At the “GSMA Millimeter Wave Technology In-depth Interpretation Seminar” held recently, Li Nan, deputy director of the Wireless Technology Research Institute of China Mobile Research Institute, said that with the support of spectrum, standards and industry, millimeter wave has made positive commercialization progress. , and is expected to have large-scale commercial capabilities in 2022.
Li Nan introduced that compared with 4G, 5G has more than 10 times improvement in speed and capacity. In order to meet 5G requirements, expanding the working bandwidth is the easiest and most efficient method, but the spectrum below 6GHz is already very tight, and it is difficult to find a working spectrum suitable for the large bandwidth of 5G. Millimeter wave emerged as the times require, and it has become the focus of the industry due to its larger bandwidth in higher frequency bands.
At the 2019 World Radio Conference, millimeter wave made a breakthrough, and a total of 17.25GHz millimeter wave division was determined, including 24.25-27.5GHz and 37-43.5GHz global division, as well as 45.5-47GHz, 47.2-48.2GHz And the regional division of 66-71GHz, these spectrum divisions have greatly inspired the industry’s confidence in millimeter waves.
The millimeter wave standard is gradually improving
In the R15 version, 3GPP included millimeter waves in its work, including the formulation of low-band standards below 6GHz and the standardization of millimeter-wave operating bands above 6GHz; in the R16 standard, many 5G NR enhancement features supporting millimeter-wave were introduced, and 3GPP focused on Focus on improving the working efficiency of millimeter-wave systems and reducing the delay of millimeter-wave communications; in the R17 phase, more 5G NR enhancement features that support millimeter-waves will be introduced, and the operating frequency will be extended to 52.6-71GHz, which can cover all millimeter-wave operating frequency bands.
3GPP’s test results for 28GHz and 39GHz in different scenarios show that the penetration loss of mmWave is significantly higher than that of 2.6GHz and 3.5GHz, especially for 39GHz, where the penetration loss is twice that of 2.6GHz. With the increase of the penetration barrier, the loss gap is also increasing. Under the test of the concrete wall, the penetration loss of millimeter wave is more than 2 times higher than that of 2.6GHz and 3.52.6GHz. Penetration loss directly affects the effect of outdoor coverage on indoors, resulting in limited millimeter-wave working scenarios, which is also an urgent problem that the industry needs to solve in the next step.
According to Li Nan, in addition to the physical layer and system mechanism design, 3GPP also provides extensive support for millimeter waves in terms of radio frequency standards. In the R15 stage, the standardization of the single frequency band is carried out for the typical millimeter-wave frequency bands that operators care about. In the R16 and R17 stages, carrier aggregation within the millimeter-wave frequency band is further supported on this basis, as well as FR1 and FR2 cross-band carrier aggregation and dual links. Basically, it can meet the basic needs of operators for millimeter wave deployment that can be foreseen at present. In the future, cross-band carrier aggregation between millimeter-wave frequency bands will be considered to further enrich millimeter-wave working scenarios and frequency band combinations.
The millimeter wave industry is basically mature
Li Nan pointed out that because the millimeter-wave operating frequency band is very high, the propagation loss and penetration loss are also very high, and large-scale antennas are the necessary technology.
Li Nan also pointed out that due to the semiconductor itself, it is difficult for a single channel of millimeter-wave frequency band to support a large power. At the same time, millimeter wave will also realize user access through beam scanning. In order to ensure the flexibility of beam configuration and beam resolution, a certain number of channels with control capabilities are required.
The industry proposes a digital-analog hybrid solution suitable for millimeter waves according to the characteristics of millimeter waves. By adding amplitude modulation and phase modulation devices on the analog side, an analog budget digital superposition hybrid replica can be realized, which can almost achieve performance comparable to a pure digital replica after testing. In this way, the cost and complexity of millimeter-wave network equipment can be greatly reduced, and it will play a very important role in promoting the industrialization of millimeter-wave in the future.
Compared with the low frequency of 6GHz, when the millimeter wave frequency rises to above 24GHz, the size of the terminal radio frequency device, including the antenna, will be greatly reduced, so there is an opportunity to integrate the radio frequency front end, including filters, etc., with the antenna into a module. The AIP technology of the packaged antenna has also become the mainstream of the millimeter wave terminal technology.
In terms of industrialization, network equipment has launched different stations for outdoor and indoor coverage; in terms of terminals, some manufacturers have launched millimeter-wave commercial smartphones, and some manufacturers have supported millimeter-wave CPE; in terms of chips, Qualcomm has supported millimeter-wave CPE. Wave commercial chips, Samsung and Huawei have already supported millimeter wave engineering prototypes. It can be seen from this that the millimeter wave industry has basically matured, making periodic contributions to commercial development and user-oriented promotion.
With the support of spectrum, standards and industry, millimeter wave has made relatively gratifying commercialization progress on a global scale. As of August this year, 22 operators have deployed millimeter-wave 5G systems, with the United States, Japan and South Korea leading the way.
Li Nan said that millimeter wave will have large-scale commercial capabilities in 2022, and China Mobile hopes to deploy a millimeter wave network based on SA. In addition, in view of the coverage bottleneck and signal occlusion of millimeter wave, it is necessary to jointly carry out technical research with the industry in order to launch a mature millimeter wave commercial system as soon as possible.
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