The maximum speed of mobile Internet according to the 3g standard. How to choose a mobile phone: data transfer issues

What is 3G?

In 3G networks (The Third Generation - “third generation”), two basic services: Data transfer and voice transfer.

According to ITU* regulations, 3G networks must support the following data rates:

• for subscribers with high mobility (up to 120 km/h) - at least 144 kbit/s;
• for subscribers with low mobility (up to 3 km/h) - 384 kbit/s;
• for fixed objects - 2.048 Mbps.

3G includes 5 standards of the IMT-2000 family (link) (UMTS/WCDMA, CDMA2000/IMT-MC, TD-CDMA/TD-SCDMA(China's own standard), DECT and UWC-136).

The most widespread in the world are two standards: UMTS (WCDMA) and CDMA2000 (IMT-MC), which are based on the same technology - CDMA (Code Division Multiple Access).

Work on standardization of UMTS is coordinated by the international group 3GPP (Third Generation Partnership Project), and standardization of CDMA2000 - by the international group 3GPP2 (Third Generation Partnership Project 2), created and coexisting within the ITU.

Technology CDMA2000 provides an evolutionary transition from narrowband code division systems IS-95 (American standard for digital cellular communication second generation) to "third generation" CDMA systems and is most widespread in the North American continent, as well as in the countries of the Asia-Pacific region.

Technology UMTS(Universal Mobile Telecommunications Service - universal system mobile telecommunications) is designed to modernize GSM networks ( European standard cellular communication of the second generation), and has become widespread not only in Europe, but also in many other regions of the world.

* (International Telecommunications Union) - International Telecommunication Union (link)

Main trends in 3G networks:

• the predominance of data-cards traffic (USB modems and PCMCIA cards for laptops) over the traffic of 3G phones and smartphones;
• permanent reduction in the price of 1 Mb of traffic, due to the transition of operators to more advanced and efficient technologies.

The graph below shows data on the main trends in the development of 3G networks in the world*:

* Source: Analysys Mason, Wireless network traffic 2008-2015: forecasts and analysis A-focus, Scenario analysys - future spectrum capacity demamds, 2008

Development of 3G technologies

The development of CDMA2000 began with the introduction of technology CDMA2000 1x with a bandwidth (channel or subcarrier) of 1.25 MHz. * Improved version - 1xEV-DO Rel. 0, then 1xEV-DO Rev.A, is on this moment basic technology for CDMA2000 networks and allows migration to " fourth generation» (4G).

HSPA "add-on" (combines HSDPA and HSUPA technologies) ** is used to upgrade UMTS. The next stage in the development of UMTS networks is associated with the introduction HSPA+, which is a transitional technology to 4G networks.

* As a result, the frequency band is used more efficiently than in UMTS (5 MHz) networks.
** HSDPA (High Speed ​​Downlink Packet Access) technology allows you to increase the data transfer rate in UMTS networks along the downlink (Down link (DL)). To increase the speed of data transfer from the subscriber to base station HSUPA (High Speed ​​Uplink Packet Access) technology was developed on the Up Link (UL).

Comparison table of 3G/4G technologies

On the way to 4G

evolution mobile communications will continue LTE technology (Long Term Evolution - long-term evolution). LTE, thanks to the SAE* flat architecture, is a further development of both UMTS and CDMA2000 networks.

LTE uses OFDMA ** and MIMO *** technologies and the All IP principle, and also allows scaling frequency bands(450 MHz - 4.9 GHz) and wideband operation (1.5 MHz - 20 MHz). The LTE architecture reduces the number of nodes, supports flexible network configurations, and provides high level service availability. In addition, LTE will provide 2G/3G (GSM, UMTS/HSPA, TD-SCDMA, CDMA2000) interconnection.

* SAE (System Architecture Evolution) is a flat architecture designed to optimize performance, improve cost efficiency, and simplify the launch of IP-based services for the mass market.
** OFDMA technology (Orthogonal Frequency Division Multiplexing - orthogonal frequency multiplexing, which uses a large number of closely spaced orthogonal subcarriers).
*** MIMO technology(Multiple Input, Multiple Output) - increasing the noise immunity of communication due to the diversity of reception / transmission using several antennas.

The diagram * below illustrates the concept of LTE technology as the main integration platform wireless networks future:

LTE technology will allow operators to reduce capital costs for network upgrades and ensure the growth of quality indicators and speed of access at a moderate cost (see chart below).

