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The future of 5G from the perspective of operators’ collective acquisition: The continuous evolution of all-band multi-antenna technology

According to the Ministry of Industry and Information Technology, by the end of June this year, 961,000 5G base stations had been built, 365 million 5G mobile phone terminals were connected, accounting for more than 80 percent of the world’s total, and there were more than 10,000 5G application innovation cases in China.

China’s 5G development is fast, but not enough. Recently, in order to build a 5G network with wider and deeper coverage, China Telecom and China Unicom jointly acquired 240,000 2.1g 5G base stations, and China Mobile and radio and television jointly acquired 480,000 700M 5G base stations, with a total investment of 58 billion yuan.

The industry pays close attention to the bidding share of domestic and foreign manufacturers, and we find the development trend of 5G from these two intensive procurement. Operators not only pay attention to user experience such as 5G network capacity and speed, but also pay attention to 5G network coverage and low power consumption.

5G has been commercially available for about two years and is expected to reach 1.7 million by the end of this year, with several million more 5G base stations to be built in the coming years (there are about 6 million 4G base stations in China and more 5G to come).

So where will 5G go from the second half of 2021? How do operators build 5G? The author finds some answers that have been ignored from the demand for collective procurement and the most cutting-edge 5G technology pilot in various places.

1、if has more advantages in 5G network construction

With the deepening of 5G commercialization and the improvement of 5G penetration rate, mobile phone traffic is increasing explosively, and people will have higher and higher requirements on the speed and coverage of 5G network. Data from ITU and other organizations show that by 2025, China’s 5G user DOU will grow from 15GB to 100GB (26GB globally), and the number of 5G connections will reach 2.6 billion.

How to meet the future 5G demand and efficiently and cheaply build a high-quality 5G network with wide coverage, fast speed and good perception has become an urgent problem for operators at this stage. What should carriers do?

Let’s start with the most critical band. In the future, low frequency bands such as 700M, 800M and 900M, middle frequency bands such as 1.8G, 2.1g, 2.6G and 3.5g, and higher millimeter wave bands will be upgraded to 5G. But next, operators need to consider which spectrum can better meet the needs of current 5G users.

First look at low frequency. Low frequency band signals have better penetration, advantages in coverage, low network construction and maintenance costs, and some operators are rich in frequency band resources, which are relatively sufficient in the initial stage of network construction.

Operators deploying 5G in low frequency bands also face problems of high interference and relatively slow network speeds. According to the test, the speed of low-band 5G is only 1.8 times faster than that of 4G network with the same low-band, which is still in the range of tens of Mbps. It can be said that it is the slowest 5G network and cannot meet users’ demands for 5G cognition and experience.

Due to the immature end industry chain of low frequency band, only two 800M 5G commercial networks have been released in the world at present, while 900M 5G commercial networks have not yet been released. Therefore, it is too early to recultivate 5G at 800M/900M. It is expected that the industry chain can only get on the right track after 2024.

And millimeter waves. Operators are deploying 5G in high frequency millimeter wave, which can bring users faster data transmission speed, but the transmission distance is relatively short, or the target of the next phase of construction. That means operators need to build more 5G base stations and spend more money. Obviously, for operators at the present stage, except for hot spot coverage requirements, other scenarios are not suitable for constructing high frequency band.

And finally the spectrum. Operators are building 5G in the middle band, which can deliver higher data speeds and more data capacity than the lower spectrum. Compared with high spectrum, it can reduce the number of base station construction and reduce the network construction cost of operators. Moreover, the industrial chain links such as terminal chip and base station equipment are more mature.

Therefore, in the author’s opinion, in the next few years, operators will still focus on the construction of 5G base stations in the middle spectrum, supplemented by other frequency bands. In this way, operators can find a balance between breadth of coverage, cost and capacity.

According to THE GSA, there are more than 160 5G commercial networks worldwide, with the top four being 3.5g networks (123), 2.1G networks (21), 2.6G networks (14) and 700M networks (13). From the terminal point of view, 3.5g + 2.1g terminal industry maturity is 2 to 3 years ahead, especially 2.1g terminal maturity has approached 3.5/2.6g.

Mature industries are the foundation for the commercial success of 5G. From this perspective, Chinese operators who build 5G with 2.1g + 3.5g and 700M+2.6G networks have a first-mover advantage in the industry in the coming years.

2、FDD 8 t8r

Help operators to maximize the value of medium frequency

In addition to spectrum, multiple antennas are also key to meet the evolution needs of operators’ 5G networks. Currently, 4T4R (four transmitting antennas and four receiving antennas) and other base station antenna technologies commonly used in 5G FDD networks by operators can no longer cope with the challenges brought by traffic growth by simply increasing spectrum bandwidth.

Moreover, as 5G users grow, operators have to increase the number of base stations to support massive connections, leading to increased self-interference between users. The traditional 2T2R and 4T4R antenna technologies do not support accurate guidance at the user level and cannot achieve accurate beam, resulting in a decrease in user speed.

