What is vectoring technology?

01 March 2012 |


Vectoring technology has emerged as a means of increasing broadband speeds without investing in an extensive fibre roll-out.

The technology uses noise cancellation, in a similar way to noise-cancelling headphones, to increase data speeds on existing copper infrastructure.

How exactly does vectoring technology work?

According to research from Alcatel-Lucent, vectoring technology works by addressing the gap between theoretical maximum speeds and the speeds that service providers can deliver in typical field conditions.

The company’s xDSL strategist for fixed access, Paul Spruyt, and marketing director for wireline fixed access, Dr Stefaan Vanhastel, identify crosstalk as one of the reasons that the highest theoretical download speeds cannot be achieved on copper infrastructure. Crosstalk is where cables that are bundled closely together interfere with each other. The more cables bundled together, the more crosstalk that is generated. Vectoring technology continually measures the crosstalk from all other lines in a bundle and works to remove it by generating anti-phase signals to cancel out the crosstalk signals. This results in almost no noise on a line.

To calculate crosstalk, vectoring technology measures and cancels interference across hundreds of lines over the full frequency spectrum they occupy. The interference is processed by subdividing the spectrum into narrow frequency bands, known as tones, and processing each tone independently. All copper lines deploying vectoring technology are processed simultaneously and the results are used in real time to develop anti-phase compensation signals for each line, based on the actual signals transmitted on other lines in the bundle. This calculation is extremely complex, which is why vectoring only emerged as a viable option for providers with recent advances in silicon technology.

Which equipment vendors are developing vectoring products?

Ovum’s network infrastructure analyst, Kamalini Ganguly, says that almost every major broadband hardware equipment vendor has some type of vectoring product in development. Ericsson was one of the first to announce a live lab demonstration in 2009, and this was followed by announcements from Nokia Siemens Networks, Huawei, ZTE and Alcatel-Lucent. Of these, Alcatel-Lucent has been the first to reach commercial availability.

What speeds can vectoring technology achieve?

According to Alcatel-Lucent, vectoring deployed on VDSL2 lines can reach downstream speeds of 100Mbps at distances of up to 400 metres, while 40Mbps can be supported with loops as long as 1,000 metres. In Alcatel-Lucent’s field trials with a number of service providers, including Belgacom, A1 Telekom Austria, Swisscom, Orange P&T Luxemburg and Turk Telekom, vectoring improved downstream bit rates by 90% to 150%. Alcatel-Lucent also achieved speeds of 300Mbps through the use of vectoring in conjunction with its VDSL2 bonding and phantom mode solutions.

What are the advantages of vectoring technology?

Vectoring technology has obvious cost advantages over fibre, as it reuses existing infrastructure. This also means it can offer a much quicker time to market. Another advantage of the technology is its reliance on DSL, which remains the main method of connecting to the internet worldwide. According to research group, Dell’Oro, two thirds of the world’s broadband subscribers are connected through DSL.

What are the disadvantages?

According to Alcatel-Lucent, sophisticated noise cancellation is CPU intensive and therefore works best over a few hundred lines. The noise cancellation process also requires measurements to be available from all lines, meaning that the lines all need to be under full control of a single service provider in order to achieve best performance. In addition, over longer distances vectoring technology is less effective at improving download speeds. This means that in some rural areas, where homes and businesses are thousands of metres away from the street telecoms cabinet, the technology will not significantly enhance the existing connection.

Where is vectoring technology being deployed?

Telekom Austria’s domestic subsidiary, A1, is one of the first companies to deploy the latest generation of vectoring technology. A1 has begun deploying Alcatel-Lucent’s VDSL2 solution in the state of Lower Austria, with a nationwide roll-out planned for mid-2012. Belgacom is also introducing vectoring technology in its domestic Belgium market through a partnership with Alcatel-Lucent. Western European countries are considered to have the most to gain from the technology due to their extensive copper infrastructure.