In the last digital twin article, we introduced the application cases of digital twin technology and 5G field network in different industries, including construction machinery manufacturing, smart mines, smart buildings, and smart medical care. Today, let's further explain the technical details of the combination of digital twin technology and 5G industry communication network, and discover how China Mobile is working on it.
First, let's recall the 5G industry communication network.The industry field network is a communication and management technology for data interoperability, and is used between field devices, external devices and business platforms. The concept of Proximity Network (literally translated as Proximity Network) was first proposed in the ISO.23247 digital twin standard in 2013. China Mobile and industry partners have jointly improved the concept and overall solution of the 5G industry communication network. Below we will start sharing industry application cases.
China Mobile Cube 365 “Digital Twin & 5G+” industry communication network Architecture
In response to the technological wave brought by digital twin technology, China Mobile proposed the Cube 365 5G+ industry communication network architecture. The 3-6-5 numbers have special meanings in the architecture:
A."3" represents the three-layer architecture of the “Digital Twin & 5G+” industry communication network, including the entity layer, the capability layer, and the application layer.
B."6" contains two layers of meaning. The first layer refers to six network development trends, including flattening, wireless, IP-based, intelligent, controllable, and refined. The second layer of meaning refers to the six technical dimensions of the industry communication network, including "sensing, communication, arithmetic, number, wisdom, and use".
C."5" represents five connection technologies for the digital twin industry communication network, namely 5G+new passive communication, 5G+new short-range communication, 5G+deterministic transmission, 5G+high-precision positioning, 5G and medium and low speed communication.
In this architecture, "sense" and "communication" correspond to the entity layer, "calculation", "number", and "intelligence" correspond to the capability layer, and "use" corresponds to the application layer. The entire Cube 365 “Digital Twin & 5G+” industry communication network Architecture is developing towards a flat, wireless, IP-based, intelligent, controllable, and precise development direction.
A.Three-layer architecture of the “Digital Twin & 5G+” industry communication network, including the entity layer, the capability layer, and the application layer.
a.The Entity Layer: Data collection entities and data transmission entities provide "sensing" and "communication" capabilities. Data collection entities include sensors, cameras, robotic arms, passive IoT labels and other industrial on-site production and management physical terminals, which can collect environmental data such as temperature and dust, production line equipment operation data, material information and location data, and equipment defects. These raw data materials reflect the operation of the physical world. With data transmission entities, including new passive, new short-range, deterministic transmission, medium and low-speed transmission, high-precision positioning, etc., the connection between the northbound transmission of perception data and the southbound transmission of control commands is completed.
b.The Capability Layer: The capability layer provides three advantages of "computing", "data" and "intelligence" for the lower-layer physical entities and upper-layer applications through a variety of technologies, including edge computing, protocol adaptation, and AI. As a result, data integration, simulation analysis, intelligent processing, twin model construction and fusion can be realized.
c.The Application Layer: The upper application layer can provide more efficient and convenient network and business life cycle management services for industry applications through technologies such as digital twins, which is a direct interface connecting to users.
B.Six network development trends of the “Digital Twin & 5G+” industry communication network, including flattening, wireless, IP-based, intelligent, controllable, and refined.
a.Flattening: The new network architecture goes flattening. The traditional network presents very fragmented characteristics: the field network structure is complex, and there are various protocols, including industrial bus protocols, industrial communication protocols and industrial wireless protocols; there are also various technologies, including Zigbee, UWB etc. At the same time, in order to collect and process data of different protocols in the traditional network, the information system also presents like "chimney type". To solve this problem, the flattening of the new network architecture using data twinning technology is conducive to the normalized management of data, so that data can be collected and transmitted according to a unified protocol.
b.Wireless: The new network architecture goes wireless. According to statistics, in the global industrial network market share in 2020, wired accounts for 94% and wireless accounts for 6%. As the need for devices to "go wireless" gradually increased, wireless networks began to replace wired networks. However, while the wireless replacement of wired brings convenience, it also introduces more unreliable factors, causing enterprises to be more cautious about introducing wireless communication in the production process. The “Digital Twin & 5G+” industry communication network is expected to combine the advantages of the two, and truly bring about a wireless change in the network connection in the production field.
c.IP-based: The new network architecture becomes IP-based. Traditional industrial networks are mostly point-to-point 2 layer communications, making it difficult to achieve data traceability, flexible routing, and refined management. However, today's industrial production requires a more flexible, stable and secure network, which brings an urgent need for network IP transformation. IPv6 has abundant address resources and can assign IP addresses to each network device. IPv6 also provides management capabilities for traffic and services, facilitating network SLA assurance.
