HabraFAQ-2014 about telecoms
Habrazhiteley constantly receive complex questions about the work of the cellular network. Below are the answers to the most interesting questions over the past six months.
- How are telephone-BS communications 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?
Quite a frequent question. Vandals are able to quickly pick a twisted pair bay and escape with it. There is no practical use for such a cable, but the insulation of the twisted pair burns well, so usually the coil is ignited along with the old tire, and the resulting lump of copper is scrapped. Profit is not comparable with the possible punishment.
- Why sometimes numbers are incorrectly determined?
Due to a number of features of regional code entries, the phone firmware often compares phones by the latest digits. Therefore, sometimes it turns out that one of two or three hundred contacts in your phone book can be defined as another, if the "tails" of numbers are similar. On a number of old firmware it is enough to match the last 7 digits.
- What is an emergency unlock phone?
This is the mode used to dial emergency numbers (112), for example, to call an ambulance. Any phone, regardless of the presence / absence of a password, installed software and a SIM card, must be unlocked for such a case. If the unlock method is not obvious, most often you need to either just press 112, or hold down the lattice key for 3 seconds. Other - more exotic - ways to unlock are described in the phone instructions.
- Why is a person registered in my address book, but his phone number is shown instead of his name?
Because, most likely, this number is somehow recorded twice under different names, and the firmware can not choose. Or there is a collision of the last digits of the number (as above), and the software considers the phones of the two contacts to be the same. More details are here .
- Where do I have unknown numbers in the last dialed?
Depending on the phone software, both the last dialed number and the last one that was connected to it can be saved. This means that if the number was redirected, it will remain the final number, and not the one that you started to dial.
- How are base stations built in Yakutia? After all, there are no roads all summer.
In the summer of Yakutia it's really impossible to get almost anywhere. All the warm season we are engaged in service and paper, and in winter, when winter roads are laid on snow and lakes, we start transportation .
The season is closed, the winter road no longer holds.
- How are the stations installed on permafrost?
At first glance, permafrost is a layer of earth that has frozen to a state of stone. Nevertheless, a warm BS from above can melt this layer, and the foundation “floats”. Therefore, seasonally operating cooling devices are used - germotrubki with refrigerant.
- Can I pay from the phone utilities?
Yes, there is a special advance account, which is shared with your number. Like a plastic card associated with a phone number, but with its own balance. Here are the details . Even from this account it is convenient to pay for parking in Moscow.
- Is it true that in Kamchatka the base station containers often fall asleep?
Yes, it is snowing up to the second floor. A layer of snow around the container improves its thermal insulation, by the way.
- How is the data stored in the telecom?
The methodology for working with Big Data implies that we have large databases of unstructured data, where the data itself often determines the order in which they are processed and control the Java robot that reads them. This is necessary for rarely repetitive untyped tasks. For routine tasks, typical databases optimized for multiple batch transactions are used. Their structure is such that the subscriber number and its balance can be in different tables. Accordingly, for operations with a large number of joines, the first type of base is used, for simple ones (with a known query) - the second one, “sharpened” just for such a query.
- What are the features of iron for storing data in a telecom?
Given the amount of information processing, telecoms and banks are always at the forefront of IT infrastructure and need the most powerful and fast machines. For example, servers and storage systems for critical areas should give maximum performance per node even in clusters.
- Why do you need ESET antivirus free for subscribers?
Under Android there is a lot of phishing and virus software, among other things, sending paid SMS. Anti-virus insures against this threat and a number of others. Here are the details .
- How are engineers trained inside 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 frequent mistakes of engineers , learning other people.
- What is LTE-A?
LTE-A is a standard that describes the development of LTE networks. It includes many different improvements, in particular, in Russia it is already possible to use the function of combining two frequency bands to get more bandwidth (and therefore more speed) for traffic. Among other things, it is worth noting that LTE-A will allow much better access where previously the speed was low due to noise such as buildings.
