Unveiling the network architecture of the 6G era! Six major design concepts, three bodies, four layers, and five aspects in one article

The development of network architecture is one of the core signs of the intergenerational development of mobile communication networks. It is the backbone and center of each generation of communication networks and the basis for carrying the design goals of mobile communication systems. The foresight, feasibility, and compatibility of network architecture design will directly affect the development path and application results of mobile communication networks and must be considered in advance.

The architecture design of 6G network should not only face the changes in the digital era and be highly consistent with the national strategy, but also consider the driving force of new scenarios and new demands, and at the same time demonstrate the development trend and feasibility of introducing new technologies in cross-border fields. In addition, comprehensive consideration of the experience of 5G existing network applications and the evolution direction of 5G-A technology have important implications for the design of 6G network architecture.

In this issue of Smart Insider, we recommend China Mobile's report "6G Network Architecture Technology White Paper", which reveals the design concept, overall design, system design, and networking design of China Mobile's 6G network. Source: China Mobile.

1. 6G network architecture design concept

The 6G network is designed based on the six major design concepts of compatibility, cross-domain, distribution, endogenous, simplicity, and twinning.

Compatible design: Mobile communication networks are developing and changing along the direction of IP, cloud, and service. The 6G architecture design will continue these flexible development directions and achieve forward and backward compatibility. In terms of connection flexibility, the 6G architecture will further realize deterministic IP on the basis of end-to-end IP; in terms of resource flexibility, the 6G architecture will further realize computing and network integration on the basis of cloud; in terms of function flexibility, the 6G architecture will further realize global service and service technology evolution on the basis of core network service. The continuous development of these three flexible directions will fully continue the architectural advantages of 5G and support the smooth development and evolution of 5G networks into 6G networks.

Cross-domain design: The 6G architecture design will support the management of multiple accesses such as fixed, mobile, and satellite, support the management of multiple networks for the public/industry, physical/digital, and support the collaboration of different domains within the network. To provide information and communication services with guaranteed quality for end-to-end and full-domain networks, the 6G architecture is required to be cross-domain integrated for multiple accesses such as fixed, mobile, and satellite, and to achieve control convergence, business convergence, and management convergence for multiple accesses at the architecture level. Facing the diverse application scenarios of the public and the industry, the 6G architecture is required to be cross-layer and integrated for multiple domains such as core networks, transmission networks, and access networks for different networking modes and different functional requirements, and to achieve network organization convergence at the architecture level.

Distributed design: 6G architecture design will shift from centralized planning to distributed autonomy to meet the requirements of massive connections and extreme performance under large-scale networking. In the 6G era, there will be extreme performance requirements of control plane latency <1ms and user plane latency <0.1ms, and the number of base stations of large-scale operators will reach tens of millions. Facing the needs of 6G, the centralized and manually managed network architecture cannot meet the performance and scale requirements of the network. It is necessary to achieve distributed management of resources, routing, functions, and business levels through centralized + distributed collaborative networking, and realize self-growth, self-optimization, and self-evolution of network autonomy, so as to achieve optimal scheduling of network resources and network capabilities in large-scale complex networking environments.

Endogenous design: 6G architecture design will shift from plug-in to endogenous, including endogenous security and AI, with core capabilities built into the architecture. For 6G networks with multi-domain integration, ubiquitous connections, and heterogeneous resources, incremental and patch-based capability enhancements are difficult to meet the diverse and diversified service needs under large-scale networking. It is necessary to build core technical capabilities such as security and AI into the 6G architecture and penetrate into the entire life cycle of various fields, networks, and units, and achieve the deepest integration of core technical capabilities such as security and AI with communication networks through endogenous design.