Development of LTE:

• IV quarter. 2008 - 3GPP released a complete set of specifications describing LTE networks;
• II quarter. 2009 - Equipment manufacturers have tested and are ready to supply End-to-end LTE solutions Alcatel-Lucent, Ericsson, Huawei Technologies, Motorola, Nokia Siemens Networks);
• III quarter. 2009 Quolcomm plans to release the first three models of LTE/UMTS/CDMA modem chips;
• IV quarter. 2009 - TeliaSonera launched the first commercial LTE networks in Oslo and Stockholm;
• IV quarter. 2009 - Samsung's first commercial LTE modems based on Kalmia's own chipset
• I sq. 2010 - Nokia, Alcatel-Lucent, Cisco Systems abandoned WiMAX support in favor of LTE;
• I sq. 2010 - Samsung's first LTE smartphone is shown at CTIA Wireless 2010;
• I sq. 2010 - GSMA adopted the VoLTE (Voice over LTE) protocol as the main protocol for voice transmission in LTE networks;
• I sq. 2010 - In Russia, the allocation of frequencies for 4 experimental LTE zones was announced. At the same time, Svyazinvest decided to develop LTE on the 2.3-2.4 GHz frequencies it won in 39 regions of Russia (previously, WiMAX was supposed);
• II-IV quarter 2010 - further deployment of LTE networks (NTT DoCoMo in Japan, American Verizon Wireless);
• IV quarter. - LTE-smartphone from Samsung will work in the LTE network of the American Metro PCS;
• 2010-2013 - LTE will gradually replace HSPA (voice will be transmitted over LTE networks via IP) * ;
• 2015 - LTE operators' revenue will be $150 billion (about 15% of the global cellular market revenue), and the number of LTE subscribers will exceed 400 million**.

* According to Nokia forecasts
** According to UMTS forum forecasts

The simplest solution for working with the Internet is a phone for third-generation networks (3G - UMTS, CDMA2000, CDMA450). You only need to rely on the quality of coverage of the operator's network. It is important to remember that the UMTS standard is not yet used in Russia, CDMA450 is only used in Russia and Romania, and CDMA2000 is only used in America and Asia, so if you need a 3G phone that works both here and abroad, it's worth buying" combined" mobile phone - GSM / CDMA or GSM / UMTS.

Theoretically, the maximum data transfer rate in 3G networks is quite high (see the table, all data are for the first, current phase of development).

In practice, the transmission / reception speed depends on many factors and often turns out to be very far from the theoretical limits. Two main factors are the quality of coverage of the area with a 3G signal and the speed of the subscriber.

Let's start with coverage. 3G signal coverage and, accordingly, the data transmission / reception speed differs in different places. As for "separate" places (see the table above) and a speed of 2 Mbps, this service is provided by the operator only at specially designated points, and often not at all where you need it. Moreover, 2 Mbit / s are intended only for sedentary users whose movement speed is less than 3 km / h.

Remember that the lower the 3G signal level (its level is shown on the display), the worse the conditions for transmitting / receiving data.

The speed of the subscriber always reduces the speed of information transfer, often by several times.

This is due to limitations in the very principle of operation of the 3G access system (WCDMA). Take this into account when driving in a car: the lower the speed of the car, the higher the transmission speed and vice versa. For mobile objects in UMTS networks, transmission speeds are provided - up to 144 kbps (12-120 km/h) and up to 384 kbps (3-12 km/h), but in practice only about 20 kbps is obtained .

GSM networks

As good as 3G data phones are, GSM phones are much more popular. When buying such a phone to work on the Internet, you need to pay attention to a number of circumstances.

First. Any GSM phone can be used to receive and transmit data, including via the Internet.

The only question is how to do it with maximum quality and minimal cost. The oldest (and most technically simple) transmission method is the circuit switching principle CS (Circuit Switch) in GSM networks. It has been used since the mid-1990s and allows you to transmit / receive data at speeds up to 9.6 kbps. Now it is not actually used.

Second. There are three main technologies that allow you to transmit data in the GSM standard:
- HSDTS (High Speed ​​Data Transmission Service),
- GPRS (General Packet Radio Service),
- EDGE (Enhanced Data for Global Evolution).

These abbreviations may appear in the description of the phone, so it is useful to have an idea of ​​what they mean.

HSDTS was used until 2001, until the new GPRS and EDGE data transmission standards came into operation, so we will not talk about it.

