The wideband demo that Comcast Chairman/CEO Brian Roberts conducted in a general session at the NCTA‘s National Show in Las Vegas a week ago won lots of attention.

To recap: Leveraging Arris‘s C4 cable modem termination system (CMTS) and Touchstone Wideband Modem (WBM) 650 to bond four downstream channels, Roberts downloaded a 17 MB commercial from the NCTA in about a second, a 300 MB Comcast commercial in eight seconds, and a 4 GB file containing the 2007 Encyclopedia Britannica and a Merriam-Webster visual dictionary in less than four minutes.

Heightened drama came from contrasting throughputs of about 150 Mbps with that offered by older technologies, such the first-generation cable modem that a younger Roberts tried out at a 1996 cable show, or simple dialup.

Roberts’ demo pushed channel bonding, a key component of DOCSIS 3.0, to the top of trade and consumer press headlines and boosted interest in a related breakfast session sponsored by Texas Instruments (TI) and hosted by Communications Technology on the following morning. (See story here.) How about eight channels? The demo also served as a kind of "atta-boy" to Arris Chairman/CEO Bob Stanzione (Comcast is Arris’ largest customer). But it was not the only wideband show in town.

At the Cisco Systems booth (which this year included Scientific Atlanta) Sonny Chen, product manager for Cisco’s modular DOCSIS 3.0 downstream channel bonding, showed downstream bonded speeds from a Cisco uBR 10000 CMTS of 100 Mbps with a three-channel Scientific-Atlanta modem and more than two and a half times as much throughput with an eight-channel Linksys modem. (See photo above. Chen said that after adding HD video content, the "speedometer" hit 293 Mbps.)

"That is the fastest modem in the world today," Chen said of the Linksys device.

The uBR sported new channel bonding cards that, among other features, allow customers to start bonding in what Chen calls a "mixed mode" – in other words, with both DOCSIS 2.0 and wideband modems.

The Cisco demo also included a DOCSIS Timing Interface (DTI) server and clients from Symmetricom, which linked a video on demand (VOD) edge QAM modulator and the uBR chassis, which Chen said is important within a "mixed mode" deployment.

Given the accelerated timetables discussed in the CT/TI breakfast, it’s not too early to begin thinking about deployment. As for transforming wideband into fully-fledged DOCSIS 3.0, Cisco is planning to submit its equipment for CableLabs certification wave (CW) 56 in October, as are other vendors.

As for where cable operators are going to get these extra channels to bond, that leads back to the bigger question of plant capacity. Operators are clearly planning ahead.

In a separate panel discussion covering much more than DOCSIS, Comcast CTO Tony Werner listed the following potential spectrum win-backs: 16 channels from switched video; 14 from statistical multiplexing and more efficient VOD techniques; 6-7 from analog reclamation; and 3 from sun-setting circuit-switched voice.

Back to data throughputs, is anyone really interested in bonding as many as eight channels? Yes, if they’re interested in IPTV. "That’s something that in Korea and Japan, they’re looking to seriously," said Chen.

"Four channels is really the minimal you’d want to deploy IPTV with," he said.

As for getting channel-bonding and DOCSIS 3.0 kick-started in North America, Chen said that business services will be an early application. – Jonathan Tombes

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