The presence of lte. VoLTE support by operator

Cellular networks of the GSM standard by their structure were not originally intended for mobile internet... Accordingly, nowadays, mobile operators are forced to invest huge amounts of money in the modernization of their networks to 3G (UMTS), and now to 4G (LTE) in order to meet the needs of the population. Of course, these investments are generously borrowed from our pockets by cellular companies, but their work is also not very easy.

Now, when the introduction of third generation networks has not yet been completed in Russia, operators have already begun work on the next generation networks - 4G or LTE.

In the photo, the first LTE base station from Yota in Sochi:

The term LTE itself stands for Long Term Evolution and translated into Russian means "long-term evolution". For a long time, the WiMAX standard claimed the role of 4G communication, but was later relegated to the background as a less popular option for fast wireless Internet.

LTE is the next generation of mobile communications after 3G and operates on the basis of IP technologies. The main difference between LTE and its predecessors is its high data transfer rate. In theory, it is up to 326.4 Mbps for download and 172.8 Mbps for uploading information. At the same time, the international standard indicates the numbers in 173 and 58 Mbit / s, respectively. This fourth generation communication standard was developed and approved by the 3GPP International Partnership.

Latest generation coding system - OFDM

Let's see what is main feature LTE standard. As well as in 3G networks, the OFDM-MIMO technology of coding and data transmission can be called the main link in LTE.

OFDM stands for Orthogonal Frequency-division Multiplexing and in Russian means orthogonal frequency division multiplexing. It is a digital modulation scheme using large numbers of closely spaced orthogonal subcarriers. All subcarriers are modeled with a standard modulation scheme such as low symbol rate IAM while maintaining the overall data rate as with simple single carrier modulation schemes in the same bandwidth. In fact, OFDM signals are generated by applying the "Fast Fourier Transform".

This technology describes the direction of the signal from the base station (BS) to your mobile phone... As for the return path of the signal, i.e. from a telephone set to a base station, technical developers had to abandon the OFDM system and use another technology called SC-FDMA. In decoding, it reads as Single-carrier FDMA and in translation means multiplexing on one carrier. Its meaning is that when a large number of orthogonal subcarriers are added, a signal with a large crest factor (the ratio of the signal amplitude to its rms value) is formed. In order for such a signal to be transmitted without interference, a high-quality and rather expensive high-line transmitter is required.

It was this device that created some difficulties in obtaining a license on the territory of Russia for the LTE network. And, nevertheless, as usually happens in our country, despite the artificially created difficulties, the Ministry of Telecom and Mass Communications of Russia admitted promising direction development of cellular networks is precisely the LTE standard. However, when tendering for distribution, often 2.3 - 2.4 GHz in 40 regions Russian Federation by the radio access method, only OFDMA technology was indicated, which excludes, directly, LTE, since in the latter case, besides OFDMA, SC-FDMA is also required. This once again implies the complete incompetence of Russian officials in the issues they deal with.

MIMO- Multiple Input Multiple Output is a technology for transmitting data using N-antennas and receiving information using M-antennas. In this case, the receiving and transmitting antennas are spaced apart by such a distance to obtain a weak degree of correlation between adjacent antennas.

LTE position on the air

On this moment frequency bands are already reserved for 4G networks. Frequencies around 2.3 GHz are considered to be the highest priority. Here, the main example is China with its cellular operator China Mobile, which has already allocated the required frequency range and is conducting test broadcasting. Given the huge volume of local consumption of cellular communications, the use of this frequency is doomed to success and dominance in China.

Another promising frequency range - 2.5 GHz is used in the USA, Europe, Japan and India. There is also a frequency band in the 2.1 GHz region, but it is relatively small - only 15 MHz are available in the 2.1 GHz range, and most European mobile operators limit the bands in this range to 5 MHz. In the future, the 3.5 GHz frequency band is likely to be the most used. This is due to the fact that wireless broadband Internet access networks are already used on these frequencies in most countries, and thanks to the transition to LTE, operators will be able to reuse their frequencies without the need to purchase new expensive licenses. If necessary, other frequency ranges can be allocated for LTE networks.

With regard to the frequency bands used and the allocation methods in LTE, everything is rather incomprehensible and contradictory, since the standard itself is flexible enough. In different structures, fourth-generation networks can be based on frequency bands ranging from 1.4 to 20 MHz, as opposed to the fixed 5 MHz in 3G (UMTS). It is also possible to use both TDD (Time Division Duplex) and FDD (Frequency Division Duplex) frequency signals. For example, the LTE network being built in China, the TD-LTE standard.

