6G Intelligent Fully Connected Network Architecture
Zhang Linfeng, Lin Yilin, Wang Qingyang
（Research Institute of China Telecom Corporation Limited, Guangzhou 510630, Guangdong, China）
【Abstract】At present, the industry has carried out a lot of analysis and research on the 6G vision, business scenarios and key technologies, and the network architecture is the basis for realizing the 6G vision and business requirements. It first analyzes the network architecture requirements of the 6G vision, then discusses the key factors that need to be considered in the design of the 6G network architecture, and finally proposes a 6G intelligent and fully connected network architecture idea.
【Key words】6G; intelligent full connection; network architecture
CLC number: TN929.5 Document code: A
Citation format: Zhang Linfeng, Lin Yilin, Wang Qingyang. 6G Intelligent Fully Connected Network Architecture [J]. Mobile Communications, 2021,45(4): 45-49.
Looking back at the development history of mobile communications, 1G provided analog voice, 2G provided digital voice and SMS, and 3G provided mobile data services, which made the development of mobile Internet gradually unfold. 4G provides mobile broadband Internet access, and mobile multimedia video services have begun to emerge. At the same time, due to the larger network bandwidth and the rapid development of smart phones, various mobile APP applications have been rapidly popularized, such as social networking, payment, shopping, navigation, taxi, takeaway and Mobile short video and other applications have greatly changed people's way of life. The goal of 5G network is to realize the interconnection of all things. In addition to supporting eMBB enhanced mobile broadband scenarios, it also supports URLLC high reliability and low latency and eMTC enhanced machine communication application scenarios, enabling thousands of industries and promoting social development through rich application scenarios. . It can be said that 4G has changed life. 5G is not only changing life, but also empowering industries and changing society. The 6G network for 2030 has the potential to change the world, including the physical world and the digital world.
1 Architecture Requirements for 6G Network Vision
Gartner's top ten technology trends for four consecutive years from 2018 to 2020 pointed out that the trend of AI artificial intelligence to engineering applications has become inevitable. AI empowers machines to adapt, reason and provide solutions. AI has experienced three levels of development: the first is computational intelligence, which is able to store and calculate; the second is perceptual intelligence, which is able to listen, speak, see and recognize; and then cognitive intelligence, which is able to understand, think, and thus Enables computers to understand and think like humans. At present, the main ones entering the practical stage are computational intelligence and perceptual intelligence. During the development of mobile communication networks from 4G to 5G, computing resources have become increasingly abundant, and they have gradually expanded from the network center to the network edge. Data resources have also become increasingly abundant, providing a foundation for AI applications. For example, the self-organizing network SON has been applied since 4G, and 5G introduced the network data analysis function NWDAF (Network Data Analytics Function) and the management data analysis function MDAF (Management Data Analytic Function) in the R16 and R17 standards, mainly defining eNA[ 1], based on big data analysis to improve the ability of intelligent scheduling and operation management of the network, but in the actual network scale deployment involves multi-source data of multi-vendor and multi-device, the data format is more difficult to achieve unified standardization. Large , the actual application effect also needs time to test.
Looking forward to the 6G network vision, it has at least the following characteristics:
(1) Immersive experience : Use the combination of XR, holography, digital twin and other multimedia technologies to simulate sensory information such as vision, hearing, touch, etc., to create a high-realistic environment, and provide users with immersive real-time experience and interactive business may become popular. 5G is mainly based on XR technology, while 6G will be based on holography and digital twin, and can combine XR to provide a more immersive and colorful new business experience, including holographic communication , holographic reality, and twin reality. This type of service embodies the fusion of communication and perception, and puts forward higher requirements for multi-sensing interaction, real-time image compression algorithm and real-time control capability of network signaling.
(2) Network intelligence [2, 5]: 5G networks introduce a certain degree of intelligence into standard or actually deployed networks, but at present the intelligence at different levels is relatively isolated, such as the access network, core network and network management level The intelligence basically has not formed linkage or closed loop. The industry generally expects that the intelligence of 6G in terminals, wireless networks, core networks, bearer networks, and network management will be further enhanced, and at the same time, intelligent coordination at different levels will form the overall intelligence of the 6G network. In addition, intelligent technology will be applied to multiple levels of 6G networks and applications, providing intelligent ubiquitous connectivity for users, applications and society. In the 6G era, communication will be deeply integrated with AI. AI will empower networks, networks will empower AI applications, and intelligent connectivity will be everywhere.
