How 4g works. LTE networks: structure and operating principle. Selecting an operator and tariff

It's hard to believe, but once upon a time mobile phones were actually called "phones", not smartphones, not superphones... They fit into your pocket and can make calls. That's all. No social networks, messaging, uploading photos. They can't upload a 5MP photo to Flickr and they certainly can't turn into a wireless hotspot.

Of course, those dark days are far behind us, but as promising next-generation wireless high-speed data networks continue to emerge around the world, many things are starting to seem confusing. What is “4G”? It's higher than 3G, but does it mean it's better? Why are all four US national carriers suddenly calling their networks 4G? Answers to these questions require a short excursion into the history of the development of wireless technologies.

For starters, "G" stands for "generation," so when you hear someone refer to a "4G network," that means they're talking about a wireless network built on fourth-generation technology. Using the definition of “generation” in this context leads to all the confusion that we will try to sort out.

1G

The story begins with the emergence of several innovative network technologies in the 1980s: AMPS in the US and a combination of TACS and NMT in Europe. Although several generations of mobile phone services existed before, the trifecta of AMPS, TACS and NMT are considered the first generation (1G) because these technologies allowed mobile phones to become a mainstream product.

In the days of 1G, no one thought about data services - these were purely analogue systems, conceived and designed solely for voice calls and a few other modest capabilities. Modems existed, but because wireless communications are more susceptible to noise and distortion than conventional wired communications, data transfer rates were incredibly slow. In addition, the cost of a minute of conversation in the 80s was so high that a mobile phone could be considered a luxury.

Separately, I would like to mention the world’s first automatic mobile communication system “Altai”, which was launched in Moscow in 1963. "Altai" was supposed to become a full-fledged telephone installed in a car. You could simply talk on it, like on a regular telephone (i.e., the sound passed in both directions at the same time, the so-called duplex mode). To call another Altai or a regular phone, you just had to dial the number - like on a desk telephone, without any channel switching or conversations with the dispatcher. A similar system in the USA, IMTS (Improved Mobile Telephone Service), was launched in the pilot area a year later. And its commercial launch took place only in 1969. Meanwhile, in the USSR, by 1970, Altai was installed and was successfully operating in about 30 cities. By the way, in Voronezh and Novosibirsk the system is still in effect.

2G

The early 90s saw the rise of the first digital cellular networks, which had a number of advantages over analogue systems. Improved sound quality, greater security, increased performance - these are the main advantages. GSM began its development in Europe, while D-AMPS and Qualcomm's early version of CDMA started in the US.

These nascent 2G standards do not yet support their own tightly integrated data services. Many of these networks support short text messaging (SMS), as well as CSD technology, which allowed data to be transmitted digitally to the station. This effectively meant that you could transfer data faster - up to 14.4 kbps, which was comparable to the speed of landline modems in the mid-90s.

In order to initiate data transfer using CSD technology, it was necessary to make a special “call”. It was like a telephone modem - you were either connected to the network or not. Given that tariff plans at that time were measured in tens of minutes, and CSD was akin to an ordinary call, there was almost no practical use of the technology.

2.5G

The introduction of the General Packet Radio Service (GPRS) in 1997 was a turning point in the history of cellular communications because it offered continuous data transmission technology to existing GSM networks. With new technology, you can use data only when needed - no more stupid CSD like a phone modem. In addition, GPRS can operate at a higher speed than CSD - theoretically up to 100 kBit/s, and operators have the opportunity to charge traffic rather than time on the line.

GPRS appeared at a very opportune moment - when people began to continuously check their email accounts.

This innovation did not allow one to be added to the mobile generation. While GPRS technology was already on the market, the International Telecommunication Union (ITU) created a new standard - IMT-2000 - establishing the specifications for "real" 3G. The key point was to provide data transfer rates of 2 Mbit/s for fixed terminals and 384 kBit/s for mobile terminals, which was not possible with GPRS.

Thus, GPRS was stuck between generations of 2G, which it was superior to, and 3G, which it was not. This was the beginning of a generational split.

3G, 3.5G, 3.75G... and 2.75G too

In addition to the aforementioned data speed requirements, the 3G specifications called for easy migration from second-generation networks. To this end, a standard called UMTS became the top choice for GSM operators, and the CDMA2000 standard provided backward compatibility. Following the precedent of GPRS, the CDMA2000 standard offers its own continuous data transmission technology called 1xRTT. The confusing thing is that although CDMA2000 is officially a 3G standard, it provides data transfer speeds only slightly faster than GPRS - around 100 kBit/s.

