2018 is a critical year for 5G standards, technology research and development, and industry maturity. It is also the starting point for 5G to move out of the laboratory and to oriented toward commercial operations. The 5G R15 specification is gradually improving, and how to strengthen the end-to-end transmission efficiency has become a hot topic in the industry. In order to overcome the technical difficulties brought about by 5GNR, chip and antenna design companies have also launched solutions to challenge them.

After the 5G R15 standard is finalized, 5G has also taken a step toward formal commercialization. After countries have successively launched spectrum auctions and assignments, telecom companies have also shouted their visions for commercialization of 5G mobile services in 2019 or 2020. However, 5G is more complicated than previous generations of mobile communications, regardless of whether it is in the networking mode or the frequency band used. Among them, the technical characteristics of 5G NR high-frequency millimeter waves have brought many challenges to the design of base stations and mobile devices. To this end, equipment and chip manufacturers continue to introduce solutions, hoping to accelerate the opening of 5G commercial mobile services.

At this stage, the focus of 5G is mainly on the discussion of enhanced mobile broadband eMBB application scenarios, hoping to develop towards higher network capacity and higher transmission rates. The increase in cellular base station capacity can be achieved through three major measures, including obtaining new spectrum, increasing base station density, and improving spectrum efficiency. In this regard, ADI's China Strategic Market of the Communications Infrastructure Business Department said that although it can be seen that the new spectrum continues to increase and the network density continues to increase, it is still very important to improve the spectrum efficiency.

At present, Massive MIMO has been proven to increase the amount of mobile data transmission by 3 to 5 times, and it is expected to continue to increase in the future. Telecom operators in various countries have also launched 5G Massive MIMO tests, and it is expected that 5G commercial deployments will begin in some regions from 2019 to 2020. After eMBB is gradually completed, Xie Yong believes that high-frequency millimeter wave technology and ultra-high reliability and low-latency communication URLLC application scenarios will become the next wave of industry focus.

Beamforming/active antenna overcomes the physical limitations of millimeter waves

Millimeter wave is a very short wavelength and very high frequency carrier communication. In addition to multiple antennas and multiplex modulation methods, it is another way to directly increase the data transmission rate. However, millimeter wave technology also faces limitations caused by physical characteristics such as transmission path loss, skin effect, etc., resulting in short communication distances, small coverage areas, susceptibility to interference, and easy shielding by the human body and buildings. Therefore, it must pass through Beam forming, Massive MIMO array antenna and other technologies can be solved.

Beamforming technology can concentrate multiple signals and point them in a specific direction to overcome the problem of millimeter wave loss and increase the distance of signal transmission. The beamforming operation must also be controlled and adjusted by the phased array antenna to form a directional beam.

In order to prevent the direction deviation from affecting the signal reception at the user end, the base station antenna must also incorporate beam tracking technology to move and scan quickly to detect the user's location at any time. To support this technology, future 5G base station antennas will adopt active and smart antenna designs.

Zheng Zhizhong, sales director of Taiwan, Hong Kong and Macau business of a mainstream equipment manufacturer, further explained that active array antennas can ensure the stability of the signal. However, in the 5G era, a base station must handle at least 64 transmitters (TRx). The array antenna will bring a huge computing load to the base station, making the processing efficiency and power consumption of the base station an important issue. To this end, the equipment manufacturer also embarked on experiments, hoping to introduce artificial intelligence (AI) technology into 5G base stations, use machine learning algorithms to improve computing performance, and further predict the path of user movement, thereby sharing the benefits of active antennas. The computing load improves the operating efficiency of the base station.

In terms of the antenna design of the terminal device, the millimeter wave beam may also be affected by the way the mobile phone is held and the material of the system (such as glass, ceramics, metal components, mechanical parts), absorbed by the material, reflected or offset, and should be radiated. Angle. In this regard, Qorvo product marketing manager Chen Qinghong pointed out that the current common solutions in the industry include the introduction of multiple millimeter-wave antenna array modules, or placement, multi-polarization and multi-band design to reduce these external effects.

5G RF front end develops towards module/IC

The 5G Massive MIMO array antenna system makes it have higher requirements for the integration, bandwidth and cost of radio frequency components. In addition, the 5G frequency band includes low frequency frequency bands below 6 GHz and high frequency millimeter wave frequency bands. The supported frequency bands are more and more complex than 4G LTE. Therefore, to meet the 5G RF performance requirements, it will bring more details to the related RF component process and circuit design. Big challenge.

The evolution of LTE technology set off the first wave of the RF front-end module market, but Yole pointed out that the emergence of the 5G NR non-independent (NSA) standard at the end of 2017 is the main reason for the substantial growth of the RF front-end market. 5G NR NSA adopts 4G/5G joint networking in the architecture, and introduces "dual connection" technology to ensure that the equipment can use the wireless resources of two base stations at the same time, which also promotes the increase in the complexity of RF front-end design and the demand for components. According to the report released by Yole, the output value of the RF front-end module market in 2023 will reach 35.2 billion U.S. dollars, with a compound growth rate of 14% from 2017 to 2023.

