Despite the fact that LTE is already available in almost all regions of our country, users still have confusion in the frequencies (Bands), as well as in the categories of this technology (LTE cat. X). Today I would like to tell you in detail what are the differences between LTE “bands”, LTE categories, as well as which of them are already used in Russia and which may appear in the future.

LTE Bands - 4G technology frequencies

Unlike GSM and UMTS, which have become standards for 2G and 3G communications, LTE technology can use a much wider range of frequencies. So, for example, in GSM only 4 bands of 850 MHz, 900 MHz, 1800 MHz, 1900 MHz are used, and in UMTS, the bands 1900-2200 MHz are still added to them.

LTE technology, in turn, can operate at frequencies from ultra-low at 450 MHz to ultra-high at 5 GHz, and moreover, it can combine several bands into one channel using LTE Advanced technology, but we will talk about it a little later.

There are 70 LTE bands in total, which differ in frequency and some other parameters, but today I will focus only on those that are used in Russia.

At the moment, Russian operators use 5 band "s:

• 3 in the range of 1800 MHz FDD;
• 7 in the range of 2600 MHz FDD;
• 20 in the range of 800 MHz FDD;
• 31 in the 450 MHz FDD band;
• 38 in the range of 2600 MHz TDD.

You may have noticed that despite the same frequency range of 2600 MHz in the 7th and 38th band, they differ in the designations FDD and TDD. Now I’ll try to explain what the difference is.

In general, the end user may not even notice this difference, however, technologically the FDD and TDD networks are fundamentally different here. When using FDD (Frequency Division Duplex), incoming and outgoing traffic are separated by frequency, that is, data is downloaded at one frequency, and unloaded at another. When using TDD (Time Division Duplex), both loading and unloading of data is carried out at the same frequency, only alternately.

From the point of view of the operator, it is more profitable to have a TDD network, since it needs only 1 frequency range for both download and upload. From the user's point of view, it is theoretically more profitable to work in the FDD network, since the upstream and downstream traffic go separately and do not interfere with each other. But in practice, as I noted earlier, the difference will be more imperceptible.

As for the differences between the other bands, here it is worth noting their range, penetration and capacity. If you do not go into details, the lower the frequency, the higher the range and the better the property of passing through urban areas, but the network capacity itself and, accordingly, less speed in it.

Band 31 in Russia is currently only used by the Tele2 operator, which sells LTE-450 equipment under the Skylink brand. According to the operator himself, this technology is popular in the most remote and sparsely populated areas with poor coverage of other mobile networks. The range of the LTE-450 base station can cover a radius of up to 20 km, which is 5-6 times larger than the base station of the LTE-2600 standard. It should be noted that this band is not supported by smartphones, only special modems and routers work with it.

The Big Three widely uses 3, 7, 20, and 38 bands in Russia, and combines them depending on several factors. The higher the population density and activity, the higher the frequency is required, since it is necessary to ensure high capacity and good speed . In the centers of megacities, in business districts, in places with high tourist activity, as a rule, 3, 7 and 38 band's are used. In regions where population density and infrastructure investment are lower, Band 20 is used, since the base station can cover a fairly large radius (up to 13.4 km) with good penetration into buildings, while the speed does not suffer, since there is much fewer users who need LTE. But mainly band20 is used either in absolutely sparsely populated areas, or in large cities as an additional range. That is, even if your device does not support band20, you will not be left without 4G, since the territory will additionally cover band 3-7-38.

There is another important factor - the presence of certain frequencies in certain regions of certain operators. Here, the operator adjusts not only to the specifics of the location, but also to his portfolio of frequencies. The frequencies themselves were played among operators at auctions that were held in our country several times.

It is also worth noting that Band 3, operating in the 1800 MHz band, is also the frequency at which 2G / 3G communication works. That is, the wider the channel the operator wants to give for LTE, the narrower it will become for 2G / 3G networks, which most Russian subscribers continue to use. Naturally, it’s too early to talk about significant refactoring of 1800 MHz networks, but this is an inevitable future, because the share of 2G / 3G gadgets in relation to 4G devices will gradually decrease.

LTE-Advanced or what will happen if you combine several Band's

When it comes to LTE Advanced, there are often notations like LTE cat.4, LTE cat.6, or LTE cat in the text. 9. Let's try to figure out what they mean, but first, what is called “on the fingers,” I will explain what LTE Advanced is in general terms.

