The electronics industry has undergone many changes over the past few years. Nowadays, millimeter wave radar and millimeter wave communication frequently appear in our sight. In particular, Huawei has made remarkable achievements in 5G, and millimeter wave technology has been put on the table. Why does millimeter wave technology play such a key role in 5G and smart cars? Next, let’s take a closer look at the past and present of millimeter wave technology and its continuation.

The history of the birth of millimeter wave technology: Born to be extraordinary

The concept of millimeter waves is not a new concept, but has a history of 30 years. Electromagnetic waves in the frequency domain of 30 to 300 GHz (wavelength of 1 to 10 mm) in radio waves are called millimeter waves. They are located in the wavelength range where microwaves and far-infrared waves overlap, so they have the characteristics of both spectra. The theory and technology of millimeter waves are the extension of microwaves to high frequencies and the development of light waves to low frequencies.

Innovative applications for mmWave technology include telecommunications, wireless communications, automotive, defense and aerospace, imaging, security, medical and other industrial applications. However, for wireless communications and automotive radar sensors, two of the fastest growing applications, mmWave generally refers to multiple frequency bands ranging from 24 to 86 GHz.

1. Characteristics of millimeter wave:

1) It is a typical line-of-sight transmission method

Millimeter waves propagate in space as direct waves, with a narrow beam and good directivity. On the one hand, millimeter waves are severely affected by atmospheric absorption and rainfall fading; on the other hand, due to the high frequency PCB band and few interference sources, the propagation is stable and reliable.

2) It has an “atmospheric window”

The main gases that affect millimeter wave propagation are oxygen molecules and water vapor. The resonance of these gases will produce selective absorption and scattering of millimeter wave frequencies. The absorption peaks caused by the resonance of oxygen molecules appear near 60 and 120 GHz, while the absorption peaks caused by the resonance of water vapor appear near 22 and 183 GHz. In the entire millimeter wave frequency band, there are four “atmospheric windows” with relatively small propagation attenuation. Their center frequencies are near 35 GHz, 45 GHz, 94 GHz, 140 GHz, and 220 GHz. The corresponding bandwidths of these “windows” are 16 GHz, 23 GHz, 26 GHz, and 70 GHz, respectively. Near these special frequency bands, millimeter wave propagation is less attenuated and is more suitable for point-to-point communication.

3) Severe attenuation during rainfall

Compared with microwaves, millimeter wave signals attenuate much more under adverse climatic conditions, especially during rainfall, which seriously affects the propagation effect. After research, it is concluded that the attenuation of millimeter wave signals during rainfall is closely related to the instantaneous intensity of rainfall, the distance and the shape of raindrops. Further verification shows that: generally speaking, the greater the instantaneous intensity of rainfall, the farther the distance and the larger the raindrops, the more serious the attenuation caused. Therefore, the most effective way to deal with rainfall attenuation is to leave enough level attenuation margin when designing millimeter wave communication systems or communication lines.

4) Strong penetrating ability against dust and smoke

Laser and infrared have poor penetration into dust and smoke, while millimeter waves have a clear advantage in this regard. A large number of field test results show that millimeter waves have strong penetration into dust and smoke, and can pass through them almost without attenuation. Even under conditions of high-intensity scattering caused by explosions and metal foil strips, even if fading occurs, it is short-term and will recover quickly. As ions diffuse and fall, there will be no serious interruption of millimeter wave signals.

2. Advantages of millimeter wave:

1) Extremely wide bandwidth

It is generally believed that the frequency range of millimeter waves is 26.5 to 300 GHz, with a bandwidth of up to 273.5 GHz, which is 10 times the total bandwidth from DC to microwave. Even considering atmospheric absorption, only four main windows can be used when propagating in the atmosphere, but the total bandwidth of these four windows can reach 135 GHz, which is 5 times the sum of the bandwidths of all bands below microwave. This is undoubtedly very attractive today when frequency resources are scarce.

2) Narrow beam

The beam of millimeter waves is much narrower than that of microwave waves at the same antenna size. For example, a 12cm antenna has a beam width of 18 degrees at 9.4GHz, while the beam width is only 1.8 degrees at 94GHz. Therefore, it can distinguish smaller targets that are closer or observe the details of the target more clearly.

