Cable Operators

Cisco Pushes DOCSIS 3.0 Past 1.5 Gig

3/17/2011 4:44 PM Eastern

Cisco Systems has shown DOCSIS 3.0 zipping over the 1.5 Gigabit per second mark, demonstrating a 48-channel downstream connection delivering nearly 1.6 Gbps over three cable modems at the recent CableLabs Winter Conference.

The equipment vendor used its uBR10012 cable modem termination system with the high-density "3G60" modular CMTS line card, which supports 72 downstream and 60 upstream channels, in the demo. Cisco used prototypes of three 16x4 cable modems (16 channels down, 4 channels up) with Broadcom's dual-chip silicon.

Using IP-based bonding at the headend, the setup delivered "just shy of 1.6 Gbps" down and around 300 Mbps up, said John Chapman, Cisco fellow and chief technology officer of the company's Access Transport and Technology Group. Cisco used 256-QAM modulation in the downstream and 64-QAM in the upstream.

"What we were going for was bolstering everybody's confidence in what we can do with DOCSIS," Chapman said. "There's a lack of proven test cases about how high DOCSIS can scale. So we wanted to simulate what a high-density solution would look like."

Cable operators have shown DOCSIS 3.0 breaking the 1 Gbps barrier in field trials. Germany's Kabel Deutschland, for example, last fall touted a download speed of 1.17 Gbps in a test conducted in Hamburg with Cisco gear.

Chapman cautioned that the Broadcom-based modems used in the demo are not available commercially, and could be a year away from hitting the market. However, he said, the test showed that bonding together dozens of channels is certainly achievable and dependent on the availability of high-capacity silicon on the modem side.

"From our perspective, if somebody put a service group together with 72 channels, by golly we could bond it," he said. "We think that modem [with 72 downstream channels] is possible to build."

Continued Chapman, "I think we'll see the day before I retire when we'll see full-spectrum DOCSIS... But it's beyond what anybody could justify today."

Also at the CableLabs Winter Conference, held Feb. 27 to March 2 in Atlanta, Cox Communications claimed to have set the world record for the fastest upstream cable transmission, showing off a 400 Mbps link using Motorola Mobility DOCSIS 3.0 equipment. Cox and Motorola demonstrated the 400 Mbps connection over 12 channels, in a 5-85 MHz return path, using Motorola's RX48 return path receiver module in a BSR 64000 DOCSIS 3.0 CMTS edge router.


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