Author, China Mobile Li Lin, Migu Beacon Project Team
As a new communication operator, China Radio and Television has licenses for 5G in the low-band 700MHz, mid-band 4.9GHz and 3.3G~3.4GHz. How to build and deploy to give full play to the advantages of the 700MHz frequency band? The advantages and key technologies of the 5G 700MHz frequency band have been introduced in the previous article. This issue will analyze the construction plan of the radio and television 700MHz and the development of related industrial chains .
1. 700MHz network construction plan for radio and television
With the completion of the signing of a specific agreement on co-construction and sharing of 700MHz network by Radio and Television and Mobile in 2021, China Mobile and Radio and Television will share 700MHz spectrum and mobile 2G\4G\5G network within 10 years. How to plan and build a low-frequency 700MHz network is a common problem faced by radio and television and mobile. According to China's 5G spectrum allocation (Figure 1), radio and television is allocated low frequency 700MHz (2×30M bandwidth), intermediate frequency 3.3GHz (shared with China Telecom and China Unicom for indoor coverage) and 4.9GHz (60MHz bandwidth); mobile is allocated intermediate frequency 2.6GHz (160MHz bandwidth) and 4.9GHz (100MHz bandwidth) .
Figure 1 China's 5G Spectrum Allocation
For mobile and broadcasting, the low-frequency 700MHz golden frequency band has the characteristics of wide signal coverage, strong penetration, and low delay, and is suitable for large-scale continuous network coverage scenarios . The intermediate frequency (2.6GHz or 4.9GHz) is the main bearer frequency band of 5G, which meets the performance requirements of 5G network speed, delay and capacity. In the construction of 5G, it is necessary to make full use of the respective advantages of low, medium and high frequency bands to build a 5G multi-frequency three-dimensional network and ensure leading network quality. The following first analyzes the networking strategy, and then introduces two network construction solutions for the co-construction and sharing mode of mobile radio and television: roaming sharing architecture and carrier sharing architecture.
1. Networking strategy: multi-frequency networking
Radio and television and mobile have both 5G low frequency and intermediate frequency. By building a 700MHz + 2.6GHz/4.9GHz combined network and adopting various enhancement technologies such as uplink transmission channel switching, uplink enhancement, and carrier aggregation, the 5G uplink bandwidth and coverage area can be improved, and the time Delay, to meet the application requirements of 5G large bandwidth eMBB and wide connection mMTC.
Among them, 700MHz is used as the base network for outdoor coverage. According to its characteristics of wide coverage and deep coverage of buildings, it can be used as the main bearer network of VoNR; 700MHz is used as a coverage support, which can release the pressure of the mid-band (uplink enhancement, downlink carrier aggregation), and moderately shrink the coverage capacity in the horizontal direction. , increase the proportion of multi-dimensional beam configuration in the vertical direction, optimize the vertical coverage capability; achieve no blind zone coverage in three aspects: breadth (wide range), depth (strong penetration), and height (high-rise buildings). Because of its low latency, it can also fully deploy IoT applications.
The intermediate frequency 2.6GHz is the main frequency band for 5G network coverage and capacity bearing, and 4.9GHz is used as a supplement for indoor and outdoor capacity. The superposition combination of 700MHz and 2.6GHz/4.9GHz, through downlink carrier aggregation, can fully ensure 5G user experience in heavy traffic or congestion scenarios, and make up for the lack of IF uplink capability through uplink transmission channel switching to ensure uplink transmission performance. After 700MHz and 2.6GHz are aggregated, the upstream edge rate can reach 3-5Mbps, and can support 720P/1080P video upload. In terms of coverage, the intermediate frequency can also realize indoor and outdoor co-frequency networking to achieve 5G coverage and capacity bearing. In high hotspot areas and government-enterprise private network application scenarios, network expansion is realized, and 700MHz + 2.6GHz/4.9GHz can meet the needs of 5G large-bandwidth scenarios, such as high-definition conferences and high-definition video live broadcast scenarios.
Figure 2 Multi-frequency networking strategy
For radio and television, you can refer to the mobile/telecom low-frequency network deployment experience to achieve thin network coverage in the early stage, and gradually improve network coverage in the later stage.
**Compared to mobile 900MHz, 700MHz covers 44% - 70% more area and requires 30 - 40% fewer sites . **Adopting the multi-frequency networking mode will greatly reduce the cost of network construction and operation, and has the advantage of high-quality coverage in the service fields of 2C and 2B vertical industries.
