The idea of creating a wireless mobile communication network appeared more than a hundred years ago. Active work in this direction was carried out in the West, but the USSR did not lag behind its “colleagues.” However, despite many years of development, the first variation of a cell phone appeared only in the early 70s, when the first cell phone released by Motorola was created in the USA.
Today, almost every inhabitant of the planet has mobile devices that operate on the basis of wireless communications. Over the past forty years alone, four generations of cellular communications have changed; today the fifth (newest) generation 5G is actively developing, which is planned to be introduced in 2021.
This article will provide general information on each generation of wireless cellular communications.
Cellular history
The evolution of cellular communication systems includes several generations of 1G, , and . Work is underway in the field of creating new fifth generation mobile communication networks (). Standards of various generations, in turn, are divided into analog (1G) and digital communication systems (others).
Let's take a closer look at them.
Communication has always been of great importance to humanity. When two people meet, their voice is enough to communicate, but as the distance between them increases, the need for special tools arises. When Alexander Graham Bell invented the telephone in 1876, a significant step was taken in allowing two people to communicate, but they only had to be near a fixed telephone set to do so! For more than a hundred years, wire lines were the only way to organize telephone communications for most people. Radio communication systems that did not rely on wires for network access were developed for specific purposes (e.g., military, police, navy, and closed-circuit car radio networks), and eventually systems emerged that allowed people to communicate by telephone using radio communication These systems were primarily intended for people driving cars and became known as mobile phone systems.
Requirements of IoT devices for communication networks
To implement the concept of the “Internet of Services”, it is necessary to unify the entire variety of access networks and home/local networks based on the IP protocol stack and the transition of subscribers from using proprietary subscriber devices, sensors and controllers to sensors and actuators made in the ideology of the “Internet of Things” with a free network access to them. For a telecom operator, the main differences between IoT devices and smart subscriber devices are a potentially significantly larger number of the former, orders of magnitude less traffic per device, but at the same time higher requirements for quality characteristics. Such characteristics include: channel availability, signal delay in the channel, level of information security, required radiation power (respectively, the battery life of devices). For telemetry IoT devices, more weight is given to the qualitative (availability, security) rather than the quantitative (capacity) characteristics of the channel. Figure 2 shows the areas of requirements of various services for data networks. Thus, for critical telemetry and telecontrol services, the availability of the communication channel with sensors and actuators should reach 99.999%.
Second generation of mobile communications (2G)
In 1982, CEPT (French Conférence européenne des administrations des postes et télécommunications) formed a working group called the GSM Special Group (French Groupe Spécial Mobile) to study and develop a pan-European terrestrial system general mobile communications - the second generation of cellular telephony systems (2G). The name of the GSM working group also came to be used as the name of the mobile communications system. In 1989, CEPT's responsibilities were transferred to the European Telecommunications Standards Institute (ETSI). GSM was originally intended only for ETSI member countries. However, many other countries also have a GSM system implemented, such as Eastern Europe, the Middle East, Asia, Africa, the Pacific, and North America (with a GSM derivative called PCS1900). The name GSM has come to mean "global system for mobile communications", which corresponds to its essence.
The first second generation (2G) mobile networks appeared in 1991. Their main difference from the first generation networks was the digital method of transmitting information, which gave rise to the beloved short text messaging service SMS (Short Messaging Service). When building second-generation networks, Europe chose to create a single standard - GSM; in the USA, most 2G networks were built on the basis of the D-AMPS standard (Digital AMPS), which is a modification of analog AMPS. By the way, it was this circumstance that caused the emergence of the American version of the GSM standard - GSM1900. With the development and spread of the Internet, WAP (Wireless Application Protocol) was developed for mobile devices of 2G networks - a protocol for wireless access to resources of the global Internet directly from mobile phones.
The main advantages of 2G networks over its predecessors were that telephone conversations were encrypted using digital encryption; The 2G system introduced data services starting with SMS text messages.
The growing need of mobile users to use the Internet from mobile devices was the main impetus for the emergence of networks, the 2.5G generation, which became transitional between 2G and 3G. 2.5G networks use the same mobile communication standards as 2G networks, but the existing capabilities have added support for packet data technologies - GPRS (General Packet Radio Service), EDGE (Enhanced Data rates for GSM Evolution – increased transmission speed for the development of GSM) in GSM networks. The use of packet data transmission has made it possible to increase the speed of information exchange when working with the Internet from mobile devices to 384 kbit/s, instead of 9.6 kbit/s for 2G networks.
