How we provided Sapsan and Allegro communications

    The construction of one of the positions in the Leningrad Region

    “Sapsan” goes from Moscow to St. Petersburg in about 4 hours, “Allegro” from St. Petersburg to Helsinki (Finland) in 3.5 hours. The speed of trains is about 200 km / h.

    Initially, the coverage on these routes was the same as on many other railways: confident reception in large cities, the practical lack of mobile communications or random base stations on the way between them.

    We had to build a continuous (seamless) coverage of the 3G / 2G mobile network along the route of the Sapsan and Allegro trains. I was responsible for the organizational and technical parts of this interesting project.

    Technical solution

    Having some experience in working with the Big Three operators, we turned to them on this project, worked out options for joint cooperation, but no mutual agreements were reached. We needed to “build up” ourselves, and somewhere to build in a “clean field” from scratch the telecom infrastructure of 3G / 2G mobile communications along railway lines.

    Coverage planning was carried out in such a way that each new base station on the routes “covered” as much as possible previously unreached settlements. Of course, it didn’t work out everywhere, but we tried to choose the location of the future towers closer to the adjacent villages and villages, wherever it was possible to provide people with modern mobile communications, rather than putting them in the “ruler” along the railway lines. Thus, our coverage was designed taking into account 3G / 2G communication in all trains operated on the routes, including Sapsan with Allegro, and in long-distance trains, and in trains, as well as in surrounding settlements.

    One of the constructed base stations on the highway in the Moscow region

    It should be noted that in contrast to the standard construction sites, it required a more accurate placement of the chain of base stations. One incorrect location of the tower, and on the railway track there will be a “hole” in the coating, which you will not close later with any network optimization. One disagreement with the landlord of the roof or land along the highway, and again there will be a "hole".

    Offsets along the route of planned points were possible, but minimal. Subsequently, on the railway routes Moscow - St. Petersburg, 650 km, and St. Petersburg - Vyborg, 160 km, we managed to negotiate points with all the lessors, which was indicated to us by the planning. By the way, the coverage on the Allegro railway line was built up to the Finnish border, but hereinafter, for the convenience of geographical location, the border city of Vyborg will be indicated.

    To ensure coverage of the tracks, both low roof positions and high-rise tower positions were designed, all for the sake of creating a continuous coverage from all possible points. To implement the tower part of the designed network, it was decided to turn to infrastructure operators, Russian Towers and Link Development companies. The organization of communication channels for the transport network for 3G / 2G base stations was planned on the basis of overhead radio-relay links (RRL).

    Peregrine Falcon


    Network building

    Moving from theory to practice, in 2012 we began to implement the project. Frequent applications were submitted to the regulator for future 3G and 2G base stations. The purchase of mobile equipment began to be carried out. The drawing of plans and plans for future positions was in full swing. Along with this, infrastructure operators obtained approvals and issued the documents necessary to begin the construction of tower positions in our coordinates. In the regions, large-scale development of virgin lands along the Sapsan and Allegro railway lines has unfolded.

    During the implementation of the project, mutual assistance between the companies was surprisingly manifested. So the building gene. the contractor of the tower infrastructure EnergoPromResurs on tractors “dragged” our “Gazelles” and containers, helping to overcome the terrain and securing the delivery of VimpelKomovsky equipment to the towers, despite the fact that we did not have direct agreements. Work in the fields and forests along the railway tracks was progressing with a “twinkle”, although it was very difficult to break through to the railway through impassable swamps and impassable roads. Each rise of the new tower and its launch on the air was given with great difficulty.

    Sinking equipment at a construction site position in the Novgorod region

    The end of 2012 took place in our four branches (and this is St. Petersburg, Novgorod, Tverskaya, and Moscow) in the struggle to fulfill the plan of launching the project’s intended positions on the air. There was a severe frost, there was snowfall, an emergency was declared in one of the regions, and somewhere, our cars with base stations and antennas got stuck in the snow and for a long time could not get to the towers. Winter that year was very snowy. And despite this, on the geographical maps of the Sapsan and Allegro trains, like on the New Year's garland, every day the points of the new “islands” of 3G / 2G coverage “flashed”, improving the coverage on the railway tracks, and closing the “hole” for “ a hole. " We completed the plan of 2012 and did not stop moving on to new intense launches of the positions of the plan of 2013.