2. Mobile radio and television co-construction and sharing model 1: Roaming and sharing architecture
Before the 700MHz 5G SA network was built on a large scale, China Mobile and China Radio and Television adopted a roaming sharing architecture, as shown in Figure 3. China Radio and Television leased China Mobile's network in the initial stage of its 5G commercial use. China Mobile shared the 2G/4G/5G access network and bearer network with China Radio and Television to carry all China Radio and Television users. China Radio and Television independently builds a core network to conduct business and connects to the mobile core network . Radio and television user services need to be forwarded to the radio and television core network through the mobile core network for processing. Account opening, billing, and policy control of both parties' services are implemented in the core network without affecting each other. In the mobile network, only the mobile PLMN (Public Land Mobile Network) operator code needs to be configured, but the home location register HLR (Home Location Register) of the core network needs to open authentication for radio and television users in advance to allow radio and television users to access and assist The mobile core network forwards the service flow to the radio and television core network for processing.
Figure 3 Roaming sharing architecture
3. Mobile radio and television co-construction and sharing mode 2: Carrier sharing architecture
After the independent scale construction of the 700MHz 5G SA network is completed, it will form a TDD/FDD heterogeneous double-layer network with the existing network 2.6GHz NR . GHz wireless access network, inter-network settlement between operators . The access networks of both parties use the same spectrum resources, share frequency bands, share carriers, and share capacity; the core network and bearer network are separated.
The carrier sharing architecture is shown in Figure 4. The 700MHz and 2.6GHz NR sites are configured with MOCN sharing, and broadcast the two operator codes PLMN of China Mobile and China Radio and Television at the same time. Both users can access the 700MHz and 2.6GHz sites. Basic interoperability such as reselection and handover can be realized between the two networks. With the development of 5G users, timely introduce load balancing between the two networks. China Radio and Television users have priority access to 700MHz for data services, and priority for voice services to be carried by 700MHz VoNR; China Mobile users have priority to access 2.6GHz NR networks. When Chinese radio and television users move from the NR coverage area to the NR coverage blind area, the service continuity is guaranteed through roaming across networks.
Figure 4 MOCN carrier sharing architecture
2. Industrial chain progress
At present, the global 5G is accelerating, and the pace of commercial use continues to accelerate. As of the end of 2020, 140 operators around the world have launched 5G commercial networks in 59 countries or regions, among which more than 18 operators have obtained 700MHz 5G licenses. By the end of 2020, eight 5G 700MHz commercial networks have been built around the world. The 700MHz industry chain will take advantage of the 5G wind and gradually mature. The following will introduce the development of the 700MHz 5G industry from the dimensions of antennas, chips, modules, terminals, base stations, test instruments, and operators.
1. Antenna
Because the size of the 700MHz low-frequency antenna is too large, it is not suitable for the use of Massive MIMO technology. It is necessary to use the previous RRU form and add a 4-port antenna . The antenna on the base station side uses 4T4R (four transmissions and four receptions), and the terminal antenna is 1T2R or 2T4R, which is basically the same as the antenna radio frequency configuration of 4G equipment and terminals, analogous to 900MHz. Therefore, the performance requirements and demand for upstream antennas, radio frequency components, optical modules and other devices for base stations and terminals in the 700MHz frequency band have not been greatly improved.
Because the 4T4R antenna of 700Mhz is relatively simple, the industry maturity of 700Mhz is easier than other frequency bands. Now it mainly includes three types of antennas: 4448 (700MHz/900MHz/1800MHz/FA), 444 (700MHz/900MHz/1800MHz), single and four-channel antennas. At present, mainstream antenna manufacturers such as Huawei, Comba, Hongxin, and Tongyu have developed 700MHz base station antenna products and completed independent testing.
2. Chip, module, terminal, and base station ecology gradually mature
In the past two years, China's 5G smartphone shipments have reached more than 1/3 of the world's total (in 2019, Chinese mobile phone brands such as Huawei, Xiaomi, and OPPO accounted for 46% of global shipments. China's annual total shipments accounted for 36% of the world's total, which is equivalent to the sum of Samsung and Apple), providing development opportunities for Chinese chip manufacturers. At present, there are five main 5G mobile phone chip manufacturers in the world: Qualcomm of the United States, Huawei HiSilicon of China, MediaTek MTK of Taiwan, Ziguang Zhanrui of China, and Samsung of South Korea (Apple acquired Intel's mobile phone baseband business in July 19 and has already started research and development). Among them, the 5G chip technology of Huawei and Qualcomm is the most superior.