The HSCSD system (High Speed Circuit Switched Data) is the simplest upgrade of the GSM system designed for data transmission. The essence of this technology was to allocate not one, but several (theoretically up to eight) time intervals to one subscriber. Thus, the maximum speed increased to 115.2 kbit/s. HSCSD provided speeds sufficient to access the Internet, however, when transmitting data, information packets are separated by indefinite intervals, so the use of this technology is extremely wasteful. The fact is that HSCSD networks, like classic GSM networks, are based on circuit switching technology, in which the subscriber is assigned a duplex channel for the entire duration of the communication session. Due to pauses in transmission, the channel resource was spent irrationally.
A further evolution of the GSM system was GPRS technology. Its implementation contributed to more efficient use of channel resources and the creation of a comfortable environment when working with the Internet. The GPRS system is designed as a packet data transmission system with a theoretical maximum transmission speed of about 170 kbit/s. GPRS coexists with the GSM network, reusing the basic access network structure. GPRS is an extension of GSM networks, providing data services on existing infrastructure, while the core network is expanded by overlaying new packet-based components and interfaces.
Progress did not stand still and, to increase data transfer speed, a new system was invented - EDGE. It provided for the introduction of a new modulation scheme. As a result, a speed of 384 kbit/s became achievable. EDGE was introduced in GSM networks in 2003 by Cingular (now AT&T) in the USA.
GPRS and EDGE technologies were called differently in different sources. They had already outgrown the second generation, but had not yet reached the third. GPRS was often called 2.5G, EDGE - 2.75G.
LTE-A (LTE Advanced)
Today, LTE Advanced (LTE-A) is understood as a set of technologies standardized in the 3GPP Rel.10 document and subsequent releases. Key features include frequency aggregation (CA), advanced antenna techniques, enhanced MIMO for increased capacity and relaying. Improvements also include optimization of heterogeneous networks (for increased capacity and improved interference management), SRVCC, eMBMS. Rel.11 also added support for CoMP, eICIC. LTE-A is the main industry trend today, with almost every third LTE network operator in the world investing in testing or deploying support for this technology.
LTE-A is expected to help cope with the strong growth in wireless data traffic and will also help improve average speeds on wireless cellular networks. This also means better coverage, greater stability and faster networks. This means a comprehensive improvement of data network parameters, and not just an increase in data download speed. LTE-A will provide operators with the opportunity to increase the capacity of their networks, improve the quality of user experience, and improve the ability to distribute network resources. To do this, a whole range of different technologies are used, some of which are not new, but have not previously been used in a unified communications system.
LTE-A is expected to deliver data at peak speeds of up to 1 Gbps, compared to 300 Mbps for LTE. Frequency aggregation provides the ability to provide subscribers with higher speeds by allowing data to be downloaded using multiple frequency bands simultaneously. A subscriber device in CA mode receives and combines several signals simultaneously, for example from two carrier frequencies or even from different frequency ranges. You can combine up to five carriers with a width of 20 MHz each, collecting a wide channel for pumping data with a bandwidth of up to 100 MHz. MIMO, as a multiple input/output technology, can increase the overall data rate by simultaneously transmitting a signal while dividing the data stream between two or more antennas. This allows you to increase the spectral efficiency of information transmission. Moreover, it is possible to dynamically create a synthesized directional antenna oriented towards a specific subscriber device.
Relay Nodes are a way to quickly increase network coverage in areas where there are no powerful digital data transmission channels. In this case, the LTE-A radio subsystem itself performs the function of a wireless core network. It is also an opportunity to place low-power BSs at the cell edges to improve coverage and capacity there.
Basic digital standards of second generation cellular communication systems:
- D-AMPS (Digital AMPS - digital AMPS; ranges 800 MHz and 1900 MHz);
- GSM (Global System for Mobile communications - global mobile communications system, bands 900, 1800 and 1900 MHz);
- CDMA (800 and 1900 MHz bands);
- JDC (Japanese Digital Cellular - Japanese digital cellular communication standard).
Table 2. Comparison of second generation (2G) cellular communication systems
Third generation of mobile communications (3G)
A further development of mobile communication networks was the transition to the third generation (3G). 3G is a standard for mobile digital communications, which under the abbreviation IMT-2000 (International Mobile Telecommunications - International Mobile Telecommunications 2000) combines five standards - W-CDMA, CDMA2000, TD-CDMA / TD-SCDMA, DECT (Digital Enhanced Cordless Telecommunication – technology of improved digital wireless communication). Of the listed components of 3G, only the first three represent full-fledged third-generation cellular communication standards. DECT is a standard for wireless telephony for home or office use, which, within the framework of third generation mobile technologies, can only be used to organize hot connection points (hot spots) to these networks.
The IMT-2000 standard provides a clear definition of 3G networks - the third generation mobile network is an integrated mobile network that provides: for stationary subscribers an information exchange speed of at least 2048 kbit/s, for subscribers moving at a speed of no more than 3 km/h - 384 kbit/s, for subscribers moving at a speed of no more than 120 km/h – 144 kbit/s. With global satellite coverage, 3G networks must provide an exchange rate of at least 64 kbit/s. The basis of all third generation standards are code division multiple access protocols. This type of network access technology is not something fundamentally new. The first work devoted to this topic was published in the USSR back in 1935 by D.V. Ageev.