The coverage area of ​​an LTE base station may vary. Usually it is about 5 km, but in some cases it can be increased to 30 or even 100 km, in the case of a high location of the antennas (sectors) of the base station.

Another positive difference of LTE is a large selection of terminals. In addition to cell phones Many other devices such as laptops, tablets, game devices and camcorders will be used on LTE networks with built-in LTE support. And since LTE technology has support for handover and roaming with cellular networks of previous generations, all these devices will be able to work in 2G / 3G networks.

Fourth generation network structure

The scheme of 4G (LTE) networks is as follows:

As can be seen from this diagram, LTE networks include 2.75G (EDGE) and 3G (UMTS) network modules. Because of this feature, the construction of fourth-generation networks will be quite specific and looks more like the next stage in the development of today's technologies, rather than something fundamentally new.

For example, in accordance with such a structure, a call or Internet session in the coverage area of ​​the LTE network can be transmitted without interrupting the connection to the 3G (UMTS) or 2G (GSM) network. In addition, LTE networks are fairly easy to integrate with WI-FI networks(designation WLAN Access NW in the above diagram) and the Internet.

Let's dwell on the radio access subsystem in more detail. In its structure, the radio access network RAN ​​- Radio Access Network - looks similar to the UTRAN UMTS, or eUTRAN, but has one addition: the transmit-receive antennas of the base stations are interconnected according to a specific X2 protocol, which unites them into a cellular network - Mesh Network - and makes it possible base stations to exchange data with each other directly, without using the RNC - Radio Network Controller.

In addition, base stations communicate with the MME - Mobility Management Entity - and the S-GW - Serving Gateway - through a “many-to-many” approach, which allows for high communication speeds with low latency.

LTE vs. WiMAX

Surely many of you wondered why the future lies in LTE? After all, literally a year or two ago, everyone considered WiMAX technology as a standard 4G, well known by such broadband wireless Internet providers as Yota and Comstar.

In reality, the LTE and WiMAX standards are quite close to each other. They both use OFDM coding technology and MIMO data transmission system. Both standards use FDD and TDD-duplexing with channel bandwidth up to 20 MHz. And both of the communication systems use IP as their protocol. Accordingly, both technologies in reality use their frequency range equally well and provide a comparable data transfer rate for Internet access. But, of course, they also have some differences.

One of these differences is the much simpler WiMAX network infrastructure, and therefore more technically reliable. This simplicity of the standard is ensured by its sole purpose for data transmission. On the other hand, LTE “complexities” are needed to ensure its compatibility with the standards of previous generations - GSM and 3G. And we certainly need this compatibility with you.

There are other details about the difference between LTE and WiMAX. For example, dispatching radio frequency resources. In WiMAX, it is produced using Frequency Diversity Scheduling technology, according to which the subcarriers provided to the subscriber are distributed over the entire channel spectrum. This is necessary to randomize and average the effect of frequency selective fading on the broadband channel.

LTE networks use a different technology to eliminate frequency selective fading. It is called Frequency Selective Scheduling. At the same time, for each subscriber station and each frequency block of the carrier, the channel quality indicators CQI - Channel Quality Indicator - are created.

Another very important point associated with the planning of communication networks of mass use - the frequency reuse factor. Its role is to show the efficiency of using the available radio frequency band for each base station separately.

The basic structure of the WiMAX frequency band reuse consists of 3 frequency channels. When using a three-sector configuration of sites (base stations of a certain frequency range), one of 3 frequency channels is implemented in each of the sectors. In this case, the frequency reuse factor is equal to 3. In other words, there is only a third of the radio frequency range at each point in space.

The LTE (4G) cellular network operates with a frequency reuse factor of 1. That is, it turns out that all LTE base stations operate on one carrier. Intra-system interference in such a system is minimized through frequency selective scheduling, flexible frequency planning, and interference coordination between individual cells. Subscribers at the center of each cell can be assigned resources from the entire free channel bandwidth, while users at the edges of the cells are assigned frequencies only from certain sub-bands.

The above features of LTE and WiMAX networks have a great impact on one of their main characteristics - the degree of radio coverage. Based on this parameter, it is determined required amount base stations for high-quality coverage of a specific area. Accordingly, it directly affects the final cost of building LTE networks.