Minimalistic design: The 6G architecture design will change from a complex incremental design to a minimal integrated design, which will be presented as an integrated system to the outside and microservices to the inside. To the outside, the interface is clear and the cost is controllable, presenting an integrated architecture that is easy to implement and deploy, shielding the exposure of internal complex logic, operation instructions and business parameters, and facilitating the use of operation and maintenance personnel, external system docking, and user/customer calls. Therefore, on the one hand, it is necessary to structure and simplify the function set as a whole, integrate scattered service functions, and reduce network complexity; on the other hand, further deepen the concept of microservices, refine the granularity of services and functions, reduce the coupling between services, and support intelligent organizational capabilities to reduce the difficulty of system maintenance.

Twin design: 6G architecture design will evolve from pure physical network entities to physical + digital twins , realizing virtual-real mapping and virtual-real interaction. 6G networks need to build parallel physical and digital networks to form virtual-real fusion management methods, which will support real-time modeling of different networks and business forms, and flexible and real-time integrated policy control from virtual to physical entities, and further support the prediction and iteration of physical systems based on digital systems.

▲ Full view of 6G network architecture

As a complex system, the design of 6G network architecture needs to be considered from multiple perspectives and designed from multiple dimensions. The white paper explains the "three bodies, four layers and five sides" 6G overall logical architecture from the spatial view, logical view and functional view. In the 6G overall logical architecture:

The "three bodies" are a spatial view of the architecture , describing the objective existence of 6G network entities, which are divided into network ontology, management orchestration body and digital twin.

The "four layers" are the logical view of the architecture , showing the structure and organization of the 6G network design. They consist of the resource and computing power layer, the routing and connection layer, the service-oriented function layer, and the enabling layer.

The "five planes" are the functional view of the architecture , showing the division and composition of 6G network functions, including the five basic functional planes: control plane, user plane, data plane, intelligence plane and security plane.

Based on the overall architecture of "three bodies, four layers and five surfaces", the end-to-end system is defined through services to form a holistic service-based architecture HSBA (Holistic Service-Based Architecture). HSBA designs the interaction form of the entire end-to-end system, including components, protocols and connections. It is based on service-based interfaces for information transmission and business processing, reflecting the system design method of the entire 6G network architecture.

Based on the overall architecture of "three bodies, four layers and five surfaces", a flexible and intelligent design is achieved in the networking, forming a distributed autonomous network architecture DAN (Distributed Autonomous Network). The networking design shows the connection relationship and networking form between 6G networks. It is composed of self-contained, homogeneous, and self-closed micro cloud units SCU (Small Cloud Unit) , which are deployed in a centralized and distributed manner. The distributed SCU adopts a simple design as the front desk close to the user, and the centralized SCU has relatively complete functions as the middle and back desk close to the user.

The "three bodies, four layers and five sides" 6G overall architecture presents a cross-domain, cross-layer and multi-dimensional 6G network from the three perspectives of space, logic and functional composition.

▲ The overall architecture of 6G with “three bodies, four layers and five surfaces”

The "body" is the spatial view of the architecture, which describes the composition of the network in three dimensions. The "layer" is the logical view of the architecture, which logically describes the hierarchical architecture of the network and can be integrated in the implementation process. The "plane" is the functional view of the architecture, which mainly refers to the functional category, and follows the concept of "plane" of the control plane and user plane in the traditional 3GPP network.

The 6G network includes three entities in the spatial view: network ontology, management orchestration, and digital twin. Among them, management orchestration and digital twin are two newly defined entities in 6G. The network ontology is the most important network entity, which realizes network functions and network operations; the management orchestration instantiates and changes the network to realize full life cycle orchestration management; the digital twin constructs the digital space of the network and realizes virtual-real mapping. With the development of digital twin technology and the increasing complexity of the entire network operation and maintenance, and considering the high cost of network failures and expensive testing costs, it is necessary to perform external abstract mapping in the traditional physical network, establish a new development system, and build a new digital twin. Through closed-loop control combining virtual and real, the established rules of existing network planning, construction, maintenance, and optimization can be changed to effectively guarantee network operation and maintenance, optimize the network in real time, and realize future network autonomy.

