Description of the device and the operation of the network of the fifth generation, deployed on the basis of the fourth generation

The fourth-generation cellular networks can be built on the basis of two technologies - LTE (Long Term Evolution) and WiMAX (Worldwide Interoperability for Microwave Access). Both of these technologies are similar, but have different developers and the time of appearance. WiMAX, based on the IEEE 802.16 standard (developed by the Institute of Electrical and Electronics Engineers, Institute of Electrical and Electronics Engineers) uses OFDM technology for data transfer in both directions (for unloading and downloading), which leads to high peak factors, that is, large loads on the power supply units of the final equipment (to put it simply, the phone battery, when using OFDM for outgoing speed, will wear out and discharge faster). Unlike WiMAX, Long Term Evolution technology uses SC-FDMA technology for outgoing speed, which allows you to avoid high peak factors, as this technology with one carrier.

LTE technology was developed by the 3GPP forum (The 3rd Generation Partnership Project), designed to solve the problems of using GSM and CDMA2000 (UMTS) technologies, which are respectively the technologies of the second and third generations of cellular communication. In Kazakhstan, first, GSM (EDGE) technology was used to operate cellular networks, then CDMA2000, so the introduction of cellular communications based on LTE Advanced (LTE Realize 12) technology was appropriate. Accordingly, the fifth generation networks in Kazakhstan should be deployed on the basis of LTE Advanced networks.

The fifth generation (5th Generation) of cellular communication should resolve issues related not to improving the quality of voice transmission, but to the problem of Internet access and increasing the speed of data transmission. Currently (February 2019), 5G standards have not been developed, but by December 2019, the International Telecommunication Union will introduce the IMT-2020 standard, describing technologies for building and accessing the network. Since the technologies of all previous generations of communication were based on previous ones, that is, to use the services of the 3G network, it was not necessary to buy a new device, and to use LTE Advanced, it was only necessary to replace the SIM card in an outdated phone, the author assumes that the first release of the IMT standard 2020 will be based on LTE Advanced non-orthogonal frequency channel separation technology, Non-OFDM.

Despite the similar architecture with LTE Advanced, 5G networks must use a wider frequency spectrum to increase speed, and since fourth-generation networks occupy a decimeter or centimeter frequency range (LTE Advanced works in the range from 2500 to 2690 MHz when loading, for example, the domestic operator Altel ”uses the frequency band of 1800 MHz.), Then for the networks of the fifth generation, the frequencies in the millimeter range (60-100 GHz) will most likely be allotted. Accordingly, to use the millimeter range, it will be necessary not only to increase the number of base stations in our country, but also to increase the power supply capacity of these base stations.
')
Another distinctive feature of 5G networks will be the introduction of cloud technologies. The use of “clouds” is needed to relieve the load on base stations, it is assumed that they will only transmit the signal without processing as it happens in 4G networks (in LTE networks, signal processing occurs on the side of the end device and the base station, mobility management unit, MME , transmits only service information, and not user traffic, it is the base station that is engaged in its transmission, therefore, with an increase in the number of connected devices, they will not be able to cope with the load).

Since the networks of the fifth generation will function on the basis of the fourth generation, then you first need to explain how the LTE Advanced network functions, then to derive assumptions about the architectural differences of the networks of the fifth generation.

An LTE network consists of two systems — the core network, System Architecture Evolution or Evolved Packet Core, consisting of Mobility Management Entity blocks, User Plane Entity blocks, service and packet gateways, and a radio access network (evolved UMTS Terrestrial) radio access network, E-UTRAN), consisting only of base stations. In the previous generation of communications, the radio access network architecture included a radio network controller, Radio Network Controller, which included the process of establishing and interrupting subscriber connections, a handover process (transferring a subscriber from one base station to another), encrypting user data, and determining the level of quality control. In LTE networks, all these functions are assigned to base stations.

All elements of LTE networks are interconnected using interfaces (the interface is a set of standardized connections connecting various equipment, for example, interfaces are the connecting cables of a computer motherboard and peripheral devices - RS-232, USB, HDMI). The interface connecting the base stations is called X2 and is responsible for keeping the subscriber in the network when moving from one base station to another. Base stations are connected to a mobility management unit via an S1 interface; The interface itself is divided into two types: S1-C, which transmits service information for the base station through the Serving GW; S1-U sending user information via Packet Data Network GW Packet Gateway. Also, in addition to S1, there are other interfaces, such as: S2 (for connecting to networks where the 3GPP forum was not a developer), S3 (connecting a packet network node for subscribers of second and third generation and MME, is responsible for the transmission of service data between LTE and previous generations), S4 (for connecting the SAE core network and the previous generation SGSN packet network node, Serving GPRS Support Node), S5 (connecting the core network and the Packet Data Network packet gateway GW), S6 (connecting the mobility management unit and subscriber data server, responsible for authentication in the LTE network ). The set of network equipment of the basic network, radio access network and connecting interfaces is the physical structure of LTE, LTE Advanced networks.

