Do you remember the time when mobile phones were still called “phones”, not smartphones, not superphones…, just “phones”? These devices were stored in our pockets and could make calls. That’s all. No social networks, messaging, uploading photos or streaming video in HD format. They could not upload a 15-megapixel photo on Instagram, snap-in Snapchat and, of course, could not turn into a wireless access point. Those gloomy days are already far behind, but promising new-generation wireless high-speed data networks continue to appear around the world, and many things begin to seem confusing.
What is 5G? This is higher than 4G, but does that mean better? Why do all major US telecommunications operators unexpectedly call their 4G networks? Why are they in such a hurry to rename them to 5G? Answers to these questions require a short excursion into the history of wireless technology.
To begin, “G” means “generation”, so when you hear that someone is referring to a “5G network”, it means that they are talking about a wireless network based on fifth-generation technology. Applying the definition of “generation” in this context leads to the confusion that we will try to understand.
The story begins with the advent of several innovative network technologies in the 1980s: AMPS in the USA and a combination of TACS and NMT in Europe. Although several generations of mobile services existed before, the three AMPS, TACS, and NMT are considered the first generation (1G), because it was these technologies that made mobile phones a mass product.
In the days of 1G, no one thought about data service. These were purely analog systems, conceived and developed exclusively for making voice calls and some other modest capabilities. Modems existed, but due to the fact that wireless communication is more prone to noise and distortion than conventional wired, the data transfer speed was incredibly low. In addition, the cost of a minute of conversation in the 80s was so high, that a mobile phone was justly considered a luxury.
Soviet engineer Leonid Kupriyanovich, in 1957-1961, developed and introduced a number of experimental handheld communication devices. The weight of the device, introduced in 1961, was only 70 g, which is close to modern mobile phones, and could easily fit in your pocket. In the USSR however, it was decided to first develop the Altai car phone system. The Altai system was originally created and designed as a telephone system for cars, not as a mobile phone in the modern sense. It could simply be spoken on it, as on a regular telephone (i.e., sound passed in both directions simultaneously, the so-called duplex mode). To call another Altai or a regular telephone, it was enough to simply dial a number – like on a desk telephone, without any channel switching or talking to the dispatcher. A similar system in the USA, Improved Mobile Telephone Service (IMTS), was launched in the experimental area a year later. The commercial launch of IMTS took place in 1969. In the USSR, by 1970, Altai was installed and successfully worked in about 30 cities.
In the early 90s, there was an upsurge in the first digital cellular networks, which had a number of advantages compared to analog systems. Improved sound quality, greater security, increased performance were some of the main advantages. GSM began its development in Europe, while D-AMPS and Qualcomm’s early version of CDMA launched in the United States.
These nascent 2G standards do not yet have the support of their own closely integrated data services. Many of these networks support the transmission of short text messages (Short Message Service or SMS), as well as Circuit Switched Data (CSD) technology, which allowed the transmission of data to the station in digital form. All these technological solutions made it possible to transmit data at speeds up to 14.4 kBit/s. Miserable? Maybe. However, at that time in the mid-90s, it was comparable to the speed of stationary modems.
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 benefit of the technology.
The appearance 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 for existing GSM networks. Using the new technology, you can use data transfer only when necessary as there was no longer a stupid CSD that looks like a telephone modem. In addition, GPRS can operate at a speed higher than CSD, theoretically up to 100 kBit/s, and for the first time, operators were able to charge traffic, not time on the line.
GPRS appeared at a very opportune moment – when people began to continuously check their email inboxes.
This innovation did not allow adding a unit to the generation of mobile communications. While GPRS technology was already on the market, the International Telecommunication Union (ITU) drafted a new standard – IMT-2000 – approving the specifications of the “real” 3G. The key point was to provide a data transfer rate of 2 Mb/s for stationary terminals and 384 kbit/s for mobile terminals, which was beyond the power of GPRS. Thus, GPRS was stuck between generations of 2G, which he excelled in, and 3G, which he did not reach.
As an easy way for GSM network operators to get the most performance from 2.5G installations without investing serious money in updating equipment, EDGE standard or Enhanced Data-rates for GSM Evolution was born. Using a phone that supports EDGE, you could get speeds twice that of GPRS, which is pretty good for that time. Many European operators did not bother with EDGE and were committed to implementing UMTS.
So where does EDGE go? Unfortunately, it wasn’t as fast as UMTS or EV-DO making it incomparable or say that it is 3G as it was not. Though, it was clearly faster than GPRS, which means that it was significantly better than 2.5G. Thus, most experts agree that EDGE technology is a kind of 2.75G.
3G and Beyond
In addition to the aforementioned data rate requirements, 3G specifications called for easy migration from second-generation networks. For this, the standard called UMTS became the top choice for GSM operators, and the CDMA2000 standard provided backward compatibility. Following the precedent with GPRS, the CDMA2000 standard offers its own continuous data technology called 1xRTT. It is confusing that, although officially CDMA2000 is a 3G standard, it provides a data transfer rate of only slightly more than GPRS – about 100 kBit/s.