d.Intelligent: The new network architecture goes intelligent. The current intelligent analysis capabilities mainly rely on cloud platforms. However, some industrial scenarios, such as safe production and industrial quality inspection, require high bandwidth, low latency, and data privacy. Various industries are now in great need of field-level intelligent analysis and processing of key data and services, thereby improving business response speed and ensuring business continuity. By applying edge intelligence technology, more "nearby" processing on industrial gateways can be realized, such as predictive maintenance, fault detection, face recognition, industrial quality inspection and other intelligent services.
e.Controllable: The new network architecture becomes more controllable. The traditional network management system has not been extended to the field network, so it cannot sense the network parameters on the client side in real time. Now, it is necessary to realize the visibility, management and control of the field network, equipment and business. By deploying quality probes on the terminal side, we can provide monitoring, analysis and alarming of key information such as device status, network coverage, and service quality at the field level, which effectively compensates for the lack of network management data and makes "the terminal side no longer a black box". All of these help to quickly locate and delimit faults and ensure network awareness of on-site customers.
f.Refined: The equipment control becomes more refined. With the development of 5G and deterministic network technology, network latency and instability are greatly improved, making it possible to deploy devices in a distributed manner and support centralized management of control. In scenarios such as remote equipment operation and equipment collaborative operation, on-site data is collected and transmitted through the 5G network. Based on the relevant software, the factory can realize industrial control and remote precise control of equipment.
C.Five connection technologies of the “Digital Twin & 5G+” industry communication network, namely 5G+ new passive communication, 5G+ new short-range communication, 5G+ deterministic transmission, 5G+ high-precision indoor positioning, 5G and medium and low speed communication.
a.5G+ new passive communication:
Passive IoT uses the principle of electromagnetic induction and signal reflection to carry out non-contact data communication through the built-in tag of the item. It consists of three parts: reader, tag and application system: The reader emits and receives reflected electromagnetic waves to the tag; The label is tightly bound to the item under test. Passive tags do not require external power supply or built-in batteries, and rely on the electromagnetic waves emitted by the reader to start and reflect signals to realize data transmission; The application system controls the transceiver to send and receive, and process the data reported by the tag.
The traditional passive IoT reader adopts a full-duplex architecture with integrated transceiver, which transmits excitation signals and receives reflected signals at the same time. This has strong system self-interference and different system mutual interference, resulting in short reading and writing distance, low recognition accuracy, and difficult equipment management.
The new passive IoT system uses a separate architecture to solve the problems of serious self-interference and difficult network deployment in the traditional integrated architecture. It can realize continuous coverage of passive system network to meet various needs, such as automatic inventory of assets, fine management of materials and intelligent logistics tracking. The new passive communication provides more efficient connection service capabilities through the separation of transceivers. After the transceiver is separated, the new passive IoT system divides the reader into two devices: the exciter and the receiver, and solves the interference problem through physical separation, which can not only increase the communication distance, improve the recognition rate of items, but also reduce the the complexity of device deployment and R&D costs.
The combination of the new passive IoT system with 5G and other cellular communication technologies will be more conducive to network deployment, which will reduce network deployment costs and enhance O&M management. Through the built-in module of the passive IoT exciter and the combination of the passive IoT receiver and the base station, it can not only achieve indoor continuous coverage for large warehouses, but also realize co-management and operation and maintenance with the base station, enhancing the performance of the passive IoT system. At the same time, the cellular network can further support passive IoT technology. The base station's multi-antenna beamforming, new air interface waveform and coding technologies borrowed from cellular communication are expected to further increase the communication distance and enable passive IoT technology to be applied to outdoor scenarios.
b.5G+ new short-range communication
Short-range wireless communication generally refers to providing point-to-point wireless communication in a small area (usually less than 100 meters). It is a typical industrial field network network, mainly used for small-scale interconnection between devices, and has the advantages of simple deployment and low cost.