LTE Advanced is a technology that allows you to combine several carrier frequency bands into one channel. So, for example, an operator who uses LTE Advanced takes 1.4-20 MHz from one band, combines them into one “tube” from 1.4-20 MHz from another band and the output is the aggregated LTE Advanced standard. Today, it is theoretically possible to combine 5 carriers with a maximum bandwidth of 20 MHz, which gives an impressive 100 MHz at the output, but this is only a theory. Now let's see what happens in practice.

The first operator in Russia to use LTE Advanced on its network was Yota, while still an independent operator. It happened on October 9, 2012, but the operator was so far ahead of time that the launch was formal, since there were no modems with LTE Advanced support then, and Yota did not offer SIM cards for smartphones and tablets.

The first commercial launch was made by MegaFon in the spring of 2014. In Moscow and St. Petersburg, the operator combined two 20 MHz carriers in Band 7, obtaining a theoretically available 300 Mbps and a network corresponding to the LTE cat category. 6.

In 2015, MegaFon swung at the LTE cat. 9 at a speed of up to 450 Mbit / s, which combined 2 carriers of 20 MHz from Band 7 and another carrier with a width of 20 MHz from Band 3. However, things did not go further than testing, since to use such a large channel width in Band 3 ( 1800 MHz) it was required to significantly reduce the capacity of the operator's 2G network.

Beeline, unlike MegaFon, does not have a large number of available frequencies, so its launch of LTE Advanced turned out to be somewhat more modest. At the end of the summer of 2014 in Moscow, the “striped” operator combined Band 7 and Band 20 with a width of 10 MHz and 5 MHz, respectively, obtaining the maximum possible speed of 112.5 Mbit / s and a network corresponding to the LTE cat category. 4. After that, during the tests, the operator added a third carrier in 20 MHz from Band 3, having reached 250 Mb / s maximum speed, but such a network was not put into commercial operation. The thing is that 20 MHz in the 1800 MHz band is the entire available Beeline band used by the GSM network, and its refactoring in 4G would lead to a threefold reduction in the capacity of the existing 2G network.

MTS, in turn, launched the first LTE Advanced network in mid-2015, combining 2 5 MHz bands from Band 3 and 1 5 MHz band from Band 38, which became a problem for most nettop smartphones, since the aggregation of unequal spectrum bands in different ranges only flagship devices are supported. But in MTS, depending on the region, another aggregation is used, which is supported by a more extensive range of gadgets.

Today, MTS has the fastest network in Bashkortostan, where aggregation of three carriers 1800 + 2600 + 800 MHz with a total bandwidth of up to 35 MHz (20 + 10 + 5) is used, which allows reaching speeds up to 260 Mbps. But such a network, despite three carriers, corresponds only to the LTE cat category. 4., since the speed does not reach 300 Mbps.

To learn more about which operator in your region is already working in LTE Advanced, enter the query "LTE Advanced in [your city]" in the Google or Yandex search box and you will surely find news that will answer this question. If you don’t find how it was with me (Kursk), then no one has launched such a network in your region. As for coverage maps on operator’s websites, only MegaFon provides information on LTE Advanced so far.

As can be seen from all of the above, MegaFon has an advantage in frequencies and successfully uses it. Other operators, having a more modest portfolio of frequencies, are eyeing the LTE-U (LTE Unlicensed) standard, which I will discuss below.

LTE-U - the future without licenses, but with limitations

As I mentioned earlier, LTE technology is unique in that it can work in different ranges from ultra-low to ultra-high, including in the 5 GHz band. This frequency is not licensed, that is, uncontrolled by the state, and modern Wi-Fi routers work on it.

LTE-U (Unlicensed) is a mixture of the usual Wi-Fi and fourth-generation mobile network, moreover, compatible with each other. The bottleneck of LTE-U, like Wi-Fi, is the small range of the base station, which makes this technology suitable only for indoor use, for example, in office buildings and shopping centers. But the unlicensed 5 GHz is a plus of the technology, since the operator can establish its base stations and cover any premises with the LTE-U network without additional approvals in government agencies.

LTE-U does not exist separately, but as an addition to LTE and LTE-Advanced, that is, the user device can simultaneously work in several LTE band-s using LTE-A and at the same time use LTE-U resources, combining all networks into a single channel, which allows to reach peak speeds at the level of 1 Gbit / s.

Moreover, Link Aggregation technology is supported, with which you can add speed to your smartphone using home Wi-Fi. That is, being at home, using LTE-U, you can combine the operator’s LTE network and home Wi-Fi into a single LTE Unlicensed network, which will use all of the above channels at the same time for data transfer.