- Why, when I go on an ordinary 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 shields the train quite well. Accordingly, the signal in it will be weaker. That is why we built a chain of base stations near the railway tracks. Do not confuse the weakening of the signal in this case with the Doppler effect or the effect of speed reduction in 3G networks during subscriber movement due to network delay.
- Why does the sniper most often have a call sign with P?
Radio traditions imply the assignment of the most distinctive call signs on the air to the most important subdivisions or specialists. "Thirty-third" almost never confuse in the air even on a narrow frequency range, when other sounds can merge. Modern networks, thanks to HD-Voice, have left this problem, but the tradition has remained. Here you can listen to the difference between the past generation and the new one.
- When will VoLTE be?
Currently, in the LTE networks of Russia, voice services and SMS are possible due to the use of Circuit Switched FallBack technology - temporary switching in the 3G / 2G network to establish a voice connection. This creates a lot of problems in the network, so we moved to the next level of the standard - VoLTE (in the pilot project, the planned launch over the network is still ahead). And kept backward compatible with CSFB devices. Details .
- How is the compatibility of equipment in telecom checked?
Any new projects are first run-in in the test zone, where a full-fledged fragment of the network is raised for testing. It is possible to look at work with all the hardware of the network, catch undocumented features and test everything in terms of anechoic chambers. In the test zone, phones usually go crazy, so we recommend turning them off before entering. And there also lives a lot of engineers in sweaters. Details .
- What are the features of cellular communication in the mountains?
The signal propagates well, but BS maintenance is a problem. For example, for one of the highest BS in the CIS in the area of ​​the Big Almaty Lake, equipment delivery on a trailer to “shishige” or other transport is used, and then - snowmobile lifting.
- What is SDR / SDN?
Simplifying, this is somewhat similar to the virtualization of iron: the change in functionality does not occur by replacing the material part, but by changing its program part. This is the philosophy of building new radio networks. For example, simplifying, if suddenly tomorrow it will be necessary to switch to new frequencies, we will not change the equipment on all the BSs, but simply throw in the new firmware over the network. Details .
- How is going to tower for BS 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 badly fixed, and in the winter blows so that it seems that you climb onto the tower in your shorts. Insects clog freecool filters. Vipers like to lie under containers in the steppe, because it's cool there. Birds hollow everything brilliant. The heat inside the container without active cooling can be up to +80. The picture is effectively complemented by the relief (hindering the maintenance of the BS), the need for a radio relay link instead of a cable, floods and charismatic locals.
- How is the BS starting up according to the emission standards?
First, before construction, radiation is calculated on the basis of data on buildings both in the vertical and horizontal planes. It turns out sanpasport project. Then the expertise 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 an additional examination - it turns out a sanitary and epidemiological conclusion on the placement of a radio transmitting facility. Upon completion of the work is carried out at the time of measurement, at the control points are sensors. SanPin compliance is checked. Then the certified organization gives the second expert opinion. After that, the object is commissioned .
- Where is it safer to talk - closer to the BS or farther from it?
The total electromagnetic radiation is less closer to the base station. The fact is that a near low-power source (telephone) gives an order of magnitude greater radiation than a more powerful but distant base station. Thus, it is better to make long conversations at the window. Here are the details of the risk of radiation from phones and base stations .
- What is a data cleaning center?
When the DDoS attack begins, even the coolest equipment can not cope if the channel is clogged. Therefore, one of the modern tasks of protection is the definition of the signature in place and the rapid penetration of traffic through the data clearing center. Such a center is a protective equipment, actually standing on the main channel. With such a scheme, a DDoS attack must go through this defense and “hammer” the backbone of the whole country. In the entire history of IT, we know only a couple of such precedents in Europe. That is why telecom data clearing centers in world practice are used as insurance against DDoS for large companies. Our practice is Radware DefensePro equipment at the client and switching 18 seconds after the start of the attack to clean up outside. Here are the details .