3) Strong detection capability

The broadband and wide spectrum capability can be used to suppress multipath effects and cluttered echoes. A large number of frequencies are available to effectively eliminate mutual interference. A large Doppler frequency shift can be obtained at the target radial velocity, thereby improving the detection and identification capabilities of slow-moving or vibrating objects.

4) Good security and confidentiality

This advantage of millimeter wave communication comes from two aspects:

a) Since millimeter waves are greatly attenuated by oxygen, water vapor and rainfall when propagating in the atmosphere, the point-to-point direct distance is very short. Beyond this distance, the signal becomes very weak, which increases the difficulty for the enemy to eavesdrop and interfere.

b) The millimeter wave beam is very narrow and has low side lobes, which further reduces the probability of being intercepted.

5) High transmission quality

Due to the high frequency band, millimeter wave communications have basically no interference sources and the electromagnetic spectrum is extremely clean. Therefore, millimeter wave channels are very stable and reliable, and their bit error rate can be maintained at the order of 10-12 for a long time, which is comparable to the transmission quality of optical cables.

6) 24/7 communication

Millimeter waves have much stronger penetration capabilities against rain, dust, smoke and plasma than atmospheric lasers and infrared. This makes millimeter wave communication have better all-weather communication capabilities and ensures continuous and reliable operation.

7) Small component size

Compared with microwaves, the size of millimeter wave components is much smaller, so millimeter wave systems are easier to miniaturize and reduce the weight of products.

3. Comparison of characteristics with microwaves, infrared, visible light and lasers:

Compared with microwaves, millimeter waves are greatly affected by adverse weather conditions, but they have high resolution, light structure and are easy to load; compared with infrared and visible light, although the millimeter wave system does not have such high resolution, it has good transmission characteristics through smoke and dust; compared with lasers, the propagation of millimeter waves is much less affected by climate and can be considered to have all-weather characteristics.

4. Millimeter wave technology from birth to commercial use:

The growth of the mmWave commercial market began with the need for cellular backhaul in the early 1990s. Long-range radio relay links at lower frequencies (1 to 18 GHz) had been in use for a long time, but the rapidly evolving cellular infrastructure required higher frequencies and shorter-range links. These point-to-point radios used licensed bands at 23, 26, and 38 GHz (Figure 2) and had a range of less than 10 km, enabling the rapid deployment phase of the global mobile communications infrastructure. These advances came as RF technology evolved to address a growing number of applications for MMICs. Recently, several higher frequencies have been added, including the unlicensed 57 to 64 GHz band and the lightly licensed bands at 71-76 and 81-86 GHz, which offer higher bandwidth, greater capacity, and smaller size, but also shorter propagation distances. All of these bands are currently being used for point-to-point digital radio links within and outside the cellular communications infrastructure, providing multi-Gbps capacity. This application has primarily been done using fiber links, but mmWave links can enable this application at lower costs and higher speeds. In addition, many locations do not even have access to fiber links due to terrain or other factors.

5G millimeter wave communication: “perpetual motion machine”, endless frequency resources

With the rapid development of mobile communications, satellite communications and satellite-borne electronics, the requirements for system capacity are getting higher and higher. Due to the extremely rich spectrum resources in the high-frequency microwave band, modern communication systems are developing towards high-frequency microwaves, especially millimeter wave bands.

The United States is the first country in the world to determine the high-end spectrum of 5G. The newly added frequency bands are concentrated in the low, medium and high frequency bands of 3.8-7GHz, 27-40GHz and 64-71GHz. According to general rules, my country will also use this frequency band or a similar frequency band. Excluding other devices such as reception, the PA chip alone is estimated to reach 4 billion US dollars by 2020. my country is the world’s largest mobile phone production base. At the same time, the sales volume of mobile phones of domestic brands such as Huawei, vivo, oppo, Xiaomi, Meizu and Lenovo accounts for more than 30% of the world. With the huge terminal market demand, the transfer of mobile phone supply chain to the mainland is an inevitable industrial trend. The demand for localization is becoming increasingly strong, and the country’s investment in high-frequency chips is bound to increase every year. It is inevitable that domestic chips will account for a certain share of millimeter wave high-end terminal chips.