    In 2013, at the construction sites of the new towers, the project work gained momentum and progressed more confidently, despite the fact that in the spring it began to “carry” winter roads, and somewhere there were no roads at all. So, one of the towers on the track for lifting at the optimum point was able to be installed only by helicopter, there were no access roads and there were prospects to build them. We brought the equipment to this tower on railcars by rail, successfully overcoming all the difficulties with launching on the air.

    Training before installing the tower by helicopter on the track in the Tver region

    In the regions, our “offensive” along the tracks was confidently controlled by the technical staff of the planning and construction departments of VimpelCom branches. Colleagues clearly and methodically traveled to fields and forests, and monitored the status of construction and launch of each new tower.

    Gradually, the planned dates for the implementation of the infrastructure part of the project in 2013 leveled off in all four geographical areas, and the process of completion began to resemble a well-coordinated clockwork. So the Tver branch confidently launched tower by tower, the Moscow region quickly overtook colleagues, showing miracles in the speed of coordinating decisions, the Novgorod branch pulled ahead, finishing first, and waited for the rest of the colleagues, the St. Petersburg branch and Russian Towers decided with the locals the question of the location of the last tower. Everyone was in their place, everyone “kept” the system, and everything was very responsible. All laid out to the full.

    Tower rise on the Allegro highway, Leningrad region

    Finally, the last towers rose above the Sapsan and Allegro railway lines. We “dressed” the remaining towers with antennas and launched all the 3G / 2G base stations on the air. Thus, we have fully complied with the construction obligations assigned to us. Together with colleagues at the headquarters of those. Directorate and in the regions we completed the construction part of the project and provided with mobile communication all 100% of the territory of the railway Moscow-St. Petersburg, 650 km, and the railway St. Petersburg-Vyborg, 160 km. The construction phase of the project was completed, and it was possible to proceed to the stage of complex network setup.

    Measurements and Settings

    To evaluate the results of the new infrastructure construction and check the speed of the subscriber’s Internet connections, a whole research work was organized. In the course of analyzing the state of the network according to the results of construction, it turned out that the standard templates for setting up mobile networks are not suitable here. At first, it was not even possible to say with certainty what happened to 3G and 2G subscriber services at train speeds of over 200 km / h. The fact is that at speeds from 180 km / h, system network delays (which have nothing to do with the Doppler effect, as is often believed) begin to have a noticeable effect on the maximum speed of Internet connections.

    In addition, the 3G network on the routes behaved like an “invisible”, “disappearing” and transferring our subscribers to a 2G network. The 3G network in Sapsan and Allegro turned out to be very “moody” in the settings. It became clear that the settings of the 3G / 2G subscriber service on the Sapsan and Allegro railway lines needed to be dealt with thoroughly. The reason for the “invisibility” of the network in Sapsan was the metallization of the double-glazed windows of this “armored train”. It was the metallized double-glazed windows of Sapsan that especially weakened the signals of the VimpelCom 3G network, and poorly passed them inside. Allegro has a similar story.

    We started “overclocking” the 3G subscriber service on the routes, “shifting” the network for metallized double-glazed windows and the “crazy” speeds of trains moving over 200 km / h (in one of the tests we recorded a speed of even 240 km / h). For information, Sapsan and Allegro sweep past one of our towers on the highway in an average of 3 minutes, which is very fast, and so almost all 810 km from Moscow to Vyborg. We achieved the availability of high-speed Internet connection service in train salons by painstaking selection of parameters at base stations and network controllers, working with an external, street signal.