- Where else are there such FAQ?
- How are telephone-BS communications 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?
Quite a frequent question. Vandals are able to quickly pick a twisted pair bay and escape with it. There is no practical use for such a cable, but the insulation of the twisted pair burns well, so usually the coil is ignited along with the old tire, and the resulting lump of copper is scrapped. Profit is not comparable with the possible punishment.
- Why sometimes numbers are incorrectly determined?
Due to a number of features of regional code entries, the phone firmware often compares phones by the latest digits. Therefore, sometimes it turns out that one of two or three hundred contacts in your phone book can be defined as another, if the "tails" of numbers are similar. On a number of old firmware it is enough to match the last 7 digits.
- What is an emergency unlock phone?
This is the mode used to dial emergency numbers (112), for example, to call an ambulance. Any phone, regardless of the presence / absence of a password, installed software and a SIM card, must be unlocked for such a case. If the unlock method is not obvious, most often you need to either just press 112, or hold down the lattice key for 3 seconds. Other - more exotic - ways to unlock are described in the phone instructions.
- Why is a person registered in my address book, but his phone number is shown instead of his name?
Because, most likely, this number is somehow recorded twice under different names, and the firmware can not choose. Or there is a collision of the last digits of the number (as above), and the software considers the phones of the two contacts to be the same. More details are here .
- Where do I have unknown numbers in the last dialed?
Depending on the phone software, both the last dialed number and the last one that was connected to it can be saved. This means that if the number was redirected, it will remain the final number, and not the one that you started to dial.
- How are base stations built in Yakutia? After all, there are no roads all summer.
In the summer of Yakutia it's really impossible to get almost anywhere. All the warm season we are engaged in service and paper, and in winter, when winter roads are laid on snow and lakes, we start transportation .
The season is closed, the winter road no longer holds.
- How are the stations installed on permafrost?
At first glance, permafrost is a layer of earth that has frozen to a state of stone. Nevertheless, a warm BS from above can melt this layer, and the foundation “floats”. Therefore, seasonally operating cooling devices are used - germotrubki with refrigerant.
- Can I pay from the phone utilities?
Yes, there is a special advance account, which is shared with your number. Like a plastic card associated with a phone number, but with its own balance. Here are the details . Even from this account it is convenient to pay for parking in Moscow.
- Is it true that in Kamchatka the base station containers often fall asleep?
Yes, it is snowing up to the second floor. A layer of snow around the container improves its thermal insulation, by the way.
- How is the data stored in the telecom?
The methodology for working with Big Data implies that we have large databases of unstructured data, where the data itself often determines the order in which they are processed and control the Java robot that reads them. This is necessary for rarely repetitive untyped tasks. For routine tasks, typical databases optimized for multiple batch transactions are used. Their structure is such that the subscriber number and its balance can be in different tables. Accordingly, for operations with a large number of joines, the first type of base is used, for simple ones (with a known query) - the second one, “sharpened” just for such a query.
- What are the features of iron for storing data in a telecom?
Given the amount of information processing, telecoms and banks are always at the forefront of IT infrastructure and need the most powerful and fast machines. For example, servers and storage systems for critical areas should give maximum performance per node even in clusters.
- Why do you need ESET antivirus free for subscribers?
Under Android there is a lot of phishing and virus software, among other things, sending paid SMS. Anti-virus insures against this threat and a number of others. Here are the details .
- How are engineers trained inside 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 frequent mistakes of engineers , learning other people.
- What is LTE-A?
LTE-A is a standard that describes the development of LTE networks. It includes many different improvements, in particular, in Russia it is already possible to use the function of combining two frequency bands to get more bandwidth (and therefore more speed) for traffic. Among other things, it is worth noting that LTE-A will allow much better access where previously the speed was low due to noise such as buildings.