Logically, the structure of the LTE network is divided into two parts: the radio access layer, Access Stratum and non-access layer, Non-Access Stratum. The radio access layer includes all the radio access network equipment and the basic packet network; the access layer includes methods for controlling (or managing) mobility, EMM, EPC Mobility Management.

Networks based on LTE Advanced provide access to high-quality network services - calls, high-speed download of multimedia data, free use (excluding traffic) of some applications (mostly messengers). Unfortunately, due to the large number of devices and improving the quality (and hence the size) of multimedia information, LTE networks will not be able to cope with heavy loads soon. In particular, the decimeter frequency spectrum used by LTE cannot provide access to resources with the required quality level (Qos) and then the device can simply be disconnected from the network (the base station fails to serve the cell phone).

In order to prevent bandwidth saturation and in the future release of the UHF spectrum for devices that consume few resources, by 2025 Europe plans to switch to the introduction of fifth-generation networks (5G). Each generation of cellular communication should differ from another: the first from the second - transition from analog types of modulation to digital; the second from the third - the emergence of additional services, such as high-speed Internet access; the fourth of the third is the transition from channel switching (distribution of incoming data) to packet and the introduction of IP addressing, as in wired networks. The fifth generation from the fourth must differ in two parameters: the frequency of the spectrum used, that is, the transition to ultrashort waves, as well as the removal of the load from the base stations due to the transfer of their functions to the virtual machines. The inclusion of virtualization and cloud technologies in the 5G architecture means more flexible and faster configuration, as well as cheaper deployment, since virtual machines can be many on a single physical machine. By flexible configuration, the author understands the creation of individual conditions for the use of communication services: personal tariff plans, tailored to the needs of each subscriber; management of the amount of data consumed by all applications.

So, according to the specification 3GPP TS 38.300 version 15.3. 1 Release 15, the general device of the fifth generation networks are built on the basis of the New Radio technology and will be divided into two parts, like the previous generation: 5GC (Core Network), that is, the core network and NG-RAN (Next Generation Radio Access Network), There is a next generation radio access network. The core network should consist of two main devices separating service and user functions. These devices are called “functions”: AMF (Access and Mobility Management Function), the function responsible for providing access and control for maintaining the network signal when a subscriber moves; UPF (User Plane Function), responsible for the transmission of user traffic.

Additionally, other “functions” are included in the network architecture: SMF (Session Management function), the session management function, distributes IP addresses for user devices, controls and monitors traffic passing through the user plane function, selects UPF to move traffic to its destination; AUSF (Authentication Server Function), user device authentication server function; UDM (Unified Data Function), is a repository of registration data, security information, and various subscriptions to a subscriber; PCF (Policy Control Function), a policy management function that controls a single policy of network behavior and policy behavior of each network plane (user and service); AF (Application Function), an application function that performs requests to the session management function, also has access to device battery charge management.

The radio access network consists of two types of base stations: gNBs operating in the fifth generation network and ng-eNB operating in the fourth generation network (E-UTRAN) or the previous generation. Both types of base stations must be connected by the Xn interface, and the connection of the base stations with the functional blocks must be connected by the NG interface. Also, as in LTE networks, the NG interface is different for devices interacting with each other. In total, the 3GPP TR 23.799 specification, released in December 2016, defines 15 types of NG interfaces, numbered from 1 to 15. It is not possible to describe all 15 types of communication complexes in the article, so the author will list only five of them. So, NG1 is a "reference point" between the user device and AMF, NG2 - connects the base station with AMF; the base station also connects via the NG3 interface to the user plane function, which, in turn, is connected via the NG4 interface to the session management function, and access to the Internet and operator services is provided via the NG6 interface. The AF applications function connects to the session management function via the NG5 interface.

From the LTE networks in the 5G network, such concepts as user and control planes have passed, so the NG interfaces associated with the user, as well as in LTE, denote NG-U and, accordingly, NG-C for the control plane, therefore the protocol levels (stacks) of interfaces are also divided only into user and service ones. User-plane interfaces connect the base station to the UPF, and control-plane interfaces (NG-C) to the AMF. It should be noted here that NG-U delivers non-guaranteed delivery (when the user device sends a protocol data element (PDU) and does not wait for a delivery report in return; guaranteed delivery is a confirmation in the form of a report that the data element is received), which significantly saves time data transmission.

