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Cape Town deploys Adva’s FSP 3000 CloudConnect for 400G metro trial
networks of optical fibres that crisscross cities, regions, and countries. To better handle the glut of information, a research team from NOKIA Bell Labs, have developed a new device that could become a crucial component of new flexible and optimised networks. The device, a bandwidth variable transmitter (BVT), converts electronic signals to optical signals – but with a bandwidth that can change depending on need, it works without service interruptions, an advantage known as being “hitless.” “It’s really the first transmitter that can transmit data in optical transmission networks with a bit rate change in a hitless way,” said Arnaud Dupas, NOKIA A dva Optical Networking and the City of Cape Town, South Africa, have successfully transmitted data rates up to 400Gbit/s across the city’s metro transport network. The trial combined existing Adva FSP 3000 infrastructure and the latest CloudConnect 400Gbit/s technology to connect the nearby townships of Nyanga and Mitchells Plain. This was one of the country’s first demonstrations to transmit traffic at data rates of 200, 300 and 400Gbit/s over a deployed metro network. Using existing WDM equipment to achieve such high capacity underlines how the Adva FSP 3000 scales to accommodate growing bandwidth demand. The trial is also notable for being one of the first field demonstrations of DP-8QAM to achieve interim capacity of 300Gbit/s. The showcase underlines the City of Cape Town’s commitment to delivering
high-speed connectivity throughout the metropolitan area and to underserved townships. ADVA Optical Networking’s Elite partner XON Systems was integral in facilitating the trial. “What we’ve showcased here with ADVA Optical Networking is a genuine technology landmark. Now that we know we have the power to create a 400Gbit/s backbone the possibilities are immense,” said Leon van Wyk, telecommunications manager, City of Cape Town. “Ultra-fast connectivity will give government departments access to innovative new solutions. It will also make a huge difference for businesses and residents in this area,” he added, “Successfully connecting the townships of Nyanga and Mitchells Plain with a 400Gbit/s transmission shows that we can bring high-speed broadband to
using adva’s latest CloudConnect technology, data rates up to 400gbit/s have been transmitted across Cape Town’s metro transport netwwork.
and makes the transmitter hitless, allowing it to work without interruption and data loss. Normally, transmitters have to reconfigure themselves when interrupted, which can take several seconds or minutes and requires the traffic to be stopped. But the new transmitter can configure itself in less than 450 microseconds. The device connects to a commercially available optical transport network switch, which aggregates all kinds of signals, such as video and audio, and puts it through the transmitter. It works at a bit rate between 10 and 107 Gbits/s. The BVT is still a prototype, and would be only one piece of a large flexible optical network. The next step, Dupas says, will be to test it in the field with network operators, integrating it with the management software and systems that control a network from end-to-end. optimisation. To achieve the phenomenally high channel capacity, the demonstrators created a two-wavelength super-channel. Data rates were then switched between 200, 300 and 400Gbit/s to show how capacity can be automatically adjusted according to the network’s shifting traffic and transmission quality requirements. Successfully transmitting a 300Gbit/s channel at just DP-8QAM is a significant milestone. This modulation format can handle lower signal-to-noise ratios for increased reliability, yet optimised fibre utilisation.
constantly evolve over time, as people add and change those filtering functions. A transmitter that can adjust for varying bandwidths allows for optimised performance without requiring constant upgrades of infrastructure – which would be impractical and expensive. Most BVTs work by changing the format of the optical signal, converting between digital and analogue formats, Dupas said. But the researchers’ new BVT instead changes the symbol rate, also known as Baud rate, which is the number of signal events transmitted per second (a single signal event can encode one or several bits of information). The advantage of focusing on the symbol rate is that it’s easier to implement with electronics and is cost-effective, Dupas explained. This approach incorporates smart processing areas that need it most. We know the power the Internet has to expand horizons, raise aspirations and enrich lives. Connecting people and local businesses with each other and with the world will regenerate entire communities.” The 400Gbit/s trial made use of the City of Cape Town’s existing WDM infrastructure, which stretches over more than 100km and covers the whole metropolitan area. The meshed network is built on the ADVA FSP 3000, a modular optical networking platform designed for scalability and bandwidth
New optical transmitter enables better communication networks A ll the world’s data – pictures, video, sounds, and text – has to traverse complex Bell Labs, France. “As network demands continue to grow, this device will help to enable optical networks of the future with seamless network optimisation and flexibility.”
Dupas will be describing the device at The Optical Fiber Communication Conference and Exposition (OFC), held 20- 24 March in Anaheim, California, USA. The growth of data traffic has required the development of elastic optical networks, which are flexible enough to handle a wide range of data types and transmission rates. But even without these networks, traffic is dynamic, depending on the time of day and changing demands. Signals also don’t simply travel from one point to another. Nodes in the networks have filtering functions that select and redirect signals, adding another level of variability. And, the networks themselves
ISSUE 6 | Q1 2016 6
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