In modern GSM-phones for data transmission are used special technologies GPRS and EDGE. The phone can support either GPRS only or both GPRS and EDGE. When buying a phone, decide what you need. Usually EDGE support is found in more expensive models.

Please note that the coverage for GPRS and conventional GSM signals is different, and where the quality of your phone is always excellent, the GPRS / EDGE service may not work at all, especially outside the city.

And further. EDGE is more common in the US than in Europe, European carriers started to develop EDGE a little later. Some parts of Central Europe still do not have EDGE coverage. At the same time, in Asia (China, etc.), phones with EDGE are in demand, and coverage is excellent there. Let's now consider each technology separately.

GSM.GPRS

Relatively new way GPRS packet data transmission has been applied since 2001. Introduced and mastered by almost everyone GSM operators, which means good network coverage. GPRS works on PS (Packet Switch) packet switching technology, in which data is transmitted in fragments (packets). In addition, this is a multi-slot technology, i.e., the subscriber can transmit / receive on several TS (Time Slot) time intervals simultaneously. At the same time, the subscriber pays for the traffic, and not for the busyness of the channel, as when making a call. GPRS technology allows the operator to increase the traffic (compared to the capabilities of HSDTS technology) hundreds of times without a significant increase in the number of communication channels.

Theoretically, GPRS can have a transfer rate of up to 171.2 kbps (8 x 21.4), but practically no one has ever received and will not receive such a speed. Moreover, there are not even (and will not be) phones capable of operating in this mode.

The speed of GPRS depends on the quality of the network coverage. The principle is known - the higher the signal level, the faster GPRS works. In addition, the speed of working with data also depends on the number of TS time slots used by one subscriber per communication session. The more TS intervals "captured" by the subscriber, the faster speed transmission and reception of data. But not everything is so simple, and no one will let you "capture" as many slots as you want.

When buying a phone, pay attention to the presence of GPRS support in the phone (not all phones have it) and the GPRS class.

The GPRS class defines the maximum number of TS timeslots allowed for the subscriber, that is, the maximum speed of your phone with data. And, although the GPRS standard itself assumes the existence of 29 different classes, we will be interested in only three, because global manufacturers usually produce only three classes of GPRS phones: 8, 10 and 12.

The GPRS class is the main thing a buyer needs to know about GPRS.

Theoretical minimum and maximum speeds the work of the three main classes are shown in the table below. Velocity calculations are made for the maximum number of TSs for each class. The number of TS intervals allowed for operation is also given there. I note that the amount of TS during operation is always selected by the system itself and you cannot influence this process.

Note that for classes 8 and 10, the traffic is asymmetric: much more resources are allocated for receiving than for transmitting.

In fact, the difference in the class determines only the speed of your transmission, and the reception for all three classes is the same in terms of speed.

I note that changes in the speed of GPRS operation (according to the table) depend on the received signal and are determined in GSM coding schemes. For four coding schemes (CS1--CS4), the following transmission rates per TS are achieved: 9.05; 13.4; 15.6; 21.4 kbps

And one more note for those who are curious: for all classes used, the maximum number of TS intervals used by a subscriber in a communication session never exceeds 5.

For example, if you are transmitting in class 12 on four TSs, you can only receive "simultaneously" on one TS, since 4+1=5 (the converse is also true). If you take, for example, only three TS per transmission, then the system will allow you to receive a maximum of two TS and vice versa (3+2=5).

In conclusion, let me remind you that the higher the GPRS class and the more TS is used for transmission, the faster your battery life is consumed. Therefore, do not be surprised that when you work intensively on the Internet, you will need to charge your phone much more often.

GSM: EDGE - the evolution of GPRS

EDGE is further development GPRS technology, aimed at increasing the transmission / reception speed.

In phones that support both EDGE and GPRS, the consumer cannot choose which technology to use during the next access session, the network decides for him: if there are sufficient conditions for high speed transmission data ( good signal etc.), then EDGE will be used, otherwise GPRS will be used.

Now about EDGE speeds. This technology can also operate on multiple TSs, so the concept of classes used in GPRS applies to EDGE as well.

For one TS, the EDGE speed changes as follows: 22.4; 29.6; 44.8; 54.4; 59.2 kbps - depending on the coding scheme (MCS5--MCS9). The table below shows the theoretical minimum-maximum data rates for the three main classes (only for MCS5--MCS9 codes, where EDGE takes precedence over GPRS).

