How to increase network bandwidth in the data center: a new PSE-3 chip is introduced
At the OFC conference next week in San Diego, Nokia will introduce a new PSE-3 optical transceiver, providing data transfer rates of 200 Gb / s per wavelength for submarine cables, 400 Gb / s in metropolitan area networks and 600 Gbps. / c for links in data centers. Nokia representatives say that PSE-3 in some cases will increase the network bandwidth by 65% ​​compared to existing solutions, while reducing power consumption by 60%.
In more detail we will tell about technology under a cat.
/ Photo Groman123 CC
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The new chip is a commercial implementation of technologies tested by Nokia over the years. In 2016, Nokia and scientists at the Technical University of Munich worked on a joint project, during which scientists were able to achieve a data transfer rate of 1 Tbit / s on the network of Deutsche Telekom. And last year, the Finnish company put into operation a 250-gigabit transatlantic fiber-optic cable for Facebook. Its length was 5.5 thousand km, and it was stretched from New York to Ireland.
The PSE-3 uses the “probabilistic signal constellation formation” technology (probabilistic constellation shaping, PCS), which is used to select the most effective (with less noise) phase / amplitude combination. The essence of the method is that signal points with a high amplitude are used less frequently than points with a low amplitude. "Constellation" adapts to the conditions of the transmission channel, which increases the resistance of the signal to distortion. PSE-3 uses QAM-64 quadrature modulation - this means that the chip can choose from 64 constellation points for adjustment.
As Peter Winzer, director of optical services at Nokia Bell Labs, noted, the task was to form the constellations in order to get as close as possible to Shannon's limit . The formation is performed by the distribution matcher function, which is “wired” in the ASIC and makes all QAM constellation symbols meet with different probabilities.
Focusing energy on symbols with a smaller amplitude while reducing bandwidth, the probabilistic conversion function gives the "square constellation" the shape of a Gauss curve (an example can be found in WP Nokia on page five by reference ). Thus, PSE-3 allows you to get closer to the Shannon limit by more than 0.3 dB, increasing spectral efficiency, while other modern high-performance optical interfaces and WDM systems operate at a distance of 1.5–2.5 dB.
/ photo Claus Rebler CC
Nokia has tested technology in the US and Germany. An experiment in the United States showed that PCS technology can increase network bandwidth by 68% and reduce the number of transponders needed by 35%, compared to 100G QPSK. Compared to 100G – 250G transceivers, the results were 25% and 25%, respectively. A similar test in Germany showed a 14% increase in throughput and a 30% reduction in the number of transceivers.
Nokia representatives and scientists at the University of Munich are convinced that in the future, PCS technology will automatically adapt to traffic needs and ensure even faster transfer of large sets of information. As for the PSE-3, then, presumably, the chip will appear on the market at the end of this year or at the beginning of 2019.
PS More materials on networks from the First Corporate IaaS blog:
In more detail we will tell about technology under a cat.
/ Photo Groman123 CC
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How does the chip work
The new chip is a commercial implementation of technologies tested by Nokia over the years. In 2016, Nokia and scientists at the Technical University of Munich worked on a joint project, during which scientists were able to achieve a data transfer rate of 1 Tbit / s on the network of Deutsche Telekom. And last year, the Finnish company put into operation a 250-gigabit transatlantic fiber-optic cable for Facebook. Its length was 5.5 thousand km, and it was stretched from New York to Ireland.
The PSE-3 uses the “probabilistic signal constellation formation” technology (probabilistic constellation shaping, PCS), which is used to select the most effective (with less noise) phase / amplitude combination. The essence of the method is that signal points with a high amplitude are used less frequently than points with a low amplitude. "Constellation" adapts to the conditions of the transmission channel, which increases the resistance of the signal to distortion. PSE-3 uses QAM-64 quadrature modulation - this means that the chip can choose from 64 constellation points for adjustment.
As Peter Winzer, director of optical services at Nokia Bell Labs, noted, the task was to form the constellations in order to get as close as possible to Shannon's limit . The formation is performed by the distribution matcher function, which is “wired” in the ASIC and makes all QAM constellation symbols meet with different probabilities.
Focusing energy on symbols with a smaller amplitude while reducing bandwidth, the probabilistic conversion function gives the "square constellation" the shape of a Gauss curve (an example can be found in WP Nokia on page five by reference ). Thus, PSE-3 allows you to get closer to the Shannon limit by more than 0.3 dB, increasing spectral efficiency, while other modern high-performance optical interfaces and WDM systems operate at a distance of 1.5–2.5 dB.
/ photo Claus Rebler CC
Technology potential
Nokia has tested technology in the US and Germany. An experiment in the United States showed that PCS technology can increase network bandwidth by 68% and reduce the number of transponders needed by 35%, compared to 100G QPSK. Compared to 100G – 250G transceivers, the results were 25% and 25%, respectively. A similar test in Germany showed a 14% increase in throughput and a 30% reduction in the number of transceivers.
Nokia representatives and scientists at the University of Munich are convinced that in the future, PCS technology will automatically adapt to traffic needs and ensure even faster transfer of large sets of information. As for the PSE-3, then, presumably, the chip will appear on the market at the end of this year or at the beginning of 2019.
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Source: https://habr.com/ru/post/350818/
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