At the moment, interest in LTE-U has been expressed by Beeline and MTS, who plan to deploy the first LTE-U networks already this 2017. But there are no smartphones on the market that support this technology, although soon such devices should go on sale. It is worth noting that Russia is not lagging behind other countries, since the world has not yet launched any LTE Unlicensed networks.

Conclusion

Today you learned about the basic terms associated with fourth-generation networks, as well as about the situation with LTE in Russia. I hope that I managed to explain such complex things in simple words. I note at the end that I deliberately did not delve into the theory and loaded you with unnecessary information that most would not be interested.

If you want to know anything else about Russian operators, their technologies and networks, you can leave your suggestion in the comments and, perhaps, I will talk about this in one of the following articles.

For some time, under the 4G label, operators have offered various data transfer technologies, including WiMAX and HSPA +, to put it mildly, not meeting the requirements of the new standard. Wanting to put everything in its place and stop attempts to mislead consumers, the International Telecommunication Union in 2012 officially assigned 4G status to the standard 4g LTE Advanced. This is the initial step towards real goals - 100 Mbit / s bandwidth for mobile devices, 1 Gbit / s - for stationary. And the developers are working to improve the characteristics of LTE-A up to a download speed of 1200 Mbps, which is available for the category of mobile devices LTE cat 8. However, while this is only theoretically.

Categories are needed to make sure that the base station can correctly interact with the user equipment receiving the signal. Based on the signal from the receiver, indicating the class of UE, the distribution equipment determines the bandwidth of the communication channel and automatically selects the optimal data transfer mode.

In addition to speed characteristics, categories also differ in other indicators. For instance, LTE cat 1does not support MIMO technology, but standards with LTE cat 2by   LTE category 4combined with a 2x2 configuration.   LTE category 5  Designed for 4x4 MIMO. Standards in turn 4g cat 6 and LTE cat 7compatible with both the first and second types of antennas. The most promising project in the above list is LTE category 8, which is theoretically capable of providing downloading data from the Internet at a speed of 1200 Mbps and downloading it - 600 megabits. Expected to work with 4g cat 8subscribers will use 8-channel MIMO 8x8 antennas.

LTE category 0

In addition to the standard classes from 1 to 8, it is worth mentioning the so-called zero category separately 4gLTE advanced. Peak speeds of downstream and upstream signals are 1 Mbps, and this is more than enough for the Internet of Things to work. We are talking about the exchange of data between M2M machines: refrigerators, cars, washing machines and various automated systems. Energy saving comes to the fore in this segment, which can hardly be overestimated when establishing communication with battery-powered automatic machines and alternative power sources that are remote from power lines. Connection to the "web" is carried out only periodically, and the required data transfer rate by today's standards is negligible. As a result, advantagesLTE cat 0  replenished with a factor of constructive simplicity of the modem, which is lighter and more compact than the terminal LTE cat 1about 50%.

Among the most common terminals in the hands of the mass consumer 4gLTE advanced  should be attributed LTE cat 3and   LTE cat 4.  At the same time, the USA and Western Europe also have a high concentration of category 0 receivers. Despite the great potential, LTE cat 8as well LTE cat 7,not yet used in practice. The main guideline of the largest global market operators is 4g cat 6.

BenefitsLTE 4g cat 6in comparison with LTE cat 3

Introducing the latest standard LTE category 6 will significantly increase not only the data transfer rate, but also the bandwidth of the networks. LTE cat 6makes it possible to download files at a speed of 300 Mbps, which is three times more than in the case LTE cat 3.  Support for the sixth category opens the door to four-channel 4x4 MIMO technology. With full arrival LTE cat 6  users can easily exchange data, including such "heavy" elements, such as virtual reality files.

Good day to all who are interested in this article! Today we will tell you about which LTE bands in Russia are used by mobile operators and which of them occupies leading positions, we will talk about the features of LTE, as well as explain what “band” is and why it is needed.

Let's not linger, let's get down to the main part of the article as soon as possible.

A few words about Long-Term Evolution and global performance

This is how the abbreviation LTE is deciphered. And it translates as "long-term evolution, long-term development." However, we are accustomed to call this technology 4G LTE or just 4G.

LTE is the modern standard for high-speed and wireless data transmission for smartphones and other devices. Today, in the developed countries of the world, the standard under discussion is no longer an innovation that surprises with its speed.

So, for 2016, according to statistics compiled by OpenSignal, the five countries with the best 4G LTE coverage include:

1. 95.7% - South Korea;
2. 92% - Japan;
3. 84.7% - Lithuania;
4. 84.5% - Hong Kong;
5. 84.1% - the Netherlands.