The EDGE standard - Enhanced Data-rates for GSM Evolution - was conceived as an easy way for GSM network operators to squeeze extra juice out of 2.5G installations without investing heavily in hardware upgrades. With a phone that supported EDGE, you could get twice the speed of GPRS, which was pretty good for the time. Many European operators did not bother with EDGE and were committed to introducing UMTS.

So, where does EDGE belong? It's not as fast as UMTS or EV-DO, so you can tell it's not 3G. But it's clearly faster than GPRS, which means it must be better than 2.5G, right? Indeed, many people would call EDGE a 2.75G technology.

A decade later, CDMA2000 networks received an upgrade to EV-DO Revision A, which offers slightly higher downstream speeds and much faster upstream speeds. The original specification, called EV-DO Revision 0, capped outgoing speeds at 150 kBit/s, but the new version makes it ten times faster. Thus, we got 3.5G! The same for UMTS: HSDPA and HSUPA technologies made it possible to add speed for incoming and outgoing traffic.

Further enhancements to UMTS will use HSPA+, dual-carrier HSPA+, and HSPA+ Evolution, which will theoretically provide throughput from 14 Mbps to a staggering 600 Mbps. So, can we say that we have entered a new generation, or can it be called 3.75G by analogy with EDGE and 2.75G?

4G is a deception all around

Just as it did with the 3G standard, the ITU has taken control of 4G by tying it to a specification known as IMT-Advanced. The document calls for incoming data speeds of 1 Gbit/s for fixed terminals and 100 Mbit/s for mobile ones. This is 500 and 250 times faster compared to IMT-2000. These are truly enormous speeds that can outpace an ordinary DSL modem or even a direct connection to a broadband channel.

Wireless technologies play a key role in providing broadband access to rural areas. It is more cost-effective to build one 4G station that will provide communication over a distance of tens of kilometers than to cover farmland with a blanket of fiber optic lines.

Unfortunately, these specifications are so aggressive that no commercial standard in the world meets them. Historically, WiMAX and Long-Term Evolution (LTE), which are destined to achieve the same success as CDMA2000 and GSM, have been considered fourth generation technologies, but this is only partly true: they both use new, extremely efficient multiplexing schemes (OFDMA, in unlike the old CDMA or TDMA that we have been using for the last twenty years) and they both lack a voice channel. 100 percent of their capacity is used for data services. This means that voice transmission will be treated as VoIP. Considering how data-centric modern mobile society is, this can be considered a good solution.

Where WiMAX and LTE fail is in data transfer speeds, their theoretical values ​​are at the level of 40 Mbit/s and 100 Mbit/s, and in practice, real-world speeds of commercial networks do not exceed 4 Mbit/s and 30 Mbit/s accordingly, which in itself is very good, but does not meet the high goals of IMT-Advanced. Updating these standards - WiMAX 2 and LTE-Advanced promise to do this job, but it is still not complete and there are still no real networks that use them.

However, it can be argued that the original WiMAX and LTE standards are sufficiently different from the classic 3G standards to warrant a generational shift. Indeed, most operators around the world that have deployed such networks call them 4G. Obviously this is being used as marketing and the ITU has no power to counter it. Both technologies (LTE in particular) will soon be deployed by many telecom operators around the world over the next few years, and the use of the "4G" name will only increase.

And that's not the end of the story. US operator T-Mobile, which has not announced its intention to upgrade its HSPA network to LTE any time soon, has decided to start branding the upgrade to HSPA+ as 4G. In principle, this move makes sense: 3G technology could eventually reach speeds faster than just LTE, approaching IMT-Advanced requirements. There are many markets where T-Mobile's HSPA+ network is faster than Sprint's WiMAX. And neither Sprint, Verizon, nor MetroPCS - the three US carriers with live WiMAX/LTE networks - offer VoIP services. They continue to use their 3G frequencies for voice and will continue to do so for some time. Plus, T-Mobile is going to upgrade to 42Mbps speeds this year without even touching LTE!

