On September 23, 2020, at the 2020 Huawei Full Connect Conference, China Academy of Information and Communications Technology (hereinafter referred to as "China Academy of Information and Communications Technology") released the "5G End-to-End Slicing SLA Industry Demand Research".
5G network slicing is a key entry point for the vertical industry of 5G services. As a business guarantee agreement between slicing service providers and slicing users, SLA will play a key role in the application expansion and commercialization of 5G industry.
How to define and classify different levels of SLA (Service Level Agreement) is very important for network slicing. At present, most industry customers do not have a clear understanding of network slicing. Communication companies and industry users need to explore together, and slice management and services The balance of needs is a big challenge.
This report studies the SLA requirements of application companies for 5G slicing services from an industry perspective, and combines the commonly used SLA standards in the industry to define the "Maslow model of industry requirements for connection SLA" for the first time. The three dimensions of "autonomous and controllable" systematically describe the hierarchical system of connecting SLA.
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research background and purpose
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Development status and existing problems
5G is not only an inter-generational transition of mobile communication technology, but also the "main front" of industry application innovation.
Compared with previous mobile communication technologies that mainly meet the communication needs of "Internet of Everything", 5G pays more attention to the communication needs of people and things, things and things, and focuses more on empowering vertical industries and accelerating the opening of the new "Internet of Everything". era.
5G network slicing cuts the shared physical infrastructure into multiple independent virtual networks, and provides independent and isolated customized private network services for different businesses. It is a key entry point for the 5G service vertical industry. Industrial, medical, energy and other industries have shown great enthusiasm for 5G slicing technology, hoping to promote business model innovation and promote industrial transformation and upgrading.
The technical standards and network foundation of 5G network slicing are basically in place.
As an on-demand end-to-end logical network, 5G network slicing involves wireless, transmission, core network and management domains. In the 3GPP R16 version frozen in July this year, 5G network slicing has initially realized the basic functions of eMBB and uRLLC-like slicing And the definition of the basic process laid a solid foundation for the first wave of 5G deployment and network slicing business commercialization.
At the same time, the initial commercial use of the 5G SA network has created basic conditions for the application of end-to-end network slicing technology. This year, my country's four major operators will focus on independent SA networking in the construction of 5G networks, and fully promote the commercialization of 5G SA networks.
China Telecom is expected to launch 5G SA commercialization in September this year. After a year of testing and adjustment, large-scale commercialization can be carried out; China Unicom also launched the 5G SA public test plan in the third quarter of this year, and is currently recruiting public beta users; China Mobile plans to launch the 5G SA public beta this year. SA matured in the fourth quarter. Shenzhen has fully completed the 5G SA network and built more than 46,000 5G base stations in total. The network construction has entered the second stage, and the implementation of various 5G industry applications will become the current focus.
5G network slicing SLA classification is very important for large-scale commercial use, and there is no clear definition yet.
Since network slicing provides a combination of different network capabilities for different industries and scenarios, how to define and classify different levels of SLA (Service Level Agreement) is very important to the providers and consumers of network slicing services. However, currently SLA levels are applied to slicing The division also faces many problems.
First of all, in terms of industry users, although some industry application scenarios have carried out some experiments based on SA networks, most industry customers do not have a clear understanding of network slicing capabilities, and do not know how network slicing matches their own industry application scenarios. The commercial value of slices and how to buy slices.
Secondly, in terms of operators, 5G slicing SLA classification involves numerous industry application scenarios and strong expertise in various industries. It requires communications companies and industry customers to conduct a lot of joint exploration and research, and industry leading companies are required to deeply participate in the definition and standardization of slicing SLA levels. Divide.
Finally, in terms of slice management, more slices are not the better. How to balance the complexity of operation management and the diversity of customer needs is a big challenge. It can meet the clear SLA specifications and service quality of both service parties. The management process can be completed only through multiple verification and update iterations of the market.
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Significance
Converged applications in the 5G industry have entered a critical period of exploration. Studying how to classify 5G network slicing SLA levels is an important prerequisite for accelerating the application and large-scale promotion of 5G network slicing in various industries. It is important for industry users, operators, and governments (industry authorities). All have positive and far-reaching significance.