The logical level of the 6G network includes four layers from bottom to top: resources and computing power, routing and connection, service-oriented functions, and open enablement, which connect the logical layer of the 6G network. The design of the "four layers" highlights the richness of the 6G architecture in terms of layered elements and capabilities, and on the other hand, reflects the concept of cross-domain connection, multi-domain collaboration and integrated development. The design concept of the resource and computing power layer highlights the "computing power" resource element, which will provide 6G with basic resources for further integration of spectrum, storage, computing power, and network. Routing and connection layer: Continue the design concept of open protocols, continuously absorb new mechanisms and new protocols (such as deterministic IP, SRv6), and evolve towards programmability and determinism. The service-oriented function layer continues the design concept of service-oriented, and SBA expands from the core network to the end-to-end field to support the organic construction of different functions. Open enabling layer: Further enrich the information and communication capabilities open to the outside world, and provide services for proprietary businesses and third-party applications through extraction, encapsulation, orchestration, and combination.

In terms of the functional composition of 6G networks, the traditional control plane and user plane functions are enhanced, and new data planes, intelligent planes, and security planes are introduced to form the "five planes". The control plane is further enhanced and evolved in the direction of full service to achieve integrated control of multiple access methods. The user plane is enhanced to evolve in the direction of programmability, service, and cross-domain determinism to achieve flexible and high-performance forwarding. A new data plane is added to solve the historical problems of user data migration and systematically provide trusted data services. A new intelligent plane is added to provide global AI capabilities through the collaboration of distributed intelligent nodes to achieve endogenous intelligence. A new security plane is added to achieve endogenous security through security perception and active protection driven by "security data + AI" and a zero-trust security system.

With the development of technologies such as digital twins and the increasing complexity of network operation and maintenance, it is necessary to perform external abstract mapping on the traditional physical network, establish a new development system, build a new digital twin, and achieve closed-loop control of the network entity through management and orchestration.

The network ontology includes physical equipment such as base stations, core networks, and transmission bearers in the traditional sense. The network ontology is a real, actually running network that provides information services to users and is the carrier for the implementation of the architecture. In terms of basic resources, "computing power" is introduced as a new resource element. The network has evolved from scheduling connections to

Scheduling computing resource expansion provides a foundation for new 6G network capabilities, such as perception capabilities and intelligent endogenous capabilities.

In terms of provisioning methods, it has evolved from cloud and software to pooling. The network itself has gradually developed into a schedulable, mobile and flexible entity. It provides integrated and pooled capabilities for connection, computing and storage.

In terms of service capabilities, further development will be made towards service-oriented and platform-based networks. 6G will deepen the network platform capabilities opened up by 5G. For example, based on basic modular services such as user management, connection management, service management, and mobility management, functions and service capabilities for specific scenarios will be built.

The management orchestration body is a functional entity that performs intelligent orchestration and management of network resources and network capabilities to achieve full life cycle management of the network.

The main operation object of the management and arrangement body is the network body, and it also arranges and optimizes the twin body. The management and arrangement body uniformly arranges the required resources and functions according to the user's business and the network's own operation and maintenance requirements, forms the required capabilities, and ensures the user's business experience. The management body can interact with the twin body, accept the network configuration parameters output by the twin body, and arrange and manage the physical network, thereby realizing network automation operation and improving the network's adaptability to the differentiated needs of new businesses, new scenarios, and new requirements.

Integrate multiple resources and connect end-to-end to achieve the upgrading of management systems. For network resources, the management and orchestration body must have the ability to coordinate and finely manage related resources such as spectrum, storage, and computing power. For network capabilities, the management and orchestration body must connect all layers and aspects of the end-to-end network, and orchestrate connectivity, computing power, intelligence, and security capabilities into services that can be provided internally and externally, and provide them externally through an open enabling layer. With the help of technical means such as network intelligence and automation, the closed-loop management and operation of network autonomy can be achieved.

A digital twin is a mapping of a physical object in a virtual space, enabling low-cost trial and error, intelligent decision-making, and high-efficiency innovation on the network.