In the past, the RF front-end mostly used discrete components, which were connected to active and passive components such as transceivers, power amplifiers, low-noise amplifiers, and filters through RF traces on the printed circuit board PCB. However, with the increase in the amount of RF components, Chen Qinghong said that the current 4G high-end mobile phone RF component modularization is an inevitable trend, and 5G will further accelerate the trend of component integration. Among them, the types of modules include packaging, low-loss sheet SMT, flexible board SMT, etc., but no matter which method is adopted, the problems of IC heat concentration and high power consumption must be solved.

Anokiwave Asia Pacific Sales Director Zhang Zhaoqiang further explained that 5G millimeter wave signals are vulnerable to loss and interference. In order to reduce signal loss during the PCB transmission process, RF components and antennas must be integrated to shorten RF traces. The ideal approach is to use RF components. Place it on the back of the antenna substrate. However, in addition to the problem of a significant increase in the amount of RF components, as the signal frequency becomes higher and the wavelength becomes shorter, the antenna size and the distance between each antenna will be greatly reduced. The size of discrete RF components is larger, so it is difficult to directly Integrate it on the antenna substrate.

Due to the above problems, the integration of 5G millimeter-wave RF components has become an inevitable trend. At present, there are already companies in the market that integrate RF components in the same package in the form of ICs or modules. In this regard, Zhang Zhaoqiang said that the company is optimistic about the maturity, high integration, and production cost of the CMOS process. Therefore, the silicon-based CMOS process is used to produce millimeter-wave RF front-end ICs and integrate them with antennas into modules to solve the problem. Signal transmission loss problem.

RF module packaging must consider heat dissipation issues

The introduction of Massive MIMO technology has increased the number of antennas in 5G base stations and terminal devices. The heat dissipation problem has therefore become another challenge in the design of RF components and antennas. The industry must ensure RF performance while taking into account thermal management and cost issues. In this regard, Zhang Zhaoqiang explained that although millimeter-wave radar and beamforming technology have been used in the military in the past, for military applications, size and cost are not the primary design considerations, so if you want to use related technologies to achieve commercial base stations In addition to overcoming the size problem, the huge cost of base station heat dissipation is also a big challenge.

To this end, Anokiwave tried to improve the heat dissipation problem from packaging. Its first-generation millimeter-wave RF front-end IC adopted QFN packaging technology, but considering the poor heat dissipation effect of plastic packaging, the second-generation product changed to wafer-level die-size packaging ( WLCSP), while improving the heat dissipation problem, it can also further reduce the package size.

Taking into account the heat dissipation problems caused by plastic packaging, Qorvo recently launched a 39GHz dual-channel RF front-end module and also proposed relevant countermeasures for plastic packaging. Qorvo pointed out that because the RF front-end module adopts GaN process, and the power density of GaN is 2 to 3 times higher than that of GaAs, it faces more difficult heat dissipation problems in package design. To this end, the company added a heat spreader in the GaN RF front-end module package base to improve the thermal management efficiency of the plastic package while ensuring product cost competitiveness.

Antenna isolation/linearity overcomes IMD interference problems

5G networking methods are divided into independent (SA) and NSA. Among them, NSA mainly sends control signals through LTE, and SA sends control signals through 5G NR. From the perspective of the current layout of telecom companies in various countries, in addition to China Mobile's intention to directly deploy 5G SA networks, most countries will still focus on NSA network deployment in the initial stage, so solutions compatible with various standards and architectures are also more important.

Regarding the influence of networking methods on antenna design, Chen Qinghong further explained that NSA's networking architecture, whether it is 1T4R or 2T4R design, the overall core network still needs 4G LTE as the control channel, and 5G NR only provides high-speed data. Transmission, therefore, under the NSA architecture, there will be application scenarios where 4G LTE and 5G NR are transmitted at the same time. In the RF front-end design, attention must be paid to the interference problem caused by intermodulation distortion (IMD). The SA networking architecture does not require 4G LTE as a control channel, but in the design of 2T4R, attention must be paid to the interference problems caused by IMD.

Faced with the application scenario where 4G LTE and 5G NR are simultaneously transmitted under the NSA architecture, Chen Qinghong suggested that the antenna of the device side should be designed with separate antennas, that is, the transmission of 4G LTE and 5G NR are located on different antennas, using the difference between the antennas. Isolation, coupled with the selection of components with better linearity, can reduce the impact of IMD on system interference. And he also pointed out that under the design of 1T4R, SA can save a set of RF transmitting components, and it does not have to face the interference problem of IMD. It is a big advantage for the RF front-end cost consideration of the terminal device, and it is equipped with mature antenna tuning. Switching elements can break through the challenges of multi-frequency and broadband antennas in full-screen mobile terminal products.

