The partnership of Bavaria based M-Net and Nokia had successfully conducted the field trial to deliver 500Gbps transmission over a single wavelength. The announcement came along with the opening ceremony of M-Net’s headquarters in Munich.
The high bit-rate data transmission trial was carried out in collaboration with the Technical University of Munich. The researchers in the technical university provided the necessary software platform required to achieve such a high bit-rate transmission.
The fiber optic cable network distance under trial was around 320 kilometers Nokia provided its new signal processor. The team announced that they utilized almost full of a fiber’s capacity, with bandwidths up to 76.8 terabits per second. The achievement is first of its kind in practical testbeds in Europe.
German Minister of state for Digital Communication, Judith Gerlach was present when the team announced their achievements.
The test field was from M-Net’s Munich headquarters (M-Cube) to its telephone exchange in Regensburg. The experiment makes use of DWDM (Dense Wavelength Division Multiplexing) technology. Multiple wavelengths can be combined together and along the length of an optical fiber. A demultiplexer at the other end separates the signals according to their destination (header information).
The silica optical fiber used in the field test on the test track between Munich and Regensburg was provided by GasLINE GmbH & Co. KG.
What is Dense Wave Division Multiplexing (DWDM)?
Dense wavelength division multiplexing (DWDM) makes use of a wide range of optical spectrum typically starting from 1530nm to 1625nm. Information can be packed in light signals that are separated at a wavelength of less than 50 nm. Since the wavelengths are very close to each other, DWDM is often affected by non-linear effects, if the optoelectronics are not selected carefully. Due to these concerns, the team applied very stringent criteria while selecting the system components.
Dense wavelength division multiplexing (DWDM) leverages the capabilities and cost of Erbium-Doped Fiber Amplifiers (EDFAs). EDFAs are effective for wavelength ranging from 1525 to 1565 nm (C band), or 1570–1610 nm (L band). EDFAs extends the transmission distance of optical signals before they get weakened. and were originally introduced to replace SONET/SDH optical-electrical-optical (OEO) regenerators.
An EDFA amplifies an optical signal in their operating range, regardless of the modulated bit rate. Depending on the pump energy, an EDFA can amplify as many optical signals as can be multiplexed into its amplification band. A basic DWDM system contains the main components below;
– EDFA Amplifiers
– Intermediate Optical Terminal/Optical Add-Drop Multiplexer
– Terminal Demultiplexer
– Optical Supervisory Channel (OSC)
ITU-T Recommendations G.694.1 frequency grid introduced in 2002 helped network builders to integrate WDM with older yet standard SONET/SDH systems.
Groundbreaking technology from Nokia to M-Net
The achievement, which is a first in Europe, was made possible by Nokia’s WDM components specially developed for DWDM systems. M-net used the new Digital Signal Processor (DSP) Photonic Service Engine 3s (PSE-3s) with coherent signal processing capabilities. The team used the intelligent signal processing technology “Probabilistic Constellation Shaping” (PCS for short), that allowed a very precise adaptation of the optical signal to the prevailing transmission conditions.
The combination of precise optoelectronics, components supplied by Nokia and the software from the University made the trial possible to optimize the transmission capacity over any distance. The transfer rate can be increased with the system used over shorter distances to up to 600 gigabits per second per wavelength, allowing a total transmission capacity of 76.8 terabits per second per fiber.
A recent update from laboratories of NTT and Huawei claims the achievement of practical transmission of 600Gbps per wavelength.
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