According to the calculation, the LTE network is able to provide the best zone coverage with the same number of base stations, which is an undoubted advantage for all mobile operators.

Nowadays, the question LTE is often asked - what is it in a phone? Modern manufacturers of devices and equipment for mobile communications are preparing the industry for a new breakthrough - the transition to the 4G communication standard. The capabilities of this standard are fantastic. In theory, 4G will provide Internet speeds of up to 100 Mbps for mobile communications in motion and up to 1 Gbps for stationary ones. This is 100 times more possibilities modern format 3G. Leading manufacturers are already equipping 3G phones with support for the "next generation" standard - LTE communications.

LTE - what is it?

The introduction of a new mobile communication standard is not easy and not fast. The implementation of the two previous formats took a decade each. Work on 4G began in 2008, but now, when asked what LTE is, one can answer that this is the first stage in the development of the 4G format. This technology makes it possible to increase so far not 100, but 10 times, but this is only the first generation of the format. The technology is rapidly popularizing and is of interest to more and more users.

LTE and 4G - what's the difference?

It is still too early to say that the high bar set by the developers of the 4G communication standard will be overcome very soon. Apparently, there are still several years before the mass transition. But the first steps have already been taken, and they have shown serious advantages over 3G. Modern technology LTE stands for high download speeds on a mobile device, and a massive upgrade of the hardware that powers the wireless networks and their infrastructure. And this will allow in the near future to increase the possibility of data exchange without the use of wired networks.

LTE Benefits

The latest models of smartphones equipped with LTE technology provide the subscriber with the opportunity to use high-speed Internet. This transitional technology, in practice, provides 100 Mbps for receiving and 50 Mbps for uploading. It should be remembered that the actual indicators are always lower than the calculated ones - theoretical. High speed LTE provides users with the following features:

• carry out two-way video communication with high quality;
• watch videos online in FullHD format;
• use any service programs and much more.

How to connect LTE?

The latest iPhone models, starting with the iPhone 5, are equipped with an LTE module. The capabilities of the module are expanding in each new generation, and if for the iPhone 5, 5c, 5s the exchange rate was 100 Mbit / s, then in the iPhone 7, 7 Plus it is already 450 Mbit / s. In order to take advantage of this technology, the question must be answered - how to enable LTE. The instruction is simple and it looks like this:

1. In the Settings menu, select Cellular, then Data and Voice.
2. In the box opposite LTE, check the box. Select "Enable LTE" in the pop-up message window
3. It is convenient to use the free utility Speedtest to check the connection speed.

Why is LTE not working?

If the LTE module does not work, there may be several reasons for this. Often this problem occurs because there is no support for LTE coverage by your network operator. If these problems are at the software level, then you can deal with the problem yourself. First, go to Settings and check the connection. If the connection is successful, but the module does not work, you can try to solve the problem using the following algorithm:

1. Reset device settings and reboot. In this case, the service information will be updated, and the data, except for Wi - Fi passwords, will be deleted.
2. You will need to install the latest iOS update on your device.
3. Reboot the device again - Reset by holding the power button, then select "home" and hold it at the same time until the boot indicator lights up.

Technologies do not stand still, and this is especially noticeable in the segment of mobile devices and communications. New gadgets set higher standards and give rise to new needs and requirements, primarily in the quality of mobile communications and information transfer speed. One of the most interesting and promising areas today is the fourth generation of 4G communications, which, in theory, should provide an increased quality of voice communication and a much higher speed of work on the Internet.

How is 4G different from previous generations of communication?

To understand what are the differences and advantages of the LTE standard and whether there is any sense in a large-scale transition to 4G, you need to consider the key differences of this format from its predecessors, starting from the very first generation. This was analog communication, which was actively used until the end of the 90s. Huge by today's standards means of communication in special cases-suitcases with a total weight of up to 5-7 kilograms - they worked on this standard.

With the introduction of second generation communications, a revolution has taken place in the mobile market. Most ordinary users know this standard under the name GSM. Now you can connect to the Internet. The format remains popular and widely used today.

Third-generation communication has fundamentally changed the idea of ​​the speed of the network on mobile devices. There are several related to 3G wireless technologies, the most popular of which are the UMTS, EV-DO and CDMA2000 standards. In theory, the maximum download speed should be 21 Mbps. In practice, however, these figures rarely even reach 5 Mbit / s. Online video watching, of course, is not very comfortable, but for normal surfing on the Internet in most cases it is enough. Definitely faster than the same EDGE, and this, in the absence of an alternative, is very pleasing.

