Cable operators around the world have vetted and deployed channel bonding in pre-standard form for several years. European MSOs announced accelerated EuroDOCSIS 3.0 rollouts in September, around the IBC show.

Last week, Comcast announced its shift from trial and limited deployment in the Twin Cities to full-scale activation of DOCSIS 3.0 in multiple markets. (See here.)

This comes close to a prediction that Comcast CTO Tony Werner slipped into a speech in late 2007 about deploying only 3.0 equipment by mid-2008. (See here.) What else lies ahead?

For a well-framed answer to the DOCSIS migration path question within a five-year scenario, see this article from late 2007 by Comcast Principal Engineer Saifur Rahman.

As for what lies behind a DOCSIS 3.0 rollout in terms of preparation, what follows are a few pertinent excerpts from a paper presented at last summer’s Cable-Tec Expo by MidContinent Communications Senior Engineer David Haigh.
DOCSIS 3.0 checklist RF bandwidth expansion
• Digital simulcast
• Digital-only
• 860 MHz or 1 GHz
• Use previously unusable channels
• Move test carriers to alternate frequencies

Headend preparation
• Additional powering
• Increased backbone capacity
• Flexible combining system
• One laser per node
• Tidy up and track headend wiring
• Additional rack space

Test equipment
• DOCSIS 3.0 test meter
• 64-QAM signal source
• Digital spectrum analyzer

Plant qualification
• Downstream 256-QAM testing and qualification
• Upstream 64-QAM testing and qualification
• Avoid frequencies near the rolloff or band edges
• Avoid frequencies susceptible to ingress or interference
• Headend RF alignment
• Beta testing

64-QAM challenges
• Avoid Fabry-Perot (F-P) analog lasers
• Use the 18-33 MHz portion of the upstream first
• Control ingress, noise, CPD and laser clipping
• Make sure that modem and EMTA firmware support TDMA and S-CDMA
• Avoid high-value taps that may cause modems to transmit beyond DOCSIS 3.0 specifications
• Use tri-shield or quad-shield drops
• Upgrade or purchase new test equipment if necessary

Preventive maintenance
• Amplifier sweeps every 12-18 months
• End-of-line digital testing (MER, BER, constellation, etc.)
• Power supply testing
• Leakage less than 5 µV/m
• Return path monitoring
• Daily reports

Target areas for initial rollout
• Locations where bandwidth capacity is initiating node splits
• Customers who demand higher speeds, such as colleges, business parks, malls and multiple dwelling units (MDUs)
• Areas where a competitor is offering higher tiers of services
• New nodes and customers on micro-nodes

– CT

Read more news and analysis on Communications Technology‘s Web site at

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