It may be this move by T-Mobile that has sparked a global rethink of what "4G" actually means among cell phone buyers. AT&T, which is in the process of transitioning to HSPA+ and will begin offering LTE in some markets later this year, calls both of these networks 4G. So all four US national carriers stole the "4G" name from the ITU - they took it, ran with it, and changed it.

conclusions

So, what does all this give us? Operators appear to have won this battle: the ITU recently backtracked, saying the term 4G "can be applied to the technology's predecessors, LTE and WiMAX, as well as other evolved 3G technologies that provide significant improvements in performance and capabilities over the initial third-generation system." . And in some ways we think that's fair - no one would argue that the so-called "4G" networks of today resemble the 3G networks of 2001. We can stream very high quality video, download large files in the blink of an eye, and even, under certain conditions, use some of these networks as a replacement for DSL. Sounds like a generational leap!

It is not known whether WiMAX 2 and LTE-Advanced will be called "4G" by the time they become available, but I think not - the capabilities of these networks will be very different from the 4G networks that exist today. And let's be honest: Marketing departments have no shortage of generational names.

UPDATE: Added information about the Altai mobile communication system.

Let's figure out what LTE is in a smartphone, and how it differs from the usual 3G. What data transmission technologies do fourth generation networks offer, and what will this give to users?

What is LTE

Many smartphones support LTE, but not all users yet know what this means.

LTE (literally from English. Long-Term Evolution- long-term development, often referred to as 4G LTE) – a communication standard for fast wireless transmission of information in any volume. Designed for smartphones and other mobile devices that require a high-speed Internet connection.

The standard is an intermediate step in the transition from 3G to 4G. Connecting to such a network significantly increases the data transfer speed of both downloading and uploading. But despite this, it does not reach the technical characteristics adopted for the next fourth generation of communications.

Data transmission technology

The new generation network provides connection speeds of up to 100 Mbit/s (theoretically maximum speed). In reality it is an order of magnitude lower, the technology is still significantly ahead of the previous standard. It is based on MIMO packet data transmission and OFDM coding system. Thanks to the distribution of transmitting antennas, correlation dependence is completely eliminated. In different countries, communication operates on different bands. Even different telecom operators within a country often use different frequency bands.

Comparison with 3G

If we compare the last two generations of the network, the current one and the one just developing, we get the following conclusions:

All these are undoubted advantages of the new network. But there are also disadvantages; 3G during its existence can boast of an extensive coverage area. LTE today is present only in a number of large cities in the country.

LTE and 4G

Both standards belong to the same generation; they have a number of differences. These technologies cannot be considered the same thing.

What is the difference between LTE and 4G:

• lower data upload speed;
• low bandwidth (LTE – 150 Mb/s, 4G – up to 1 GB);
• lower reception speed.

Pros of using it on phones and tablets

What benefits does the introduction of new communication standards bring to users?

LTE on the phone:

• watch videos in high quality without delays;
• use of video communications for calls and video conferencing;
• effective use as a router for WiFi distribution.

Increasing data transfer speeds helps expand services and reduce their costs.

Which operators provide in Russia

All leading companies provide subscribers with this opportunity. Operators also provide users with modems and pocket routers to access the network.

• Megafon has a wide coverage area, but a higher cost of services, unlike its competitors. Offers up to 40 GB monthly; a separate option is connected to access the Internet via LTE.
• MTS has a smaller coverage area. The subscription fee for communication services is lower than that of the previous competitor, and volumes are limited to 25 GB.
• Beeline provides a special SIM card with LTE support. It is worth noting that the coverage area of ​​this operator is wider than that of MTS.
• Tele2 is also introducing LTE. But so far access is only in large cities.

How to connect to LTE

If the smartphone supports LTE, then to connect it is enough to have a correctly configured access point. As soon as the gadget is in 4G coverage area, it will automatically switch to a high-speed network.

LTE is a wireless mobile communications standard that became widespread in 2010. The new fourth generation standard that replaced 3G 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 site, even loaded with a variety of content, but also to fully use Skype and watch videos of any quality through them. The presence 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 the radio channel), and at the network level is based on IP technologies.

4G LTE Specifications and Features

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

Bandwidth

A distinctive feature of 4G LTE is the provision of peak reverse channel throughput of more than 100 Mbit/s. Theoretically, the fourth generation standard can provide Internet speeds of up to 300 Mbit/s.

