Packet Bonding Gains Key Endorsement

A key Cable Television Laboratories Inc. working group developing the DOCSIS 3.0 specification has selected “packet bonding” as the development path that will allow MSOs to offer high-speed data services of 100 Mbps or more.

With packet bonding, MSOs would control service flows at the cable-modem termination system level.

A competing channel-bonding infrastructure called for service flow control within edge devices.


The decision was good news for certain vendors, such as Motorola and Arris Inc., which are developing pre-Data Over Cable Service Interface Specification 3.0 software that can downloaded to existing DOCSIS 2.0 CMTS units for channel-bonding purposes.

Motorola and Arris also are working on new “channel-bonded” cable modems that would fall under the realm of DOCSIS 3.0.

So-called wideband or channel-bonding techniques have been around for several years. But interest in the technology has picked up momentum in the past six months, as Verizon Communications Inc. began launching high-speed Internet service with up to 30 Mbps of download capacity in its fiber-to-the-premises builds across the country.

Today, a cable operator sets aside one 6-MHz channel for high-speed Internet. With a 256 QAM (quadrature amplitude modulation) system, that 6-Mhz channel can deliver 37.5 Mbps to a node.

High-speed data users share that spectrum, which tops out at a level of 4 Mbps to 5 Mbps per home, set by the operator.

Under channel bonding, an operator would set aside four or even eight or more 6-Mhz slots for HSI service. (As operators move to digital simulcast, plenty of spectrum will be freed up for channel bonding.)


In a four-channel channel bonding situation, the operator effectively combines those channels to create 160 Mbps of throughput. Those 160 Mbps would then to parceled out to a subset of subscribers in a given node.

Marketers would have to determine appropriate pricing and service-level packages: Verizon is currently selling its 30 megabit service for $180 a month.

But in order for subscribers to share channel-bonded bandwidth, operators need DOCSIS 3.0 type CMTS units and cable modems.

The final DOCSIS 3.0 specification is expected to be ready later this year, which would then set off certification waves. But some broadband operators are sending their vendors signals that they intend to rapidly move their attention to channel bonding, due to telco competition.

Given that, Arris is developing pre-DOCSIS-3.0 software for its existing DOCSIS 2.0 CMTS units, which could be downloaded into those legacy units, according to Tom Cloonan, chief technology officer in Arris’s broadband division.

Arris also is working on a pre-DOCSIS 3.0 cable modem, entitled FlexPath, that would support four DOCSIS channels.


Cloonan said Arris is about to go into field trials with several MSOs outside North America for the new pre-DOCSIS-3.0 gear. “Europe and Asia is where wideband channel bonding is being pushed,” Cloonan said.

As for the 3.0 modem, he said, “we have customers who need this, this year.”

Cloonan said U.S. MSOs will likely begin channel bonding trials later this year. Arris expects to have pre-DOCSIS 3.0 modems available in volume by the fourth quarter, he said. “We hope to sell in bulk this year in the worldwide market,” he said.

Cloonan added that speed to market gave packet bonding a big lift in the specification race. The technology will allow MSOs to deploy channel bonding, and thus higher speed services, much quicker, using legacy DOCSIS 2.0 CMTS gear.