Partial or complete twinning of the network ontology. Building a network twin requires four key elements: data, model, mapping, and interaction. All network functions in the 6G network architecture can build corresponding network function twins on demand. The twins can interact with the real physical network in real time, restore the operating status and environment of the real physical network through modeling and mapping, and perform pre-verification before network deployment, thereby providing the optimal solution for network strategy and improving the reliability of network decision-making and deployment.

Through internal and external closed loops, 6G networks can be helped to realize the intelligent side and achieve goals such as flexible networks and endogenous intelligence. Network operation and maintenance and optimization, network intelligent applications, intent-driven network intelligent autonomy, as well as new network technologies and new business innovations can all be input into the twin through the northbound interface, and the business can be deployed and verified through the modeled instances of the network twin. Through the endogenous closed loop of the twin, the network capability is verified. After verification, the twin sends the control update to the physical entity network through the southbound interface.

The resource and computing power layer is the physical resource of the 6G network, including basic resources such as spectrum, storage, computing power, and network. 4G completes the decoupling of core network software and hardware, and the 5G core network completes cloudification and expands to wireless cloudification. Based on this, the 6G network evolves to an integrated network with computing power network as a typical feature. The cross-domain design and distributed design ideas of the 6G network require the integration of wireless and network architectures and resource sharing. Therefore, the 6G network will aggregate the physical resources of the end, edge, network, and cloud, with computing power as the core, to achieve deep integration of network, computing power, and storage, realize intelligent scheduling and optimal utilization of information and communication resources, and provide physical resources for upper-layer services.

The routing and connection layer connects the physical nodes in the 6G network into a network, realizing state perception, deterministic forwarding, and flexible service calls.

Realize physical connection downward. The routing and connection layer connects various physical nodes of the resources and computing power layer through static and dynamic connections according to time, space and other factors to form an organic network. It also dynamically senses the node status and link status, adjusts the network connection in real time, and realizes the optimal path and real-time reachability of the network.

Build logical connections upward. The routing and connection layer provides secure, QoS-guaranteed logical connections between entities in the service-oriented functional layer, perceives the working status and load of the functional layer in real time, receives and parses microservice messages and data packets of the functional layer, and implements efficient routing, stateless transmission, and deterministic forwarding. Build an efficient, intelligent, secure, and reliable connection base. According to the principle of minimalist design, a universal and unified interface protocol can be used in the specific design of the routing and connection layer.

The service-oriented functional layer in the 6G system architecture has many core network links and capabilities that need to be added and considered separately. Therefore, on the basis of enhancing the traditional control plane and user plane, independent data plane, intelligent plane and security plane are added to achieve endogenous intelligence and security.

2. Full Service Based System Architecture (HSBA)

The concept of HSBA (Holistic Service-Based Architecture) comes from the 6G architecture paper published by China Mobile in China Communications.

The full service-oriented architecture is the core cornerstone of the "three bodies, four layers and five surfaces" 6G overall architecture, and is the basic design of each functional surface in the service-oriented functional layer. The various surfaces in the service-oriented functional layer, as well as the various network functions within each surface, are unified under the service-oriented architecture, using modular and service-oriented design, and using a unified service framework technology for service self-organization, and interacting through service-oriented interfaces.

The full service architecture is an extension of the service architecture in multiple fields. The access network service and the core network user plane service are organic components of the full service architecture. The control plane in the service function layer is further enhanced based on the functions of the traditional control plane, and naturally supports service. The data plane, intelligent plane and security plane are newly defined. These planes are mainly based on signaling processing. As the functions of these planes are gradually clarified, modular and service-oriented designs will be adopted natively. The functions of base station equipment include signaling control, data processing, and intelligent QoS scheduling. Although it is physically manifested as a single base station device, it can be logically implemented by five planes or some of the five planes. Reconstructing the wireless network into a service-oriented RAN with finer granularity and adopting a service-oriented framework that is unified with the core network will bring new interaction methods to the end-to-end network process. At present, the core network user plane is an isolated island of core network service, and the traditional customized interface is still used between it and the control plane, which restricts the agile development of the network. Therefore, it is necessary to realize the modularization and service-orientedness of the user plane in the 6G stage.