The 5G network slicing SLA classification helps industry users understand slicing and make good use of slicing.
Users’ understanding of network slicing requires a certain cognitive process. Clear SLA indicators help industry users to intuitively feel the service categories and differences that network slicing can provide, and refer to the service levels defined by SLA standards to choose what suits them. The industry-specific network slicing service reduces the barriers to inter-industry communication, promotes the landing of 5G converged applications, and allows industry users to enjoy the dividends brought by 5G technology as soon as possible.
5G network slicing SLA classification can effectively improve the ability of operators to serve users in the industry.
First of all, operators can have a deeper understanding of the industry's application requirements for 5G when participating in the SLA standard formulation process, and develop network slicing services that meet the needs of most industries.
Secondly, SLA standards help reduce the operating costs of operators. Operators formulate flexible and differentiated pricing services based on different SLA standards, and provide a communication platform with negotiable service prices and guarantee levels, which helps to achieve effective results between meeting the diverse needs of industry customers for customized networks and reducing 5G operation and maintenance costs. balance.
Finally, SLA standards can improve the service quality of operator slices. With the help of the slice SLA management platform, operators can provide 5G network slicing services for a large number of industry applications, while being able to accurately control the service quality of a single slice.
The 5G network slicing SLA classification provides decision-making reference for industry authorities.
The first is to provide judgment standards and reference basis for policy supervision research. Various industries have higher security requirements. The application of 5G to various industries requires the formulation of security technical indicators for 5G networks, terminals, and data from the top level of industry management, and the establishment of a security authentication docking mechanism between the communications industry and various industries.
In order to use 5G as one of the optional technologies for industry networks, the government needs to refer to the quantitative indicators and industry standards of 5G network capabilities in the process of formulating technical indicators. Clear SLA level indicators will be an important reference.
The second is to lay the foundation for the construction of an evaluation system for the "connectivity" of the industrial Internet. Through the SLA classification, it is possible to quantify the connection capabilities of the industry's digitalization, which can be used by the country to evaluate the actual effects of the industry's digitalization, analyze the existing shortcomings and adjust the investment direction.
In summary, a clear SLA classification is a communication bridge between thousands of industries and 5G technology, and is the first step for 5G end-to-end slicing to meet the diverse and differentiated communication capabilities of various industries and to move towards large-scale commercial operations. It is an important task at this stage to fully understand the 5G business needs of various industries and their deterministic SLA requirements for 5G network slicing, and to support customers' deterministic connection experience.
Typical network architecture of 5G end-to-end slicing
5G network slicing has been defined in 3GPP TS23.501. By dividing the physical network into multiple logical networks, one network can be used for multiple purposes, enabling operators to build multiple dedicated, virtual, isolated, Logical networks customized on demand to meet the different needs of users in different industries for network capabilities (such as delay, bandwidth, number of connections, etc.).
5G network slicing needs to be implemented based on the SA network architecture. The 3GPP R15 protocol defines slice identification and E2E identification user groups based on the 5G SA architecture, and explains how slices enable differentiation. Usually only complicated network and terminal configuration can realize the differentiation of a certain type of user group, and protocols such as 2G/3G/4G/5G NSA lack E2E means to uniformly identify a certain type of user group.
5G network slicing is an end-to-end architecture design that includes multiple sub-domains and involves three levels: management plane, control plane, and user plane.
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End-to-end slice management architecture
It mainly includes the following key components:
CSMF (Communication Service Management Function) is the entrance to slice design. Transform the requirements of undertaking business systems into end-to-end network slicing requirements, and pass them to NSMF for network design. The CSMF function is generally provided by the operator's BSS transformation.
NSMF (Network Slice Management Function) is responsible for end-to-end slice management and design. After obtaining the end-to-end network slicing requirements, NSMF generates a slicing instance, decomposes and combines them according to the capabilities of each subdomain/subnet, and transfers the deployment requirements for the subdomain/subnet to NSSMF. The NSMF function is generally provided by the cross-domain slice manager.
NSSMF (Network Slice Subnet Management Function) is responsible for the slice management and design of subdomains/subnets. The core network, transmission network and wireless network have their own NSSMF.