And in the top five “nimble” states were:

1. 50 Mbps - Singapore;
2. 46 Mbps - South Korea;
3. 40.6 Mbps - Hungary;
4. 35.6 Mbps - Romania;
5. 35 Mbps - New Zealand.

Let's get back to the technology itself. The reason for the appearance of this type of standard was the developers' goal to increase the speed and throughput of networks using a new method of modulation and digital signal processing, as well as to simplify the architecture of networks working with IP addresses.

Detailed overview of the functioning of the standard

The 4G LTE specification can provide download speeds of up to almost 173 Mbps and data download speeds of up to approximately 326 Mbps! However, the maximum speed of information transfer in different countries, regions, cities and other settlements differs depending on the distance from the station and radio frequency.

As for the bands, the 1800 MHz band is mainly used in the world.

Interestingly, the described standard is of two types: FDD and TDD.

Frequency Division Duplex, which means “frequency division of channels”, gives up part of the traffic for downloading, and the second part for sending data. This ensures parallelism, i.e. simultaneous work in two directions.

And in Time Division Duplex ("temporary division of the channel") the channel is either completely given up for sending information, or completely for downloading.

Now let's talk about the frequency. LTE networks are not compatible with 2G and 3G networks. Therefore, separate frequencies are allocated for them, which should catch and support your mobile phones. Certain frequency ranges are allocated into 4G LTE bands and are called bands with the addition of a serial number.

For example, band 7 for FDD download corresponds to the range 2620-2690, and for unloading - 2500-2570.

LTE in the Russian Federation

Well, now we decided to tell you about the situation in Russia.

As for the named state, the coverage percentage almost reaches 70%, however 4G LTE does not work in all regions and not at full capacity. In some localities, this network covers only administrative centers.

However, Russian mobile operators are actively expanding their coverage areas and are tirelessly participating in auctions for the sale of 4G frequencies. Due to this, for 2017, the LTE specification successfully operates a little more than in 80 regions.

Now let's look at the ranges and frequencies.

In the Russian Federation, the standard operates in the ranges of 800 MHz, 1800 MHz and 2600 MHz. And popular bands (band), as in Europe, are band 3, band 7, band 20.

The "Big Five" of Russian mobile operators that provide their customers with 4G LTE include:

1. Yota - uses band 7 and provides a channel width of 2 × 30 MHz;
2. Megaphone - uses band 7, 20, the maximum channel width is 2 × 10 MHz;
3. MTS - uses all four LTE bands, the maximum channel width is 2 × 10 MHz;
4. Beeline - in the arsenal of band 7 and band 20, and the channel width reaches 2 × 10 MHz;
5. Tele2 - everything also uses bands 20 and 7, the maximum width is 2 × 10 MHz.

All networks are FDD.

It should also be noted that not all smartphones catch a similar network. The best devices that support 4G LTE are iPhone 6s, iPhone 5, 5s and 7th generation models.

So we told you all about the LTE standard and its development in Russia.

We hope that you have learned a lot of interesting and new things. We are waiting for you among the blog subscribers, and also do not forget to join our groups in popular social networks and services: Vkontakte, Facebook, Twitter and Youtube  . See you soon!

Regards, team site

The LTE network has recently been approved by the 3GPP consortium. Thanks to the use of such a radio interface, it is possible to obtain a network with unprecedented operational parameters in terms of the maximum speed at which data is transmitted, the delay time when sending packets, and also the spectral efficiency. The authors say that the launch of the LTE network allows for more flexible use of the radio spectrum, multi-antenna technology, channel adaptation, scheduling mechanisms, organizing data retransmission and power control.

Background

Mobile broadband, which is based on the technology of transmitting high-speed data packets according to the HSPA standard, has already become quite widely recognized by users of cellular networks. However, it is necessary to further improve their services, for example, by using an increase in the speed of data transmission, minimizing the delay time, and also increasing the overall network capacity, as the requirements of users for such communication services are constantly increasing. It was for this purpose that the specification of the HSPA Evolution radio interfaces and the LTE consortium 3GPP was made.

Major differences from earlier versions

The LTE network differs from the previously developed 3G system in improved technical characteristics, including the maximum speed at which information is transmitted - more than 300 megabits per second, packet transfer delay does not exceed 10 milliseconds, and the spectral efficiency has become much higher. The construction of LTE networks can be carried out both in the new frequency bands, as well as in the operators' existing ones.

This radio interface is positioned as a solution to which operators will gradually switch from the standard systems that currently exist, such as 3GPP and 3GPP2. And the development of this interface is an important stage in the formation of the IMT-Advanced standard for 4G networks, that is, a new generation. In fact, the LTE specification already contains most of the features that were originally intended for 4G systems.

