What is 1G, 2G, 3G, 4G and everything in between?
It is hard to believe, but once mobile phones were really called “phones”, not smartphones, not superphones ... They go into your pocket and can make calls. That's all. No social networks, messaging, photo uploads. They cannot upload a 5 megapixel photo on Flickr and, of course, cannot turn into a wireless access point.
Of course, those dark days are already far behind, but promising high-speed wireless data networks of the new generation continue to appear around the world, and many things are beginning to seem confusing. What is 4G? This is higher than 3G, but does that mean better? Why do all four US national operators suddenly call their 4G networks? Answers to these questions require a small excursion into the history of the development of wireless technologies.
To begin with, “G” means “generation”, so when you hear that someone is referred to a “4G network,” it means that they are talking about a wireless network built using fourth-generation technology. The use of the definition of “generation” in this context leads to all the confusion in which we will try to understand.
The story begins with the emergence in the 1980s of several innovative network technologies: AMPS in the United States and the combination of TACS and NMT in Europe. Although several generations of mobile services existed before, the three AMPS, TACS and NMT are considered to be the first generation (1G), because it was these technologies that allowed mobile phones to become a mass product.
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At the time of 1G, no one thought about data services - these were purely analog systems, conceived and developed exclusively for voice calls and some other modest features. Modems existed, but because wireless communication is more susceptible to noise and distortion than conventional wired data transfer rates were incredibly low. 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 be a full-fledged phone installed in the car. It was simply possible to speak on it, as on a regular telephone (i.e., the sound passed in both directions simultaneously, the so-called duplex mode). To call another “Altai” or a regular phone, it was enough just to dial the number — just like on a desk phone, without any channel switching or talking to a dispatcher. A similar system in the United States, IMTS (Improved Mobile Telephone Service), was launched in the pilot zone one year later. And its commercial launch took place only in 1969. Meanwhile, in the USSR, by 1970, Altai was installed and successfully operated in approximately 30 cities. By the way, in Voronezh and Novosibirsk, the system is still in effect.
In the early 90s, the rise of the first digital cellular networks was observed, which had a number of advantages in comparison with analog systems. Improved sound quality, greater security, improved performance - these are the main advantages. GSM began its development in Europe, while Qualcomm's D-AMPS and the early version of CDMA were launched in the United States.
These nascent 2G standards do not yet have support for their own, closely integrated, data services. Many of these networks support the transfer of short text messages (SMS), as well as CSD technology, which allowed transmitting data to the station in digital form. This actually meant that you could transfer data faster - up to 14.4 kbit / s, which was comparable to the speed of stationary modems in the mid-90s.
In order to initiate data transmission using CSD technology, it was necessary to make a special “challenge”. It looked like a telephone modem - you were either connected to the network or not. Given that the tariff plans at that time were measured in tens of minutes, and the CSD was akin to an ordinary call, there was almost no practical benefit from the technology.
The emergence of the General Packet Radio Service (GPRS) in 1997 was a turning point in the history of cellular communication, because it proposed continuous data transmission technology for existing GSM networks. With the use of new technology, you can use data transfer only when it is needed - there is no more stupid CSD, similar to a telephone modem. In addition, GPRS can work with more than CSD speeds - theoretically up to 100 kbits / s, and operators were able to charge traffic, and not time on the line.
GPRS appeared at a very opportune moment — when people began to continually check their email inboxes.
This innovation did not allow to add one to the generation of mobile communications. While GPRS technology was already on the market, the International Telecommunication Union (ITU) has compiled a new standard - IMT-2000 - approving the specifications of “real” 3G. The key point was to ensure the data transfer rate of 2 Mbit / s for fixed terminals and 384 kbit / s for mobile, which was beyond the power of GPRS.
Thus, GPRS was stuck between the generations of 2G, which it exceeded, and 3G, which it did not reach. This was the beginning of a split generation.
In addition to the above data rate requirements, 3G specifications called for easy migration from second-generation networks. For this, a standard called UMTS became the top choice for GSM operators, and CDMA2000 provided backward compatibility. Following the use of GPRS, the CDMA2000 standard offers its own technology for continuous data transfer, called 1xRTT. It is embarrassing that, although CDMA2000 is officially the 3G standard, it provides data transfer rates only slightly higher than GPRS - about 100 kbit / s.
The EDGE standard - Enhanced Data-rates for GSM Evolution - was conceived as an easy way for GSM network operators to squeeze out extra juices from 2.5G installations without investing serious money in upgrading equipment. Using an EDGE phone, you could get a speed twice the speed of GPRS, which is quite good for that time. Many European operators did not bother with EDGE and were committed to the introduction of UMTS.