NSSMF reports the capabilities of subdomains/subnets to NSMF. After obtaining the decomposition and deployment requirements of NSMF, the autonomous deployment and enabling in the subdomains/subnets are realized, and the subdomains/subnets are sliced during operation. Network management and monitoring.
Through the decomposition and collaboration of CSMF, NSMF and NSSMF, the end-to-end slice network design and instantiation deployment are completed. End-to-end slice lifecycle management, including slice instance creation, monitoring, and release, such as decomposing network requirements to each single domain of wireless network, bearer network, and core network, completing slice E2E configuration, collecting information of each single domain, and summarizing to form a slice level Statistical indicators are subsequently visualized; integrated with the BSS system to support the design and launch of industry slice templates.
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A typical implementation scheme of 5G slicing end-to-end network technology
End-to-end 5G network slicing includes three parts: wireless network slicing, core network slicing, and transmission network slicing:
Wireless network slice
Wireless slicing resources include air interface resources (spectrum, cells), equipment resources (AAU, BBU resources); splitting methods include hard cutting (resource isolation) and soft cutting (resource preemption).
For example: during air interface resource scheduling, resource reservation (a certain air interface time-frequency resource is dedicated to a certain slice, resource isolation), priority-based resource preemption (high-priority slices preempt air interface resources of low-priority slices), Air interface resource guarantee and quota for slicing business capacity. During device resource scheduling, device resources such as CPU, memory, and queues are used exclusively by a certain slice or shared preemptively based on slice priority.
The implementation of wireless network slicing technology is divided into two stages in rhythm.
The first stage is mainly to complete the wireless network's perception of slices, open up the end-to-end process for terminals to access the slice network, and support slice priority (that is, the group priority set for the user group in the slice), such as the high priority slice Internal users set the minimum guaranteed rate and set the maximum rate for users in low-priority slices; when the network is congested, users in high-priority slices can preempt the resources of users in low-priority slices.
Different slices in the second stage can select the most suitable PHY/MAC/RLC/PDCP wireless protocol stack according to the business requirements. For uRLLC slices, in order to ensure low latency and high reliability, the PHY layer uses a low-latency optimized coding method, the MAC layer uses HARQ blind retransmission, and the RLC layer does not use the acknowledge mode; for eMBB slices, to ensure large bandwidth, PHY The layer adopts the encoding method optimized for heavy load, the MAC layer adopts HARQ retransmission, and the RLC layer adopts the confirmation mode; for the mMTC slice, in order to ensure deep coverage and low power consumption, the PHY layer adopts the encoding method with increased coverage and optimized energy consumption. Multiple HARQ retransmissions are used to provide in-depth coverage, and the data plane uses the Data over NAS signaling plane transmission method. The first stage of wireless slicing technology has matured, and the second stage is still being explored.
Core network slice
Under the SA network architecture, the network functions of the core network are divided into parts and divided into many fine-grained modular components. Microservices are the smallest modular components of the 5GC core network network functions. The core network slicing is implemented as follows:
Microservices are arranged flexibly according to different business needs to form different slices. For example, FWA slicing, fixed terminals do not need to deploy mobility management, but need to deploy CPE access management. In addition, considering the IPTV services carried on FWA, IPTV multicast functions need to be deployed; such as uRLLC slicing, because of low latency and high reliability It is required that the 1+1 hot backup function needs to be added to the session management, and the user plane function needs to add low-latency forwarding/latency monitoring functions.
According to different requirements such as delay or bandwidth, sliced microservices can be flexibly deployed in different locations on the network.
For example, FWA slicing, because it is not sensitive to latency, the core network microservices corresponding to FWA slicing can be deployed in the core data center; while for uRLLC slicing, due to the low latency requirements, the user plane microservices of the slice must be deployed nearby. Edge data center. Signaling surface microservices that are not sensitive to delay, such as access mobility management and session management functions, can be deployed in core data centers or regional data centers as required.
Each microservice can be exclusive or shared by different slices. The exclusive mode is equivalent to each slice has a set of core networks that do not affect each other; or partly shared and partly exclusive, such as some microservices can be shared by multiple slices (such as unified user access authentication management, unified user Data management, unified user policy management), and other microservices (mobility management, session management, user plane functions, etc.) each slice has its own set.