(3) Integration of heaven and earth : 3GPP introduced NTN  (Non-Terrestrial Network, non-terrestrial network) in the R17 version of 5G, which supports the integration of satellite and mobile communication networks in transparent mode and regeneration mode. The industry expects 6G to provide ubiquitous three-dimensional coverage for wide-area sparse scenarios and realize the integration of space and earth, so that it can serve more business scenarios such as remote areas, aviation, navigation, and high-speed rail. At the same time, the 6G network should also realize intelligent collaboration between different network accesses such as heaven and earth, and realize intelligent ubiquitous connection.
(4) Fixed-mobile convergence: 3GPP established 5WWC (Wireless and Wireline Convergence for the 5G System), ATSSS (Access Traffic Steering, Switching and Splitting), and 5G LAN (5G Local Area Network) in the R16 version of 5G. Other projects related to fixed-shift fusion. Among them, 5WWC supports fixed wireless and wired access (including PON) unified access to the 5GC core network, and realizes unified authentication of multiple access methods. It is suitable for industrial application scenarios where multiple access methods such as 5G, WLAN, and PON coexist ( factory/park) and home scenarios (whole house Wi-Fi + home broadband). ATSSS further realizes multi-access and multi-stream intelligent scheduling of 5G and WLAN. 5G LAN realizes the establishment of a local area network across UPF between 5G UEs, and the 5G UE and the wired terminals of the enterprise intranet can form a fixed-mobile integrated local area network, providing a wide-area virtual local area network solution for enterprises. 6G requires a multi-network integrated network architecture , and it is expected that 6G can achieve a wider and more comprehensive integration of space and earth and fixed-mobile integration.
(5) Endogenous security : 5G network is based on cloud-native design, enabling the integration of 5G network and NFVI cloud infrastructure. In addition, 5G is based on a service-oriented communication architecture, the signaling protocol is directly based on HTTPv2, and supports Restful interfaces externally. At the same time, the introduction of MEC edge computing makes 5G more open and can better integrate with Internet applications. While gaining business flexibility and richness, it also introduces the security risks faced by NFVI cloud infrastructure and the Internet. Therefore, at the beginning of 6G network design, it is necessary to consider how to avoid the embarrassment that 5G networks can only enhance security through external security solutions, learn from the development of blockchain technology, and combine distributed identity authentication, zero trust, and trusted networks discussed in the industry. , building an endogenous security mechanism has become a problem to be solved in the design of 6G network architecture.
2 Overall Considerations for 6G Network Architecture Design
From the evolution of the first generation of analog cellular mobile networks to the current 5G network, it can be seen that no network architecture is completely separated from the previous generation out of thin air. However, based on the needs of different business and application scenarios, and the impact of technological progress, each generation of network architecture is significantly different from the previous generation, with both inheritance and change.
Therefore, the design of the 6G network architecture has the following considerations:
(1) Route selection: 6G is a bridge connecting the real world and the virtual world. It is the engine for the harmonious development of human society and the natural environment. It has a larger historical mission than 5G. 6G cannot be simply evolved on the basis of 5G. It is recommended to give priority to revolutionary advanced technologies, which will form a significant generational difference with 5G.
(2) Green environmental protection: From the very beginning of 6G architecture design, green environmental protection should be regarded as the fundamental requirement of 6G R&D and operation, so as to contribute to China's "carbon peak" in 2030. 6G should implement dynamic scheduling of resources by introducing intelligent technology to maximize resource efficiency. The resources here are not only wireless air interface resources, but also resources at all levels of the network. How to make the overall energy efficiency of the network through global intelligent scheduling and control Optimal is an important issue that 6G needs to solve.
(3) Consider the basic framework that supports full connectivity: Full connectivity includes two types of connections: satellite access and ground access, and ground access includes two categories of wireless connections and wired connections. The 6G basic framework should consider how to achieve intelligent management of full connections in ubiquitous access scenarios where various connections coexist in space, earth, sea, fixed and mobile, and how to realize ubiquitous connections that are available anytime, anywhere, and provide users with diverse Customized QoS services.
(4) Considering the needs of new services and new scenarios: 4G networks are mainly based on 2C services. The expansion of bandwidth has spawned a number of mobile Internet services that enrich people's lives. 5G will expand 2B applications and bring new development momentum to all walks of life. . The 6G network needs to consider the needs of the harmonious development of human society and the natural world in 2030 and beyond, including providing ubiquitous and ubiquitous connectivity, and network flexibility and programmability to meet customized needs.
