5G radio frequency, literally, Radio Frequency means radio frequency. Radio frequency signals specifically refer to wireless electromagnetic waves in the frequency range of 300KHz~300GHz.
Everyone knows that the reason why mobile phones can communicate with base stations is to send and receive wireless electromagnetic waves to each other.
A series of circuits, chips, components, etc. that are responsible for sending and receiving wireless electromagnetic waves in mobile phones are collectively referred to as radio frequency systems, referred to as "radio frequency" (the same below).
Radio frequency and baseband are the cornerstones for mobile phones to realize communication functions. If we regard the communication between the mobile phone and the outside world as a "express service", then the duty of the baseband is to "package/unpack" the data. The responsibility of the radio frequency is to transmit/receive the "package" through the designated radio frequency band.
From an architectural point of view, a complete radio frequency system includes three parts: radio frequency transceiver, radio frequency front-end, and antenna. The radio frequency front-end includes multiple components such as power amplifiers, envelope trackers, low-noise amplifiers, filters, antenna switches, and antenna tuners.
1. Architecture of 5G radio frequency
The role of each component of the radio frequency front-end is not complicated. For example, the amplifier is to amplify the signal to make the signal farther; the filter is to remove the clutter and make the signal more "pure"; the antenna switch is used to control the enabling and closing of the antenna; the antenna tuner is mainly used It's about "fiddling" with the antenna to get the best results...
A large number of radio frequency components cooperate with each other and cooperate with each other in order to complete the "finishing step" and transmit the packaged data of the baseband "biu~biu~biu~".
If the radio frequency design is unreasonable and the performance of components is backward, it will directly affect the wireless signal sending and receiving ability of the mobile phone, and then affect the communication ability of the mobile phone. The specific performance is that the wireless signal is poor, the communication distance is short, the network speed is slow, and so on.
In other words, a mobile phone with insufficient radio frequency capabilities is like a car with insufficient power. No matter how fancy other functions are, they cannot be accepted by users.
Therefore, when mobile phone manufacturers develop and design mobile phones, they usually put a lot of effort into radio frequency, repeatedly deliberate and conduct testing and verification before they dare to launch the final product.
2. Challenges of 5G radio frequency
Now, we have entered the 5G era with our heads held high. Has the radio frequency system of 5G changed compared to traditional 4G?
The answer is yes. Not only have there been changes, but dramatic changes.
Compared with 4G, 5G has greatly improved its performance indicators. The 5G eMBB (Enhanced Mobile Broadband) scenario will increase the speed of mobile phones to Gigabit or even 10 Gigabit, which is 10 times / 100 times that of the early LTE speed (100Mbps).
2G/3G/4G, plus 5G, plus MIMO (multi-antenna technology), plus dual card dual standby, the number of antennas and supported frequency bands of mobile phones have doubled. In the early days of 4G, there were fewer than 20 band combinations. In contrast, 5G has more than 10,000 frequency band combinations, and the complexity is terrifying.
At the same time, in order to ensure that users are willing to upgrade, the thickness and weight of 5G mobile phones cannot be increased, the power consumption cannot be increased, and the standby time cannot be reduced.
If you were a mobile phone manufacturer, would you go crazy?
Therefore, mobile phones with 5G radio frequency must reshape themselves and vigorously create miracles and innovations.
How to solve the design problems of radio frequency system? Qualcomm put forward a macro idea, directly providing "complete modem and radio frequency system". Popular understanding means that the baseband, radio frequency transceiver, radio frequency front-end, antenna module, software framework, etc. are all done well, and a complete solution is given to the manufacturer.
That is to say, the design concept of terminal components such as 5G mobile phones must abandon the previous thinking of "buy horses in the east market, saddles in the west market, bridles in the south market, and long whips in the north market" and focus on individual components. Packaged design" all-in-one system-level solution.
For example, in the past, factory A made the baseband, factory B made the radio frequency, and factory C made the antenna, and then the mobile phone factory D figured out how to integrate and connect. Now, it is changed to a powerful manufacturer that directly packages and designs the baseband, radio frequency, and antenna together, and then hands it over to the mobile phone manufacturer, who can use it quickly after taking it.
System-level integration is an inevitable result of the dramatic increase in 5G baseband and radio frequency complexity.
It's like a train. In the past, the speed of the green leather car was slow, and the car and the front could be designed and manufactured separately, and then put together to run. However, in the era of high-speed rail, the speed index has doubled. If the design and manufacture continue to be separated, the car and the front will not be able to coordinate deeply. Not only will the speed index be difficult to achieve, but safety problems may also arise.
Therefore, EMUs for high-speed rail are usually designed and manufactured in a unified manner.
That is to say, in the face of the harsh 5G indicators mentioned above, it is necessary to conduct an overall design of the baseband and radio frequency from the perspective of system-level integration. In this way, the two can achieve perfect software and hardware coordination and play the best performance (throughput rate, coverage, etc.).
In addition to achieving the target, the integrated design is also conducive to reducing the final size of the system and reducing the occupation of mobile phone space. For system power consumption and thermal control, the integrated design also has obvious advantages.
The last point is also a very important point. Providing a system-level integration solution can reduce the design difficulty of mobile phone manufacturers, and facilitate them to launch products at a faster speed and seize the market.