    Recording a drive test of a 3G / 2G subscriber service in the Sapsan salon

    Together with colleagues, a measuring series of road tests was carried out on the routes of various trains on the routes Moscow - St. Petersburg and St. Petersburg - Vyborg. And soon the recordings of measurements about the behavior of the network through the eyes of the subscriber began to take shape in a single "picture". It must be said that this principle of network configuration was applied in the project: first, the 3G / 2G service of the constructed network was measured at the exits by subscriber modems and terminals at speeds above 200 km / h, and then the parameters and parameters of the network equipment were monitored and adjusted. The difficulty here was that to check the 3G / 2G subscriber service, I had to constantly look for colleagues who could find the time and travel on trains between the two capitals with measuring equipment. The temporary ability of our engineers to “drive” on trains with drive tests was limited. Each trip was worth its weight in gold: they waited for it, prepared for it, the results were discussed collectively, with the subsequent settings, something happened right away, something had to be abandoned.

    According to the results of road measurements, a lot of settings for infrastructure parameters were changed and re-sharpened. This was reminiscent of the solution of a large differential equation with many unknowns: it was extremely careful to change the parameters of 3G / 2G base stations for high-speed trains. As a result, we began to better understand the mobile speeds of subscribers moving on trains over 200 km / h. After going through a lot of network parameters, we were able to balance and select the optimal settings, “cloning” the experience of colleagues in the sections of railway tracks between themselves. The principle of scaling in a large company suited us very well.

    Implemented infrastructure

    Finally, the 3G / 2G network coverage on the railway tracks was optimized. Replacing the antennas on the towers with narrow ones with a large gain, and aligning the antenna beams strictly on the track, we were able to “break through” the double-glazed windows with a 3G signal, although the signal lost some of the power due to attenuation in the windows. Thus, we tried to configure and make the mobile network more universal for all trains: for Sapsan with Allegro, and for ordinary long-distance trains, and for electric trains as well. We “dispersed” subscriber speeds on Sapsan and Allegro trains, starting from the optimization of the parameters of our 3G / 2G street network.


    The total length of our coverage of the Sapsana and Allegro railway lines is 810 km. 82 new 3G / 2G positions were built on railway lines and 46 3G positions were modernized.

    The probability of providing 2G voice service is now 99% on the Sapsan (Moscow - St. Petersburg) and Allegro (St. Petersburg - Vyborg) routes, both inside high-speed trains and in all other trains. Measurements of the average data transfer speed of the 3G service showed 2.2 Mbit / s in all trains without window metallization. At the same time, the probability of providing 3G service in conventional trains without metallization and in trains is also 99%.

    In the settlements adjacent to the tracks, where we were optimally able to put the towers, the indicated Internet speeds are also achieved. Thus, the socially significant effect of the project was achieved: 3G / 2G service was improved in about 60 settlements near the Sapsan highway, and in 15 points near the Allegro highway. And as you can see from the statistics from our base stations, traffic in adjacent villages and villages is only growing, local residents have "tried" the Internet.

    Inside the Sapsan and Allegro trains, a 3G data service is also provided, although metallized double-glazed windows will lower average speeds to some extent. According to the measurement results, the current speeds of 3G Internet connections in such "armored trains" are 1.0 Mbit / s. At the same time, the probability of providing 3G service in such trains is 90%, and in the remaining 10% of cases, the subscriber confidently “picks up” the 2G network. Personally, this was enough for me to download and show the cartoon on the road to my little daughter. However, this is not the limit. Network improvement work is ongoing.

    Now the built and optimized 3G / 2G networks on the studied railway lines are in commercial operation and “collect” traffic. The growth of voice and data traffic exceeds the initial forecast, so we can safely expect that in the future the project will reach self-sufficiency.

    General map of 3G / 2G network coverage on the Sapsan and Allegro train routes, 810 km long (autumn 2013)

    In conclusion, I would like to thank all the colleagues who took part in the development, implementation and research of the project, the branches and regional departments of VimpelCom, infrastructure operators and contractors. Only thanks to the well-coordinated work of our colleagues, we were able to optimally reach the high-speed train routes and adjacent settlements with mobile communications. We have invested a part of our soul in this project, and for many of us it has become a favorite.

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