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Comcast CEO Shows Off Superfast Modem
Gary writes "Comcast CEO dazzled cable industry audience by showcasing a super quick modem, using a technology called DOCSIS 3.0. It was developed by the cable industry's research arm, Cable Television Laboratories. It bonds together four cable lines but is capable of allowing much more capacity enabling a data download speed of 150 megabits per second, or roughly 25 times faster than today's standard cable modems. 'The new cable technology is crucial because the industry is competing with a speedy new offering called FiOS, a TV and Internet service that Verizon Communications Inc. is selling over a new fiber-optic network. The top speed currently available through FiOS is 50 megabits per second, but the network already is capable of providing 100 mbps, and the fiber lines offer nearly unlimited potential.'"
They're competing with FiOS? The connection promised by every phone company 10 years ago that was never delivered despite being given money by the government to do so? The connection technology just now being rolled out by ONE phone company in a handful of cities?
That's competition?
More information can be found at:a tions30.htmls 30_080706.html0 .html
1. Specifications: http://www.cablemodem.com/specifications/specific
2. Press release: http://www.cablelabs.com/news/pr/2006/06_pr_docsi
3. Ars Technica article: http://arstechnica.com/news.ars/post/20060808-745
instead, multiple upstream or downstream channels are used. The real factor in achieving these speeds depends on what modulation type your cable op decides to configure on the CMTS. In a perfect world everything is 256-QAM/128-QAM, but you will often see 32-QAM implimented because the end to end cabling can't support the rf throughput required for higher bandwidth modulation types. The wiki article on DOCSIS is a good place to start for more information.
The description stating that it "It bonds together four cable lines" is a horrible description of what is likely going on here.
Cable/tv channels are 6 MHz wide. On a typical cable system you can use 256QAM to encode digital data for transmission. In 6 MHz you can get about 39 Mbps. If you bond four channels together (24 MHz) that's 156 Mbps using 256QAM.
So what it sounds like is DOCSIS 3 supports channel bonding or perhaps simply a very wide channel.
The "four cable lines" has nothing to do with how much physical coax comes to your house. On paper an all digital 750 MHz plant could deliver on the order of 4.5 Gbps. But having 70 channels of analog really cuts into that.
They mean 4 channels/frequencies, not 4 cables. 40Mbps over a single channel is normal, so 160Mbps over 4 channels makes sense. Channel bonding is very normal to speed things up, they use it in 802.11n and most newer cellular data transmission protocols. I don't see why this should make slashdot. It is nothing new and nothing revolutionary.
It only takes one man to change the Wisdom of the Crowd to Tyranny of the Masses.
The article description isn't very accurate - when they say "lines", they really mean "channels". Cable modems now operating on a single 6mhz "channel" on the cable line. DOCSIS3 lets the modem "bond" several channels to increase bandwidth. Only one physical cable is still required. This takes away from the # of channels available for TV, but as they move more of the channels off analog to digital (which fit multiple channels in a single 6mhz band) frequency space is being freed.
Just having a faster modem will not result in faster downloads. It is like fixing a huge 150" tap to a 1" pipe. Unless the internet backbone, the servers, the routers, switches, bridges increase their capacities we are not going to see an across the board increase in download and upload speeds. We might see some fast on demand IP based TV solution provided by the ISP and stuff like that. But slashdot.org is probably going to load at the same speed it is currently loading and your email attachments are going to take as much to upload as it is currently taking.
"Be the change you wish to see in the world" - M. K. Gandhi
It is not clear whether the "it" referred to is the modem or the "technology called DOCSIS 3.0". In either case, the quoted information is not true.
DOCSIS 3.0 is a suite of specifications that represents the newest release of the DOCSIS specifications that have been around for nearly a decade now. CableLabs (the usual name for "Cable Television Laboratories, Inc.") managed the process of creating the specs, and performed the actual publication, but the specs themselves were developed in almost entirely by equipment manufacturers, with input from interested (mostly large) cable operators.
Similarly, the modem that was demonstrated was built not by CableLabs but by one of those equipment manufacturers (ARRIS, for whom I work, although I have no direct association with the group that builds the DOCSIS 3.0 modem; I was a contributor to the DOCSIS 3.0 specs).
The complete sleep-inducing suite of specs may be downloaded from www.cablelabs.com.