HabraFAQ-2014 about telecoms

    Difficult questions about the work of the cellular network are constantly coming from the hawkers. Below are answers to the most interesting questions over the past six months.

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    - How are telephone-BS communication tests done without interference?
    Here in such anechoic chambers, as in the photo above. The cut-off of external signals is incomplete: the more expensive the camera, the less external influence.

    - Why do people steal twisted pair?
    A fairly common question. Vandals are able to quickly pick up a twisted-pair bay and hide with it. There is no practical use for such a cable, but the twisted pair insulation burns well, so usually the bay is ignited along with the old tire, and the resulting lump of copper is scrapped. Profit is not comparable with possible punishment.

    - Why are numbers sometimes incorrectly determined?
    Due to a number of features of regional code entries, phone firmware often compares phones by the last digits. Therefore, sometimes it turns out that one of two or three hundred contacts in your phone book can be defined as the other, if the “tails” of the numbers are similar. On a number of old firmware, the last 7 digits are enough.

    - What is emergency phone unlocking?
    This is the mode that is used to dial emergency numbers (112), for example, calling an ambulance. Any phone, regardless of the presence / absence of a password, installed software and SIM card, must be unlocked for this case. If the unlock method is not obvious, most often you just need to press 112 or hold the pound key for 3 seconds. Other - more exotic - unlock methods are described in the telephone instructions.

    - Why is the person recorded in my address book, but instead of the name his phone number is shown?
    Because, most likely, this number is somehow recorded twice under different names, and the firmware can not select. Or there is a conflict of the last digits of the number (as above), and the software considers the phones of the two contacts the same. More details are here .

    - Where did I get the unknown numbers from the last dialed?
    Depending on the phone software, both the last number dialed and the last one with which the connection was established can be saved. This means that if there was a call forwarding, the final number will be saved, and not the one you started dialing.

    - How are base stations being built in Yakutia? After all, there are no roads all summer.
    In the summer, it is really almost impossible to get anywhere in Yakutia. The whole warm season, we are engaged in service and paperwork, and in winter, when winter roads are laid in the snow and lakes, we begin transportation .

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    The season is closed, the winter road no longer holds.

    - How are stations installed in permafrost?
    At first glance, permafrost is a layer of earth that is frozen to the state of stone. Nevertheless, a warm BS from above can melt this layer, and the foundation will “float”. Therefore, seasonally operating cooling devices are used - pressurized tubes with refrigerant.

    - Is it possible to pay from the telephone housing and communal services?
    Yes, there is a special advance account that is shared with your number. Like a plastic card associated with a phone number, but with its own balance. Herethe details . It’s also convenient to pay for parking in Moscow from this account.

    - Is it true that in Kamchatka containers of base stations often fall asleep?
    Yes, there is snow up to the second floor. A layer of snow around the container improves its thermal insulation, by the way.

    - How is data stored in telecom?
    The methodology of working with Big Data implies that we have large databases of unstructured data, where often the data itself determines the processing order and controls the Java robot reading them. This is necessary for rarely repeated untyped tasks. For routine tasks, typical databases are used, optimized for many batch transactions. Their structure is such that the subscriber number and its balance can be in different tables. Accordingly, for operations with a large number of join'ov, the first type of base is used, for simple (with a known request) - the second, "sharpened" just for such a request.

    - What are the features of iron for data storage in telecom?
    Given the amount of information processing, telecoms and banks are always at the forefront of IT infrastructure and need the most powerful and fastest machines. For example, servers and storage for critical sites should provide maximum performance per node, even in clusters.

    - Why do I need a free ESET antivirus for subscribers?
    Under Android, there are a lot of phishing and virus software, among other things sending out paid SMS. Antivirus insures against this threat and a number of others. Here are the details .

    - How are engineers trained inside the telecom?
    We have this: if there is a specialist with the necessary knowledge, for example in Kamchatka, we call him to Moscow. Within 2-4 days, he takes a special course on how to teach other specialists, and then speaks. Here, for example, details about the most common mistakes made by engineers teaching other people.

    - What is LTE-A?
    LTE-A is a standard that describes the evolution of LTE networks. It includes many different improvements, in particular in Russia it is already possible to use the function of combining two frequency ranges to obtain a larger band (and therefore higher speed) for traffic. Among other things, it is worth noting that LTE-A will provide much better access where previously the speed was low due to interference like buildings.