From 2015 to 2020, more than US$6 billion (RMB 40 billion) will be invested in 5G R&D and trials worldwide. The millimeter wave-related market accounts for up to 30% of this, about US$1.8 billion (RMB 12 billion). When the 5G market enters the formal commercial application stage after 2020, this market will be massive and have unlimited development prospects.

The “treasure trove” of 5G millimeter wave communications

1. The value of 5G lies in its faster speed than 4G LTE (peak speed can reach tens of Gbps).

2. There are generally two ways to increase the transmission rate of wireless transmission. One is to increase the spectrum utilization, and the other is to increase the spectrum bandwidth.

The millimeter wave (frequency band of 26.5 to 300 GHz) used by 5G uses the second method to increase the speed. Taking the 28 GHz band as an example, its available spectrum bandwidth reaches 1 GHz, while the available signal bandwidth of each channel in the 60 GHz band is 2 GHz.

3. Compared with traditional 4G networks operating at 2.6GHz or 3.5GHz, the transmission channel of the millimeter wave frequency band network will have an additional propagation loss of tens of dB.

4. Existing 4G base stations have only a dozen antennas, but 5G base stations can support hundreds of antennas, which can form a large-scale antenna array through Massive MIMO technology, which means that the base station can send and receive signals from more users at the same time, thereby increasing the capacity of the mobile network by dozens of times or more. MIMO (Multiple-Input Multiple-Output) means multiple input and multiple output. In fact, this technology has been applied to some 4G base stations. But so far, Massive MIMO has only been tested in laboratories and several field trials.

5. Starry pointed out that the transmission distance of millimeter waves is only about 200 meters at most, which is not possible for long-distance transmission. In addition, millimeter waves have weak penetration ability and cannot function when encountering walls or other obstacles.

6. The latency of 5G data transmission will be no more than 1 millisecond (in comparison, the latency of today’s 4G network is about 70 milliseconds), and the peak speed of data download will be as high as 20Gb/s (4G is 1Gb/s).

7. In order to unify the global millimeter wave frequency standards, the International Telecommunication Union (ITU) announced a recommended list of globally available frequencies between 24 GHz and 86 GHz after the recent World Radiocommunication Conference. Finally, the three frequency bands of 28 GHz, 39 GHz and 73 GHz gradually stood out. There is a continuous bandwidth of 2 GHz in 73 GHz that can be used for mobile communications, which is the widest range in the proposed frequency spectrum; 28 GHz only provides 850 MHz of bandwidth; in the United States, there are two frequency bands near 39 GHz that provide 1.6 GHz and 1.4 GHz bandwidth. In addition, according to Shannon’s law, that is, higher bandwidth means higher data transmission volume, 73 GHz has more advantages than the other two frequencies.

8. We conservatively estimate that the market size of my country’s 5G millimeter wave frequency band base station RF system will be RMB 2.4 billion in 2019, RMB 7.2 billion in 2020, and RMB 12 billion in 2021.

5G mobile communication network: Can’t live without you, millimeter wave

1. Due to the advantages of frequency bands below 6 GHz in wide-area coverage, the spectrum has been widely used in fields including civil mobile communications. Available frequency band resources, especially large-bandwidth resources, have been very limited. The requirements of 5G for ultra-high-speed and large-capacity communications require large-bandwidth frequency band resources. It is necessary to develop unused frequency band resources in frequency bands above 6 GHz. There are a large number of large-bandwidth spectrum resources in the millimeter wave band that can be effectively utilized.

Using the millimeter wave frequency band, 5G wireless air interface technology will be planned to consist of two parts: high-band new air interface and low-band new air interface. The high-band new air interface and low-frequency air interface will be used mainly in hotspot coverage scenarios. The allocation of 5G millimeter wave frequency band resources has been rapidly promoted internationally. The Federal Communications Commission (FCC) of the United States issued a proposed regulatory announcement in October 2015, proposing new and flexible service rules for the 28GHz, 37GHz, 39GHz, and 64-71GHz frequency bands. Japan’s NTT has also proposed the 3.5GHz, 4.5GHz and 28GHz frequency bands as potential alternative frequency bands for 5G services. After the Ministry of Industry and Information Technology of my country released a plan for soliciting opinions on millimeter wave frequency bands in June, it determined in July that the millimeter wave high frequency bands of 24.75GHz-27.5GHz and 37GHz-42.5GHz would be used for 5G R&D trials.