The principle of organization of the radio interface

Radio communication has a characteristic feature, which consists in the fact that the radio channel in quality is not constant in time and space, but depends on the frequency. Here it must be said that the communication parameters change relatively quickly as a result of multipath propagation of radio waves. In order to maintain a constant speed of information exchange over the radio channel, a number of methods are usually used to minimize such changes, namely, various methods of diversity transmission. At the same time, in the process of transmitting information packets, users may not always notice short-term bit rate fluctuations. The LTE network mode assumes as a basic principle of radio access not reduction, but the use of rapid changes in the quality of the radio channel in order to ensure the most efficient use of the radio resources available at any given time. This is implemented in the frequency and time domains through OFDM radio access technology.

LTE network device

What kind of system can be understood only by understanding how it is organized. It is based on the conventional OFDM technology, involving several narrowband subcarriers. The use of the latter in combination with a cyclic prefix makes it possible to make OFDM-based communications resistant to temporary dispersions of radio channel parameters, and also makes it possible to virtually eliminate the need for complex equalizers on the receiving side. This circumstance turns out to be very useful for the organization of a downward channel, since in this case it is possible to simplify the processing of signals by the receiver at the main frequency, which reduces the cost of the terminal device itself, as well as the power consumed by it. And this becomes especially important when using a 4G LTE network along with multi-stream transmission.

The upstream channel, where the radiated power is significantly lower than in the downstream, requires the mandatory inclusion of an energy-efficient method of transmitting information to increase the coverage area, reduce the receiving device, as well as its cost. The studies have led to the fact that now for the LTE uplink, a single-frequency technology of transmitting information in the form of OFDM with dispersion corresponding to the discrete law is used. terminal device design.

The basic resource used in transmitting information in accordance with ODFM technology can be demonstrated as a time-frequency network, which corresponds to a set of OFDM symbols, and subcarriers in the time and frequency domains. The LTE network mode assumes that two resource blocks are used here as the main element of data transmission, which correspond to a frequency band of 180 kilohertz and a time interval of one millisecond. A wide range of speeds for data transmission can be realized by combining frequency resources, adjusting communication parameters, including the coding rate and the choice of modulation order.

Specifications

If we consider the LTE network, what it is, it will become clear after some explanation. In order to achieve the high targets that are set for the radio interface of such a network, its developers organized a number of rather important points and functionality. Each of them will be described below with a detailed indication of what influence they have on such important indicators as network capacity, radio coverage, delay time and data transfer rate.

Radio spectrum flexibility

Legislation that applies in a given geographical region affects how mobile communications are organized. That is, they prescribe a radio spectrum allocated in different frequency ranges by unpaired or paired bands of different widths. Flexibility of use is one of the most important advantages of the LTE radio spectrum, which allows you to use it in different situations. The architecture of the LTE network allows not only working in different frequency ranges, but also using frequency bands having different widths: from 1.25 to 20 megahertz. In addition, such a system can operate in unpaired and paired frequency bands, supporting time and frequency duplex, respectively.

If we talk about terminal devices, then when using paired frequency bands, the device can operate in full-duplex or half-duplex mode. The second mode, in which the terminal receives and transmits data at different times and at different frequencies, is attractive because it significantly reduces the requirements set for the characteristics of the duplex filter. Thanks to this, it is possible to reduce the cost of terminal devices. In addition, it becomes possible to introduce paired frequency bands with negligible duplex spacing. It turns out that LTE mobile networks can be organized with almost any distribution of the frequency spectrum.

The only problem with the development of radio access technology, which provides for the flexible use of the radio spectrum, is to make communication devices compatible. For this purpose, an identical frame structure is implemented in LTE technology in the case of using frequency bands of different widths and different duplex modes.

Multi Antenna Data Broadcast

The use of multi-antenna broadcasting in mobile communication systems can improve their technical characteristics, as well as expand their capabilities in terms of subscription services. Coverage of the LTE network involves the use of two methods of multi-antenna transmission: diversity and multi-threaded, as a special case of which the formation of a narrow radio beam is allocated. Spaced information can be considered as a way to equalize the signal level that comes from two antennas, which eliminates deep dips in the level of signals that are received from each antenna separately.