Baseband chip factory seizes commercialization opportunities

To realize the commercialization of 5G mobile services, in addition to overcoming the RF front-end and antenna design problems of base stations and terminals, baseband chips are also the key. In order to accelerate the 5G business transfer, Qualcomm, Samsung, Intel and other chip manufacturers have also released 5G baseband chips one after another, and launched call tests one after another. For example, Qualcomm and Ericsson jointly announced a few days ago that they will use the Snapdragon X50 chip-equipped smartphone-sized test device to complete 5G NR calls in the 39GHz frequency band that meets the 3GPP R15 specifications; Samsung also said that it has already used terminals equipped with Exynos Modem 5100. The prototype device and 5G base station completed the 5G NR data call wireless transmission (OTA) test.

It is reported that the baseband chip launched by Samsung can reach a maximum download transmission rate of 2Gbps in the sub-6GHz frequency band, and a download transmission rate of 6Gbps in the millimeter wave frequency band. Compared with the previous version, the transmission rate of Exynos Modem 5100 in the above two frequency bands is 1.7 times and 5 times that of the previous generation respectively. In addition, this baseband chip can also reach a download transmission rate of 1.6Gbps in a 4G network. According to the results of Qualcomm's recent demonstration, Snapdragon X50 can reach an overall transmission rate of 1.2Gbps using two 28mm millimeter wave channels.

In addition to baseband chips, Qualcomm has also released integrated RF modules that can be used in smart phones and mobile terminal devices. According to his statement, the QTM052 millimeter wave antenna module can work with the Snapdragon X50 baseband chip to support 800MHz bandwidth in the 26.5-29.5GHz (n257), 27.5-28.35GHz (n261) and 37-40GHz (n260) frequency bands. The module is designed to integrate radio transceiver, power management IC, RF front-end components and phased antenna array functions into a package size. A smart phone can accommodate up to 4 QTM052 modules.

However, Qualcomm also stated that the regulatory requirements for materials, dimensions, industrial design, heat dissipation, and radiated power are all challenges that will be faced before 5G millimeter wave is officially transferred. The industry must overcome the above-mentioned problems in order to accelerate the commercialization of 5G millimeter wave mobile devices.

MIC: 5G mobile terminal devices will not grow significantly until 2021

Looking at the commercial progress of 5G, the Institute for Information on Information Technology (MIC) predicts that 5G terminals will be launched one after another at the end of 2018. However, the first wave of products on the market will be mainly mobile routers and home routers; mobile devices and smart phones will It will come out one after another in 2019, but it will not have obvious growth in shipments until 2020 when the 5G infrastructure in various countries is complete and officially transferred.

Han Wenyao, senior industry analyst and product manager of MIC, said that the frequency bands supported by 5G include 4G LTE frequency band, 5G NR sub-6GHz and 5G millimeter wave. Different frequency bands require different technologies. Therefore, To support the operation of the three frequency bands at the same time, it is bound to bring cost, size, circuit design and power consumption issues to the development of terminal devices. And he also revealed that the current 5G millimeter wave terminal prototype device still consumes a lot of power.

In addition to technical challenges, insufficient market demand for millimeter wave devices in the early stage of the 5G commercial transition is also a major problem. The industry must try to strike a balance between frequency band support and cost. Due to the increase in component usage, antenna cost and design complexity, the cost of 5G millimeter wave RF front-end will also increase significantly. However, the frequency bands that were initially opened up in various countries are not completely the same. Although smart phones contain high-frequency components, they can only support 5G NR millimeter wave communications in some countries, and the market demand is not high.

Han Wenyao further analyzed the open frequency bands in various countries. The United States and South Korea Telecom Chambers of Commerce took the lead in opening the 5G NR high-frequency frequency band. Therefore, terminal device manufacturers in these two countries have a better chance of becoming the first wave of 5G millimeter wave mobile devices. As far as China is concerned, since the initial deployment of its telecom companies focused on sub-6GHz, the possibility of the industry launching millimeter wave mobile devices in the near future is low.

Looking at the overall 5G mobile device market, MIC estimates that the shipment of 5G smartphones in 2019 will reach 4.2 million units, but it will not see significant growth until 2021. It is estimated that it will be released in 2022. The volume can reach 310 million units.

Li Jianxun, senior industry analyst and research director of MIC, said that although chip manufacturers and many Android mobile phone manufacturers announced the launch of 5G mobile devices in 2019, plus the world’s largest telecommunications company China Mobile will also purchase 5G mobile phones in early 2019. However, with the exception of the United States, South Korea and China, most telecom operators will not launch 5G commercial networks until 2020. Therefore, before the 5G technology is not mature and the network coverage rate has not been greatly improved, the shipment volume will still not have a significant growth, and the products launched in the early stage may mostly belong to the types of telecom companies purchasing models. Based on the above, the time for the 5G mobile device market to really take off is expected to fall after 2021