Thanks to the FCC‘s 100 squared plan for 100 million U.S. homes to have affordable access to download speeds of at least 100 Mbps and real upload speeds of at least 50 Mbps there, seems to be some renewed interest in copper. Both Bell Lab and AT&T have announced experiments to extend the useful life of copper infrastructure.
According to Broadband Reports, Bell Labs, Alcatel-Lucent’s research arm has achieved speeds of 800 Mbps using a pair of traditional DSL lines. Reuters says that AT&T is going to trial 80 Mbps DSL this month. Broadband Reports says that Alcatel-Lucent (ALU) achieved the speeds during lab tests by combining three technologies.
First, AlcaLu uses a phantom circuit–a technique developed in 1886 to create virtual analog phone lines. The firm uses a second, supplementary pair of wires to create a third “phantom” channel to supplement the two physical wires common with DSL.
In “phantom mode,” a digital signal is normally transmitted through two wires twisted together–one positive and the other negative. John J. Carty electrical engineer, telephony pioneer, and future president of ATT realized that it is possible to send a third signal on top of four wires separated into two twisted pairs. The negative half of this “phantom” connection is sent down one twisted pair (which is already carrying a conventional signal), and the positive half down is sent down another twisted pair. At the destination, analog processors are used to extract all three signals–two real and one “phantom”–from the two pairs.
The second component is bonding which treats multiple lines as if they were a single cable to increase the speed of DSL broadband connections by a multiple almost equal to the number of cables involved. Finally vectoring is used on the third channel for error correction to cancel noise or “crosstalk” between adjacent copper wire pairs.
Stefaan Vanhastel, Director Product Marketing, Alcatel-Lucent Wireline Networks told Broadband Reports that “by using vectoring, which is a noise-canceling technology to eliminate noise” they can improve the performance of the copper lines. The lab tests showed that the technology is capable of offering 100 Mbps over 1,000 meters (3,820 feet). Alcatel-Lucent doesn’t believe it will roll out the combination technology until after 2011.
Despite the focus on wireless broadband over at AT&T (T) they are trying to push the boundaries of its existing wireline copper plant to deliver broadband services. According to Reuters, beginning this month, AT&T is going to trial 80 Mbps DSL. This will surpass its top 24 Mbps speed. AT&T’s Seth Bloom told Broadband Reports the trial will look at “pair bonding, vectoring, (and) spectrum management,” which “can be done very inexpensively and on a per-user basis.” AT&T’s experiment will be limited by the quality of existing copper facilities and the distance the end-user is from either the CO or the remote terminal (RT) cabinet The U-verse end-user won’t get all that bandwidth because it also has to carry bandwidth-hungry HDTV signals.
An interesting wrinkle in AT&T’s 80 Mbps test is that Alcatel-Lucent, which is demonstrating 300 Mbps supplies the VDSL2 access gear to AT&T but hasn’t yet shipped access gear that can bond VDSL2 because CPE vendors haven’t done so, an official said. “We will have VDSL2 bonding-ready equipment going into production soon, and we will add the bonding software to the equipment once the CPE for VDSL2 bonding is available.” according to ConnectedPlanet.
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Clearly, the incumbent telcos are feeling the pressure from the cablecos DOCSIS 3.0 rollouts. The Alcatel-Lucent 300 Mbps VDSL2 technology should be scooped up by incumbent telcos who need to squeeze a couple more years out of their thousands of miles of copper wireline last mile and keep a hand in the FCC’s 100 Mbps broadband plan.
In the enterprise space, the improved DSL technology may cut into the optical cable business by reducing the long-term cost-effective argument for private fiber. That is of course if you can get the service. All of the “improved DSL” services need more copper pairs, which may not be available. This of course has to be balanced against increasing your exposure to AT&T.
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- Half of U.S. Connections Slower Than 25 Mbps – (dslreports.com)
Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.