The full service architecture is a further deepening of the service architecture. It is enhanced from the aspects of service framework, service interface, atomic service, etc., to adapt to the distributed organization of the network, intelligent scheduling of services, and flexible deployment of industry-specific networks . The service-oriented framework technology has realized the automated management of network functions and services. However, in the future network, with the increase in network scale and the growth of personalized needs of industry networks, 6G networks will present a combination of centralized and distributed deployment. Therefore, it is necessary to further deepen the service-oriented framework technology. On the one hand, it supports the automatic registration, discovery and call of distributed network functions and services, and on the other hand, it supports the automated management of distributed networks, that is, the distributed network and the network functions and services therein can be automatically found by other network nodes. The service-oriented interface is further upgraded to realize more flexible and reliable service calls. Services will be further decoupled, and the best service calls will be realized intelligently according to the scenario, forming the simplest network that best meets customer needs, and even providing users with more lightweight function-level services.

In summary, the full service provided by the HSBA architecture has been further developed in breadth and depth:

(1) In terms of breadth, HSBA will implement service-oriented design across the entire system and all network elements, and uniformly adopt service-oriented interfaces.

(2) In terms of depth, HSBA will further implement the service-oriented design concept, optimize service design, and further eliminate the coupling between atomic services.

(3) Introducing new protocols and enhancements to service-oriented technologies, such as HTTP/3, serverless mechanisms, function services, and more service-oriented technologies.

▲ HSBA architecture diagram

Since the introduction of service-oriented architecture in the 5G control plane, after three release iterations, service-oriented architecture has been implemented in the core network control plane and billing system. The advantages brought by the service-oriented architecture are gradually showing.

The service-oriented user plane helps realize the full cloud deployment of 6G networks. As the main function of mobile network data processing, the user plane needs to strengthen the support for service design, including defining typical services of the user plane and supporting service-based interfaces to replace the current packet forwarding control protocol interface.

User plane services can be designed as data processing and forwarding services, PDU session tunnel management services, policy control services, session anchor services, security management services, capability exposure services, and customized services.

The data processing and forwarding service forwards, discards, and caches the user's uplink and downlink service data. The PDU session tunnel management service implements data encapsulation and decapsulation; tunnel establishment and release. The policy control service supports the predefined rules of the management orchestration body; supports dynamic policy configuration of the control plane, such as service quality assurance policy and service data forwarding rules. The session anchor service provides data access; supports multiple anchors within a single session. The security management service provides privacy protection for user data; access device security monitoring; access address security verification; interface security monitoring. The capability exposure service exposes session and node information; exposes the required user service and behavior data to the intelligent plane; exposes node information to the management orchestration body; and exposes user and node information to vertical industries.

At present, the minimum granularity of base stations is the centralized unit (CU) or distributed unit (DU), which is relatively large and still cannot meet the needs of rapid launch and flexible deployment of specific new functions. From the interface perspective, point-to-point dedicated interfaces are still used for interconnection within base stations, between base stations, and between base stations and core networks. Whenever the network functions of base stations or related core networks change, adjustments need to be made on related interfaces, which requires a large amount of standardization work and high complexity of operation and maintenance management. In order to agilely respond to more diverse business function requirements, quality of service (QoS) requirements, management strategy requirements, deployment requirements, and open requirements in the future, and make the network more forward compatible, the next generation of wireless access networks needs to start from the perspective of service capabilities, deeply decouple the wireless network control plane functions from the user plane functions, and reconstruct them into a service-oriented RAN with finer functions.

The control plane functions of RAN are reconstructed into multiple services through service-oriented, which can roughly include the following types: radio bearer management service, connection and mobility management service, local positioning service, multicast broadcast service, data collection service, signaling transmission service, access network open service, etc. The service-oriented control plane of RAN can directly interact with the services of the core network, reducing unnecessary forwarding of connection and mobility management functions in the network. In addition, the interaction between the control plane services of RAN and other services (including core network services and other RAN control plane services) can be transformed from serial interaction to multi-party parallel interaction, thereby optimizing the control plane process.

