What is 1G, 2G, 3G, 4G and everything in between the technologies

It's hard to believe, but once the mobile phones really called "phones", not smart phones, not super phones ... They enter your pocket and can make calls. That's all. No social networks, messaging, photo uploads. They cannot download a 5-megapixel photo to Flickr and, of course, cannot turn into a wireless access point. 

Of course, those gloomy days are already far behind, but promising wireless high-speed data networks of a new generation continue to appear around the world, and many things start to seem confused. What is "4G"? This is higher than 3G, but does that mean its better? Why do all four US national operators suddenly call their 4G networks? The 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 as a "4G network," that means they are talking about a wireless network based on fourth-generation technology. The application of the definition of "generation" in this context leads to all that confusion in which we try to understand.

1G

The story begins with the appearance in the 1980s of several innovative networking technologies: AMPS in the US and the combination of TACS and NMT in Europe. Although several generations of mobile communication services have existed before, the AMPS, TACS and NMT are considered to be the first generation (1G), because these technologies enabled mobile phones to become a mass product.

At the time of 1G, no one thought about data transmission services - they were purely analog systems, conceived and developed exclusively for making voice calls and some other modest possibilities. Modems existed, but due to the fact that wireless communication is more susceptible to noise and distortion than conventional wired data, the data transfer rate was incredibly low. In addition, the cost of a minute of conversation in the 80's 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 to become a full-fledged phone, installed in the car. It was easy to speak on it, like on a regular telephone (ie, the sound passed in both directions simultaneously, the so-called duplex mode). To call another Altai or a regular phone, it was just enough to dial a number-like on a desk phone, without any channel switching or talking to the dispatcher. A similar system in the USA, IMTS (Improved Mobile Telephone Service), was launched in the experimental zone a 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,

2G

In the early 90s, the first digital cellular networks were upgraded, which had a number of advantages over analog systems. Improved sound quality, greater security, higher performance - these are the main advantages. GSM began its development in Europe, while D-AMPS and the early CDMA version of Qualcomm started in the US. 

These emerging 2G standards do not yet have support for their own, tightly integrated, data services. Many of these networks support the transmission of short text messages (SMS), as well as CSD technology, which allowed data to be transmitted 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 fixed modems in the mid-90's.

In order to initiate the transfer of data 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 the 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 emergence of the General Packet Radio Service (GPRS) service in 1997 was a turning point in the history of cellular communications, because he proposed the technology of continuous data transmission for existing GSM networks. With the use of new technology, you can use data transfer only when it is necessary - there is no more silly CSD, similar to a telephone modem. In addition, GPRS can work with more than CSD, theoretically up to 100 kbit / s, and operators were able to rate traffic, not time on the line. 

GPRS appeared at a very opportune moment - when people began to continuously check their e-mail boxes.

This innovation was not allowed to add a unit to the generation of mobile communications. While GPRS technology was already on the market, the International Telecommunication Union (ITU) made up a new standard - IMT-2000 - approving the specifications of the "real" 3G. The key was to ensure a data rate of 2 Mbps for fixed terminals and 384 Kbps for mobile, which was beyond the power of GPRS. 

Thus, GPRS was stuck between the generations of 2G that it surpassed, and 3G, which it did not reach. This was the beginning of a split of generations.

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

In addition to the aforementioned data rate requirements, 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. After the precedent with GPRS, the CDMA2000 standard offers its own technology for continuous data transmission, called 1xRTT. It's embarrassing that although officially CDMA2000 is the 3G standard, it provides data transfer speed only slightly more than GPRS - about 100 Kbps / s.

Standard EDGE - Enhanced Data Rates for GSM Evolution - was conceived as an easy way for GSM network operators to squeeze out additional juices from 2.5G installations without investing serious money in upgrading the equipment. Using a phone that supports EDGE, you could get twice the speed of GPRS, which is quite good for that time. Many European operators did not bother with EDGE and were supporters of the introduction of UMTS. 

So, where do you put EDGE? It's not as fast as UMTS or EV-DO, so you can say it's not 3G. But this is clearly faster than GPRS, which means that it should be better than 2.5G, is not it? Indeed, many people would call EDGE technology 2.75G.

After a decade, CDMA2000 networks received an upgrade to EV-DO Revision A, which offers slightly higher incoming speed and much higher upstream speed. In the original specification, called EV-DO Revision 0, the outgoing speed is limited to 150 kBit / s, the new version allows doing this ten times faster. So we got 3.5G! The same for UMTS: HSDPA and HSUPA technologies allowed to add 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 Mbps to a staggering 600 MB / s. So, is it possible to say that we are in a new generation, or is it possible to call 3.75G by analogy with EDGE and 2.75G?

4G - all around cheating

Just as it was with the 3G standard, ITU took control of 4G, tied it to a specification known as IMT-Advanced. The document calls for incoming data rate of 1 Gbit / s 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 that will provide communication at a distance of tens of kilometers than cover the farmland with a blanket of fiber optic lines.

Unfortunately, these specifications are so aggressive that no commercial standard in the world does not match 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 partially true: they both use new, highly efficient multiplexing schemes (OFDMA, in the difference from the old CDMA or TDMA that we used for the last twenty years) and in both of them there is no 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 much modern mobile society is focused on data transfer, this can be considered a good solution.

Where WiMAX and LTE fail, it is in the data transfer rate, they theoretically have these values ​​at 40 Mbps and 100 Mbps, and in practice the real speeds of commercial networks do not exceed 4 MBit / s and 30 MBits / s respectively, which in itself is very good, but does not meet the high goals of IMT-Advanced. The update of these standards - WiMAX 2 and LTE-Advanced promise to do this work, but it is still incomplete and the real networks that use them still do not exist.

Nevertheless, it can be argued that the original standards for WiMAX and LTE are quite different from the classic 3G standards, so that you can talk about the change of generations. Indeed, most operators around the world who deployed such networks call them 4G. Obviously, this is used as marketing, and the ITU organization does not have the authority to counter. Both technologies (LTE in particular) will soon be deployed from many carriers around the world in the next few years, and the use of the name "4G" 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 branding upgrades to HSPA + as 4G. In principle, this step makes sense: 3G technology can ultimately achieve speeds greater than LTE, approaching the requirements of IMT-Advanced. There are many markets where HSPA + T-Mobile is faster than WiMAX from Sprint. And neither Sprint, nor Verizon, nor MetroPCS - three American operators with live WiMAX / LTE network - do not offer VoIP services. They continue to use their 3G frequencies for voice and will do it for some time. In addition, T-Mobile is going to upgrade to a speed of 42 MBit / s this year, without even touching LTE!

Perhaps this is the step T-Mobile has caused a global rethinking of what really means "4G" among mobile phone buyers. AT & T, which is in the process of transitioning to HSPA + and will begin offering LTE in some markets at the end of this year, calls both these 4G networks. Thus, all four national operators of the USA stole the name "4G" from ITU - they took it, fled with it and changed it.

conclusions

So, what does this all give us? It seems that the operators have won this battle: ITU recently retreated, saying that the 4G term "can be applied to the predecessors of this technology, LTE and WiMAX, as well as other evolved 3G technologies, which significantly improve performance and capabilities compared to the initial third generation system" . And in a sense, we believe that this is fair - no one will argue that the so-called "4G" networks today resemble the 2001 3G network. We can stream high quality video streams, download large files in no time and even, under certain conditions, use some of these networks as a replacement for DSL. It sounds like a leap of generations!

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 do not lack the names of generations.