3. Black technology of 5G radio frequency
Let's take a closer look at the interesting black technologies of system-level integrated 5G radios.
First of all, the first black technology is broadband envelope tracking.
When the radio frequency architecture was introduced earlier, there was a power tracker inside. Power trackers are used with power amplifiers.
The power amplifier is the core component of radio frequency, it is like a horn, it turns a small sound (signal) into a loud sound (signal).
If you want to blow the horn, you must muster your strength (power supply). The function of the power tracker is to control the strength (power) of blowing the horn.
The traditional blowing method is the APT method, which is the average power tracking. For a certain period of time, the blowing force remains constant.
And broadband envelope tracking (ET) technology can precisely control the force. That is to say, the baseband (modem) can control the envelope tracker in the radio frequency according to the change of the signal, and then accurately control the transmission power of the wireless signal.
3.1 The waste power consumption of envelope tracking is significantly smaller than that of traditional average power tracking
In this way, the physical strength (energy) is greatly saved, the power consumption of the radio frequency is also reduced, and the standby time of the mobile phone can be increased.
Accurate transmission power control helps mobile phones to obtain the best signal transmission efficiency, thereby obtaining better channel quality. In the process of "two-way communication" between the mobile phone and the base station, when the mobile phone obtains better channel quality, the base station can support the mobile phone to achieve better uplink and downlink services, such as supporting 2×2 MIMO, and the network speed is smoother. In addition, better channel quality also creates conditions for the base station to assign higher-order modulation methods (such as 256QAM) to mobile phones, which can improve mobile phone throughput and support faster and better data transmission services.
Qualcomm's previous generations of Snapdragon 5G modems and radio frequency system integrated broadband envelope trackers have adopted the above technology. And its latest wideband envelope tracker, the QET7100, is 30% more energy efficient than the most advanced products offered by other manufacturers on the market today.
3.2 AI-assisted signal enhancement technology.
This technology is the latest new technology released in the 5G modem and radio frequency system just launched in February, and it is also the first time in the industry to introduce the hot AI technology into the mobile phone radio frequency system to enhance the signal.
The core of AI-assisted signal enhancement technology is to introduce AI technology into the antenna tuning system. Antenna tuning is divided into two ways, one is impedance matching, and the other is aperture tuning.
Let's look at impedance matching first.
The so-called impedance matching, we can understand it as a kind of "water pipe" work.
The connection between the radio frequency system components and the antenna is like the connection between two water pipes. When the impedances are consistent, the positions are perfectly matched, the water flow is the largest and the signal efficiency is the highest. If the impedance of the element is shifted, the water pipe will be crooked, the water flow will be small, and part of the water flow will be wasted.
There are many reasons for impedance changes, such as hand touch, plugging in data cables, installing mobile phone cases, etc. Even different holding gestures (left hand, right hand, one hand, two hands) will bring different resistance.
The traditional impedance matching method is to test various causes of impedance changes in the laboratory, find the characteristic value of the antenna, and then control the radio frequency components through the modem to adjust the impedance, so that the water connection pipe is aligned with the water delivery pipe as much as possible.
The AI-assisted signal enhancement technology is to introduce AI algorithms to perform big data analysis and machine learning on the antenna eigenvalues caused by various impedance changes, so as to realize intelligent adjustment of impedance and achieve the most perfect matching effect.
To put it bluntly, it is a bit like installing a butt hose between the water supply pipe and the water receiving pipe, so that the water flow will not be wasted as much as possible.
3.3 AI-assisted signal enhancement, which is equivalent to the docking hose between the radio frequency and the antenna
Aperture tuning is relatively simple, which is to adjust the electrical length of the antenna.
From a radiological point of view, the perfect length of the antenna should be a quarter of the wavelength. Today's mobile phones, because of full Netcom, dual-card dual-standby, etc., the operating frequency of the mobile communication system is dynamically changing. For example, sometimes it works on 2.6GHz and sometimes it works on 3.5GHz.
If the working frequency changes, it means that the optimal wavelength also changes. Therefore, it is necessary to tune the aperture of the antenna, adjust the length of the antenna, and elongate the peak to achieve the best effect.
All in all, the antenna tuning technology based on impedance matching and aperture tuning is mainly used to overcome the influence of the external environment on the antenna signal, dynamically adjust the signal, and improve user experience.
According to actual verification, with the help of AI-assisted signal enhancement technology, the system's situational awareness accuracy can be increased by 30%, which can significantly reduce the call drop rate and improve speed, coverage and battery life.
4. Summary of 5G radio frequency
There are still many innovative black technologies in the 5G radio frequency system, such as multi-carrier optimization, decoupling tuning, multi-SIM card enhanced concurrency, etc. These black technologies are all the results of technological innovation. They condensed the wisdom of engineers and laid the foundation for the smooth launch of 5G terminals.
Today's 5G radio frequency is no longer an auxiliary baseband, but an important mobile phone component that can sit on an equal footing with the baseband and complement each other.
With the continuous deepening of 5G network construction, in addition to mobile communication, more and more 5G vertical industry application scenarios have also begun to blossom. The form of 5G terminals will become varied, and a greater test will be placed in front of the 5G RF front-end.