The user plane functions of RAN are reconstructed into multiple RAN user plane services through service-oriented operation, and can be flexibly combined on demand when needed to better meet various business needs. In essence, user plane service-oriented operation aims to break through the traditional layered protocol design concept, so that the calling relationship between functions is no longer limited by the relationship between upper and lower layer protocols, and functional modules can be flexibly called.

5G network opens the door for telecom network to evolve towards service-oriented, but as the first generation system to introduce service-oriented architecture, 5G service-oriented design still has the problem of incomplete decoupling of atomic services, and some emerging service-oriented technologies have not yet been introduced into 5G network. Therefore, the full service-oriented architecture needs to further eliminate the coupling relationship between atomic services, absorb more service-oriented technologies, enhance the service framework, service interface, atomic services and other aspects, and give full play to the advantages of service-oriented technology.

The service framework evolves in a more distributed direction and optimizes the decoupled design of services. Decouple the network's business processing and general communication functions, and further make the communication function independent as part of the service framework. This will establish a stable communication mechanism in massive services, complex architectures, and networks. When introducing new functions, you only need to focus on the function itself, without providing basic capabilities such as service communication, which greatly reduces the threshold for introducing new functions. The independent service-oriented framework, based on the 5G service-oriented framework's support for automated management of network functions and services, further expands support for network-level automated management. The agents of the service-oriented framework can be distributed in different distributed networks, supporting the distributed deployment of the network through collaboration between frameworks.

The service interface is developing towards a more flexible, open, efficient and reliable direction. Protocols such as QUIC are becoming more mature. While ensuring network reliability, the QUIC protocol effectively reduces the time to establish a connection. Multiplexing can achieve head-of-line blocking. At the same time, the QUIC protocol improves the congestion control mechanism of TCP. In the process of 6G network evolution, it is also necessary to actively absorb new IT protocols, and the control plane and user plane protocol design will evolve towards the next generation of Internet protocols.

Atomic services are further decoupled and reconstructed to support more flexible combinations and lighter calls. By further decoupling and reconstructing atomic services and introducing function service technology (Serverless), we can make full use of its advantages such as free operation and maintenance, high availability, elastic scalability, and pay-as-you-go. We can divide the 6G service-oriented architecture into functions. Through Serverless service classification processing, we can truly deploy applications without considering infrastructure construction, and realize automated construction, one-click deployment, and service startup.

3. Distributed Autonomous Network Architecture (DAN)

Distributed deployment of 6G networks will become inevitable. In order to cope with large-scale connections, ultra-low latency communications, and diversified customization requirements in the 6G era, the network needs to introduce a distributed deployment mechanism.

Large-scale connections have led to an increase in the scale of base stations, which urgently need efficient management. It is expected that the traffic density in the 6G era will increase by 10-1000 times compared with 5G (the traffic density of 5G is 10Mbps/m2), and the connection density will reach 100-100 million devices/km3. In the 6G era, higher bandwidth spectrum is expected to be used to carry 6G services, and communication base stations will be "densified", which is expected to reach tens of millions. How to manage large-scale connections of terminals, as well as large-scale base stations and small base stations have become key issues to consider in the design of 6G network architecture.

Ultra-low latency communication requirements. Immersive interaction and Internet of Vehicles services are becoming more mature. To achieve a high real-time service experience, these services require the network to have lower latency and faster response capabilities. The network must be deployed close to the user end and support local deployment of control devices (such as robotic arms, smart cars, positioning services, etc.).

The need for data localization. For security and privacy reasons, enterprise users have high requirements for the privacy and confidentiality of their own production and business data, and have a strong demand that data does not leave the factory. This requires the network to not only realize local transmission and analysis of data, but also local transmission and processing of control signaling.

