Quote:
Originally Posted by General Maximus
it is a shame Igni isn't around to provide more info, I haven't seen him in ages.
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This had better be really good. What's up General?
---------- Post added at 13:42 ---------- Previous post was at 13:14 ----------
Quote:
Originally Posted by Sephiroth
Incidentally, if one channel is on 16QAM then that will drag the overall upstream capacity down. 16QAM has 4 bits per symbol & 64QAM has 6 bits per symbol. But because a data packet is split across all the upstream channels, it can only be reassembled at the bit density rate of the slowest channel.
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A packet will almost always go on a single channel. Remember that the modem receives its grants in 2 or 4 ms increments, the CMTS scheduler tries to service each request on a single upstream, and what the minimum and maximum burst sizes are.
---------- Post added at 13:48 ---------- Previous post was at 13:42 ----------
So there is a programme to get all areas up to 4 upstreams, targeting 64QAM but obviously the modulations will respond to SNR drops on the channels.
Getting 4 upstreams at 64QAM requires either
DFB lasers in the nodes or digitised return paths. In some areas nodes and amplifiers need replacing.
There are also issues in hubsites with regards to space and power. There are some areas where it took some quite extreme measures to get new CMTS in, or they haven't been installed yet and area awaiting those extreme measures. These will not have any space for new optics so will need some equipment and intelligence moved out into the field via
Remote PHY and other options in the
Distributed CCAP deployments.
It is possible to cram 4 upstreams into a 42MHz network but tricky, and areas that have this limitation have run out of downstream bandwidth anyway. There's also the problem of the legacy set top boxes and modems that need to be gotten rid of.
There are no plans to get all tiers onto 10:1 ratios, but some of them it's certainly doable.
Once areas are onto 24 downstream channels that's the end of the upgrades on that score. 4 upstream channels is not necessarily the end-game there.
DOCSIS 3.1 rollout will not be using 3.1 upstreams initially, it will use the same upstreams as the 3.0 network. This is not unusual, I'm not aware of any 3.1 deployments in the USA and Canada, where they are ahead of us, that are using 3.1 upstreams.
Business are likely to get higher speeds somewhat before residential.