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

KDDI offers a symmetric 1Gbps service for around £40 a month, but it only has limited availability. The news of a 160Mbps connection seems somewhat dull in contrast, but this was picked up due to the service using DOCSIS 3.0 which is the technology Virgin Media is using for its 50Mbps product. Virgin Media has hinted that it can increase speeds, but for this to happen the remaining analogue TV channels will need to be switched off to allow for bonding.

Speeds of 1Gbps into the home while sounding exciting bring other issues. Sharing this between multiple computers can be fun as home routers have trouble coping with 50Mbps connections sometimes and Gigabit network connections on computers are still far from standard. If you use a wireless connection you will also be limited by the speed of this before that of your broadband service. There is also the issue of whether people will ever actually get data at speeds of 1Gbps. Many websites are still hosting on 100Mbps links in datacentres, though the most likely bottleneck will be where 100’s or 1000’s of 1Gbps connections aggregate onto the backhaul network.

For those bemoaning the price of the Virgin Media XXL product at £36 to £50 a month, they can afford to charge a premium price in the UK as they have little competition at this speed point. Hopefully in two years with competition increasing as FTTC appears ,the pricing may be more competitive. Lower pricing is a double edged sword though, as the usual way to lower pricing is to increase contention or introduce other limits.

source: thinkbroadband.com