The Xn and NG interfaces should have open, accessible to all manufacturers, specifications for interfacing with different base stations. It should be noted here that some groups of scientists working on the development of requirements and standards of 5G, in particular, the NGMN (Next Generation Mobile Networks) forum, in their reports adhere to the opinion of the complete openness of all technologies, that is, the entire network device, starting with the physical and ending with the application layer should be available to all users. NGMN also believes that the design and construction of the 5G network should not be carried out by each operator separately, but jointly by all operators of the regions.

The process of working in the fifth generation network is approximately the same: the user device detects the network with the help of the built-in antenna (this stage remains unchanged from the second generation and GSM technology), the network, that is, the AMF requests the service data of the phone through the base station.

The user device sends its registration data through the base station to the access and mobility management function (AMF), this function matches the registration data of the device with the server that contains all subscribers' data and if the provided data match, access to the network is allowed. After registration, the user device gains access to the UPF, and through it - to the network services.
Another distinction of the fifth generation network — service virtualization and data processing in cloud operating systems — added another concept to the architecture definition: in addition to “Plane” - “plane”, the concept of “Slicing” - “cut” appeared, meaning different settings (or characteristics networks) for individual users and groups, as well as for equipment. It is assumed that the 5G network provider will create special templates - virtual machines (NST, Network Slice Template), and users will be able to optimize these templates for themselves, that is, to connect the required services, to rent software. The slice architecture should not be open, since virtual machines operating remotely (in the “cloud”, that is, in the 5G provider Data Storage Center) may be from different manufacturers. For example, the largest provider of wired telephony in Kazakhstan - Kazakhtelecom JSC uses cloud services from Microsoft (Hosted Lync, Hosted SharePoint, Hosted Exchange), as well as virtual hosting with Windows operating systems (IIS web server) and Linux (web server). Apache).

In 2016, the NGMN forum released a “Description of Network Slicing Concept” document, “Network Breakdown Concept”, in which the logical structure of the slices consists of three parts (bottom to top): the resource level, the instance level of the network segment and the service instance level.
The level of resources includes all physical and logical resources. Physical resources are all the components that make up the network: base stations, storage systems, servers, routers, switches, even cross-overs (connecting equipment such as copper or fiber optic cable is a physical resource). Logical resources are physical resources grouped according to a certain criterion or for any purpose, for example, to logical resources intended for virtual hosting (services that provide storage space for a constantly running computer, that is, a network server computer) : in fact, a computer server with an operating system, a data storage system — a complex consisting of several hard disks connected to each other, switches, routers and connecting cables, as well as ogrammnoe software on demand. Network functions are not related to resources, they are part of the network segment slice. At the same time, the network segment plan, which is a description of the structure and the required network functions, relates to logical resources.
An instance of a network segment is “Slice” - a slice, which is a set of characteristics, settings, allocated resources for deploying services and services provided by the network operator. For example, a slice intended for data exchange between machines (sensors, counters) does not require a data storage system, only a server, a switch and a router, as well as connecting cables, because a single bit of data is sometimes enough to transmit a signal from a device to a device — or 1. If we recall the handover procedure (the transition of a user device from one base station to another), then it immediately shows that the base stations and the user device exchange text messages with each other, yaschimi from one - two words (for example: HO REQUEST, HO RESPONSE and so on). At the same time, the cut for M2M (car and car) connections must be extremely reliable, that is, the message must be delivered and ultra-low delay, that is, the message must be delivered very quickly, for example, if the car's remote control program sends a message to the car sensor. Another sample of the slice - for providing Internet TV services, on the contrary, needs a data storage system, several servers, routers and interconnecting equipment to ensure constant access to a multimedia service, which also requires ultra-low latency, but it doesn’t have to be extremely reliable, since multiple data packets may be overlooked by the user.

A network segment can use various resources, consist of several logically complete subnets, while networks can use resources not only of their own slice, but also of another. , , ( , - ) , (, – ) .

– , . . – , Gmail, , , Microsoft Outlook , .

, LTE, . 5G : , , , , , .

, , (, ) , , . , 3GPP Non-OFDM, LTE Advanced.

, LTE , , , .

, , , «», 100% «Altel», LTE 75% «Kcell». , - . 5G (IMT-2020) 2019 , «» 2025 .