Network autonomy means that 6G networks have the ability to self-organize, self-manage, and self-optimize. Self-organization enables flexible deployment of network capabilities, dynamic connections, efficient interoperability, and plug-and-play. Compared with 5G and previous networks that rely on advance planning, fixed configuration, and long network deployment time, 6G's future-oriented distributed deployment needs to support dynamic establishment and dynamic tuning of network connections. Therefore, it is possible to consider introducing a universal IP protocol that can quickly interoperate.

The management complexity brought by distributed deployment needs to be solved by network self-management. Compared with the centralized network architecture, the distributed deployment of network nodes (thousands or tens of thousands) and the rapid interaction between edge peer nodes have doubled the complexity of network management, which requires the introduction of network autonomy. 6G network control plane functions such as mobility management, session management, data storage and other core capabilities need to be deployed in a distributed manner, and control information must be reasonably processed and responded to at the edge of the network. In order to support the on-demand sinking of capabilities, its related network resources and network connections also need to be deployed in a supporting manner.

Managing diverse network functions and adapting to diverse scenarios requires the introduction of network self-optimization capabilities. Diversified customized functions/services derived from adapting to the customized requirements of thousands of industries will appear on a large scale in 6G networks. It will be extremely complex to design diverse services on demand, quickly launch them, manage their versions, and schedule them throughout their life cycle. With the introduction of satellite communications and the emergence of various exponentially growing user terminals and IoT devices, the management and organization of various types of terminals have become increasingly difficult.

Distributed and network autonomy are considered from the network dimension for 6G design, and self-containment is considered from the network unit capability. 6G distributed nodes need to support self-containment, have complete functions, resources, and connection capabilities, and can independently complete closed-loop network process processing. Distributed nodes are required to have a complete system framework, that is, support control plane information processing, user plane business processing, user data, security protection, network self-management and self-optimization, etc.

Based on the above distributed, autonomous, and self-contained design concepts, this white paper proposes a 6G networking design, namely: Distributed Autonomous Network (DAN) architecture . The DAN network architecture consists of distributed micro cloud units (SCU) and their related protocols. SCU is the most critical module unit that constitutes the DAN architecture. It can support distributed deployment in the network and has self-contained and autonomous capabilities.

▲ 6G Distributed Autonomous Network Architecture (DAN)

Modular design: Introducing the distributed micro-cloud unit SCU that is flexibly deployable, plug-and-play, and resource-sufficient. SCU includes the following technical features:

The consistent organizational framework includes the "four layers and five aspects" capabilities described in Chapter 3. The service-oriented functional layer is organized and communicated according to the HSBA architecture, and has the ability to complete data and signaling processing locally to achieve efficient network response.

Customized on demand, its infrastructure specifications, connection protocols, service capabilities, and open capabilities can all be customized according to scenario requirements. It can be established on demand in the network, and SCUs can be networked quickly and conveniently.

With autonomous capabilities, it can achieve unmanned management, autonomous operation, automatic perception of environmental changes, and real-time network adjustments to meet differentiated and diverse business needs.

Protocol design: Introduce a universal transmission protocol to support connection automation, flexible connection between multiple SCUs, and on-demand intercommunication. Realize plug-and-play and rapid deployment of SCU, support flexible communication with other SCUs, and the SCU's external network interface supports a universal transmission protocol. In 2G to 5G mobile networks, the control plane and user plane use multiple protocols to interact, making the network complex and the protocol maintenance difficult. Therefore, in the design of 6G networks, unified control plane and user plane protocols are introduced as much as possible. For user plane protocols, user plane protocols that are integrated with bearer network protocols, such as SRv6, can be considered. Through the source routing concept design, end-to-end tunnels are no longer required, and the network can easily control and adjust the forwarding path of data packets.

The distributed micro cloud unit SCU is the basic unit of the DAN network. Its specific design is shown in the figure below, including "four-layer" capabilities and "five-face" functions.

▲ SCU structure diagram

SCU is an open enabling layer that provides external open interfaces to support third-party customization. It mainly includes three capabilities: opening network information to the outside world, opening network customization capabilities, and customizing network functions; it can also open network computing resources and intelligent processing capabilities.

