Cable Tech

Comcast Ready to Reclaim Bandwidth

DENVER -- Comcast Corp. (Nasdaq: CMCSA, CMCSK) can reclaim roughly 240 MHz of spectrum, equivalent to about 40 channels, by using switched digital video, a new compression scheme, and other bandwidth-boosting techniques, its CTO said here today.

Comcast executive vice president and chief technology officer Tony Werner discussed those options at The Cable Center , site of the 2007 Women in Cable Telecommunications Rocky Mountain and Communications Technology Professionals (CTP) "Tech It Out" conference. [Ed. note: He's one of the latter, we assume.]

Werner says Comcast has started testing the "improved" compression scheme and plans to roll it "across the board" sometime next year. He did not dive into the technical specifics of the compression plan nor note any specific vendor partners, but he said it will improve bandwidth efficiency by 50 percent without affecting video quality.

Just as important, it will work with the MSO's massive base of MPEG-2 set-tops, Werner said. At the end of the second quarter, Comcast had 14 million digital video subs, all served by MPEG-2-based set-tops.

Comcast is also working on an "open" Residential Network Gateway (RNG) project that will include two set-top models -- the RNG 200 and the RNG 1000 -- that will also support MPEG-4. (See Intel Goes Inside Cable... Again.)

A more efficient video bit rate will come in handy as Comcast looks to make room for more broadcast high-definition video, video-on-demand, and spare 6 MHz channels for Docsis 3.0, a next-gen CableLabs spec that will push shared speeds beyond 100 Mbit/s. Werner reiterated that Comcast is trialing Docsis 3.0 "as we speak." (See Comcast Preps Docsis 3.0 Trials.)

Comcast has already placed purchase orders for 3.0 gear and expects to introduce it to a "substantive portion of our footprint" in 2008, he said.

In addition to faster speeds, Werner also talked up Docsis 3.0's support of IPv6, noting that Comcast will need a deeper pool of addresses to keep pace with the deployment of set-tops with IP capabilities. Another IP address magnet is an emerging market of "early adopter entertainment" users, who might have 30 or more devices hooked to the Internet at any given time. The IPv4 address pool will be exhausted by 2009 or 2010, Werner predicted.

Comcast, he said, has about 10 million IP-enabled devices hanging off its networks today. Werner expects that number to double next year, and triple in 2009.

Back to the bandwidth issue, Comcast, Werner pointed out, is also testing SDV, another bandwidth-saving technique that only delivers broadcast channels in a "switched" tier when customers in a given service group select them. Comcast has already identified Denver and Cherry Hill, N.J., as its early tech trial markets. (See Comcast Reveals SDV Test Beds, Comcast Puts SDV Vendors to the Test, and Comcast Taps Arris for Edge QAM Initiative .)

Werner, citing some system data, said Comcast can reclaim about 16 MHz (four channels) using SDV.

In addition to better compression, SDV, and analog reclamation, Werner said Comcast has three or four other bandwidth-boosting "mechanisms" at its disposal. He did not name it, but outright bandwidth expansion -- beyond 750 MHz or 860 MHz, in some cases -- could be one of the tools under consideration. Vendors such as Scientific Atlanta , Aurora Networks Inc. , and C-COR Corp. (Nasdaq: CCBL) are pushing 1 GHz systems. Vyyo Inc. (Nasdaq: VYYO), meanwhile, is hawking a 3 GHz overlay that expands both downstream and upstream spectrum.

In August, Vyyo revealed that Comcast and Charter Communications Inc. have been conducting tests on the vendor's UltraBand platform. (See Vyyo Gets Foot in Door at Comcast, Charter .)

— Jeff Baumgartner, Site Editor, Cable Digital News

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