In July 2020, the Ministry of Industry and Information Technology issued the "Radio Frequency Technical Requirements for 5G System Equipment in Low and Medium Frequency Bands", which was officially implemented. The first batch of manufacturers that obtained the Ministry of Industry and Information Technology's 5G system equipment model approval certificate included Huawei, ZTE, Ericsson, vivo, Qualcomm, MediaTek MTK, etc. As of the end of December 2020, 7 base stations, 58 mobile phones, 10 CPE and industrial modules, 3 tablet PCs and 1 notebook can all support the 5G 700MHz frequency band, marking the gradual maturity of China's 5G 700MHz industrial chain ecology .
Mobile phone baseband chip: The baseband chip is one of the core components of the terminal. As of Q4 2020, five mainstream chip manufacturers Qualcomm, Huawei HiSilicon, MediaTek MTK, Zhanrui, and Samsung support 30MHz bandwidth in the 700MHz frequency band.
IoT chips/modules: Currently, mainstream chip manufacturers supporting 700MHz IoT include: Qualcomm, Huawei, MediaTek, France Sequans, Israel Altair (acquired by Sony), etc., all of which support the B28 (Band 28) 700MHz frequency band. IoT module manufacturers currently supporting the 700MHz frequency band include: Switzerland u-blox, China Quectel, Fibocom, Neoway, etc.
Qualcomm is the leader in 5G chips and has released three generations of 5G chips. In 2020, the third-generation Snapdragon X60 chip will be released, which is the world's first 5nm-based chip. In addition to supporting all frequency bands and standards of 5G, it also supports the aggregation of different frequency bands of low, medium and high, and supports FDD+TDD aggregation of n28 frequency band and other frequency bands, which can meet the commercial needs based on 700MHz.
In terms of 700MHz commercial deployment, in 2020, Qualcomm and ZTE will complete the first 700MHz VoNR high-definition video voice call; complete the world's first 5G data call service with 700MHz 2×30M bandwidth with China Radio and Television; complete smartphones equipped with Qualcomm Snapdragon 5G chips Terminal testing, assisting vivo, ZTE and other manufacturers to launch the first batch of 5G commercial terminals supporting the 700MHz frequency band.
Huawei HiSilicon: The Kirin 9000 chip will be released in 2019, using a 5nm SOC process, integrating the Huawei Balong 5000 baseband chip, supporting the n28 frequency band, and 5G SA dual-carrier aggregation. Compared with Qualcomm's second-generation baseband chip X55, the Sub-6G uplink rate is increased by 6.8 times, and the downlink rate is increased by 2.6 times.
In addition, Huawei's HiSilicon IoT chip Boudica 150 can support the 700MHz B28 frequency band, and is jointly developed with Quectel and u-blox to support the B28 IoT module.
Terminal: As of December 2020, 58 domestic terminals support 700MHz, including mainstream mobile phone manufacturers such as Apple, Samsung, Huawei, Xiaomi, vivo, OPPO, and ZTE. According to the requirements of the "China Mobile 5G Commercial Mobile Phone Product White Paper (2021)", from January 1, 2021, it is recommended that network access terminals above 3,000 yuan support the 700MHz n28 frequency band. It is expected that in the first half of 2021, most mid-to-high-end models of various manufacturers can support 700MHz.
Base stations: As of December 2020, a total of 7 5G base stations from 5 domestic base station equipment manufacturers support the 700MHz frequency band, including Huawei, ZTE, Ericsson, Nokia and China Information Technology.
Ericsson is the world's earliest and most involved equipment manufacturer in the deployment of 5G 700MHz commercial networks. In April 2020, Ericsson assisted Vodafone Germany in realizing the world's first 700MHz 5G commercial network. Provide base station equipment for 700MHz commercial networks in 5 countries including Germany, Norway, and Sweden within 2020. Ericsson has the deployment capabilities of multi-operator co-construction and sharing and aggregation of high, medium and low frequencies, as shown in Figure 5.
In China, Ericsson will complete field testing of VoNR end-to-end voice call services based on Huawei's core network and 5G terminals in 2020. In the same year, it cooperated with China Radio and Television and MediaTek to complete the end-to-end verification of 5G video broadcasting based on 700MHz 2×30M large bandwidth.
Figure 5 Ericsson co-construction and sharing and low-medium-high-frequency aggregation case
Huawei is a practitioner of China's 5G network construction. In terms of 700MHz network commercialization, actively cooperate with operators, and make many explorations in new technology development and business innovation. In August 2020, Huawei's 5G 700MHz large bandwidth base station, 5G mobile terminal and CPE became the first batch of products in my country to complete the 700MHz equipment model approval. At the same time, completed the domestic industry's first end-to-end 5G SA 700MHz core network test; the first 5G 700MHz 2×30MHz terminal performance verification; the first 5G SA 700MHz VoNR high-definition audio and video call opening; the first low-frequency intermediate frequency combined network Coverage and service testing; the first 5G NR video broadcasting service, etc., gradually promote the maturity of the 700MHz industry chain.
