. "EMTA and media gateway designers have to support both codecs."

The final benefit of the revised PacketCable specs comes come on the processing side. By having only two codecs to support, Gleiter said that designers can deliver more optimized solutions to the market. "Now chip designers can optimize their VoIP designs," Gleiter said

The codecs will be offered through CableLabs through a royalty-free license. PacketCable systems must support the codecs from April 2005 and beyond.