You can take a closer look at the LTE network: what is it and how does it use all of these modes? Diversity transmission here is based on the method of spatial-frequency coding of data blocks, which is supplemented by time diversity with frequency shift when using four antennas simultaneously. Diversity transmission is usually used on shared downlink channels where the scheduling function cannot be used depending on the state in which it is. Diversity transmission can be used to send user data, for example, VoIP traffic. Due to the relatively low intensity of such traffic, the additional overhead that is associated with the scheduling function mentioned earlier cannot be justified. Thanks to the diversity of data transmission, it is possible to increase the radius of cells and network capacity.

Multithreaded transmission for simultaneous transmission of a number of information streams over one radio channel involves the use of several receiving and transmitting antennas located in the terminal device and the base network station, respectively. This significantly increases the maximum speed of data translation. For example, if the terminal device is equipped with four antennas and such a quantity is available at the base station, then the simultaneous transmission of up to four data streams over one radio channel is quite realistic, which allows you to actually make its throughput four times larger.

If a network with a small workload or small cells is used, then thanks to multi-threaded transmission it will be possible to achieve a sufficiently high throughput for radio channels, as well as to efficiently use radio resources. If there are large cells and a load of a high degree of intensity, then the quality of the channel will not allow the use of transmission in multi-stream mode. In this case, the signal quality can be improved by using several transmitting antennas to form a narrow beam for data transmission in

If we consider the LTE network - what this gives it to achieve greater efficiency - then it’s worth concluding that for high-quality operation under various operating conditions, this technology implements adaptive multi-stream transmission, which allows you to constantly adjust the number of streams transmitted simultaneously, in accordance with a constantly changing the state of the communication channel. When the channel is in good condition, up to four data streams can be transmitted simultaneously, which allows achieving a transmission speed of up to 300 megabits per second with a frequency bandwidth of 20 megahertz.

If the condition of the channel is not so favorable, then fewer streams are transmitted. In this situation, antennas can be used to form a narrow radiation pattern, increasing the overall reception quality, which ultimately leads to an increase in system capacity and expansion of the served area. In order to provide extensive radio coverage areas or data transmission at high speed, it is possible to transmit a single data stream with a narrow beam or use diversity transmission of data on common channels.

Adaptation and scheduling mechanism of the communication channel

The principle of operation of LTE networks implies that scheduling will mean the distribution of network resources between users for data transmission. It provides for dynamic scheduling in the downstream and upstream channels. LTE networks in Russia are currently configured to balance the communication channels and the overall performance of the entire system.

The LTE radio interface assumes the implementation of a scheduling function, depending on the state of the communication channel. With its help, data is transmitted at high speeds, which is achieved through the use of high-order modulation, transmission of additional information streams, reducing the degree of coding of channels, as well as reducing the number of retransmissions. For this, frequency and relatively good communication conditions are involved. It turns out that the transfer of any specific amount of data is performed in a shorter period of time.

LTE networks in Russia, as in other countries, are built in such a way that traffic of services that are busy sending packets with a small payload after equal time intervals may necessitate an increase in the volume of signaling traffic that is required for dynamic scheduling. It may even exceed the amount of information broadcast by the user. That is why there is such a thing as static scheduling of an LTE network. What is it, it will become clear if we say that the user is allocated a radio frequency resource designed to transmit a specific number of subframes.

Thanks to adaptation mechanisms, it is possible to “squeeze everything possible” out of a channel with dynamic communication quality. It allows you to select a channel coding and modulation scheme in accordance with what communication conditions are characterized by LTE networks. What is it, it will become clear if we say that its operation affects the speed of data transmission, as well as the likelihood of any errors in the channel.

Power in the uplink and its regulation

This aspect concerns the control of the power level emitted by the terminals in order to increase the network capacity, improve communication quality, make the radio coverage area larger, and reduce energy consumption. To achieve these goals, power control mechanisms strive to maximize the level of the useful input signal while reducing radio interference.

Beeline LTE networks and other operators suggest that the signals in the uplink remain orthogonal, that is, there should be no mutual interference between users of the same cell, at least as far as ideal communication conditions are concerned. The level of interference that is created by users of neighboring cells depends on where the radiating terminal is located, that is, on how its signal decays on the way to the cell. The Megafon LTE network is designed exactly the same. It will be correct to say this: the closer the terminal is to a neighboring cell, the higher will be the level of interference that it creates in it. Terminals that are located at a greater distance from a neighboring cell are capable of transmitting signals of greater power in comparison with terminals located in close proximity to it.

Due to the orthogonality of the signals, the signals from terminals of different powers in the same channel on the same cell can be multiplexed in the uplink. This means that there is no need to compensate for signal level spikes that occur due to multipath propagation of radio waves, but they can be used to increase the speed of data transmission using adaptation mechanisms and scheduling communication channels.