Figure 6 Huawei test case
3. Test instrumentation
The construction and testing of the wireless side of the 700MHz 5G network is a crucial part of ensuring network quality. The test needs to consider multiple aspects such as wireless access, terminal verification, field frequency clearing/interference test, antenna field, and network delay. Some sites need to share the 700MHz antenna with the existing mobile mid-low band antenna. At the same time, there will be a lot of inter-band interoperability between 700MHz and medium and low frequencies, requiring the 700MHz network to cover strictly according to the plan. This will require more precise testing equipment and more manufacturers to invest.
In response to the above requirements, VIAVI provides an end-to-end base station test solution, including RF Vision handheld test equipment, NB-IoT-based antenna status monitoring solution IOA (IoT for Antennas, an antenna based on the Internet of Things sensors) and the industry's first chip-level antenna status monitoring solution AMP (Antenna Motion Processor, Antenna Motion Processor). RF Vision has latitude and longitude positioning function, and can test the azimuth, roll angle, downtilt angle, horizontal position and altitude of the antenna. At the same time, it also supports mobile APP remote operation and cloud synchronization, which improves test efficiency and data security, and reduces the impact of human factors on test results. IOA and AMP provide a long-term monitoring solution. Through real-time monitoring of the entire antenna network, the antenna system becomes a white box state, and operators can obtain antenna information anytime and anywhere at a low cost.
The MT8000A test platform launched by Anritsu is a network emulator for testing the radio frequency performance and protocol functions of 5G terminals and chipsets. Support 700MHz and Sub-6GHz signaling radio frequency test, support NSA (non-standalone networking) and SA (standalone networking) modes.
4. Operator progress
Nearly 20 operators around the world are building or planning 5G 700MHz networks. By the end of 2020, Vodafone, Telia, Claro, TDC and other international operators have successively launched eight commercial 5G networks in the 700MHz frequency band in countries such as Germany, Norway, Sweden, Brazil, and Denmark, and more than ten 5G 700MHz networks are still in development . deployment stage.
In China, China Radio and Television obtained the exclusive 700MHz frequency band license certification in 2020, and started large-scale network construction that year. In addition, China Radio and Television plans to build 400,000 5G base stations in 2021, which can cover more than 90% of the country's administrative villages.
Since 2020, China Radio and Television has accelerated the pace of promoting the 5G 700MHz industry chain and explored an industrialized operation model. At the technical level, a number of technical verification, product testing and integrated business development have been completed. Completed the world's first 700MHz 2×30MHz terminal performance verification, the first 5G 700MHz VoNR voice call, built the China Radio and Television 5G Converged Video APP, etc. In practical scenarios, China Radio and Television has completed a number of business scenario tests and demonstrations, verifying that based on 700MHz + 4.9GHz networking, it can realize high-definition conferences, program production, telemedicine, industrial control, smart transportation and other industrial applications.
China Radio and Television has promoted my country's 5G 700MHz industry chain to enter a gradually mature stage. However, due to various factors such as frequency clearing, capital, and network integration, the deployment of the 700MHz frequency band of Radio and Television still faces enormous pressure and challenges in network construction, business operations, and marketization.
China Mobile is also speeding up the layout of 700MHz. In May 2020, China Mobile and China Radio and Television entered into a cooperation framework agreement on 700MHz co-construction and sharing. In January 2021, the two parties signed a specific cooperation agreement for the implementation rules, with a view to carrying out the joint construction of 5G networks and the win-win cooperation of platforms and content. In June 2020, Zhejiang Mobile joined hands with Huawei to open the first 700MHz 5G base station, and completed the industry's first uplink enhancement technology verification of 700MHz and the existing network 2.6GHz frequency band; 5,000 sets) project to explore the best solution for 700MHz network construction for Zhejiang Mobile's "5G city" project; in 2020, the "China Mobile 5G Commercial Mobile Phone Product White Paper (2021)" was released, clearly requiring all 5G network access from July 21 The terminal must support the 700MHz frequency band with high quality, and the terminal industry chain is matured according to the requirements of the white paper.
It is believed that under the coordinated promotion of China Radio and Television and China Mobile, China's 700MHz will be officially commercialized in the near future, and cooperate with the medium and high frequency bands to create a 5G high-quality boutique network, which will help empower immersive experience and industry digitalization.