So where does EDGE go? It is not as fast as UMTS or EV-DO, so you can say that it is not 3G. But this is clearly faster than GPRS, which means that it should be better than 2.5G, right? Indeed, many people would call EDGE 2.75G technology.
A decade later, CDMA2000 networks received an upgrade to EV-DO Revision A, which offers a slightly higher incoming speed and much higher outgoing speed. In the original specification, which is called EV-DO Revision 0, the outgoing speed is limited to 150 kbits / s, the new version allows you to do it ten times faster. So we got 3.5G! The same is true for UMTS: HSDPA and HSUPA technologies allowed adding speed for incoming and outgoing traffic.
Further enhancements to UMTS will use HSPA +, dual-carrier HSPA +, and HSPA + Evolution, which theoretically provide throughput from 14 Mbit / s to a staggering 600 Mbit / s. So, can we say that we have fallen into a new generation, or can it be called 3.75G by analogy with EDGE and 2.75G?
Just as with the 3G standard, ITU took control of 4G, tying it to a specification known as IMT-Advanced. The document calls for input data rate of 1 Gbps for fixed terminals and 100 Mbps for mobile. This is 500 and 250 times faster than IMT-2000. These are really huge speeds that can outrun an ordinary DSL modem or even a direct connection to a broadband channel.
Wireless technologies play a key role in providing broadband access in rural areas. It is more cost-effective to build one 4G station, which will provide communication at 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) technologies, which are designed to achieve the same success as CDMA2000 and GSM, are considered fourth-generation technologies, but this is only partly true: they both use new, extremely efficient multiplexing schemes (OFDMA, difference from the old CDMA or TDMA which we used for the last twenty years) and both of them lack a channel for voice transmission. 100 percent of their bandwidth is used for data services. This means that voice transmission will be treated as VoIP. Considering how strongly the modern mobile society is focused on data transfer, this can be considered a good solution.
Where WiMAX and LTE fail, it’s in data transfer speed, these values theoretically are at 40 Mbit / s and 100 Mbit / s, and in practice the real speeds of commercial networks do not exceed 4 Mbit / s and 30 Mbit / s. accordingly, which is very good in itself, but does not meet the high goals of IMT-Advanced. Updating these standards - WiMAX 2 and LTE-Advanced promise to do this work, but it has not yet been completed and the real networks that use them still do not exist.
Nevertheless, it can be argued that the original WiMAX and LTE standards are quite different from the classical 3G standards, so that we can talk about the change of generations. Indeed, most operators around the world who have deployed such networks call them 4G. Obviously, it is used as marketing, and the ITU organization has no authority to counteract. 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 grow.
And this is not the end of the story. The American operator T-Mobile, which did not announce its intention to upgrade its HSPA network to LTE in the near future, decided to start a modernization branding to HSPA + as 4G. In principle, this step makes sense: 3G technology can ultimately reach speeds greater than just LTE, approaching the requirements of IMT-Advanced. There are many markets where the HSPA + T-Mobile network is faster than WiMAX from Sprint. And neither Sprint, nor Verizon, nor MetroPCS — the three US carriers with a live WiMAX / LTE network — do not offer VoIP services. They continue to use their 3G frequencies for voice and will continue to do so for some time. In addition, T-Mobile is going to upgrade to a speed of 42 Mbps this year, without even touching LTE!
Perhaps it was this T-Mobile move that brought about a global rethinking of what 4G really means among mobile phone buyers. AT & T, which is in the process of switching to HSPA + and will begin offering LTE in some markets later this year, calls both of these 4G networks. Thus, all four US national operators stole the name “4G” from ITU - they took it, ran away with it and changed it.
So what does all this give us? Operators seem to have won this battle: ITU recently retreated, stating that the 4G term “can be applied to the predecessors of this technology, LTE and WiMAX, as well as other evolving 3G technologies that provide significant improvements in performance and capabilities compared to the initial third generation system” . And in a sense, we believe that this is true - no one will argue that the so-called “4G” networks today resemble 2001 3G networks. We can stream video of very high quality, download large files in the blink of an eye and even, in certain conditions, use some of these networks as a replacement for DSL. It sounds like a generational leap!
It is not known whether WiMAX 2 and LTE-Advanced will be called “4G” by the time they are 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 don't lack generational names.
