In August 2019, in Russia, for the first time in the world (Yes, itβs true), a commercial project was completed for the wireless backup of a 40 Gbps backbone optical cable. The operator Unity, a subsidiary of Norilsk Nickel, used such a channel to send an 11-kilometer wireless backup across the Yenisei.
Periodically in the press, including on HabrΓ©, appear . They are interesting from the point of view of technological progress, but these are always research tests. And here is a real commercial project, and not in the conditions of Silicon Valley or a European university, but right in the taiga on the Arctic Circle. Surprisingly, but it is a huge country, difficult geographical and climatic conditions that create the prerequisites for projects that give odds to the best research laboratories.
Chronology of recent wireless records:
- May 2013, at an experimental frequency of 240 GHz as a joint experiment by scientists from the Karlsruhe Institute of Technology, Radiometer Physics GmbH and the Fraunhofer Institute for Applied Solid State Physics. The signal frequency is not available for commercial use.
- May 2016: in the 70/80 GHz band, the same team, but as a new experiment on frequencies allocated for commercial projects,
- November 2016: , research center Facebook Connectivity Lab,
- January 2019, , a Deutsche Telekom test site on serial Ericsson equipment, in May 2019 scaling the same links on the same test site to 8 in a row already gave about 100 Gb / s,
- August 2019, , Norilsk operator "Edinstvo" on the serial equipment of OOO "DOK" (St. Petersburg).
As a matter of fact, there could not have been any wireless communication record in the conditions of the Arctic Circle if it were not for the ice drift on the Yenisei. The prehistory of the project is as follows - in 2017, after the Big Three operators refused to develop communications in the direction of Taimyr, the PJSC MMC Norilsk Nickel corporation at its own expense built a huge length (956 km) fiber-optic backbone (FOCL) from Novy Urengya to Norilsk with a capacity of 40 Gbit / s. This is a really difficult track, passing through difficult terrain, and its builders received government awards for this work.
One of the problems during operation - the transition of a 40-gigabit FOCL cable across the Yenisei, in the absence of bridges, was decided to be launched along the bottom of the river, and several cables were laid for reliability. But ice drift easily damages the optics. Moreover, the ice drift on the Yenisei is far from a one-day event, and no repair work on the water is allowed all this time due to the high danger to people.
In addition to additional cables at the bottom of the Yenisei, the route was backed up by a 1 Gbit / cc wireless radio relay channel of telecommunication towers on both sides of the river, in Igarka and the village of Priluki (this radio channel is visible in the top photo - a large plate). But what is 1 Gbit / s to ensure the entire Norilsk industrial region in case of damage to the optics ... - tears. Therefore, in the autumn-winter period of 2018-2019, the Norilsk operator Unity, which is part of the structure of PJSC MMC Norilsk Nickel, began design work to build a wireless channel across the Yenisei with a capacity that is not inferior to the FOCL backbone.
To the surprise of Unity specialists, none of the world telecommunications brands accepted the offer to supply equipment for a 40-gigabit wireless channel at a distance of 11 km. And the point here is precisely in the complex combination of high channel capacity and range. Modern serial equipment with a capacity of 10 Gbit / s or more for the 70/80 GHz band has such a feature as a very limited range. This is due to the fact that with complex coding schemes such as QAM128 or QAM256 - and only they can give a throughput of 10 Gb / s or more - it is difficult to provide any significant transmitter power. Routes of 3-5 km are easy, but at 11 km the signal attenuation becomes excessively large and no connection can be obtained in the 10GE standard.
The challenge was accepted by a domestic developer from St. Petersburg - . She already had the development of radio bridges, which provided the necessary range. And before this project, they tested a 40 Gb / s channel in the form of 4 cooperating radio bridges of 10 Gb / s at their 4 km test site, and they were sure that it was possible to obtain such a capacity. But in practice, no one in the telecommunications industry has ever tried to put together 4 parallel radio bridges of 10 Gb / s at a distance of 11 km.
Having received refusals from world brands, the customer, represented by Unity LLC, was also not sure that domestic equipment would cope with the project. Therefore, it was decided to initially install as a pilot stage only one 10 Gbit / s radio bridge for 11 km. And if it shows itself well, then scale the task up to 4 parallel radio bridges.
From a technical point of view, it is completely optional to transmit 40 Gb / s in one channel, both over the air and over an optical cable. It is much easier to transfer data over several parallel "threads" of 10 Gb / s. 10GE network equipment is cheaper and more affordable than 40GE switches. In addition, parallel "threads" give greater reliability for the entire channel.
But there was a problem that, unlike an optical cable, where the signal over parallel fibers does not affect each other in any way, radio channels have mutual interference up to a complete communication failure. This is combated by applying different signal polarization and spreading the signals in frequency. But this is easier to say, much more difficult to implement βin hardwareβ. Petersburgers made circuitry on large microwave microcircuits (MMIC, Monolithic Microwave Integrated Circuit) based on gallium arsenide and were confident in their circuitry solution.
βModern 10GE radio bridges around the world are made on purchased microwave microcircuits. In this area, it is inefficient to conduct vertically integrated development, when all technical processes are carried out in one company - from the deposition of microwave chips to the assembly of components into a finished product. This is about the same as many companies make computer boards based on chips from Intel and AMD. However, unlike mass-produced boards for PCs, setting up microwave chips, then amplifying the signal and feeding it to the antenna requires special expertise, and this, in fact, is the subject of know-how of companies,β commented Valery Salomatov, project manager LLC "DOK"
The pilot 10 Gbit/s radio bridge of the PPC-10G-E-HP model has successfully worked on towers along the banks of the Yenisei for a couple of months (May-June 2019). Summer rains are the most difficult time for millimeter-wave radio communications, because. raindrops are commensurate with the wavelength (about 4 mm), which generates signal attenuation. In winter, this problem does not happen, because. snowflakes, like fog and smoke, are radio transparent for 70/80 GHz wireless communications.
The 10 Gbit / s radio bridge from DOK LLC coped with weather conditions and distance, after which, based on the communication line availability statistics, the Unity operator decided to scale into 4 parallel wireless channels with a capacity of 10GE each. The installation was carried out by the specialists of the "Unity" company, who independently figured out the intricacies of the settings according to the instructions for the equipment. At the end of July 2019, the radio bridge
40 Gbit / s (4x 10 Gbit / s) through the Yenisei was put into commercial operation in the presence of the installation supervision team from the DOK company.
Source: habr.com