For the techies:
Currently standard DOCSIS build networks built to US standards offer the frequency band between 5 and 42MHz for upstream traffic.
This band supports the PPV, interactive, return traffic for VOD, etc, etc.
This band is noisy due to 'beats' or harmonic 'reflections' of various things, from power cables to baby monitors to street lights, which means some of it is unusable.
After all of that garbage you're going to have perhaps 20MHz which is usable, and the most advanced and efficient system in use at the moment offers 4 bits per Hz or a total of 80Mbit per network area of which 25% goes byebye due to overheads. There are more efficient systems however these require cleaner quality networks, and also place a greater strain on the lasers carrying the upstream traffic as the higher up you go with the modulation the more load it imparts on the lasers, that's not including the extra load from carrying multiple signals simultaneously.
Downstream wise presently the standard 'Service Control Group' for a cable modem card which presently supports a maximum bandwidth on the Telewest platform of 38Mbps will be around 600 cable modems, 100 cable modems per 3.2MHz 4.8/9.6Mbit upstream.
To supply these guys with 100Mbit will in theory maintaining present contention require 60 modems per 38Mbps equivalent service control group, 10 downstreams serving each 600 homes taking service.
Of course it's easy, honest guv, especially when BT, Bulldog etc have had accessible ADSL2+ kit for a couple of years.
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Originally Posted by Chrysalis
docsis3 if I am right also requires customers cable modems replacing.
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Yep every customer taking a service requiring DOCSIS 3 would require a modem swap.