Transmission network slice
The realization of transmission network slicing is divided into two levels: the forwarding plane and the control plane. The forwarding plane has optical/IP hard pipes (physical isolation) and IP soft pipes (hierarchical QOS scheduling); the control plane realizes the difference between each slice Logical topology and intelligent routing.
Isolation of soft and hard pipes on forwarding plane
Optical layer hard pipe: by allocating different wavelengths (A or different ODUk within a single wavelength) (optical channel data unit, that is, different time slot units within a wavelength) for different services, realize the exclusive use of optical transmission resources and services for each slice isolation;
IP layer hard pipe: FlexE (Flexible Ethernet) technology is used to realize the allocation of unique interface resources for different slices, and service isolation based on hard pipes (FlexE technology: the physical layer of the Ethernet interface divides time slots, and the MAC layer flexibly selects one or more Time slots constitute a variable bandwidth interface, for example, 20 10G bandwidths are provided on a 5*40G interface);
IP-layer flexible pipes: Construct flexible pipes for different services through TE tunnel technology (TE : Traffic Engineering, negotiate link bandwidth by configuring control protocols on each router node to achieve bandwidth reservation for each node on the logical tunnel) Slicing allocates link bandwidth resources, and implements priority scheduling of different users and different business flows through HQos (hierarchical QOS: using multi-level scheduling to finely distinguish the traffic of different users and different services, and provide differentiated bandwidth management).
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The industry rhythm of 5G slicing
Since slicing is based on the 5G SA architecture, the commercial implementation of slicing requires close joint technical verification and commercial innovation by operators, equipment vendors, and vertical industries. The pace of commercial implementation is expected as follows:
1) From 2020 to 2022, with the commercialization of 5GSA in 2020, it will gradually mature in the next 1-2 years. A small number of industries that have a strong demand for SLA will take the lead in innovative exploration in the slicing field, such as industrial Internet, smart medical care, and smart grid , AR/VR/games, distance education, etc.
2) In 2023 and beyond, with the further maturity of 5G slicing technology, more industries will choose slicing services. my country is currently in a leading position in 5G slicing. At the Mobile World Congress in Barcelona in 2018, China Mobile, Huawei, Deutsche Telekom, Fraunhofer FOKUS, State Grid, China Electric Power Research Institute, Tencent, Telecom Italia, Volkswagen and Digital Domain announced the establishment of 5G Slice alliance. After two years of exploration, Chinese operators have carried out a lot of practice in multiple fields such as VR live slicing, game slicing, smart grid slicing, and smart oil field slicing, and 5G slicing technology has gradually matured.
5G end-to-end SLA classification recommendations
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SLA indicator reference
SLA: An agreement reached through formal negotiation between the two parties, sometimes called a service level guarantee. It is a contract (or part of a contract) between a service provider and a customer, which aims to establish a common understanding of services, priorities, responsibilities, etc.
Specification (SLS): It can be regarded as the technical components and indicators of the SLA, used to define the parameters and related thresholds of the SLA indicators.
At present, the industry has proposed some SLA-related standards, combining GSMA and 3GPP standards, the SLA indicators of 5G slices mainly include "user bandwidth, delay, packet reliability, throughput, positioning accuracy, isolation, etc.".
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Maslow model of industry SLA requirements
After sorting out existing standards and investigating the needs of industry users, we summarized and concluded that there is a "Maslow model" in the needs of enterprises for the network. The basic level is from basic business availability to security and credibility, and then to Autonomous and controllable.
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5G slice SLA classification recommendations
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SLA palette specific grading recommendations
Single user bandwidth level
This indicator can be checked and accepted by performing packet filling tests on the UE side or the server side, or it can be calculated and accepted by counting the successful data transmission of the slice service within a specified time.
Delay level
This indicator can be checked and accepted by the ping packet test on the UE side or the server side, and the RTT delay of the data packet is counted.
Isolation level
This indicator needs to test the influence of a business slice on the background slice. If the video surveillance slice is under the influence of the background slice and the user rate is not affected, it is physical isolation, otherwise it is logical isolation.
Management level
This indicator is checked and accepted by operating the management interface on the UE side or the server side, and judges based on whether the corresponding function is provided.