(5) Consider the blessing of technological innovation in cross-domain: SDN concept and NFV technology have been applied to a certain extent in the later stage of 4G network, and have been fully applied in 5G; technologies in IT fields such as cloud computing, containers, microservices, and HTTP have also been introduced The 5G network makes the network more flexible; the introduction of big data and AI technology also makes the 5G network have preliminary intelligence. In the preliminary research of 6G, innovative ideas such as the integration of AI and air interface technology and the application of blockchain in spectrum sharing have emerged. Therefore, the future 6G network will support the deep integration of ICDT, and the design of the network architecture needs to fully consider how Absorb various emerging technologies to realize the 6G network of cloud-network edge-end integration [11-12].
3 6G Intelligent Fully Connected Network Architecture Assumption
Compared with 5G, the future-oriented 6G network will provide higher peak rate, lower end-to-end latency, and denser number of connections, and support richer and more complex business scenarios and applications, especially AI-based applications. Ubiquitous features, whether in the cloud, at all levels of the network, wireless, or terminals, will support "smart" features.
The envisaged 6G intelligent fully connected network architecture, from a horizontal perspective, includes three parts: access network, edge network, and core network. The access network provides satellite access, wireless and mobile access, and wired access. Ubiquitous access and controlled by the edge network, the edge network provides regional mobility and access services, and is usually deployed on the edge cloud, and the core network realizes the interconnection of each edge network and the interconnection with the Internet network, usually deployed on the core cloud. The access network, edge network, and core network can be provided by the same operator, or by different operators, and can also be provided by multiple parties in a co-construction and sharing manner.
From a vertical perspective, the 6G intelligent fully-connected network architecture includes three layers from bottom to top: cloud-network integration layer, intelligent network layer, and intelligent service layer, as shown in Figure 1.
The cloud network integration layer is the infrastructure for 6G network deployment, providing traditional bearer network connections, cloud computing resources and cloud network operating systems for 6G networks. Finally, the resource supply of a new information infrastructure that is concise, agile, open, integrated, safe and intelligent will be realized.
The intelligent network layer is the core functional layer of the 6G network, which realizes the intelligent control of signaling and the intelligent processing of user data, and follows the design principle that control and bearer work as independently as possible. However, the implementation of the core network and the edge network is different, as follows:
(1) Core network: It consists of a communication plane and a management plane. The communication plane is divided into three layers from top to bottom: intelligent service control (control plane), intelligent connection scheduling (control plane), and intelligent core processing (user plane), which respectively implement session control at the service layer, session control at the network layer, and Implement intelligent forwarding and media processing for user data streams from edge networks. Through layered design, the signaling plane realizes flexible and intelligent scheduling of multi-channel and multi-flow strategies from the service layer and the network layer. The user plane also has the intelligence of independent routing, and realizes distributed forwarding processing through P2P networking. The management plane includes intelligent data acquisition and control and intelligent operation management, realizing intelligent collection, big data analysis, AI modeling, and data training, and can realize a closed loop of feedback through the intercommunication of the signaling plane or the user plane, thereby improving the efficiency of network operation and maintenance. The level of automation, the level of business-oriented operations, and the ability to intelligently defend network security gradually realize the autonomy and self-evolution of the network.
(2) Edge network: Following the principle of separation of control and bearer and extremely simplified design, intelligent access control (control plane) and intelligent edge forwarding (user plane) realize distributed edge access control and mobility management, as well as user data Edge forwarding and processing of flows. All edge networks and core networks share a mobility management database, which can technically be achieved through blockchain or distributed ledgers. When the user accesses locally, moves within an area, or only uses services provided by the edge network, the edge network implements mobility management and autonomous control of edge access, and the signaling plane of the core network does not need to be involved at this time; When the user is in a roaming scenario, the edge network and the core network jointly complete the signaling control. The edge network has a high degree of intelligence. In addition to the intelligent control of the current access layer full connection, it also has a high degree of autonomy and self-evolution capabilities, which is convenient for lowering the operating threshold and attracting third-party partners to participate in the edge network. regional operating services.
The intelligent network layer should be compatible with various infrastructures in the specific implementation. At the same time, functional entities should have flexible customization and good scalability, and support dynamic on-demand deployment and elastic scaling according to business scenarios. Therefore, the granular design of functional entities should be more flexible, and the agreements between entities should be flexible, dynamic and flexible. Features such as simplicity, so that the core functions of the 6G network can be programmable, choreographed, and support P2P networking.