Operation speed

The availability of an Internet speed of at least 100 Mbit/s, as well as the standard speed of more than 300 Mbit/s, largely depends on the congestion of the networks and the location of the subscriber. At the same time, the possible incoming Internet speed (LTE Advanced) can be up to 3 Gbit/s, and outgoing up to 1.5 Gbit/s.
The transition from LTE to LTE Advanced is not difficult. To do this, you just need to update the software and change the operator's base stations.

Advantages

Support for 4G LTE networks by a smartphone will provide the user with inexpensive traffic and reliable communication channel, provide high throughput and reduce latency.

The best 4G LTE smartphones

1. One of the best smartphones that supports the 4G standard is Samsung Galaxy S4, which is the top seller among devices running on the Android platform. In addition, its smaller version (Mini) also retained support for LTE, without reducing functionality and speed characteristics.
2. Another great 4G LTE smartphone is HTC One. The presence of a presentable appearance and powerful functionality is perfectly complemented by fast and reliable LTE Internet.
3. Among Nokia representatives, an excellent model that supports the use of 4G networks is Nokia Lumia 925. This is one of the best smartphones running on the Windows operating system. 4. One of the best representatives on the smartphone market is definitely 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 lost its position a little, it still remains a very popular phone with support for a 4G LTE network and a QWERTY keyboard.

Modern technologies, in particular the development of the Internet and wireless communications, have transformed the world beyond recognition. The population enjoys not only free access to all kinds of information, but also unique opportunities for communication and fun leisure activities. At the same time, the level of quality of the Internet connection, as well as the speed of data transfer, is of great importance. And in our time, the development of these technologies has reached unprecedented heights. Despite the widespread introduction of the new generation of communications, few people still know what 4G means.

1. What is 4G

4G in English means fourth generation. This is a promising generation of wireless communications, which has high data transfer speeds, as well as higher quality voice communications. This generation of communications includes such promising technologies that provide data transmission speeds over a wireless network of at least 10 Mbit/s to moving users. So what does 4G mean? This is the fourth generation of mobile communications, which has a lot of undeniable advantages.

Based on research and numerous evaluations of various 4G broadband technologies, which is known as IMT-Advenced. Based on the evaluation results, only two technologies were awarded the official title of IMT-Advenced. These are promising technologies LTE-Advenced, as well as WirelessMAN-Advenced. These two technologies today fall under the 4G standard - the fourth generation of wireless communications.

2. How 4G works

4G communication systems are based on packet data transfer protocols. This technology uses the IPv4 protocol to transmit information, but in the future it is planned to support the IPv6 protocol.

Modern 4G technology is of great importance in providing broadband Internet access in rural areas, since it is more justified to install one 4G station than to install a fiber optic connection. One station is capable of providing high-speed communications over tens of kilometers.

3. Benefits of 4G

Today it is very difficult to evaluate the advantages of high-speed fourth generation communications, since they are very numerous. Using such technologies, enormous amounts of all kinds of information become available to users. The need to wait for complex and consuming web pages to open, as well as long waits for downloading a large enough file, such as a movie, etc., are becoming a thing of the past.

It is the high speed of data transfer over a wireless network, as well as high quality voice communications, that are the main advantages of the fourth generation of 4G mobile communications. This in turn entails increased convenience and significant time savings, which is the main requirement of users. In addition, 4G mobile communications provide users with the opportunity to access the Internet absolutely anywhere (where there is 4G coverage) and at any time.

Thanks to the introduction of fourth-generation wireless communication technology, Internet television in high quality (HD) will become available to users. In addition, people will be able to create video calls as well as video conferences. 4G support for mobile devices opens up a lot of new opportunities.

4. WHAT IS 4G LTE: Video

Thanks to such technologies, many people will be able to perform certain actions remotely. For example, doctors will be able to manage robotic operating rooms while on another continent.

These days, there are several technologies that claim to be the fourth generation of mobile communications. These are technologies such as:

• TD-LTE;
• Mobile WiMAX;
• HSPA+.

Despite this diversity, most mobile operators choose LTE technology, and it is this technology that is developing in Russia and Ukraine. Currently, the data transfer speed in 4G networks based on LTE technology is about 30 Mbit/s, but in the future this figure is planned to increase to 300 Mbit/s.