Demand analysis of SLA palette in typical industries
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Medical industry
At present, the main applications in the 5G+ medical and health field include three categories:
One is diagnostic guidance applications based on real-time interaction of images and videos, such as real-time remote consultation, wireless surgical teaching, etc.;
The second is remote control applications based on force feedback, such as remote robotic surgery;
The third is monitoring and nursing applications based on wireless collection, such as wireless infusion, mobile nursing, and real-time patient location monitoring.
On the other hand, from the perspective of the use scenarios of medical institutions, 5G smart medical applications can be divided into three main scenarios: pre-hospital, in-hospital, and inter-hospital, to fully empower the medical industry.
The medical industry SLA standard classification can be divided into three categories: diagnostic guidance slices based on real-time interaction of images and videos, remote control slices based on force feedback, and monitoring and nursing slices based on wireless collection.
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Manufacturing Industry
The in-depth application of 5G in the industrial manufacturing industry has become an important direction for the industry to explore. 5G integrates cloud computing, big data, artificial intelligence and other technologies. Empowering discrete and process industries, in key links such as design, manufacturing, quality inspection, operation and maintenance, safety, etc., collaborative design, simulation verification, auxiliary assembly, precision control, flexible processing, visual inspection, remote maintenance, Typical application scenarios such as unmanned inspections have initially shown the effects of cost reduction, quality improvement, and efficiency enhancement.
The SLA standard classification of the manufacturing industry can be divided into three categories: peripheral auxiliary slices based on uplink high bandwidth, auxiliary production slices based on massive information collection, and core production slices based on high reliability and precise control.
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Power Industry
The power system includes five major links: power generation, power transmission, power transformation, power distribution, and power consumption. With its technical advantages, 5G has been applied to all aspects of the power system to help clean and friendly power generation, safe and efficient power transmission and transformation, and flexible and reliable power distribution. , Diversified and interactive electricity consumption, accelerate the digital transformation and upgrading of the power grid.
For the three major links of power generation, transmission, and transformation, 5G technology mainly uses new business methods such as mobile inspection, video surveillance, and environmental monitoring to enhance power system management capabilities. In the power distribution link, 5G technology will effectively promote the automation and flexible transformation of power distribution.
On the one hand, by improving the level of digitization, networking, and intelligence of power distribution equipment, the power distribution network equipment can be managed and controlled, and the level of precision control will be improved;
On the other hand, ubiquitous access and intelligent management of distributed energy can be realized through 5G to ensure the stability of the distribution network. In terms of power consumption, 5G helps power consumers to develop toward service and intelligence. For example, by supporting services such as stepped electricity prices and real-time electricity prices, it can accurately predict electricity demand and improve the coordination of supply and demand. Judging from the current development of the application business, 5G technology has a greater impact on the power distribution and power utilization sectors, and the trend of change is more obvious.
The power industry SLA standard classification can be divided into three categories: inspection slices based on high-definition video, power grid control slices based on low latency, and monitoring slices based on wireless acquisition.
Development proposals
As a business guarantee agreement between slice service providers and slice users, SLA will play a key role in the application expansion and commercialization of the 5G industry. In order to promote the development of the 5G industry and the further implementation of 5G slice SLA classification, we propose the following suggestions.
One is to call on all parties to actively participate in SLA research.
The current SLA research work is mainly based on communication operators and equipment vendors, while 5G convergence applications involve many industries, and each industry is highly professional. Leading enterprises in vertical industries need to increase their participation and understand the business of slicing to the industry through in-depth communication. Value, and discuss the next research work together.
The second is to accelerate the test verification based on SLA network slicing.
At present, SLA definition of network slicing is still in the stage of theoretical exploration. There is still a certain distance between SLA classification and the real landing of certain industries. It needs to be judged and adjusted in conjunction with a large number of repeated 5G application trials in the industry, and further optimize SLA parameters. Promote standardization related work.
The third is to accelerate the commercial implementation of 5G slice SLA.
Through the participation of all parties in the SLA industry, we will jointly explore the business model of 5G slicing, accelerate product development, reduce barriers to communication between industries, and promote the landing of 5G integrated applications, so that industry users can enjoy the dividends brought by 5G technology as soon as possible.
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