Data relay

Almost any communication system, and LTE networks in Ukraine are no exception, from time to time makes mistakes in the process of sending data, for example, due to signal fading, interference or noise. Error protection is provided through retransmission techniques for lost or distorted pieces of information designed to guarantee high quality communications. The radio resource is used much more rationally if the data relay protocol is organized efficiently. To make the most of the high-speed radio interface, LTE technology has a dynamically efficient two-level data relay system that implements Hybrid ARQ. It is characterized by low overhead required to provide feedback and resend data, supplemented by a highly reliable selective retry protocol.

The HARQ protocol provides the receiver with redundant information, enabling it to correct any specific errors. HARQ relaying leads to the formation of additional information redundancy, which may be required when retransmission was not sufficient to eliminate errors. Relays of packets that have not been patched by the HARQ protocol are relayed using the ARQ protocol. The LTE networks on the iPhone operate in accordance with the above principles.

This solution allows you to guarantee a minimum delay in the transmission of packets with low overhead, while the reliability of communication is guaranteed. The HARQ protocol allows you to detect and correct most of the errors, which leads to a rather rare use of the ARQ protocol, as this involves considerable overhead, as well as an increase in the delay time for packet transmission.

It is the end node that supports both of these protocols, providing a close connection between the layers of these two protocols. Among the various advantages of this architecture can be called a high speed of eliminating errors that remained after HARQ, as well as an adjustable amount of information transmitted using the ARQ protocol.

The LTE air interface is high performance due to its main components. The flexibility of using the radio spectrum allows you to use this radio interface with any available frequency resource. LTE technology provides a number of features that enable the efficient application of rapidly changing communication conditions. Depending on the condition of the channel, the scheduling function provides the best resources to users. The use of multi-antenna technologies leads to a decrease in signal fading, and using channel adaptation mechanisms, signal coding and modulation methods can be used to guarantee optimal communication quality in specific conditions.

The terms LTE and 4G have long been heard and gradually become part of the vocabulary of a modern person, and with the advent of a new generation of Android smartphones and the release of iPhone 5, we just need to know more about this technology, just so that there is no confusion, well, for general development.

In this article we will try to give the simplest answers to the most popular questions about LTE.

What is LTE?

Developed by the 3GPP Long Term Evolution consortium (translated literally, “long-term development”), in the generally abbreviated version, LTE is the new standard for mobile networks with increased bandwidth and data transfer speed. LTE uses various frequencies, however, it operates on the basis of the GSM / HSPA networks used, in fact being their improved version. The term 4G, or “fourth-generation wireless communications,” is used synonymously with LTE, highlighting the differences between this standard and 3G. According to preliminary forecasts, by 2016, the total number of mobile broadband subscribers can reach 5 billion people.

How LTE (4G) differs from 3G

First of all, you need to understand that 4G LTE is an evolutionary rather than revolutionary way of development, involving the use of the existing infrastructure. 3G networks for a long time and with no less efficiency will fulfill the task of delivering broadband services to billions of mobile device users. But 4G, nevertheless, confidently prophesies the role of the generally accepted standard of mobile communications in view of a number of obvious advantages of 4G LTE technology, the main of which are:

• higher performance and throughput;
• simplicity - LTE supports flexible bandwidth options with a carrier frequency from 1.4 MHz to 20 MHz, as well as duplex data transmission with the possibility of separation by frequency (FDD) and time (TDD).
• latency - in LTE there is a significantly lower latency in data transfer for user plane protocols compared to existing third-generation technologies (an advantage is extremely important, for example, for servicing multi-user online games).
• a wide range of end devices - LTE-modules are planned to equip not only smartphones and tablets, but also laptops, game consoles, video cameras and other portable and household devices.

LTE speed

The capabilities of LTE technology provide data transfer rates of up to 299.6 Mbit / s for download (download) and up to 75.4 Mbit / s for upload (upload). However, in LTE, the speed in each case largely depends on both the user's location and the current load on the network. But LTE is evolving: two years ago, at the MWC-2010 congress, a possible peak bandwidth of up to 1.2 Gbps was demonstrated. Nevertheless, for example, in Singapore, where the national LTE coverage is provided by the M1 operator, the average download speed in LTE does not exceed 75 Mbps. In the near future, the company is going to increase the speed up to 150 Mbps by using the frequencies that are currently used to support the outdated 2G standard.

Why are LTE frequencies different in different countries?