Facing the intelligent manufacturing scenario, China Mobile and its partners have jointly realized the innovative application of 5G + Spark-link fusion communication technology in motor synchronous control. In the traditional solution, wired connections must be used between the servo drives to meet the microsecond-level delay requirements for the synchronization of gear speeds. But now through innovation, multiple sets of servo servers can be replaced by industrial cables with a short distance from Spark-link, and the protocol can be transformed at the basic service layer of Spark-link communication nodes. It can not only ensure the communication requirements of microsecond-level delay between servo drives, but also actively deliver QoS policies such as business priority and delay jitter management through 5G cloud applications. By adjusting short-distance air interface resources in real time, the transmission reliability of on-site control data flow can be improved, thereby realizing higher-level flexible manufacturing.
c.5G+ deterministic transmission
The industry communication network deterministic network refers to the network that can guarantee the deterministic bandwidth, delay, jitter, and packet loss rate of services. The determinism here means that the indicators can be expected, such as the deterministic delay of 10ms, and the jitter of the delay is ± 10μs. The need for deterministic networks is widespread in industrial communications. Due to the large number and complexity of communication protocol standards, the compatibility with each other is very weak.This has led to closed technologies and poor reusability, which has restricted the development of industrial network interconnection. The advent of 5G technology offers new options.
5G and TSN/TAN solve the deterministic problem between data transport layers. In order to meet the needs of the wireless access network to support the deterministic industrial network interconnection using TSN technology, 3GPP R16 has considered and defined the architecture of the 5G system as a TSN logical bridge to complete the networking and interconnection with the TSN network. Use 5G to extend the coverage of the existing TSN network of the field network. Later, in order to combine the wired and wireless deterministic technology, simplify the system architecture and promote the development of the industry, the industry proposed the deterministic technology of wired local area network Time Aware Network (TAN) technology. It provides deterministic transport services for industry applications in a lightweight, plug-and-play manner. The integration of 5G technology and TAN will further expand the application fields and scenarios of TAN.
d.5G+ high-precision indoor positioning
At present, there are three main technical directions in the industry for positioning needs. One is UWB positioning, which transmits data by sending and receiving extremely narrow pulses with sub-nanosecond or picosecond pulses, resulting in GHz-order bandwidths in the frequency domain. The second is the Bluetooth angle positioning, which is based on the angle positioning of the antenna array (AoA/AoD), which is a high-precision positioning scheme based on the angle measurement between the received and sent signals. The third is the co-deployment method of positioning base stations and 5G distributed pico base stations. In the traditional 5G positioning method, most algorithms such as RTT, AOA/AOD, TDOA rely on the measured time, angle and other information for calculation. There are high requirements for chip processing time, angle measurement accuracy and domain synchronization accuracy. In the future, 5G-based positioning technology will be explored to achieve a high-precision positioning solution under the condition of limited bandwidth and without affecting existing services.
e.5G and medium and low speed communication
Medium and low-speed networks are IoT connections with a downlink transmission rate of less than 10Mbps and an uplink transmission rate of less than 5Mbps. In order to meet the development needs of IoT applications, medium and low-speed network technologies with a variety of network standards have emerged. Currently, they have been widely used, including NB-IoT, Cat. LoRa and Sigfox et al. Specifically, NB-IoT meets the needs of low-power wide-area coverage services in terms of coverage, power consumption, and transmission rate, and is suitable for low-speed IoT applications that require long-distancetransmission, small amount of communication data, and low latency requirements. Cat.1 technology is suitable for services that require high mobility and speed, a large amount of data, and a voice function.
LoRa is a representative of wide-area low-power technology that uses unlicensed spectrum. Compared with NB-IoT, LTE Cat.1 and other technologies that use licensed frequency bands, its reliability and credibility are relatively weak. In particular, there are gaps in identity credential security, authentication mechanism, and key management. Zigbee and BLE are limited by limited coverage, and it is difficult to meet those IoT applications that require long-distance transmission, small amount of communication data, and long-term battery power supply.
Industry communication network technology is an important technical realization of digital twin network connection, and it is the last "hundred meters" between field networks and equipment in industrial, medical, transportation and other scenarios. Here, we call on industry enterprises to work together with China Mobile in the field of 5G+ industry communication network to jointly promote the digital and intelligent transformation of vertical industries.
Co-authors: Research Institute of Internet of Things Technology and Application of China Mobile Communications Co., Ltd., Huawei Technologies Co., Ltd., Beijing Ziguang Zhanrui Technology Co., Ltd., H3C Technology Co., Ltd., Xuzhou Heavy Machinery Group Co., Ltd., Shougang Group, Nanjing Iron and Steel Co., Ltd., Baosight Software, Baosight Software, MediaTek Inc.
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