    - Why, when I ride the usual fast train from Moscow to St. Petersburg, the signal in the compartment was much better than in the Sapsan?
    Because the Sapsan has metal in the windows, which screens the train well enough. Accordingly, the signal in it will be weaker. That is why we built a chain of base stations near the railway tracks. In this case, signal attenuation should not be confused with the Doppler effect or the effect of speed reduction in 3G networks when a subscriber moves due to network delay.

    - Why does a sniper most often have a call sign with P?
    The traditions of radio communications imply the designation of the most distinguishable callsigns on the air to the most important units or specialists. "Thirty-third" almost nothing to confuse on the air, even on a narrow frequency range, when other sounds can merge. Modern networks, thanks to HD-Voice, have moved away from this problem, but the tradition has remained. Here you can listen to the difference between the past generation and the new.

    - When will there be VoLTE?
    Currently, voice services and SMS are possible in Russia’s LTE networks thanks to the use of Circuit Switched FallBack technology - temporary switching in 3G / 2G network to establish a voice connection. This creates a lot of problems on the network, so we moved on to the next level of the standard - VoLTE (in the pilot project, the planned launch over the network is yet to come). And retained backward compatibility with CSFB devices. Details .

    - How is the compatibility of equipment in telecom checked?
    Any new projects are first run in the test zone, where a full-fledged fragment of the network for testing is raised. There is an opportunity to look at working with all the network hardware, catch undocumented features and test everything in anechoic chamber conditions. In the test area, phones usually go crazy, so we recommend turning them off before entering. And there are also many engineers in sweaters. Details .

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    - What are the features of cellular communications in the mountains?
    The signal propagates well, but BS service is a problem. For example, for one of the highest BS in the CIS in the area of ​​the Big Almaty Lake, equipment is used to transport equipment on a trailer to a shishiga or other transport, and then to climb a snowmobile.

    - What is SDR / SDN?
    To simplify, this is somewhat similar to virtualization of iron: a change in the functional does not occur by replacing the material part, but by changing its software part. This is the philosophy of building new radio networks. For example, simplifying, if tomorrow it will be necessary to switch to new frequencies, we will not change the equipment on all BSs, but simply drop the new firmware over the network. Details .

    - How is the tower for the BS going out of the blue?
    Here is an example .

    - What are the difficulties of installation in the southern regions of the Russian Federation?
    In Astrakhan, for example, there is a complete set of difficulties. The wind breaks everything poorly fixed, and in the winter it blows so that it seems that you are climbing into the tower in only your underpants. Insects clog freecooling filters. Vipers like to lie under containers in the steppe because it is cool there. Birds hammer everything shiny. The heat inside the container without active cooling can be up to +80. The picture is effectively complemented by the relief (making BS maintenance difficult), the need for RRL instead of cable, floods and charismatic local residents.

    - How is the launch of the BS coordinated by radiation standards?
    First, before construction, radiation is calculated on the basis of data on buildings in both the vertical and horizontal planes. It turns out the project passport. Then, an examination of the projects is carried out: external organizations check the calculations, if necessary, make adjustments, for example, change the location of the antennas. An expert opinion is given. Based on these documents, Rospotrebnadzor gives its permission after additional examination - a sanitary and epidemiological conclusion is obtained on the placement of a radio transmitting facility. Upon completion of work, an inclusion is made at the time of measurement, sensors are located at control points. SanPin compliance is checked. Then the certified organization gives a second expert opinion. After that, the facility is put into operation .

    - Where is safer to say - closer to the BS or further from it?
    The total electromagnetic radiation is less closer to the base station. The fact is that a close low-power source (telephone) gives an order of magnitude greater radiation than a more powerful, but distant base station. Thus, long conversations are best done at the window. Here are the details on the radiation hazard of telephones and base stations .

    - What is a data center?
    When a DDoS attack begins, even the coolest equipment can not cope if the channel is clogged. Therefore, one of the modern protection tasks is to determine the signature in place and quickly forward traffic through the data cleaning center. Such a center is protective equipment actually standing on the main canal. With such a scheme, a DDoS attack must pass this defense and “clog” the backbone of the entire country. In the history of IT, we know only a couple of such precedents in Europe. That is why telecom data cleaning centers in world practice are used as DDoS insurance for large companies. Our practice is the client’s Radware DefensePro equipment and switching 18 seconds after the start of the cleanup attack from the outside. Here are the details .

    - Where else are there such FAQs?

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