2G, 3G, 4G, and everything in between: an Engadget wireless primer
UPDATE: Added information about the Altai mobile communication system.
Of course, those dark days are already far behind, but promising high-speed wireless data networks of the new generation continue to appear around the world, and many things are beginning to seem confusing. What is 4G? This is higher than 3G, but does that mean better? Why do all four US national operators suddenly call their 4G networks? Answers to these questions require a small excursion into the history of the development of wireless technologies.
To begin with, “G” means “generation”, so when you hear that someone is referred to a “4G network,” it means that they are talking about a wireless network built using fourth-generation technology. The use of the definition of “generation” in this context leads to all the confusion in which we will try to understand.
1G
The story begins with the emergence in the 1980s of several innovative network technologies: AMPS in the United States and the combination of TACS and NMT in Europe. Although several generations of mobile services existed before, the three AMPS, TACS and NMT are considered to be the first generation (1G), because it was these technologies that allowed mobile phones to become a mass product.
')
At the time of 1G, no one thought about data services - these were purely analog systems, conceived and developed exclusively for voice calls and some other modest features. Modems existed, but because wireless communication is more susceptible to noise and distortion than conventional wired data transfer rates were incredibly low. 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 be a full-fledged phone installed in the car. It was simply possible to speak on it, as on a regular telephone (i.e., the sound passed in both directions simultaneously, the so-called duplex mode). To call another “Altai” or a regular phone, it was enough just to dial the number — just like on a desk phone, without any channel switching or talking to a dispatcher. A similar system in the United States, IMTS (Improved Mobile Telephone Service), was launched in the pilot zone one year later. And its commercial launch took place only in 1969. Meanwhile, in the USSR, by 1970, Altai was installed and successfully operated in approximately 30 cities. By the way, in Voronezh and Novosibirsk, the system is still in effect.
2G
In the early 90s, the rise of the first digital cellular networks was observed, which had a number of advantages in comparison with analog systems. Improved sound quality, greater security, improved performance - these are the main advantages. GSM began its development in Europe, while Qualcomm's D-AMPS and the early version of CDMA were launched in the United States.
These nascent 2G standards do not yet have support for their own, closely integrated, data services. Many of these networks support the transfer of short text messages (SMS), as well as CSD technology, which allowed transmitting data to the station in digital form. This actually meant that you could transfer data faster - up to 14.4 kbit / s, which was comparable to the speed of stationary modems in the mid-90s.
In order to initiate data transmission using CSD technology, it was necessary to make a special “challenge”. It looked like a telephone modem - you were either connected to the network or not. Given that the tariff plans at that time were measured in tens of minutes, and the CSD was akin to an ordinary call, there was almost no practical benefit from the technology.
2.5G
The emergence of the General Packet Radio Service (GPRS) in 1997 was a turning point in the history of cellular communication, because it proposed continuous data transmission technology for existing GSM networks. With the use of new technology, you can use data transfer only when it is needed - there is no more stupid CSD, similar to a telephone modem. In addition, GPRS can work with more than CSD speeds - theoretically up to 100 kbits / s, and operators were able to charge traffic, and not time on the line.
GPRS appeared at a very opportune moment — when people began to continually check their email inboxes.
This innovation did not allow to add one to the generation of mobile communications. While GPRS technology was already on the market, the International Telecommunication Union (ITU) has compiled a new standard - IMT-2000 - approving the specifications of “real” 3G. The key point was to ensure the data transfer rate of 2 Mbit / s for fixed terminals and 384 kbit / s for mobile, which was beyond the power of GPRS.
Thus, GPRS was stuck between the generations of 2G, which it exceeded, and 3G, which it did not reach. This was the beginning of a split generation.
3G, 3.5G, 3.75G ... and 2.75G too
In addition to the above data rate requirements, 3G specifications called for easy migration from second-generation networks. For this, a standard called UMTS became the top choice for GSM operators, and CDMA2000 provided backward compatibility. Following the use of GPRS, the CDMA2000 standard offers its own technology for continuous data transfer, called 1xRTT. It is embarrassing that, although CDMA2000 is officially the 3G standard, it provides data transfer rates only slightly higher than GPRS - about 100 kbit / s.
The EDGE standard - Enhanced Data-rates for GSM Evolution - was conceived as an easy way for GSM network operators to squeeze out extra juices from 2.5G installations without investing serious money in upgrading equipment. Using an EDGE phone, you could get a speed twice the speed of GPRS, which is quite good for that time. Many European operators did not bother with EDGE and were committed to the introduction of UMTS.
