Very High Bit Rate DSL 2 (VDSL2), a new standard is likely to be ratified by next week, making it possible for carriers to provide upto 100 megabits per second connections (both up and down) over copper lines. VDSL2 standard has been under review with the International Telecommunications Union for sometime now, and the decision on the standard could come early next week.
VDSL2 is really really fast. How fast? According to Ikanos estimates, it takes an “ADSL network more than 45 minutes to transmit up to 50 high-resolution photos at 3 Mb per photo. Sending the same number of photos can take less than a minute over VDSL/VDSL2 networks.”
VDSL, though once thought of as a good solution for bringing more bandwidth to the home has lagged because of its lack of reach. It has become popular in the overseas markets because densely populated countries like China and Korea have central offices that are much closer to consumer premises. VDSL2 standard, which uses about 30 MHz of spectrum (versus 12 MHz in VDSL) allows more data to be sent at higher speeds and over longer distances. BellSouth and SBC have plans to use super-fast DSL to connect their fiber nodes to consumer homes. Qwest for instance has about 40,000 customers who are using VDSL technologies.
But eventually if they want to offer true triple play with high-definition streams, they will eventually have to migrate to VDSL2 technology which can handle three HDTV streams with relative ease. (Three HD streams at the very least because at present average American home has 3.1 televisions.) Of course there is that whole issue of US homes being too far from the Central office. The good news is that VDSL2 is going to be backward compatible with ADSL, ADSL2 and VDSL.
Here is a little comparison of more recent flavors of DSL
- ADSL has speeds up to 8 Mbps downstream and 1 Mbps upstream. Can be deployed from Central office and has a range of 15,000 feet and longer.
- ADSL2+ has a maximum speed of 25 Mbps downstream and 1 Mbps upstream. Can be deployed from Central office and has a range of 15,000 feet and longer
- VDSL , some chipsets that use the optional spectrum of 30 MHz can do 100 Mbps downstream and 50 Mbps upstream. Current carriers include NTT, KDDI, Korea Telecom, and Softbank BB of Japan. Has a range of about 5,000 feet
- VDSL2 has speeds of 100 Mbps downstream and 100 Mbps upstream. Has a range of about 12000
VDSL2 is expected to be a fiercely contested market place, with early leader Ikanos like to fend off challengers like Infineon, which is expected to announce new VDSL2 chipsets at SuperComm trade show. Other players competing for the VDSL2 pie could include Broadcom, TI, and existing VDSL chip maker, Metalink. Santa Clara-based Electriphy is another recent entrant in the VDSL space.
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Why is Verizon so bent on FTTH then? I’m not sure I understand. This must be a significantly cheaper alternative.
OM,
An otherwise excellent post could have used more clarification on the number of physical copper pairs required to attain the speeds over VDSL2 for the distance indicated. Granted, to do so might become too cumbersome to depict in a blog message, given the gradations that exist with respect to the number of pairs needed at various speeds versus a distance scale. But still, IMO, some mention of this characteristic should have been included.
While some of the results that you’ve noted are truly remarkable, I note a gross lopsidedness between up and down speeds for most versions of xdsl shown. Such asymmetric bahavior is well suited to the service providers who are also providing content in their vertical services bundles, but at the same time this serves to ensure that consumers will forever remain, well… consumers of data, rather than allowing them to become producers of it, as well, fwiw.
Frank Coluccio
Frank
good point. i think it is more than one twisted pair for now. I am sorry I did not include this. Apparently this is not going to be a big issue because most US homes have more than two phone lines coming in by default. Call it the legacy of the Bell system, redundant fax lines and the now unused DSL lines.
OM, agreed. With all of the lines that have been disconnected due to the shift to cellular and email, I’m sure there’ll be plenty of copper available out there for everyone!
Keeping on the same subject, what do you think about the RBOCs, in particular, Verizon, disconnecting and then tearing out entirely the copper lines that once went to homes where they have insalled its Fios service?
Please, please don’t fall into the up to trap! As all flavors of xDSL, VDSL2 speeds fall off with distance. Thus we are unlikely to seee 50+ Mbps speeds above 2000 feet, which is way to little to feed the 95% of home within 6000 feet of the node. Even with VDLS2 telcos are going to need deep fiber to compete with cable or even think of offering HDTV. Futhermore why bother with inaccurate statements about xDSL performance when a single picture will tell more than a thousand words.
http://www.convergedigest.com/blueprints/ttp03/images/2005/ti-fig4.gif
well this is information that is coming from the documents etc filed for the standards, of course the real life performance is still something else. 6000 feet is still not bad – nearly a mile from the central office, it can be quite helpful in the dense locations like houston or chicago
Given that it’s possible to bond multiple ADSL connections, it’s not fair to compare single-pair ADSL against N-pair VDSL.
If you want symmetric connectivity, look to Ethernet in the First Mile Copper instead of DSL.
Om, as per Zed’s post, there is an inverse relationship between the loop length and the bandwidth. Moreover, I say that for future proofing purposes, 19 Mbps is the minimum. Take the fact that more than 50% of SBC’s loop lengths are over 10 kilofeet, and that still means that FTTN with ADSL2+/VDSL, etc. (i.e. a last-mile copper solution) is not the final solution. It’s the “go after the low hanging fruit” solution.
The idea behind whether you go with FTTP or xDSL is about whether you want to pay now or later. Eventually demmand will be so great that you will be forced to use fiber everywhere but dense urban areas (where distance from the CO will always be small). I think Verizon decided that they had the money to do it now and would thus be ready to respond to future needs on short notice. Carriers going the DSL route run the risk of finding they can’t afford to go all fiber, when the time comes.
While this article is interesting, clicking on ‘Electiphy’ which is supposed to be a vdsl company gives pictures of graphic pornography!! Oh is that what the VD stands for??? I think that this should be removed and I do not appreciate having porno on my computer through deception.
You should check your articles for this kind of spam!!!
Your writer no longer has any credibility.
Pair bonding + vdsl2 will allow for loop lengths of 1600 feet + with sufficient bandwidth to support a minimum of 1 hd 3 sd streams. This is and will be the final solution.