The rule of using only five TSs at the same time is also valid for EDGE, so the actual achievable speed in existing EDGE networks is a maximum of 236.8 kbps. At the same time, do not forget that with an average signal level, the speed of operation drops at least two to three times.

Unfortunately, many manufacturers and operators significantly inflate real numbers on the data transfer rate in mobile networks, providing the user with information that is not applicable to real conditions.

So, for EDGE data transfer rates are usually declared at the level of 384 kbps or 473.6 kbps. For GPRS, most often they write 115 kbps or even 171.2 kbps. These are completely unrealistic numbers, because there are simply no phones capable of operating at such speeds with these technologies.

This time we are talking about simpler things, but directly related to each 3G user. Namely, what determines the speed of data transfer in mobile network.

The most meticulous subscribers, seeing the phrase “up to 42 Mbps” in the advertising of the third generation network, run to check with the help of various puzomerok (Speedtests, that is), how much they receive from the operator. Not having found the “declared” 42 Mbps (although in the advertisement they actually promised “to”), they run to complain on social networks and other authorities that they were deceived. Let's figure out who, how, when, and whether or not they were deceived with the declared speed, what makes up the result voiced by the operator, and in which case there really is something to complain about.

As usual, there is no single determining factor. And one way or another affects the speed mobile internet not only the operator, but also the subscriber. The operator is in charge of such things as coverage, coverage quality and network capacity (literally in a couple of sentences more on all this). The subscriber is responsible for the choice of the terminal ( in simple words- smartphone, tablet, mobile router and other gadgets) to connect to the network.

What depends on the operator?

With coverage, everything is simple - you either have it or you don't. If you are traveling to the secret corners of the country, you can check coverage information on the operator’s website or in the call center to be sure.

When they say that in some place there is poor coverage, the concept of “coverage” is confused with the concept of the quality of this coverage. In essence, network coverage is a radio signal. Radio signals tend to overlap. The superposition of radio signals leads to quality problems, interference occurs. Subscribers feel this as "metallization" in the voice of the interlocutor, breaks in calls, squeaks, noises, and dropouts.

Interference can be intra-system and extra-system. In the first case, the operator's engineers must plan the network very carefully to avoid interference.

In the case of 2G, it is necessary to separate the frequencies as much as possible so that they do not have an interference effect. In a 3G network (where there are three channels and three frequencies, and all three of them are repeated, but they share codes), it is important output power equipment. If it is too large, and several signals are mixed at one point, then it will be very difficult for the system to distinguish one from the other, and the connection at this point will turn into a vinaigrette. Given that each azimuth gives out three frequencies, and the neighboring base station also gives, the task of the operator's team is to zone the coverage from these base stations so that 8 or 10 sectors with a sufficiently strong signal do not appear at one point. But such interferences are not very scary, since they can be affected by the operator's command.

Read also:

By the way, the 900th frequency does not affect the 1800th, the 1800th frequency does not affect the 2100th and 900th.

Extra-system interference is caused by industrial radiation. For example, radar. The equipment may operate in a different frequency sector, but have such a strong signal that the attenuation from it affects the neighbors.

In this case, operators can use a special additional filter that "chokes" other people's signals. In the receiving part of the call, it is difficult to influence something, but in the transmitting part it is possible.

At the moment, 3G frequencies in Ukraine are distributed as follows: lifecell, 3mob, Vodafone, Kyivstar, the mysterious First Investment Union, hereinafter - Intertelecom, which builds LTE stations in the CDMA standard.

“We specifically chose the cleanest lot at the tender, and so far we do not feel the influence of the “neighbors” on our network,” describes the situation with the lifecell 3G network Yuri Grigoriev, Head of the Mobile Network Operations Department of the Central Region. “We had to use additional filters in the 900 band on the 2G network, but this is not necessary in 3G.” In the case of lifecell, this is due to “quiet neighbors”. The 3mob network has not been developed for a long time, and there are already rumors that it will completely depart from Vodafone. Other operators have a risk of influencing each other's networks (but there are several players, it seems that over the years of existence, everyone has already learned to live together and negotiate.

Thanks for the visual infographics to our colleagues from delo.ua. It shows which of the operators assigned to which frequencies of the spectrum.

Also, the quality of the network is affected by the number of base stations, there should be enough of them.