2. Massive MIMO is very suitable for use with millimeter wave bands in mobile communications. The shorter wavelength of millimeter waves allows more antenna units to be arranged on the antenna plane in theory. Since millimeter wave propagation attenuation is more serious, large-scale antenna arrays and beamforming can effectively improve antenna gain to compensate for the transmission loss of high-frequency communications, so that it can form a coverage target of 100-200 meters in hotspot coverage scenarios.

Massive MIMO was proposed by Thomas L. Marzetta, a scientist at Bell Labs, at the end of 2010. Compared with LTE, Massive MIMO can achieve a cell throughput of 1200Mbit/s and a frequency utilization rate of 60Bit/s/Hz/cell with the same bandwidth of 20MHz. MIMO technology has been widely used in LTE, WIFI and other fields. In theory, the more antennas there are, the higher the spectrum efficiency and transmission reliability will be. In the 4G mobile communication era, base station antennas support 4×4 and 8×8 MIMO, with a downlink peak rate of 100Mbps. LTE-A can already support 64×64 MIMO, with a downlink peak rate of 1Gbps. MIMO technology provides broad prospects for mobile communications in high frequency bands, which can multiply wireless spectrum efficiency, enhance network coverage and system capacity, and help operators maximize the use of existing site and spectrum resources. From a theoretical perspective, assuming there is a 20 square centimeter antenna physical plane, if the antennas are arranged at a spacing of 0.5λ, then if the operating frequency band is 3.5 GHz, 16 antennas can be deployed, if the frequency band is 10 GHz, 169 antennas can be deployed, and if it is 20 GHz, 676 antennas can be deployed.

Because 5G needs to meet the needs of multiple industries and scenarios, its spectrum also has three requirements: low, medium and high. The shortage of low-frequency spectrum resources has always been an international issue. For a long period of history, the millimeter wave band was a wild land. Why? The reason is simple, because there are almost no electronic components or devices that can send or receive millimeter waves. Why are there no electronic devices that send or receive millimeter waves? There are two reasons. The first reason is that millimeter waves are not practical. Although millimeter waves can provide larger bandwidth and higher data rates, previous mobile applications do not require such large bandwidth and such high data rates, and there is no market demand for millimeter waves. In addition, millimeter waves have some obvious limitations, such as too large propagation loss and too small coverage. The second reason is that millimeter waves are too expensive. Producing sub-micron-sized integrated circuit components that can work in the millimeter wave band has always been a major challenge. Overcoming propagation loss and improving coverage also means a lot of money. However, in the past decade, everything has changed. With the rapid development of mobile communications, frequency resources within 30GHz have almost been used up. Governments and international standardization organizations have allocated all the “good” frequencies, but there are still frequency shortages and frequency conflicts. The development of 4G cellular systems and the upcoming 5G both rely on the proper allocation of frequencies. The problem is, there are almost no frequencies left. Now, frequencies are like houses, which can be described in one word: “expensive”! For houses, the first is location, the second is location, and the third is location. The same description applies to wireless frequencies.

Millimeter waves are like the New World of America, providing mobile users and mobile operators with “endless” frequency resources.

Current status of domestic 5G millimeter wave communications

As early as June 8, the Ministry of Industry and Information Technology publicly solicited opinions on the frequency planning of 5G systems in high-frequency bands 24.75-27.5GHz, 37-42.5GHz or other millimeter wave bands. The 3.3GHz-3.6GHz band for which opinions were solicited this time has been used in previous 5G trials and is an expected frequency band. The high-frequency bands, especially the 24.75GHz-27.5GHz and 37GHz-42.5GHz millimeter wave bands, will be used for 5G, significantly exceeding market expectations.

Wang Zhiqin, vice chairman of the IMT-2020 (5G) Promotion Group, once said in a public speech that in terms of high-frequency band communications, 20GHz-40GHz has a higher priority for early pre-commercial use. At the same time, the 26GHz, 28GHz, 38GHz and 42GHz bands can use the same set of RF devices , which will make it more likely to achieve global coordination and unification.

According to the 3GPP 38.101 protocol, 5GNR mainly uses two frequency bands: FR1 band and FR2 band. The frequency range of FR1 band is 450MHz-6GHz, also known as sub 6GHz band; the frequency range of FR2 band is 24.25GHz-52.6GHz, which is what we usually call millimeter wave (mmWave).