As for 4G, there is still no officially approved full-fledged network of this format in the world. In order for an authorized organization to officially "recognize" this protocol, it is necessary that it provide data transmission at incredible speeds compared to previous generations of communication: 100 Mbit / s for mobile electronics and 1 Gbit / s for stationary devices with Internet access. The most promising technologies, which, with a competent approach, have every chance of being called a full-fledged 4G, are WiMAX and LTE protocols.

Main features and characteristics of the LTE standard

The principle of LTE technology becomes well understood from the decoding of this abbreviation: "Long Term Evolution". In literary translation into Russian given expression means long-term development. The companies developing the standard take into account all the mistakes and failures of the transition from one communication format to another. As practice shows, the main problem is to ensure the compatibility of new technologies with old equipment and, of course, the costs required for a full transition.

In theory, LTE cells will be able to provide the highest quality communication at a distance of up to 100 km. This is especially true for hard-to-reach and sparsely populated areas. For comparison, the maximum for the most common communication format today is a distance of 30 km. That is, it will be much more profitable for cellular companies to install one 4G point than several 3G or GSM towers.

The new format should provide more high quality head connection. GSM and 3G networks transmit voice in a band up to 3.5 kHz, which is a rather modest indicator. Modern technologies will be able to transmit voice in a full-fledged mode, i.e. 20 Hz to 20 kHz. In practice, this should provide the most believable and realistic sound, as if the interlocutor is not talking on the phone, but is nearby.

Currently, specialists different countries active work is underway to improve and develop the communication format, specialists are gradually approaching the previously mentioned data transfer rates. At the moment, the maximum that has been achieved is 173 Mbps for downloading information from the network and 58 Mbps for uploading. In practice, these numbers are often reduced to 10 or more times, but even in such conditions, "defective" 4G confidently surpasses the speed of third-generation communications.

LTE is a wireless mobile communication standard that has received wide use in 2010 year. Replacing 3G, the new fourth generation standard marked the beginning of the era of truly fast and reliable mobile Internet. 4G allowed users, using smartphones, not only to easily open almost any sites, even loaded with a variety of content, but also to fully use Skype, view videos of any quality through them. The availability of a high-quality Internet connection of the fourth generation wireless mobile communication standard is based on the fact that 4G LTE uses orthogonal frequency control (in a radio channel), and at the network level is based on IP technologies.

4G LTE specifications and features

The carrier frequency of the bandwidth of 4G networks is in the region from 1.4 MHz to 20 MHz. Compared to the previous 3G standard, 4G LTE has lower latency in data transmission, which is an extremely important factor when exchanging significant volumes of media content.

Bandwidth

A distinctive feature of 4G LTE is the provision of a peak throughput of the return channel in excess of 100 Mbps. In theory, the fourth generation standard can provide internet speeds of up to 300 Mbps.

Work speed

The presence of an Internet speed of at least 100 Mbit / s, as well as the speed of more than 300 Mbit / s provided for by the standard, largely depends on the congestion of the networks and on the location of the subscriber. At the same time, the possible incoming Internet speed (LTE Advanced) can be up to 3 Gbps, and outgoing up to 1.5 Gbps.
Moving from LTE to LTE Advanced is easy. To do this, you just need to update software and change operator base stations.

Advantages

Support for 4G LTE networks by a smartphone will provide the user with low-cost traffic and reliability of the communication channel, provide a high throughput and will reduce delays.

Best 4G LTE smartphones

1. One of the best smartphones supporting 4G standard is Samsung Galaxy S4, which is the best-selling Android device. In addition, its smaller version (Mini) also retained LTE support, without reducing functionality and speed characteristics.
2. Another great 4G LTE smartphone is Htc one... The presence of a presentable look and powerful functionality is perfectly complemented by a fast and reliable LTE Internet.
3. Of the representatives of Nokia, an excellent model that supports the use of 4G networks is Nokia Lumia 925... This is one of the best smartphones running on operating system Windows. 4. One of best representatives in the smartphone market is certainly IPhone 6... The availability of 4G LTE networks, including for residents of Russia, along with powerful functionality, put it on a par with the most popular phones in the world.
5. It is worth noting such a business smartphone as BlackBerry Q10... Having slightly lost its position, it is still a very popular phone with support for 4G LTE network and having a QWERTY keyboard.