DOCSIS 3.0 (sometimes DOCSIS 3) is a standard developed by CableLabs to upgrade Hybrid Fiber Coax (HFC) networks to deliver high bandwidth broadband Internet service. It is used by MSOs (cable TV companies) to compete against Telcos using FTTH and FTTN/FTTC with VDSL2. DOCSIS 3 is estimated to cost approximately $70 per subscriber in addition to the cost of a new DOCSIS 3 compliant cable modem required on the subscriber premises, which is inline with the cost of installing DSL in an existing OutSide Plant (OSP) cabinet. What DOCSIS avoids is drastic upgrades to an HFC network, and this is its fundamental appeal. Cable companies can deliver very high Internet access bandwidth for very little additional investment with the various DOCSIS standards, especially DOCSIS 3.
The most important thing about DOCSIS 3.0 is bonding cable TV channels for more bandwidth. Previous versions of DOCSIS only used a single channel and were limited in their throughput. With 4 channels, rates of about 160/120Mbps are possible. With 8 channels, rates of 320/120Mbps are possible. Of course, the cable companies with have to give up these analog video channels to devote them to DOCSIS 3.0, but this can be done incrementally, and it does not have to be done throughout the network all at once.
The equipment required to deliver DOCSIS 3.0 services is the Cable Modem Termination System (CMTS) and the DOCSIS 3.0 cable modems on each subscriber premises. Both must be upgraded to support DOCSIS 3.0 over an existing HFC network, shown below before an upgrade. Note that the HFC network is unchanged with the upgrade to DOCSIS 3.0. The only change is in equipment that is installed in the headend and on the subscriber premises.
Source: fttxtra
Comcast can now put another point in its DOCSIS 3.0 upgrade wins column. The MSO announced this week that it completed its DOCSIS 3.0 upgrade in its greater Chicago area market, including Northwest Indiana. In July, Comcast reported it had upgraded about 50 percent of its nationwide HFC network to DOCSIS 3.0, and it remains confident it will pass 80 percent of its total homes and businesses with DOCSIS 3.0 by the end of 2009. This projection is up from the initial 65 percent target Comcast set in February.
And it appears that Comcast is well on the path of achieving its 80 percent penetration goal. The MSO’s DOCSIS 3.0-based service is currently available in 11 U.S. cities, including: Atlanta, Baltimore, Boston, parts of Connecticut, Fort Wayne, parts of New Jersey, Philadelphia, Pittsburgh, Portland, the Twin Cities and Seattle. Subscribers can choose from two DOCSIS 3.0 service sets.
Cable’s DOCSIS 3.0 race is certainly on. Comcast’s fellow cable brothers Cox Communications, Canadian operator Rogers and the U.K.’s Virgin Media have been making DOCSIS 3.0 waves lately. Similar to Comcast, Cox has also taken a tactical approach to its DOCSIS 3.0 rollouts by launching its wideband service in not only Verizon’s FiOS territories (Fairfax County, Virginia and Rhode Island), but more recently Qwest’s FTTN territories in Phoenix. Meanwhile, Rogers launched its wideband service in parts of Toronto last week.
Of course, DOCSIS 3.0 is not just a large MSO’s game. With its conversion to all-digital video complete in its major metro markets, competitive cable operator RCN said it will begin rolling out DOCSIS 3.0-based services initially in its New York and Boston markets this fall.
source: fiercetelecom
Telstra has been quick to respond to criticism of the capabilities of DOCSIS 3.0, and HFC networks in general, with a blog post on Nowwearetalking from its CTO, Hugh Bradlow.
Bradlow was particularly upset about accusations from Optus’ government relations chief, Maha Krishnapillai, who was reported to have described Telstra’s upgrade was a poor second choice because it was a ‘shared network’, and therefore slowed down as the number of users increased.
Well if this is so, given all that Telstra has said about the need for and benefits of widespread high speed broadband one has to ask why it is dipping its toe into the water with DOCSIS 3.0 announcing only a Melbourne rollout when, on a simple extrapolation of the $300m cost, it could have 2.5m households in major cities able to access the network for about $700 and probably finish the job my mid 2010.
You can read Bradlow’s full rap on the wonders of DOCSIS 3.0 on Nowwearetalking. According to Bradlow, it stacks up very favourably against FTTN. “When we say that Telstra’s upgraded cable network will deliver up to 100Mbps downstream speeds, we mean it. Even in peak periods, the cable network will deliver 70 – 100Mbps burst downstream speeds, – a higher peak speed, in fact, than FTTN would offer.”
Dermot Cox of C-COR Broadband – the main supplier of HFC gear to Telstra – made a submission to the Senate enquiry into the NBN. He had the hubris to claim that “The next wave of technology development will be driven by the world’s leading cable operators to meet customers’ increasing demand for more bandwidth and video-centric applications like IPTV, interactive video, distance education and video telephony. Not once did he mention that the capacity of DOCSIS 3.0 is shared between all users on a co-ax cable.
True, but it’s a fact that cable people seem particularly reluctant to discuss. I’d asked Telstra’s GMD Networks and Services, Michael Rocca the day of Telstra’s announcement how many users in Telstra’s Melbourne HFC network typically shared a single run of coax and if Telstra intended to reduce this number as part of the upgrade. I had great difficulty in getting him to answer the question, and he never did give me a number but did say that about 100 addition nodes would be rolled out as part of the DOCSIS 3.0 upgrade. According to Bradlow, the number of users per node in HFC networks is “typically 150″ (but he did not suggest that this applied to Telstra’s network).
source: itwire.com