Since 3GPP decided that 5G NR will continue to use OFDM technology, compared with 4G, 5G does not have any disruptive technological innovation, and millimeter wave has almost become the biggest “novelty” of 5G. The introduction of other new technologies in 5G, such as massive MIMO, new numerology (subcarrier spacing, etc.), LDPC/Polar code, etc., are closely related to millimeter wave, all for the purpose of better extending OFDM technology to the millimeter wave band. In order to adapt to the large bandwidth characteristics of millimeter wave, 5G defines multiple subcarrier spacings, among which the larger subcarrier spacings (60KHz and 120KHz) are specially designed for millimeter wave. The massive MIMO technology mentioned above is also tailored for millimeter wave. Therefore, 5G can also be called “enhanced 4G extended to millimeter wave” or “enhanced LTE extended to millimeter wave”.

Some people think that millimeter waves (mmWave) can only refer to the EHF band, that is, electromagnetic waves with a frequency range of 30GHz-300GHz. Because the wavelength of 30GHz electromagnetic waves is 10mm, and the wavelength of 300GHz electromagnetic waves is 1mm. The wavelength of 24.25GHz electromagnetic waves is 12.37mm, so it can be called millimeter waves or centimeter waves. But in fact, millimeter waves are just a conventional name, and no organization has ever strictly defined them. Some people think that electromagnetic waves with a frequency range of 20GHz (wavelength 15mm)-300GHz can be considered millimeter waves. Can we use any millimeter waves between 20GHz and 300GHz at will now?

Some people divide the commonly used millimeter wave bands into four segments:

Ka band: 26.5GHz – 40GHz ;
Q band: 33GHz – 50GHz;
V band: 50GHz – 70GHz;
W band: 75GHz – 110GHz .

3GPP protocol 38.101-2 Table 5.2-1 defines three frequency bands for the 5G NR FR2 band , namely:

n257 (26.5GHz-29.5GHz);
n258 (24.25GHz-27.5GHz);
n260 (37GHz-40GHz);
all use TDD standard.

The US FCC recommends that 5G NR use the following frequency bands: 24-25GHz (24.25-24.45/24.75-25.25GHz), 32GHz (31.8-33.4GHz), 42GHz (42-42.5GHz), 48 GHz (47.2-50.2GHz), 51GHz (50.4-52.6GHz), 70GHz (71-76GHz) and 80 GHz (81-86GHz). It also recommends studying the use of frequencies higher than 95GHz to carry 5G.

Why can’t millimeter wave frequencies be used at will? In addition to the consideration of scale economic benefits, some frequencies in millimeter waves have particularly bad “locations”. Here, the factor affecting the “location” is the air, so to be precise, the “sky segments” of these frequencies are particularly bad. When radio waves propagate, the atmosphere selectively absorbs electromagnetic waves of certain frequencies (wavelengths), causing the propagation loss of these electromagnetic waves to be particularly serious. There are mainly two atmospheric components that absorb electromagnetic waves: oxygen and water vapor. The resonance caused by water vapor absorbs electromagnetic waves near 22GHz and 183 GHz, while the resonance absorption of oxygen affects electromagnetic waves near 60GHz and 120GHz. So we can see that no matter which organization allocates millimeter wave resources, they will avoid the frequency bands near these four frequencies. Due to technical difficulties, millimeter waves above 95GHz are not considered for the time being. In addition to this “sky segment” factor that can only be avoided, we can only face other limitations of millimeter waves and find ways to overcome them. Otherwise, millimeter waves cannot be used.

One of the most critical limitations is that the propagation distance of millimeter waves is really limited. The laws of physics tell us that the shorter the wavelength, the shorter the propagation distance when the transmission power remains unchanged. In many scenarios, this limitation will cause the propagation distance of millimeter waves to not exceed 10 meters.

According to the idealized free space propagation loss formula, propagation loss L=92.4+20log(f)+20log(R), where f is the frequency in GHz, R is the distance in kilometers, and L is in dB. After a 70GHz millimeter wave propagates 10 meters, the loss reaches 89.3dB. Under non-ideal propagation conditions, the propagation loss is much greater. Millimeter wave system developers must compensate for such large propagation losses by increasing transmit power, increasing antenna gain, and improving receiving sensitivity.