So where does EDGE go? It is not as fast as UMTS or EV-DO, so you can say that it is not 3G. But this is clearly faster than GPRS, which means that it should be better than 2.5G, right? Indeed, many people would call EDGE 2.75G technology.
A decade later, CDMA2000 networks received an upgrade to EV-DO Revision A, which offers a slightly higher incoming speed and much higher outgoing speed. In the original specification, which is called EV-DO Revision 0, the outgoing speed is limited to 150 kbits / s, the new version allows you to do it ten times faster. So we got 3.5G! The same is true for UMTS: HSDPA and HSUPA technologies allowed adding speed for incoming and outgoing traffic.
Further enhancements to UMTS will use HSPA +, dual-carrier HSPA +, and HSPA + Evolution, which theoretically provide throughput from 14 Mbit / s to a staggering 600 Mbit / s. So, can we say that we have fallen into a new generation, or can it be called 3.75G by analogy with EDGE and 2.75G?
4G - around deception
Just as with the 3G standard, ITU took control of 4G, tying it to a specification known as IMT-Advanced. The document calls for input data rate of 1 Gbps for fixed terminals and 100 Mbps for mobile. This is 500 and 250 times faster than IMT-2000. These are really huge speeds that can outrun an ordinary DSL modem or even a direct connection to a broadband channel.
Wireless technologies play a key role in providing broadband access in rural areas. It is more cost-effective to build one 4G station, which will provide communication at 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) technologies, which are designed to achieve the same success as CDMA2000 and GSM, are considered fourth-generation technologies, but this is only partly true: they both use new, extremely efficient multiplexing schemes (OFDMA, difference from the old CDMA or TDMA which we used for the last twenty years) and both of them lack a channel for voice transmission. 100 percent of their bandwidth is used for data services. This means that voice transmission will be treated as VoIP. Considering how strongly the modern mobile society is focused on data transfer, this can be considered a good solution.
Where WiMAX and LTE fail, it’s in data transfer speed, these values theoretically are at 40 Mbit / s and 100 Mbit / s, and in practice the real speeds of commercial networks do not exceed 4 Mbit / s and 30 Mbit / s. accordingly, which is very good in itself, but does not meet the high goals of IMT-Advanced. Updating these standards - WiMAX 2 and LTE-Advanced promise to do this work, but it has not yet been completed and the real networks that use them still do not exist.
Nevertheless, it can be argued that the original WiMAX and LTE standards are quite different from the classical 3G standards, so that we can talk about the change of generations. Indeed, most operators around the world who have deployed such networks call them 4G. Obviously, it is used as marketing, and the ITU organization has no authority to counteract. 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 grow.
And this is not the end of the story. The American operator T-Mobile, which did not announce its intention to upgrade its HSPA network to LTE in the near future, decided to start a modernization branding to HSPA + as 4G. In principle, this step makes sense: 3G technology can ultimately reach speeds greater than just LTE, approaching the requirements of IMT-Advanced. There are many markets where the HSPA + T-Mobile network is faster than WiMAX from Sprint. And neither Sprint, nor Verizon, nor MetroPCS — the three US carriers with a live WiMAX / LTE network — do not offer VoIP services. They continue to use their 3G frequencies for voice and will continue to do so for some time. In addition, T-Mobile is going to upgrade to a speed of 42 Mbps this year, without even touching LTE!
Perhaps it was this T-Mobile move that brought about a global rethinking of what 4G really means among mobile phone buyers. AT & T, which is in the process of switching to HSPA + and will begin offering LTE in some markets later this year, calls both of these 4G networks. Thus, all four US national operators stole the name “4G” from ITU - they took it, ran away with it and changed it.
findings
So what does all this give us? Operators seem to have won this battle: ITU recently retreated, stating that the 4G term “can be applied to the predecessors of this technology, LTE and WiMAX, as well as other evolving 3G technologies that provide significant improvements in performance and capabilities compared to the initial third generation system” . And in a sense, we believe that this is true - no one will argue that the so-called “4G” networks today resemble 2001 3G networks. We can stream video of very high quality, download large files in the blink of an eye and even, in certain conditions, use some of these networks as a replacement for DSL. It sounds like a generational leap!
It is not known whether WiMAX 2 and LTE-Advanced will be called “4G” by the time they are 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 don't lack generational names.
Literature
2G, 3G, 4G, and everything in between: an Engadget wireless primer
UPDATE: Added information about the Altai mobile communication system.
Source: https://habr.com/ru/post/112535/
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