Tag Archive for Orthogonal frequency-division multiplexing

ALU Gets 31 Tbps

ALU Gets 31 TbpsDavid Meyer at GigaOM noted the latest tests by Alcatel-Lucent’s (ALU) venerable Bell Labs division. The lab has figured out how to increase the bandwidth of submarine cables by a factor of three. They were able to move traffic at 31 Terabits per second (Tbps).

Alcatel-Lucent logoAlcatel-Lucent says it has broken the record for the amount of data that can be pushed through submarine cables. They claim to have achieved 31 Terabits per second over a single fiber that’s 4,474 miles long. For comparison, the Register figured that the average 15 minute, low-res movie is about 100Mb in size. They calculate that the new cable could speed 40,632 flix across the Atlantic every second. That would be enough for 423 days and nights of non-stop video viewing – in just one second.

It is important to remember we’re talking about a lab test. The test took place at ALU’s Innovation City campus in Villarceaux near Paris. The GigaOm article notes that the researchers with Bell Labs squeezed almost 10 Tbps more out of the fiber than the 21.7Tbps that NEC (6701) and Verizon (VZ) managed last year. This is three times roomier than in today’s most advanced commercial undersea cables.

Transoceanic cable

transoceanic cableThe author points out that that’s just one fiber and a transoceanic cable may have eight pairs of fibers. Again, this is a lot of capacity. However, it’s also worth noting that Alcatel-Lucent’s tests required a signal amplifier every 100km along the line.

The article claims that ALU’s Bell Labs division has done this type of research since 1925 in New Jersey. This type of work is more critical to ALU than ever. In June 2013, Alcatel-Lucent announced its “Shift Plan”, which involves moving away from being a telecoms equipment generalist. They want to be a specialist in IP networking and mobile and fixed broadband access. Philippe Keryer, Alcatel-Lucent’s chief strategy, and innovation officer said in a statement:

Undersea fiber-optic transmission is integral to the digital economy, delivering vast amounts of video and data between countries, regions and continents. As our customers cope with increasing demand on their networks for data capacity and higher-speeds of transmission, our researchers are intensifying their application with tests like this to develop new technology solutions to transform global data networks.

Wavelength division multiplexing (WDM)Mr. Meyer explains the test used Bell Labs’s technique for squeezing 200Gbps through a single data channel. It used 155 lasers, each one carrying 200Gbps at a different frequency. This represents an enhancement to the wavelength division multiplexing (WDM) techniques that run at up to 100Gbps in today’s commercially deployed cable.

Normally such signals suffer from distortions and noise, which limit performance. But GigaOM understands that Alcatel-Lucent was able to resolve this by using an enhanced version of WDM. The enhanced WDM works by splitting light up into different wavelengths so that it can carry more data.

Long-haul high-speed networking

Increasing bandwidthThe pace of development in the long-haul high-speed networking field is impressive. It’s easy to see just how far we’ve come. GigaOM provided a quick look at some of the other recent developments in long-haul high-speed networking.

  • May 2011 a team of German, UK, and Swiss scientists successfully used Orthogonal Frequency-Division Multiplexing (OFDM) to send data at a rate of 26Tbps over a 50km long single-mode fiber optic cable.
  • January 2012 a Japanese team working out of NEC successfully transmitted 4Tbps over a single “ultra-long haul” (10,000km) fiber optic cable without repeaters by making use of WDM just like Alcatel-Lucent.
  • May 2013 a more exotic approach with the UK test of hollow fiber optic cable that delivered speeds of 73.7 Tbps.

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Remember that the NSA has a submarine, the USS Jimmy Carter designed to tap undersea telecom cables on the bottom of the sea. This new speed record could be used to spy on more people.

 The Undersea Cables that Connect the World

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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 LinkedInFacebook, and Twitter. Email the Bach Seat here.

D-Light-ful LED Broadband

D-Light-ful LED BroadbandTEDGlobal has an intriguing presentation by Harald Haas who is developing a new type of light bulb that can access the Internet using light instead of radio waves. According to TEDGlobal, the professor of engineering at Edinburgh University, has been designing modulation techniques that pack more data onto existing networks, but his latest work leaps beyond wires and radio waves to transmit data via an LED bulb. The new technology will turn LED lights on and off, so fast the change is imperceptible to the human eye to enables broadband data transmission without any noticeable change in room lighting.

The system, which he calls D-Light, and hopes to commercialize under the new VLC (Visible Light Communications) brand uses OFDM (orthogonal frequency division multiplexing), The article reports the signal can be picked up by simple receivers. As of now, Haas is reporting data rates of up to 10 MBPS (faster than a typical broadband connection), and 100 MBPS by the end of this year and possibly up to 1 GB in the future.

Professor Haas says:

It should be so cheap that it’s everywhere. Using the visible light spectrum, which comes for free, you can piggy-back existing wireless services on the back of lighting equipment …As well as revolutionizing internet reception, it would put an end to the potentially harmful electromagnetic pollution emitted by wireless internet routers and has raised the prospect of ubiquitous wireless access, transmitted through streetlights.

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So in 2008, Boston University under a National Science Foundation grant started this research to piggyback data communications capabilities on low-power LEDs to make an LED light the equivalent of a Wi-Fi access point.

Some of the advantages of this technology include:

  • Security: Since white light does not penetrate opaque surfaces such as walls, eavesdropping is not possible and should not extend beyond building perimeters like current Wi-Fi technology. It also requires line-of-sight which will allow the user to see where the data is going.
  • Green: The development of this new technology coincides with the switch from incandescent and compact fluorescent lighting to LEDs. LED lights consume far less energy than RF technology, making it possible to build a communication network without added energy costs and reducing carbon emissions over the long term.

One downside is that the technology seems to be a one-way (down) transmission.

Possible applications could include automotive safety by enabling car brake lights to alert the car behind or traffic signals could alert cars when they change. It could also have applications in indoor mobile location and positioning services.

What do you think?

Does D-Light have a future as a green, wireless access point light?

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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 LinkedInFacebook, and Twitter. Email the Bach Seat here.