Everything has two sides. The short propagation distance can sometimes be an advantage of the millimeter wave system. For example, it can reduce interference between millimeter wave signals. The high-gain antennas used in millimeter wave systems also have good directivity, which further eliminates interference. Such narrow beam antennas not only increase power and expand coverage, but also enhance security and reduce the probability of signal interception.

In addition, the limiting factor of “high frequency” will reduce the size of the antenna, which is another unexpected surprise. Assuming that the size of the antenna we use is fixed relative to the wireless wavelength, such as 1/2 wavelength or 1/4 wavelength, then the increase in carrier frequency means that the antenna becomes smaller and smaller. For example, the length of a 900M GSM antenna is about tens of centimeters, while the millimeter wave antenna may be only a few millimeters. This means that in the same space, we can cram more and more high-frequency band antennas. Based on this fact, we can compensate for the high-frequency path loss by increasing the number of antennas without increasing the size of the antenna array. This makes it possible to use massive MIMO technology in 5G millimeter wave systems.

After overcoming these limitations, 5G systems operating in millimeter waves can provide many services that 4G cannot provide, such as high-definition video, virtual reality, augmented reality, wireless base station backhaul, short-range radar detection, dense urban information services, stadium/concert/shopping center wireless communication services, factory automation control, telemedicine, security monitoring, intelligent transportation systems, airport security checks, etc. The development and utilization of millimeter wave bands provides a broad space and unlimited imagination for 5G applications.

If one day millimeter waves are also congested, how can mobile communication systems expand new territory? If the wavelength is less than 1 mm, it enters the wavelength range of light (the wavelength range of the infrared band is 0.76 microns-1 mm). Transistors above 100GHz have been developed in the laboratory. However, this transistor is basically useless at around 300GHz. So what electronic components should be used? Infrared works at 150THz-430THz, visible light works at 430THz-750THz, and ultraviolet light works above 740GHz. Laser devices, LEDs and diodes can generate and detect these lights. However, these devices cannot work in the frequency range of 300GHz-100THz. This frequency range seems to have become a blind spot at present. However, this phenomenon is temporary. As long as there is demand, new technologies and new components will definitely eliminate this blind spot.

Millimeter-wave automotive radar: I am your eyes

“Life-saving” artifact: millimeter wave escort

According to statistics, about 1.3 million people die in road traffic accidents (traffic accidents) every year, of which 94% are caused by driver errors, while less than 6% are caused by the vehicle itself, weather or road conditions. Among these 94% errors, 41% are due to cognitive errors (such as mistaking a car for a person due to weather conditions), 33% are due to misjudgment (such as accelerating when you should brake, turning left when you should turn right), and 11% are due to operational errors (such as failing to brake in time when you should brake).

With the development of automobile intelligence, automotive millimeter wave radar has become an indispensable and important equipment in automobile collision warning, adaptive cruise, active safety (ADAS) and even autonomous driving technology due to its advantages of long detection distance, long bandwidth, small antenna, high integration, stable detection performance, no influence from the surface shape and color of the detected object, no influence from airflow, and good environmental adaptability. Thus, most human operation errors can be avoided through functions such as ADAS or driving assistance.

my country is the world’s largest automobile producer and consumer. In 2015, the Chinese automobile market had reached 170 million vehicles (including 125 million private cars), and will grow rapidly at an annual rate of nearly 20 million vehicles in the future. The Chinese automobile market accounts for more than 30% of global automobile sales, but the ADAS share is significantly lower than 30%. With the upgrading of consumption structure and the increase in car purchasing demand among the middle class, the demand for ADAS based on millimeter-wave radar will show explosive growth in the future.

According to statistics from authoritative organizations, China’s automobile sales in 2015 were 24.598 million units. If the compound growth rate of my country’s passenger cars from 2015 to 2020 is 4%, the annual sales of passenger cars in 2020 will be about 30 million units.

By 2020, if 15% of China’s automobile sales are equipped with automotive millimeter-wave radars, and each car is equipped with two, the demand for millimeter-wave radars in 2020 is expected to be nearly 9 million, with a compound growth rate of about 50% in the next five years. The total market system value will exceed RMB 20 billion, and the total value of its millimeter-wave core chips will exceed RMB 3 billion.