Technically, code division networks work as follows: each user is assigned a specific numeric code, which is distributed over the entire frequency band allocated for the network. In this case, there is no time division of signals, and subscribers use the entire channel width. In this case, of course, the subscribers’ signals overlap each other, but thanks to the numeric code they can be easily differentiated. As mentioned above, this technology has been known for a long time, but until the mid-80s of the last century it was classified and was used exclusively by the military and intelligence services. After the secrecy classification was removed, its active use began in civilian communication systems.
Phone instructions
The phone manual will provide useful information regarding the issue. The corresponding section lists the supported frequencies. Some devices will allow you to customize the reception area. You should choose a phone model that receives generally accepted Russian channels:
- 900 MHz – E-GSM. The ascending branch is 880..915 MHz, the descending branch is 925..960 MHz.
- 1800 MHz – DCS. The ascending branch is 1710..1785 MHz, the descending branch is 1805..1880 MHz.
LTE technology adds a 2600 MHz region, and an 800 MHz channel has been introduced.
Fourth generation of mobile communications (4G)
In March 2008, the radiocommunication sector of the International Telecommunication Union (ITU-R) defined a number of requirements for the international mobile wireless broadband standard, called the International Mobile Telecommunications Advanced (IMT-Advanced) specifications, specifically setting data rate requirements for subscriber service: 100 Mbps speed should be provided to high mobility subscribers (eg trains and cars), and low mobility subscribers (eg pedestrians and fixed subscribers) should be provided 1 Gbps speed.
Since the first versions of mobile WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long Term Evolution) support speeds significantly less than 1 Gbit/s, they cannot be called technologies corresponding to IMT- Advanced, although they are often referred to by service providers as 4G technologies. On December 6, 2010, ITU-R recognized that the most advanced technologies are considered 4G.
The main, basic technology of the fourth generation is the technology of orthogonal frequency division multiplexing OFDM (English: Orthogonal Frequency-Division Multiplexing - multiplexing with orthogonal frequency division of channels). In addition, for maximum transmission speed, the technology of data transmission using N antennas and their reception by M antennas is used - MIMO (English: Multiple Input/Multiple Output - multiple inputs/multiple outputs). With this technology, the transmitting and receiving antennas are spaced so as to achieve weak correlation between adjacent antennas.
Thus, the evolution of mobile communication standards can be represented as follows:
Rice. 1. Evolution of mobile communication standards
Comparative characteristics of the standards of different generations of mobile communications can be summarized in the following table:
Table 3. The evolution of mobile telephony
| 1G | 2G | 3G |
|
|
|
| since 1980s | since 1990s | since 2000s |
Fifth generation of mobile communications (5G)
Pre-commercial and commercial launches of networks are currently underway. More information about the launches of 5G networks in Russia and the world can be found at the corresponding links.
The following requirements are stated for fifth generation networks (in comparison with LTE):
— 10-100 times increase in data transfer speed per subscriber;
— Increase by 1000 times the average traffic consumed by a subscriber per month;
— Ability to service a larger (100 times) number of devices connected to the network;
— Multiple reduction in energy consumption of subscriber devices;
— Reduction of network delays by 5 or more times;
— Reducing the overall cost of operating fifth generation networks.
Requirements for 5G networks in digitized form are presented here.
For more detailed information about the evolution of mobile communication networks, the current state, trends and prospects for its development, read the latest reference book “Mobile communications on the way to 6G”.
4G communication standard - LTE and WiMax
4G is the fourth generation of communications , where the letter "G" stands for "Generation".
Despite the fact that the 3G network is not losing momentum and is actively used in Russia and Europe, it has been replaced by the already well-proven fourth generation network, which fully meets the high demands and requirements of subscribers.
LTE and WiMax became 4G network standards
LTE is a kind of follower of the GSM/UMTS we are used to. Initially, LTE did not belong to the new generation network, but gradually, due to more advanced data transmission technologies, it began to be considered the main standard of the 4G network. The maximum speed at which data can (theoretically) be transmitted in the LTE standard is 326.4 Mbit/second. Actual speed may vary and depend on numerous factors. The largest range width for LTE frequencies is provided by the Megafon operator (40 MHz and 300 Mbit/second, respectively). The rest of the range does not exceed 10 MHz, which corresponds to 75 Mbit/second.
WiMAX continues the wireless standard for mobile data transmission. Today, there are several versions of this standard - fixed, which are intended for subscribers who are stationary, as well as mobile versions - for subscribers on the move.
