VDSL and Vectoring are Important Parts of Broadband Deployment

Next Generation Communications Blog

VDSL and Vectoring are Important Parts of Broadband Deployment

By: Wendy Zajack, Dir. Product Communications, Alcatel-Lucent

From original on Alcatel-Lucent corporate blog

A few months ago our home WiFi slowed to a crawl. At first we thought it was a temporary thing, but after my son ran a diagnostic there was a problem with our high-speed broadband.  

While the technician was fixing it, he mentioned that for an extra $10 a month we could get a faster plan.  Living in the US we already (in my opinion) pay enough for our monthly broadband package so I immediately said ‘no.’ But I told my kids that IF they wanted to pay for it … we would consider it.

A serious discussion ensued. I have three kids – a 14-year old boy, 12-year old girl and 10-year old boy. Their share of the internet service would be roughly an extra $3.33 a month. Doesn’t sound bad to us as adults – but let me put this in perspective in my kids’ economic reality. My children do receive a weekly allowance, but they are poorly paid -- on average a measly $3 a week. Think about that math: my kids actually entertained paying  ¼ of their monthly income to have a better connection speed. That willingness showed how vitally important the broadband connection is to their lives.  My older kids have mobile phones, but for my younger son our household wireline is his communications lifeline. 


In today’s telecom world we spend a lot of time talking about cloud and wireless. But here is an interesting fact: two-thirds of us connect to our broadband world via DSL. So while this is considered a ‘legacy’ technology, it is still very much a part of the bandwidth boosting fabric of our towns. Sixteen years ago, Alcatel-Lucent was first to launch this technology. It was revolutionary at the time to use your home phone line to connect to the Internet at then blazing speeds like 28 or 56kbps.This was based on ADSL (asymmetric digital subscriber line) technology, meaning the download speed was faster than the upload speed. This kept users happy for a while, but as the Internet continued to evolve as a way to distribute all kinds of content users were soon clamoring for more.

The next big improvement came in 2007 with something aptly named VDSL (very high speed DSL). The way that our engineers got to a higher speed was to use more frequency bands; each frequency can carry bits meaning ultimately more bandwidth. This was able to get 40 Mbps, but the distance the data could travel shortened. The reason is based in simple physics where the higher the frequency goes, the shorter the distance the data can travel. One other problem with VDSL was the way telephone lines are typically installed – in big bundles containing hundreds of tightly packed lines. These lines interfere with each other in something called ‘cross talk’, limiting the amount of bandwidth the solution was able to deliver in the ‘real world.’

Then in October 2011, vectoring made the promise of 100 Mbps possible. Developed by Bell Labs, scientists were able to use a ‘noise cancellation’ technique (similar to the way a noise cancelling headphone works) to cancel out the interference.  The concept is simple, but the implementation is more challenging. In a real network you could have competing noise on every line (anywhere from 100, 200 or 400 lines to a bundle) and with usually around 4000 frequencies both upstream and downstream. All of this would have to be done with real time adjustments. It was possible but there was still one small problem. When you moved from the lab into the real world, rolling out vectoring meant updating the entire neighborhood with vectoring software.  As you can imagine this slowed down the roll-out of this technology. If you have to upgrade an entire neighborhood  before you can start serving even a single customer the technology wasn’t instantly appealing.

In order to address this issue, Alcatel-Lucent came up with a technology called “Zero-Touch Vectoring”, which basically automatically turns every legacy customer premise equipment or CPE into a “vectoring friendly” CPE. This allows operators to offer vectoring friendly equipment. They can roll out updates at their own pace, and the most important point: they can start today.

So, the question here is where does all of this leave more highly praised solutions like fiber-to-the-home (FTTH) or even wireless as a home option? At the end of the day, all are completely viable.  There really is no right answer.The best broadband option is going to depend on a combination of existing infrastructure, economic barriers and willingness to wait. As we have seen in the last few years, fiber initially requires a lot of investment and time to add new lines. Wireless also is a possibility, but it may have coverage (or economic) challenges for the end users, especially when you want to match fixed line bandwidths. We know that it is 4 times faster to deploy vectoring than other access solutions. That means more bandwidth to more people – faster. 

I don’t think anyone, anywhere would argue this is a bad thing. Definitely not in my household, where our most prized commodity is bandwidth.  Why? I think it is pretty simple.Today that wire – whether it is fiber, copper or something else – links us to our friends, to our work, and to our lives. That is a powerful connection. So living without it ... is frankly something we just can’t do without.

You can see a great range of our fixed broadband technology next week (October 21-23) at Broadband World Forum at the RAI Exhibition Center in Amsterdam, Hall 11 booth #B10 or to learn more you can check out some of the more technical details here


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