In 2015, the global automotive millimeter-wave radar market size reached US$1.9 billion (more than RMB 13 billion); it is estimated to reach US$5 billion (more than RMB 34 billion) in 2020.

Millimeter-wave radar: GaAs → SiGe → CMOS

Automotive millimeter-wave radar is a key core component of automotive active safety (ADAS) products. Currently, the frequencies of automotive radars are mainly divided into 24GHz and 77GHz. Strictly speaking, 77GHz radars are millimeter-wave radars, but in fact, 24GHz radars are also called millimeter-wave radars.

It is worth mentioning that the 77GHz millimeter-wave radar can quickly perceive the distance, speed, azimuth and other information of surrounding objects within the range of 0-300 meters in all-weather scenarios.

In the process of development, low cost, miniaturization and high integration have become important indicators of millimeter wave radar, and millimeter wave technology is also closely related to the development of the semiconductor industry. “The early CMOS process could not achieve ultra-high frequency, and it has only been achieved in recent years.”

From GaAs in 1990 to SiGe in 2007, the number of MMICs has been reduced from 7-8 to 2-5. Today, technological advances have made it possible to apply CMOS technology to 77GHz millimeter wave chips.

“CMOS makes it possible for a single chip to support the entire radar mission. In addition, CMOS also reduces development time, reduces costs, reduces size, and improves heat dissipation.” It is understood that millimeter-wave chips using CMOS can reduce the overall cost by an average of 40%.

Mainstream automotive millimeter-wave radars at home and abroad use the 24GHz frequency band for short- and medium-range (15-30 meters) environmental detection, and 77GHz for long-range (100-200 meters) environmental detection radars. Now 24GHz radars are gradually fading out of sight. In 2016, my country officially launched the research and test work of 77-81GHz frequency for automotive millimeter-wave radars in my country.

Since the functions of ADAS are often sold in a bundled form through sensors and processors, system suppliers play a core role in the industry chain. ADAS technology based on millimeter-wave radar is mainly monopolized by traditional component system suppliers such as Continental, Bosch, Denso, and Autoliv. Domestic manufacturers such as Huayu Automotive, Hangzhou Zhibo, Wuhu Sensortech, and Beijing Xingyidao have also made breakthroughs in the development of millimeter-wave radar products, and some products have been released or are about to be released. However, most of them are redeveloped based on the purchase of foreign chips, and their performance and price are completely controlled by others.

Front-end monolithic millimeter-wave integrated circuit (MMIC) technology is mainly controlled by foreign semiconductor companies, and is basically in the hands of a very small number of foreign chip manufacturers such as Infineon, ST, NXP/Freescale. Domestic 24G/77GHz millimeter-wave integrated circuits (MMICs) have made breakthroughs. Xiamen Yixing 24GHz integrated circuits (MMICs) have been mass-produced and are on trial, but they do not have production capacity, and with the advancement of technology, they are no longer mainstream products. However, due to foreign blockades, the development of 77GHz millimeter-wave integrated circuits (MMICs) has not been deeply accumulated in China. The only national key laboratory for millimeter-wave radars, Southeast University, has also been developing 77GHz millimeter-wave integrated pcb , but it does not yet have mature MMICs. Shenyang Chengtai and Xiamen Yixing are also currently conducting research and development but have not yet launched products.

Accelerating the development of domestically produced 77GHZ millimeter-wave radar chips and applying them to vehicles as soon as possible will be an opportunity for my country’s automotive millimeter-wave radar industry to break free from being controlled by others.

Compared with monocular or stereo cameras and infrared radars, millimeter-wave radars have a longer measurement distance and are not affected by day or night. Millimeter-wave radars also perform better in bad weather conditions. However, under current technical conditions, millimeter-wave radars are still relatively weak in detecting smaller obstacles such as pedestrians and bicycles. This phenomenon will be more prominent in China. Since the frequency bands above 3mm can overcome the above defects, there is a possibility of extending to higher frequency bands such as the 3mm band as technology develops and processes mature. Similar products have already been launched in Germany.

Applications in other fields: “Safety Guard” of life

1. Civilian helicopter and drone market

With the development of my country’s national economy and the opening of low-altitude flights, civil helicopters and drones are becoming more and more popular. Recently, there have been reports of the use of drones for express delivery. However, there is an inevitable risk of collision with high-voltage wires. In order to avoid accidents, this also provides an opportunity for the rapid development of civil 3mm anti-collision radar systems. With the increase in volume, the cost will inevitably be greatly reduced.

