The Challenge of Network Architecture Flexibility
5G carries a wide variety of services with different service characteristics and different network requirements. The diversity of business requirements brings new challenges to 5G network planning and design, including customized design challenges in many aspects such as network functions, architecture, resources, and routing. 5G network will realize network virtualization and cloud deployment based on NFV/SDN and cloud-native technologies. Currently, due to the fact that container technology standards are not yet clear and the industry development is not yet mature, 5G network cloud deployment will face the problem of user plane forwarding performance. Challenges in upgrading and safety isolation technology to be improved. The 5G network is designed based on a service-oriented architecture. Through enabling technologies such as network function modularization and separation of control and forwarding, the network can be rapidly deployed according to different business needs, dynamic capacity expansion and shrinkage, and full life cycle management of network slicing, including end-to-end network slicing. The flexible construction of end-to-end network slicing, flexible scheduling of service routing, flexible allocation of network resources, and end-to-end service provision across domains, platforms, manufacturers, and even operators (roaming), etc. Management brings new challenges.
The challenge of flexible and efficient carrying technology
High speed , low latency, flexibility requirements and cost constraints of the bearer network : 5G network bandwidth is expected to increase by dozens of times compared to 4G, resulting in a sharp increase in bearer network speed requirements. 25G/50G high speed will be deployed to the network edge, 25G The low-cost implementation of /50G optical modules and WDM transmission are a major challenge for the bearer network; the ultra-low latency requirements of the millisecond level proposed by the URLLC service require the flattening of the network architecture, the introduction of MEC, and the rational layout of sites. Ultra-low latency performance is another challenge for bearer equipment; 5G core network cloudification, partial function sinking, network slicing and other requirements lead to higher requirements for connection flexibility in 5G backhaul networks. How to optimize routing forwarding and control technology , to meet the 5G bearer network routing flexibility and O&M convenience requirements, is the third challenge of the bearer network.
Terminal Technology Challenges
Compared with 4G terminals, 5G terminals will develop in the direction of form diversification and technical performance differentiation in the face of the needs of diverse scenarios. In the early stage of 5G, the terminal product form is mainly mobile phones in the eMBB scenario, and the terminal planning of other scenarios (such as URLLC and mMTC) will gradually become clear as the standards and industries mature.
5G's multi-band, large-bandwidth access and high-performance indicators pose new challenges to terminal implementation in terms of antennas and radio frequencies. From the perspective of network performance, in the future 5G mobile phones can first use 2T4R as the basic transceiver solution in the sub-6GHz (below 6GHz) frequency band. The increase in the number of antennas will cause terminal space and antenna efficiency issues, and the antenna design needs to be optimized. For the RF front-end devices in the sub-6GHz frequency band, hardware and algorithm optimization needs to be carried out according to the new requirements of 5G (such as high frequency band, large bandwidth, new waveform, high transmit power, low power consumption , etc.) to further promote the development of the RF front-end industry chain in this frequency band.
China Telecom 5G target network architecture
The overall architecture of the "Three Clouds" network
In order to meet the demand scenarios of 5G and meet the needs of network and business development, the future 5G network will be more flexible, intelligent, integrated and open. The 5G target network logical architecture is referred to as the "Three Clouds" network architecture, including three logical domains of access cloud, control cloud and forwarding cloud, as shown in Figure 1.
| Pipe control | Value-added services |
|---|---|
| Capability opening 5G virtual control cloud |
Wireless resource policy path
The "Three Clouds" 5G network will be a converged network that can be flexibly deployed according to business scenarios. The control cloud completes global policy control, session management, mobility management, policy management, information management, etc., and supports service-oriented network capability opening functions, realizes customized networks and services, meets the differentiated requirements of different new services, and expands new services. network service capability. The access cloud will support users' intelligent wireless access under various application scenarios and business needs, and realize the efficient integration of various wireless access technologies. Edge computing capabilities. The forwarding cloud cooperates with the access cloud and the control cloud to realize the function of service aggregation and forwarding. Based on the bandwidth and delay requirements of different new services, the forwarding cloud realizes enhanced mobile broadband, massive connections, high-speed Internet access under the path management and resource scheduling of the control cloud. Efficient forwarding and transmission of different service data streams, such as reliability and low latency, ensures the end-to-end quality requirements of services. The "Three Clouds" 5G network architecture consists of the control cloud, the access cloud and the forwarding cloud, which are inseparable and coordinated, and can be implemented based on SDN/NFV technology.