- Why, when I go on an ordinary 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 shields the train quite well. Accordingly, the signal in it will be weaker. That is why we built a chain of base stations near the railway tracks. Do not confuse the weakening of the signal in this case with the Doppler effect or the effect of speed reduction in 3G networks during subscriber movement due to network delay.
- Why does the sniper most often have a call sign with P?
Radio traditions imply the assignment of the most distinctive call signs on the air to the most important subdivisions or specialists. "Thirty-third" almost never confuse in the air even on a narrow frequency range, when other sounds can merge. Modern networks, thanks to HD-Voice, have left this problem, but the tradition has remained. Here you can listen to the difference between the past generation and the new one.
- When will VoLTE be?
Currently, in the LTE networks of Russia, voice services and SMS are possible due to the use of Circuit Switched FallBack technology - temporary switching in the 3G / 2G network to establish a voice connection. This creates a lot of problems in the network, so we moved to the next level of the standard - VoLTE (in the pilot project, the planned launch over the network is still ahead). And kept backward compatible with CSFB devices. Details .
- How is the compatibility of equipment in telecom checked?
Any new projects are first run-in in the test zone, where a full-fledged fragment of the network is raised for testing. It is possible to look at work with all the hardware of the network, catch undocumented features and test everything in terms of anechoic chambers. In the test zone, phones usually go crazy, so we recommend turning them off before entering. And there also lives a lot of engineers in sweaters. Details .
- What are the features of cellular communication in the mountains?
The signal propagates well, but BS maintenance is a problem. For example, for one of the highest BS in the CIS in the area of ​​the Big Almaty Lake, equipment delivery on a trailer to “shishige” or other transport is used, and then - snowmobile lifting.
- What is SDR / SDN?
Simplifying, this is somewhat similar to the virtualization of iron: the change in functionality does not occur by replacing the material part, but by changing its program part. This is the philosophy of building new radio networks. For example, simplifying, if suddenly tomorrow it will be necessary to switch to new frequencies, we will not change the equipment on all the BSs, but simply throw in the new firmware over the network. Details .
- How is going to tower for BS 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 badly fixed, and in the winter blows so that it seems that you climb onto the tower in your shorts. Insects clog freecool filters. Vipers like to lie under containers in the steppe, because it's cool there. Birds hollow everything brilliant. The heat inside the container without active cooling can be up to +80. The picture is effectively complemented by the relief (hindering the maintenance of the BS), the need for a radio relay link instead of a cable, floods and charismatic locals.
- How is the BS starting up according to the emission standards?
First, before construction, radiation is calculated on the basis of data on buildings both in the vertical and horizontal planes. It turns out sanpasport project. Then the expertise 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 an additional examination - it turns out a sanitary and epidemiological conclusion on the placement of a radio transmitting facility. Upon completion of the work is carried out at the time of measurement, at the control points are sensors. SanPin compliance is checked. Then the certified organization gives the second expert opinion. After that, the object is commissioned .
- Where is it safer to talk - closer to the BS or farther from it?
The total electromagnetic radiation is less closer to the base station. The fact is that a near low-power source (telephone) gives an order of magnitude greater radiation than a more powerful but distant base station. Thus, it is better to make long conversations at the window. Here are the details of the risk of radiation from phones and base stations .
- What is a data cleaning center?
When the DDoS attack begins, even the coolest equipment can not cope if the channel is clogged. Therefore, one of the modern tasks of protection is the definition of the signature in place and the rapid penetration of traffic through the data clearing center. Such a center is a protective equipment, actually standing on the main channel. With such a scheme, a DDoS attack must go through this defense and “hammer” the backbone of the whole country. In the entire history of IT, we know only a couple of such precedents in Europe. That is why telecom data clearing centers in world practice are used as insurance against DDoS for large companies. Our practice is Radware DefensePro equipment at the client and switching 18 seconds after the start of the attack to clean up outside. Here are the details .
- Where else are there such FAQ?
Source: https://habr.com/ru/post/241688/
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