The intelligent service layer mainly provides services for 6G network applications. First of all, it supports intelligent interaction. The future mobile network should consider the AI application scenarios and requirements for consumers and industries, and realize the connection between AI terminals and AI applications. This connection may transmit computing requests, control instructions, or models, Data may also be a novel and intelligent interaction method such as brain-computer interface. Secondly, it supports external intelligent services, including AI as a Service, Blockchain as a Service, etc., and various services for all scenarios of 2C, 2H, and 2B. The intelligent services provided by the 6G network are different from the traditional centralized capability opening based on NEF. In order to adapt to the development trend of WEB3, distributed on-chain services (for example, computing services) are provided by connecting with the blockchain or distributed ledger system. , algorithm services, data services, etc.) are likely to become mainstream.
From the perspective of the network, intelligence is not centrally deployed, but moves from centralization to distribution. There may be intelligent control functions in various entities such as the cloud, network, edge, and terminal. According to the difference of applications, some applications use core intelligence Mainly, some applications are dominated by edge intelligence, and some applications are dominated by terminal intelligence, thus forming an intelligent fully-connected architecture system for cloud-network edge-end collaboration. Inside the network, intelligence is also dispersed in multiple layers and multiple functional entities. Through the intelligent coordination of multiple layers, intelligent full-connection control of the access layer, network layer, and service layer is realized. From the perspective of terminals, 6G The network provides a wide-area ubiquitous connection between the sky, the earth and the sea, and supports satellite access, wireless and mobile access, wired access and other full-scenario access and application-layer full-connection services. The core connotation of intelligent full connection is that the network should provide users with access to services in all business scenarios through intelligent management of connections.
4 Technical advantages of 6G intelligent fully connected network architecture
Compared with the 5G network, the 6G intelligent fully connected network architecture proposed in this paper has the following technical advantages:
(1) The roles of the edge network and the core network are separated: the edge network is responsible for mobility management, access control, and local connection control, while the core network is responsible for backbone connection control, supporting a new multi-operator collaboration business model and ecological environment. Operators have more flexibility in co-construction and sharing.
(2) The control plane and the user plane work independently, and their interfaces are extremely simplified: the traditional SDN architecture adopts the idea of separating control and bearer. The control plane entity has strong policy intelligence and completely controls the behavior of the user plane entity. User plane entities can only execute according to control plane policies, and have no autonomous decision-making ability. Since the user plane is completely controlled by the control plane and cannot work independently, the two appear to be separate on the surface, but in fact they are tightly coupled and cannot work independently. In the intelligent fully-connected network architecture, the control plane and the user plane are completely separated and loosely coupled. The network functional entities of the control plane and the user plane both support the autonomous networking of the P2P mode. What is pursued is that the two work independently, and the user plane can provide emergency services for users even in the event of a failure of the control plane. The user plane also has strong policy intelligence. It can independently perform routing selection and report to the control plane, and can also execute according to the specific policies of the control plane, which will improve the autonomy of the edge network and make the network more scalable as a whole. sex.
(3) Distributed network intelligence: 5G R16 defines an eNA framework based on NWDAF network elements and big data analysis, which is a centralized intelligence, while 6G introduces AI endogenous distributed intelligent collaboration, which will be based on machine learning (such as deep learning). , Federated Learning) as an endogenous technology implementation, supports multi-layer intelligent collaboration between various layers of the network, as well as multi-party intelligent collaboration between the terminal and the 6G cloud network edge.
(4) Full-connection control and scheduling: 5G R17 NTN realizes satellite-ground integration, 5WWC realizes wired and wireless integration, each scheme is independently superimposed, and each scheme is suitable for specific scenarios. In the 6G intelligent fully-connected network architecture, the edge network solution will natively support all access methods such as satellite access, wireless and mobile access, and wired access, as well as the sharing of mobility location data.
5 concluding remarks
The goal of 6G is to meet the needs of mobile networks from business applications, technological progress and social development after 2030, and the 6G network architecture is the basis for achieving this goal. Based on the current prospect of the 6G vision, the consideration of the characteristics of the mobile network evolution architecture, and the preliminary judgment of the technological progress, this paper proposes a 6G intelligent and fully connected network architecture assumption. However, 6G research is still in the preliminary stage, and the 6G standard work has not yet officially started. Based on the gradual deepening of the research, it is necessary to further refine and optimize it on the basis of the current architecture assumption.
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