What kind of multi-antenna technology will allow operators to achieve 5G’s breadth of coverage while also taking into account factors such as base station capacity and user experience? As we know, the transmission speed of wireless network mainly depends on the working mode of sending and receiving signals between network base station and terminal devices such as smart phones, while multi-antenna technology can double the capacity of base station (precise beam based on multi-antenna can control interference).

Therefore, the rapid development of 5G requires the continuous evolution of FDD to 8T8R, Massive MIMO and other multi-antenna technologies. In the author’s opinion, 8T8R will be the future construction direction of 5GFDD network to achieve “both experience and coverage” for the following reasons.

First, from a standard point of view, 3GPP has been enhanced in each version of the protocol with full consideration of terminal multi-antennas. The R17 version will reduce terminal complexity and test terminal channel status through phase information between the upstream and downstream bands of the base station. The R18 version will also add high-precision coding.

The implementation of these standards requires at least 5G FDD base stations to have 8T8R antenna technology. At the same time, the R15 and R16 protocols for the 5G era have significantly improved their performance and support for 2.1g large-bandwidth 2CC CA. The R17 and R18 protocols will also drive the continued evolution of FDD Massive MIMO.

Secondly, from the terminal point of view, the 4R (four receiving antennas) of smart phones and other terminals can release the capacity of 2.1g 8T8R base station, and 4R is becoming the standard configuration of 5G mobile phones, which can cooperate with the network to maximize the value of multiple antennas.

In the future, 6R/8R terminals have been laid out in the industry, and the current technology has been realized: the 6-antenna layout technology has been realized in the terminal whole machine, and the mainstream baseband 8R protocol stack has been supported in the terminal baseband processor.

The relevant white paper of China Telecom and China Unicom regards 5G 2.1g 4R as a mandatory mobile phone, requiring all 5G FDD mobile phones in The Chinese market to support Sub3GHz 4R.

In terms of terminal manufacturers, mainstream middle and high-end mobile phones have supported 5G FDD mid-frequency 1.8/2.1g 4R, and future mainstream 5G FDD mobile phones will support Sub 3GHz 4R, which will be standard.

At the same time, network uplink capability is the main advantage of FDD 5G. According to the test, the uplink peak experience of 2.1g large-bandwidth 2T (2 transmitting antennas) terminals has exceeded that of 3.5g terminals. It can be predicted that, driven by the competition in the terminal market and the demand of operators, more high-end mobile phones will support uplink 2T in 2.1g band in the future.

Thirdly, from the perspective of experience, 60% to 70% of the current mobile flow demand comes from indoor, but the heavy cement wall inside will become the biggest obstacle for outdoor Acer station to achieve indoor coverage.

2.1g 8T8R antenna technology has strong penetration ability and can achieve indoor coverage of shallow residential buildings. It is suitable for low-latency services and gives operators more advantages in future competition. In addition, compared with the traditional 4T4R cell, the capacity of 8T8R cell is increased by 70% and the coverage is increased by more than 4dB.

Finally, from the perspective of operation and maintenance cost, on the one hand, 8T8R antenna technology is the best choice for both urban uplink coverage and rural downlink coverage, because it has the advantage of iteration and does not need to be replaced within 10 years after the operator invests.

On the other hand, 2.1g 8T8R antenna technology can save 30%-40% of the number of sites compared with 4T4R network construction, and it is estimated that TCO can save more than 30% in 7 years. For operators, the reduction in the number of 5G stations means the network can achieve less energy consumption in the future, which is also in line with China’s “dual carbon” goal.

It is worth mentioning that the sky resources of the current 5G base station are limited, and each operator has only one or two poles in each sector. The antennas supporting the 8T8R antenna technology can be integrated into the 3G and 4G antennas of the live network, greatly simplifying the site and saving the site rent.

3、FDD 8T8R is not a theory

Operators have piloted it in several places

FDD 8T8R multi-antenna technology has been commercially deployed by more than 30 operators around the world. In China, many local operators have also completed the commercial validation of 8T8R and achieved good results.

In June this year, Xiamen Telecom and Huawei completed the opening of the world’s first 4/5G dual-mode 2.1g 8T8R joint innovation site. Through the test, it is found that the coverage depth of 5G 2.1g 8T8R is improved by more than 4dB and downlink capacity is increased by more than 50% compared with the traditional 4T4R.

In July this year, China Unicom Research Institute and Guangzhou Unicom joined hands with Huawei to complete the verification of China Unicom Group’s first 5G FDD 8T8R site in the Outfield of Guangzhou Biological Island. Based on the FDD 2.1g 40MHz bandwidth, the field measurement of 8T8R improves the coverage of 5dB and the capacity of the cell by up to 70% compared with the traditional 4T4R cell.