Control the cloud
The control cloud is logically the centralized control core of the 5G network, controlling the access cloud and forwarding cloud. The control cloud consists of multiple virtualized network control function modules. Specifically, it includes: access control management module, mobility management module, policy management module, user information management module, path management/SDN controller module, security module, slice selection module, traditional network element adaptation module, capability opening module, and Corresponding network resource arrangement, etc. These functional modules can be analogous to the control network elements of the previous mobile network in terms of logic function, and complete the mobile communication process and service control. In the implementation, the control cloud is based on virtualization technology, and re-optimizes the relationship between network functions through modular technology, realizing the separation of network control and bearer, network slicing and network component function service, etc. The entire architecture can be based on Customized tailoring and flexible deployment of business scenarios.
The network capability open module is the core of 5G network opening to the outside world. The modularization and slicing technology of the 5G network, the centralization of network control, and the centralization of data resources bring the convenience of network opening. The 5G network capability opening module aggregates and integrates the opening capabilities of network module components to form network-level opening capabilities, and provide capability opening to the outside world in a unified manner.
The network resource orchestration module is the core of 5G network virtualization resource management and control, which includes three sub-modules: orchestrator, VNFM and VIM. This module provides a manageable, controllable and operable service provision environment for 5G networks in a virtualized environment, so that basic resources can be easily provided to 5G network applications.
Access the cloud
In the future mobile communication system, multiple wireless access systems will coexist for a long time. In view of the diverse business characteristics, it is necessary to combine factors such as business requirements, network status, user preferences and terminal capabilities to carry out differentiated data transmission and bearer, including flexible scheduling and allocation, distribution and aggregation, etc., to achieve system resource utilization and service quality. Good balance guaranteed. The 5G access cloud will be a multi-topology, multi-layered, and dynamically changing network. Centralized, distributed , and layered deployments can be selected for various business scenarios, and flexible wireless access technologies can be used to achieve high speed. Access and seamless switching provide the ultimate user experience. 5G wireless network deployment needs to comprehensively consider multiple factors such as business application attributes, network functional characteristics, and network environmental conditions, and reasonably deploy the selected network functions in the physical nodes of the 5G wireless network.
5G access cloud functional requirements include new wireless access technologies, flexible resource collaborative management, deep integration of cross-standard systems, wireless network virtualization, edge computing and wireless capability opening. In order to achieve the high-performance indicators proposed by 5G network scenarios and business applications, it is necessary to consider the introduction of new wireless access technologies, including large-scale antenna arrays, new multiple access technologies, and full-spectrum access. Wireless access technology for effective control and support. Based on the access centralized control module, the 5G network can build a fast, flexible and efficient coordination mechanism, realize the integration of different wireless access systems, improve the utilization of mobile network resources, and greatly improve the user's service experience. In the future, mobile communication will be a user-centered all-round information ecosystem . The in- depth integration of communication technology and IT technology will deploy IT computing and service capabilities at the edge of the mobile access network, and gradually realize virtualization and cloudification. Efficient, differentiated, and diversified mobile broadband user service experience with tightly coupled environments. At the same time, combined with the advantages of IT technology, by building a standardized and open edge computing platform, the wireless network information and control capabilities are opened up, a new value chain is formed, new service categories are opened, and rich user services are provided.
Forward Cloud
The 5G network realizes the complete separation of the control plane and the data plane of the core network, and the forwarding cloud focuses on the high-speed forwarding and processing of data streams. Logically, the forwarding cloud includes a simple high-speed forwarding unit and various service enabling units. In traditional networks, service enabling network elements are deployed in a chain behind the gateway. To improve the service chain, additional service chain control functions or enhanced control network elements need to be added to the network. In the forwarding cloud of the 5G network, the service enabling unit and the forwarding unit are deployed in a mesh, and accept the path management and control of the control cloud together. According to the centralized control of the control cloud and based on user service requirements, the software defines the service flow forwarding path to realize forwarding. Flexible selection of network elements and service-enabled network elements.
In addition, the forwarding cloud can cache hot content according to the caching policy issued by the control cloud, thereby reducing service delay, reducing egress traffic from the mobile network and improving user experience. In order to improve the data processing and forwarding efficiency of the forwarding cloud, the forwarding cloud needs to periodically or aperiodically report network status information to the control cloud for centralized optimization control. Considering the propagation delay between the control cloud and the forwarding cloud, some events with strict delay requirements need to be processed locally in the forwarding cloud
References
Lianshi Data Security and Personal Information Protection Technical White Paper V1.0.5 2021