Despite the fact that LTE is very actively developing all over the world, there is no single frequency range on which 4G operators work in different countries of the world. This is due to the fact that the radio frequency spectrum in many states is under the control of government structures, and the activities of operators are licensed. In different countries, certain frequencies are already used by other services (such as digital TV), because telecommunication companies have to use the ones that are currently available and wait for access to the new band, as is the case with Singaporean M1.

Most commonly used LTE frequencies

In Asian countries, this is 1800 MHz or 2600 MHz. It is at these frequencies that operators in Singapore, Hong Kong and South Korea operate. In Japan and the USA - 700 MHz or 2100 MHz. In Europe - 1800 MHz or 2600 MHz.

In Russia, Rostelecom (791-798.5 / 832-839.5 MHz, Band 20), MTS (798.5-806 / 839.5-847 MHz, Band 20), and Megafon (806-813.5 / 847) received LTE licenses. -854.5 MHz, Band 20) and VimpelCom (““) (813.5-821 / 854.5-862 MHz, Band 20), which will start providing 4G LTE services from July next year.

In Ukraine, LTE networks are just beginning to develop, and, according to experts, at least one and a half years will pass before its full commercial operation. The reasons for this lag are problems with regulation and licensing, as well as the insufficient capacity of the transport network.

Universal LTE smartphone?

There is no such device yet, since manufacturers have not yet developed such a compact antenna that could provide signal reception and transmission at least at the most popular LTE frequencies at the same time. Therefore, they say that iPhone 5 purchased in the States may not work in Asian and European LTE networks. But you still don’t really need to be upset, it always remains universal, available in all countries of the world. However, if we take into account the global tendency to shift telecom operators towards the LTE standard and the pace of release of previously occupied frequency ranges, then in the future we can expect the appearance of a common frequency range in different countries and regions of the world. So the problem of developing a universal LTE smartphone can be somewhat simplified and its creation is only a matter of time. Hopefully this will happen very soon.

4G LTE is expensive

Like the 3G standard at the time, the new 4G is also not yet very democratic in tariff setting. Cheap 4G LTE is not yet offered, because users have to pay more for speed and speed. However, truly LTE becomes expensive if you do not pay attention to the amount of downloaded or transmitted data.

LTE smartphones on sale

In addition to the mentioned iPhone 5, which Apple will start selling from September 21 this year, several other smartphones can work with LTE networks: HTC One XL, Samsung Galaxy S II LTE, LG Optimus True HD LTE and the Galaxy Note LTE. Also, LG Optimus G and Galaxy S3 LTE should appear on sale soon.

LTE Technology News

In our country, the 4G LTE standard is still only a prospect, but not the closest one. However, for those who often travel abroad, there are plenty of opportunities to experience all the benefits of LTE. The growing popularity of this communication standard is also evidenced by the fact that Apple’s new iPhone 5 is available in three different versions at once, each of which is designed for a specific range of LTE frequencies. So the model A1428 (GSM) iPhone 5 supports LTE only in the USA and Canada and operates at a frequency of 700MHz. Model A1429 (CDMA) is focused on the network of US operators Sprint and Verizon, as well as Japanese KDDI.

And, finally, the A1429 (GSM) iPhone 5 operates at frequencies of 850 MHz, 1800 MHz and 2100 MHz and is the most universal, since these frequencies are used for LTE communication in many countries of the world (except the USA and Canada). Apple support says the A1429 (GSM) is LTE compatible in Australia, Hong Kong, Germany, Korea, Japan, Singapore and the UK. In other words, this means that if you live in Ukraine and often visit Europe, then ordering iPhone 5 from other countries, choose A1429 (GSM). Accordingly, those who visit the United States more often should buy the A1428 (GSM) iPhone 5. Also, do not forget that such regional distinction applies only to the LTE-specific devices, in 3G networks each of them will work in any region of the planet.

Samsung may acquire Nokia Siemens Networks(August 3, 2012)
South Korean Samsung is exploring the possibility of acquiring one of the largest manufacturers of universal equipment for communications networks NSN. According to independent analysts and experts, the amount of this transaction may be fifty-five billion dollars. An NSN spokesman said Samsung’s leadership is interested in bulk deliveries and global production of equipment for unique wireless mobile networks.

It should be recalled that today there are not so many mobile companies capable of making this purchase in the world, and only Ericsson or Huawei could afford such an asset on the international market for operator equipment. However, such a financial transaction does not fit into Ericsson’s strategic policy, and the second corporation already has a similar infrastructure. It is worth mentioning that the Chinese corporation is considered as a potential buyer of NSN. As for the South Korean manufacturer of mobile equipment, Samsung previously produced branded stations for the WiMAX model, but this service has lost the leading position in the innovative LTE technology.