One of the core elements of the 3mm anti-collision radar and helicopter landing radar system is the radar vision sensor. As for the market size of this single product, according to the radar vision sensor market report released by the world’s authoritative organization, it is expected to reach US$30 billion (RMB 200 billion) by the end of 2022.

2. 3mm security inspection system

In recent years, with the complexity and changeability of the international situation, various terrorist activities have occurred one after another, such as explosions, hijacking of aircraft, kidnapping, assassination, armed attacks, and mail bombs. Especially in important places with dense crowds, how to quickly identify terrorists and quickly check and warn of dangerous and explosive items such as knives and explosives hidden on people is a difficult problem faced by personal security inspections in important places. In order to effectively prevent and combat the occurrence and expansion of these criminal activities, police in various countries use security inspection technology and equipment to conduct targeted explosion-proof security inspections on dangerous and prohibited items. Traditional security inspection equipment, such as X-ray detectors and metal weapon detection doors, can detect dangerous items such as metal weapons and ordinary explosives, and have played an important role in security inspections.

However, in recent years, as the weapons equipped by terrorists have become more and more advanced (such as Semtex plastic explosives, ceramic knives, plastic guns, high-precision bombs, etc.), a “body search” inspection is required, which has brought about a series of problems such as low efficiency and privacy infringement, prompting countries around the world to explore and research more advanced new security inspection technologies and equipment. The channel-type 94GHz millimeter wave security inspection system is a new type of security inspection equipment proposed in response to current security inspection needs and combined with the latest research results in the millimeter wave field. Because it can accurately, quickly and non-invasively check whether the detection target carries prohibited items, it will definitely meet the growing special needs of security inspections and has an extremely broad market and development prospects.

Millimeter wave security gates (94GHz, 3mm millimeter wave) will be widely used in airports, stations, conference venues, large stadiums, customs security, jewelry stores, mines and other important places in the future. In terms of application locations, all airports, railway stations, bus stations, passenger terminals and other facilities can be equipped with human body security equipment in a number that matches the passenger flow. In the field of public transportation alone, the potential market size of terahertz human body security equipment can reach billions or even tens of billions. In fact, the equipment can also be used in various other public facilities such as government buildings, schools, hospitals, prisons, courts, etc. Its visible market size is estimated to be in the hundreds of billions of yuan, and the total amount of its core chips will also reach about 20 billion yuan.

3. Millimeter wave electronic fence

At present, infrared radio equipment is widely used in electronic fence monitoring in China. Its advantages are simple technology and low price. At the same time, its disadvantages are also quite significant, such as high false alarm rate of infrared radio equipment and failure to work normally in rain, fog and snow. It is generally not suitable for places with high requirements. The millimeter wave warning alarm monitoring radar system can provide regional protection for irregular terrain. When the intruder enters the protection area, the monitoring center detects the intrusion information and issues an alarm sound.

Millimeter wave beam radar has the advantages of simple installation, easy operation, low bit error rate and normal operation around the clock.

The system is mainly composed of millimeter wave beam sensor components, which can operate outdoors all-weather, and its performance is less affected by the environment. It is mainly used in important occasions such as factories, warehouses, offices, oil pipelines, high-voltage substations, and traffic intersections. The annual output value can be no less than 200 million yuan.

4. Foreign object inspection on airport runways

The world’s first and only supersonic aircraft is no longer in service due to an accident in July 2000. The cause of the accident was debris on the runway that punctured the aircraft’s tires, which in turn punctured the aircraft’s fuel tank, causing a fire and eventually causing the aircraft to crash into a small hotel on the outskirts of Paris. Since then, debris obstacle detection on the runway has become a major concern for major airports.

Since 3mm radar has extremely high resolution and accuracy, it can often be placed on both sides of the runway to detect tiny foreign objects, birds, and other animals that are easily sucked into the aircraft engine and thus pose a safety hazard to the aircraft flight. If deployed at all military and civilian airports, it will greatly improve the safety of aircraft takeoff and landing. Compared with the microwave and 8mm radars currently installed abroad, 3mm radar is very small and light, can detect more subtle objects, and is easy to install and deploy quickly.