bsoft
join:2004-03-28
Boulder, CO
1 edit | reply to Pashune
Re: Ugh. said by Pashune:I acknowledge they all work differently, but seriously... I almost want to face-palm myself when I see these huge monsters providing "up to" 24 mbps internet. But look at cable? Sure, they've got amps every few hundred feet or so but they're much, much smaller, they can easily be hidden, and on top of that you can get much higher speeds thanks to DOCSIS 3. As far as FiOS goes, I think nothing needs to be said about how wonderful it is. VDSL2 can deliver far better than 24mbps. Qwest for example is delivering 40Mbps today, and it's not infeasible that we could see 100Mbps in the future (VDSL2 can deliver 100Mbps at 500m, although there are some pretty stringent line requirements).
Also consider that DSL is a dedicated line technology from your DSL modem to the DSLAM. Since the DSLAM (VRAD) is usually served by fiber (Ethernet these days), it's easy to deliver more bandwidth there.
The major problem that cable systems will probably have in the future is the sharing of bandwidth. A typical HFC system serves 500 or so subscribers from a single optical node. Even with 100MHz devoted to Internet services (way more than current systems that are typically 24MHz or less), there's only about 1.3Mbps (continuous) per subscriber. DOCSIS 3.0 doesn't really fix this problem either. Cable broadband works today because most subscribers don't use their connections heavily most of the time. The problem is that Internet video could dramatically change that.
Even a single HD stream (at 8Mbps) for (say) 250 of 500 subscribers in a node requires 2Gbps, which is peanuts for fiber today (10G Ethernet is common) but requires 300MHz of bandwidth in a cable system - which is about a third of the total bandwidth of a modern cable system.
Add in multiple streams, higher bit-rates, or more simultaneous users, and it's not impossible for the cable system to simply not have the bandwidth. That's why cable providers are being so aggressive with analog reclamation - every analog channel that's removed delays the need to take more drastic measures to increase capacity. Unfortunately, most of that analog reclamation has gone to HD channels, which require drastically more bandwidth than SD channels. 200 HD channels is roughly 600Mhz which only leaves about 350MHz or so left over for Internet service and other offerings like on demand video.
We have a ways to go before this really becomes a problem, since Internet video is still a small player compared to traditional TV services, and other usage (like file downloads) is generally too sporadic to result in high average bandwidth usage. |
|
|
|
| 300Mbps is one third of total bandwidth in a modern cable system?
That's less than 10 6MHz channels or 60MHz. How did you come up with one third? |
|
patcat88
join:2002-04-05
Jamaica, NY
kudos:1 | said by fifty nine:300Mbps is one third of total bandwidth in a modern cable system? That's less than 10 6MHz channels or 60MHz. How did you come up with one third? (870mhz/6)*38[qam256]=5.5gbps |
|
bsoft
join:2004-03-28
Boulder, CO | reply to fifty nine
said by fifty nine:300Mbps is one third of total bandwidth in a modern cable system? That's less than 10 6MHz channels or 60MHz. How did you come up with one third? I actually meant 300MHz, not 300Mbps. |
|
