Because the volume of traffic on cellular networks is growing much faster than the operators manage to build them. This is if in brief. A more detailed analysis, as well as the results of a small experiment and a hint at a solution to the problem under the cut.

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Theory

Many of us paid attention to the fact that in places of mass gathering of people the mobile Internet works either very slowly or does not work at all. It is intuitively clear that this phenomenon is akin to a traffic jam - the narrow neck of the operator's infrastructure is tightly plugged with subscriber traffic.



In fact, the situation with the mobile Internet is much harder than the road: the volume of traffic on cellular networks shows an exponential growth (it is a geometric progression) with rates from 50 to 100% per annum in different countries, and there is no end to this trend. It is terrible to imagine what would happen on the roads if the number of cars doubled every year.

The authoritative annual study of world traffic is the Cisco Visual Networking Index (VNI) . According to the current forecast, the volume of mobile traffic in the world will grow 13 times over the next five years, with an average annual growth rate of 66%, reaching a cosmic 11 exabytes per month. In Russia, in the same period, a 16-fold increase in mobile traffic is predicted, which corresponds to expectations of growth rates higher than the world average.



Having erected "about 100%" of the annual growth to the tenth degree, it is easy to get a thousandfold increase in the load on the network over 10 years. This figure is actively promoting the manufacturer of electronic components Qualcomm.

The problem of lack of capacity of cellular networks, associated with an exponential growth of the load, was called the “capacity crisis” (“Capacity Crunch”), ominously consonant with the English-speaking ear for the 2008 financial crisis (“Credit Crunch”).

In short, the reasons for such rapid growth, the main thing is, of course, the “smartphone revolution”. So, only in 2012, the number of mobile Internet users (read: owners of a smartphone and / or tablet) in Russia increased by 88% to 79 million people. In turn, the wide distribution of smartphones and tablets leads to the spread of mobile use of popular services. For example, Youtube provides statistics on the fact that 40% (in time) of all viewed content falls on mobile devices. In addition, the average number of mobile Internet devices per subscriber is growing, as well as an increasing number of devices in addition to smartphones and tablets are connected to the mobile Internet and begin to generate and consume traffic.

Finally, mobile traffic is consumed and generated more and more unevenly in space, which further complicates the problem of lack of capacity of cellular networks in the “hot spots”. Indeed, if a voice call can be made on the run, then the consumption of “heavy” traffic, such as mobile video, will go to tables, shops, etc. The illustration below ( source ) shows the distribution of twitter traffic (blue) and flickr (orange) in London.



It is also important to remember that according to various data, from 70% to 80% of mobile traffic is generated indoors (see, for example, Huawei data ), which makes large public buildings natural hot zones for mobile traffic.

Practice

You may notice that the arguments above refer to the data of equipment manufacturers (Cisco, Qualcomm, Huawei) and service providers (Youtube). Among the mobile operators themselves, you can meet the opposite opinion that the problem of capacity crisis was invented by manufacturers to stimulate sales of equipment (it’s as if you believed that asphalt paver manufacturers invented traffic jams).

To illustrate the real situation, we went to the food court of the nearest large shopping center on Saturday evening, capturing a laptop and a set of 2G / 3G / LTE modems of all major metropolitan mobile operators.

The bandwidth of the mobile internet connection was measured using the speedtest.net service, in cases where the speedtest client could not connect to its server, ping 8.8.8.8 was used. We made sure to connect and pay the “most unlimited” tariffs for all operators. For operators providing LTE services in Moscow at the time of the experiment, we connected LTE.

Below, immediately after the disclaimer, the results of this small study.

DISCLAIMER

• We do not advertise or criticize the quality of services of individual operators.
• We are not affiliated with any of the mobile operators.
• We express our personal value judgment based on measurements of the quality of data transmission by publicly available tools.
• Measurement results for different operators are given in arbitrary order.

Megaphone

2G - network coverage is, the signal level is maximum, the modem is connected to the network. Speedtest can not connect to the server, ping does not go. Mobile Internet is virtually absent.



3G - the situation is similar, the signal level is at the maximum, there is a connection, there is no Internet.



4G / LTE - the modem showed the minimum signal level and refused to connect to the network. This happens in large buildings even with a satisfactory level of coverage outside.

Beeline

2G - a situation similar to 2G of the other operators, screenshots, unfortunately, have been lost.

3G - fixed speed!



Measured: yes, indeed, there is speed. Instability testimony indirectly indicates a high network load.



At the time of the experiment, Beeline had not yet launched 4G / LTE in commercial operation in Moscow.

Yota

We connected to the LTE Yota network via a mobile Wi-Fi router, so in the screenshot, the network is visible as a Wi-Fi network with the SSID “yotanelovit”. The router is connected to the LTE network, and the laptop is connected to the router. However, speedtest could not connect to the server, and ping showed at the same time a huge delay, packet loss, and even duplicate packets. Based on these data, it is difficult to make an unambiguous conclusion about the cause of problems - in a low signal level or in network overload, we leave this question unanswered.

Free wifi

In addition to the results for Yota, the illustration above shows another interesting phenomenon - as many as three free Wi-Fi networks. In practice, we failed to connect to any of these networks - the capacity crisis concerns Wi-Fi networks to the same extent, if not more, than cellular networks.

The presence of a Wi-Fi network with the SSID “AndroidAP” most likely indicates that, apart from us, someone else at the food court could not connect to free Wi-Fi and preferred to “distribute” Wi-Fi from the phone.

Also note the Wi-Fi network with the SSID “Megafon_MR100-1” is the name of the mobile 2G / 3G / LTE router in Wi-Fi branded for Megaphone. Probably, someone from the mall visitors is more lucky than us with the connection to the network of this operator, which once again testifies in favor of the hypothesis of network overload.

Mts

2G - network coverage is, the signal level is maximum, the modem is connected to the network. Speedtest can not connect to the server, ping does not go. Mobile Internet is virtually absent.



3G is the same as 2G



In the 4G / LTE MTS network, we recorded a decent speed (see illustration below).



Repeated the measurement, the speed is normal and relatively stable, which may indicate an unloaded network.



In general, we tend to explain the good results of LTE from MTS to the low prevalence of subscriber equipment compared to 3G and LTE from Yota. Recall that the MTS and Megaphone use in Moscow and the region a unique for Russia version of TD-LTE in the frequency range of 2595-2620 MHz.

Summary

So, the crisis of the capacity of cellular networks in a particular shopping center is a real problem faced by all cellular operators in the Moscow region. The key symptom is a very low or zero data transfer rate with a high signal level.

Is there a way out?

Yes. Shaping, compression and caching of traffic, radio frequency spectrum, LTE and LTE-A, Wi-Fi offload, as well as femto cells, pico cells, micro cells, metros and (except for jokes) nanocell - all of this in the next article.

Happy New Year holidays!