Network quality indicators:

• disconnected calls - measured as a percentage of the number of successful calls (now operators are fighting to improve performance by hundredths of a percent, in rural areas they are more than average, because the stations are farther from each other, in the city there are much fewer);
• unnatural voice ("metallic") or poor hearing;
• busy network (it is also considered as a percentage of the ratio of call requests to successful calls, there should be no more than 2% of such calls, but in fact there are fewer, thousandths of a percent).

If you imagine how the operator measures the percentage of network breaks or imperfect calls quite simply, then the sound quality is a more subjective parameter and is not always noticeable even for the subscriber himself. The operator will not listen to all your conversations!

Operators count the percentage of "drops" of bits. There are several calculation methods, the most popular is the Mean Opinion Score (however, judging by the description of this method on Wikipedia, the human factor is still present in it), it allows you to assess that even if there is a network and other factors contributing to good communication, there is interference.

The capacity of the network in normal times is calculated on the fact that it is used by a certain number of people. But there is also a seasonality factor, when people from cities massively go to the sea or to the mountains. Or a factor of large-scale events. For example, a big concert, football or other mass gathering of people. Wherever there are many times more users than usual, the load on the network increases significantly. Operators monitor such events as well, and they have a number of measures aimed at temporarily increasing network capacity in a particular location. such as mobile base stations. They are of local action, although the standard allows you to “turn around” up to 30 kilometers, if you raise the antenna higher and put it more profitably. But at local events, such a task is not worth it, the main thing here is to provide capacity for a large number of subscribers gathered in one place.

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“We try to follow all the key mass events of the country and prepare for them in advance. If we did not do this, then subscribers would have missed calls due to network congestion. About 8 years ago we bought additional mobile base stations. I don't know if you've been paying attention or not, but there may be minibuses nearby at the big outdoor concerts in the city. The capacity for which mobile station can increase the network, depends on our planning, more precisely, on how many people we will count on it. For example, in the fan zone of the Euro 2012 championship, we placed 3 such stations, where the infrastructure was deployed. The base station is inside. There is special equipment on the car that transmits data to a neighboring cell, from there to the network, ”says about mobile solutions Yuri Grigoriev, head of the mobile network operation department of the lifecell Central region.

Deployment of a mobile base station takes approximately eight hours with all the complexities that may arise along the way (for example, a specific architecture).

If there are no nuances with urban development, then 3-4 hours are enough for preparation.

For seasonal factors, operators also have a large amount of "mobile" equipment. Stationary stations are being expanded, additional transmitters are being installed, equipment is brought to them, and it is also installed for stationary life for three months, for example, in summer, the network configuration is changing. In autumn, the equipment is taken away, and it begins its nomadic life in the cities of the country, where “City Days” are massively held. In winter, the locations of the greatest demand change again. The main thing is to keep the equipment idle as little as possible.

In the 2G network, operators have always had the priority of voice over data transmission. Therefore, if the network was congested in a certain place, it was more difficult to download something from the Internet. The reason is simple - the transmission of data packets can wait or be slow, in background. Voice data cannot wait because people are talking to each other in real time. There is no need for priorities in the 3G network in Ukraine yet, the networks are still underloaded. As soon as we start using the mobile Internet more massively and actively (and this will not happen soon, because the operators built the network with a margin), voice will again take precedence over data.

What depends on the subscriber?

This is where the nuances with the network end and the nuances with the equipment begin, which we will analyze using the example of lifecell marketing communication. The company says that its subscribers can use 3G+ mobile Internet at speeds up to 63.3 Mbps. This operator's 3G advertisements indicate a different figure, 42.2 Mbps. Where do these speeds come from, who can get them and how?

As we already wrote, in terms of speed, the 3G standard is not very different from 4G, both can provide quite comfortable and fast work, the task of 4G is to increase capacity.

The most modern equipment used in the 3G network is capable of delivering speeds up to 63.3 Mbps due to the ability to aggregate channels.

Let me remind you that operators received three channels, each of which is capable of providing a data transfer rate of 21.1 Mbps. Accordingly, the aggregation of two channels gives a speed of 42.2 Mbps. Three channels - 63.3 Mbps.

Not all subscribers can get such a speed, even it is rather an exception that a person has a terminal in his hands that supports three-channel data transfer. In Turkey, the homeland of lifecell, the parent operator Turkcell sells branded smartphones that can handle the speed of 63.3 Mbps. For example, the Turkcell Turbo T50 model (nee - ZTE Blade X3) with good performance everything, including online. She is very popular. The Ukrainian lifecell network has a certain number of such terminals brought from abroad. But officially they are not delivered to us.