The SCU service-oriented functional layer includes five distributed aspects: a distributed control plane based on a unified platform-based, distributed service framework. The service framework for automatic registration, discovery, and authorization of network functions/services based on NRF is further expanded.

Distributed user plane enables fast local data processing. Currently, the UPF of 5G networks has been deployed in a distributed manner, and data forwarding and processing can be performed in counties, cities, and regions. For future 6G networks, user plane capabilities will further support service-oriented interfaces to enable on-demand loading and deletion of processing capabilities.

The distributed data plane, based on distributed database and other technologies, manages different types of data on demand and provides safe and nearby access. User context data, model data, etc. in the SCU are distributed and stored in adjacent SCU units through DHT (Distributed Hash Table).

Distributed intelligence plane, based on federated learning, multi-agent decision-making and other technologies, realizes intelligent parallel computing and distributed intelligent collaboration. The micro-network composed of micro-cloud units has the ability to operate and manage itself independently, and can be independently packaged, deployed, upgraded, scaled, and managed, with fault management and local autonomy.

Distributed security plane ensures the information security and access security of SCU units and prevents attacks. SCU is deployed on demand at the edge of the network, far away from the traditional core control domain of the network, which brings greater security risks. Distributed security plane is used to ensure the information security and access security of SCU units and resist external attacks.

SCU routing and connection layer capabilities enable information routing and planning between SCUs. On-demand, fast, and dynamic path establishment is achieved between SCUs based on simple, universal transport layer protocols (such as SRv6), supporting on-demand, real-time interaction of distributed SCUs.

SCU resources and computing power layer capabilities can provide computing power and storage resources for the full operation of an SCU.

Under the requirements of diverse scenarios, the capabilities and functions of each layer of SCU can be customized. The unified logical architecture greatly reduces the complexity of network design and deployment, and supports on-demand deployment, rapid generation, and rapid construction of network connections for 6G SCU units.

The capability differences between SCUs are determined by business needs. Under normal circumstances, SCUs will have ordinary equipment specifications and network capabilities. Under certain circumstances, some SCU units need to have higher reliability, stability, and the ability to handle large concurrent traffic, which has higher requirements for hardware specifications, software design, and computing resources.

SCU supports cross-domain design (such as air and ground, mobile network and bearer network) and can be flexibly customized. Taking satellite access as an example, the network topology changes quickly and the transmission delay is large, resulting in the inability of existing access and mobility management strategies to meet network requirements. It is necessary to design an efficient mobility management solution and an efficient collaborative session management mechanism for multiple access and multiple connections to meet the user experience of satellite access.

SCUs have the following two potential deployment forms. 6G networks will be flexibly organized through distributed collaboration. When deploying SCUs at the edge of the network, they can also adapt to different wireless access network capabilities, such as SCUs can carry wireless centralized units (Central Unite).

SCU only includes core network capabilities. In this networking form, SCU includes core network capabilities, routing control capabilities and resource layers, and can be quickly connected to local base stations.

SCU converged access network control capabilities. Based on wireless cloudization, CU functions can be deployed in SCU units as needed, and access network control is used to control the access network. The networking form of SCU can include ring networking, star networking and hybrid networking modes. Among them, ring networking mainly relies on the edge SCU and the nearby edge SCU to form a network; the star network is composed of a central SCU node and its associated edge SCU, and the edge SCU is controlled by the central SCU; hybrid networking refers to the networking form where the ring network and star network coexist.

Zhidongxi believes that innovation in the system architecture is related to the overall development of the network and is one of the most core innovations of 6G networks. The emergence of new needs, new scenarios and new technologies have given the 6G network architecture multi-dimensional capability requirements such as computing, perception, intelligence, and security beyond traditional connections and forwarding, and has also brought new driving force for the innovation of 6G network architecture. All parties in the industry need to further pay attention to the leading role of system architecture in the technological direction, grasp the essence of its technological change, and work with operators to achieve rapid iteration and update of 6G network architecture.