4G communications are the future of wireless networks. Many users today have the opportunity to experience all the benefits of this technology for themselves. At the same time, once you try 4G, you will never want to go back to 3G and such a slow connection.

Although the standards of the third generation of mobile communications provide users with a wide range of services and provide high speed information exchange up to 14 Mbit/s, the volume of information in communication networks continues to grow and therefore the 3GPP organization began work on the creation of a fourth generation standard back in 2004 4G - LTE (Long Term Evolution). The main requirements for the new standard included: increasing the data transfer rate to 100 Mbit/s, increasing system security, reducing energy consumption, reducing system delays, and compatibility with previous generations of mobile networks. Already in 2009, the first LTE network was launched in Sweden. Theoretically, 4G networks are capable of transmitting data at speeds of up to 326.4 Mbit/s for reception and up to 172.8 Mbit/s for transmission. At this speed, it will take no more than one minute to download a movie in good quality.

The structure of the LTE network differs significantly from the networks and. The base station subsystem and switching subsystem have undergone changes, as well as the technology for data exchange between the user terminal and the base station, and protocols for transmitting information between network elements. Thus, now absolutely all information (voice, packet data) is transmitted in the form of packets.

In the standard network switching subsystem LTE The following nodes can be distinguished:

• Service gateway Serving Gateway (SGW) replaces the MSC, MGW and SGSN of the UMTS network and performs the functions of processing and routing packet data from the base station subsystem. The serving gateway connects directly to the 2G and 3G networks of the same operator. This greatly simplifies the transfer of connections to previous generation networks when the coverage area deteriorates or the network is congested.
• Gateway for connecting to networks of other operators Public Data Network Gateway (PGW) routes information (voice, packet data) from the network (to the network) of a given operator.
• Mobility Management Node Mobility Management Entity (MME) designed to manage the mobility of LTE network clients.
• Subscriber data server Home Subscriber Server (HSS) is a combination of VLR, HLR, AUC registers in one device.
• Billing Node Policy and Charging Rules Function (PCRF) is intended for generating invoices to clients for communication services provided.

There is only one traditional element left in the base station subsystem - the base station eNodeB, which, in addition to the functions of the base station itself, also performs the functions of an LTE base station controller. This solution simplifies network expansion, since there is no need to add new controllers or expand the capacity of existing ones.

LTE networks use MIMO data transmission technologies and the OFDM coding system. Technology MIMO (Multiple Input Multiple Output) provides for data transmission via N-antennas and reception via M-antennas, with the receiving and transmitting antennas located at such a distance from each other as to obtain minimal correlation. Orthogonal frequency division multiplexing OFDM (Orthogonal Frequency-Division Multiplexing) is a digital modulation scheme that uses a large number of adjacent orthogonal subcarrier frequencies.

Currently, the highest priority for 4G networks are frequencies in the 2.3 GHz range. For example, the Chinese mobile operator China Mobile operates on this frequency. Another frequency range, 2.5 GHz, is widely used in Europe, Japan, India and the USA. There is also a frequency of 2.1 GHz, but a very narrow range is available here - only 15 MHz, and many European mobile operators have even less - up to 5 MHz. In the future, most likely, the 3.5 GHz frequency range will become promising, due to the fact that in many countries wireless broadband Internet access networks already exist in this range and the transition to the LTE network will allow operators to use the frequency without purchasing new expensive licenses. If necessary, other frequencies can be allocated for fourth generation networks. Different 4G network structures can use frequency bands in the range of 1.4 - 20 MHz. For comparison, the UMTS standard uses fixed 5 MHz bands. LTE networks use temporary TDD (Time Division Duplex) and frequency FDD (Frequency Division Duplex) signal separation.

Typically, an LTE network base station can serve an area with a radius of up to 5 km, although if necessary, due to the high location of the base station antennas, this size can be increased to 30 or even 100 km. The big advantage of the LTE standard is the large selection of terminals. In addition to cell phones, laptops, tablet computers, video cameras and gaming devices with built-in modules for compatibility with fourth generation networks can be used.

LTE standard technology supports handover and roaming with cellular networks of the 2G and 3G generations, which allows these devices to be compatible with these networks. Network structure 4G allows you to immediately redirect a call or Internet session to a 3G or 2G network (UMTS or GSM). In addition, LTE networks easily integrate with WI-FI and Internet networks.