A decade later, the CDMA2000 networks received an upgrade to EV-DO Revision A, which offers slightly higher inbound speed and much higher outbound speed. In the original specification, called EV-DO Revision 0, the outgoing speed is limited to 150 kBit/s. The new version allowed you to do this ten times faster. Therefore, we got 3.5G! The same for UMTS: HSDPA and HSUPA technologies added speed for inbound and outbound traffic.
Further enhancements to UMTS will use HSPA+, dual-carrier HSPA+, and HSPA+ Evolution, which theoretically provide bandwidths from 14 Mb/s to a staggering 600 Mb/s. So, can we say that we are in a new generation, or can it be called 3.75G by analogy with EDGE and 2.75G?
4G – all-around marketing
As with the 3G standard, the International Telecommunications Union has developed the IMT-Advanced specification, which is the modern 4G standard. The document calls for an incoming data rate of 1 Gbit/s for fixed terminals and 100 Mbit/s for mobile. It is 500 and 250 times faster compared to IMT-2000. These are really tremendous speeds that can overtake an ordinary DSL modem or even a direct connection to a broadband channel.
Rural areas are a little more complicated, and therefore, wireless technology plays a key role in providing broadband access to these areas. It is more cost-effective to build one 4G station, which will provide communications over a distance of tens of miles than to cover farmland with a blanket of fiber optic lines.
Unfortunately, the specification attributes initially were too aggressive that no commercial standard in the world complying with them for a long time. Designed to achieve the same success as CDMA2000 and GSM, WiMAX and Long-Term Evolution (LTE) technologies historically, are considered fourth-generation technologies. However, there is only slight truth in this statement. They both use new, extremely efficient multiplexing schemes (OFDMA, unlike the old CDMA or TDMA that we have used over the past twenty years) and they both lack a voice channel. 100 percent of their bandwidth is used for data services. This means that voice transmission will be considered as VoIP. Given how strongly modern mobile society is focused on data transfer, this can be considered a good solution.
Where WiMAX and LTE fail, it’s in the data transfer speed. They theoretically have these values at the level of 40 Mb/s and 100 Mb/s. In practice, the real speeds of commercial networks do not exceed 4 Mbit/s and 30 Mbit/s, respectively. This in itself is very good, but it does not meet the high goals of IMT-Advanced. That is why the updated WiMAX 2 and LTE-Advanced standards were developed to fully comply with the fourth generation of communications.
Nevertheless, it can be argued that the original WiMAX and LTE standards are quite different from the classic 3G standards, so we can talk about a generational change. Indeed, most of the operators around the world who have deployed such networks call them 4G.
Obviously, initially this was used as marketing, and the ITU organization does not have the power to oppose it. Both technologies (LTE in particular) are now implemented and used by most carriers in the United States and around the world.
And this is not the end of the 4G story. The American operator T-Mobile, which did not announce its intention to upgrade its HSPA network to LTE, decided to start branding the upgrade to HSPA+ as 4G. In principle, this step made sense: 3G technology can ultimately reach speeds greater than just LTE, approaching the requirements of IMT-Advanced. Surprisingly, there are a numerous amount of markets with HSPA+ T-Mobile network being faster than WiMAX from Sprint; and neither Sprint, Verizon, or MetroPCS — three US carriers with a live WiMAX / LTE network — have offered VoIP services until very recently. The fact is, there are rumors that such plans and developments are underway. They will probably continue to use their 3G frequencies for voice and will do so for some short time.
5G is the mobile network that has replaced 4G, with a copious amount of improvements from improved rates of transmission speed to network coverage, and reliability. 5G works on other antennas with different frequencies that allow Internet access more devices minimizing delays in data transmission, allowing more accuracy in transmissions, and providing ultra-fast speed with peak speeds in 5G networks reaching at least 20 Gbit/s, and for 4G – 1 Gbit/s. The upgrade of 4G to 5G was needed because the number of devices requiring an Internet connection is becoming more frequent. Many devices need network bandwidth to function normally, which 4G can no longer cope with. 5G uses extremely high frequencies ranging from 30 GHz to 300 GHz. On the other hand, 4G uses frequencies that are extremely low, going under 6 GHz. One of the key technologies for implementing 5G cellular networks is the use of multi-element digital antenna arrays with the number of antenna elements 128, 256 and more as part of base stations. The corresponding systems are called Massive MIMO. To increase spectral efficiency, along with spatial multiplexing, 5G can use a variety of technologies of non-orthogonal multiple access (NOMA) and N-OFDM signals.
So that you do not miss this significant step into the future, Allvoi has prepared separate material comparing 4G and 5G.
Should We Expect 6G?
Obviously, after the completion of the deployment of 5G networks, which began in April 2019, engineers will find something to do and will be able to implement the ideas for 6G networks in the future. Experts agree that it will further advance approaches that are not fully developed in the previous generation based on the use of artificial intelligence, and quantum communications, which will allow achieving data transfer speeds from hundreds of Gbit/s to 1 TB/s.
Users can only enjoy modern technology, hope that they will be affordable and that our brains will not melt in the end!