This article mainly discusses Sub 6G VS mmWave, the new antenna technologies for 5G millimeter-wave, and 5G Sub-6G applications.
What are the new antenna technologies for 5G? 5G has a 5G millimeter wave and a 5G Sub-6G.
Antenna process
2G mobile phones have one antenna, a single transmitter, and a single receiver. Beginning with 3G, some mobile phones are the same as 2G, while the other 3G mobile phones have started with single transmission and dual reception.
Starting from 4G, all mobile phones have been upgraded to a single transmitter and dual receiver design. We call the two receiving antennas the main antenna and the diversity antenna.
Two independent antenna radiators need to be designed, corresponding to two sets of receiving loops at the receiving end, so the RF cost of 4G mobile phones is also much higher than that of 2/3G mobile phones.
Sub 6G VS mmWave's 5G millimeter-wave antenna technology
In the 5G era, the most advanced aspect is the application of millimeter waves. However, the American operators who were the first to use millimeter waves encountered trouble. The rapid attenuation of millimeter waves caused the coverage area of base stations to be too small and the construction cost of base stations was too high.
The Chinese operators have just completed the joint debugging of millimeter-wave base stations. At present, they have not yet seen the white papers of the three major Chinese operators on millimeter-wave applications. Whether China will launch millimeter waves in the past two years is a question mark.
Sub 6G VS mmWave’s 5G Sub-6G antenna technology
Global 5G network frequency bands are mainly divided into two major ranges: Sub-6GHz and millimeter wave (mmWave). China is currently mainly developing 5G networks based on the Sub-6GHz frequency band, while the United States is mainly promoting 5G millimeter-wave networks.
The number of antennas on the 5G large macro base station side has been upgraded from 4G 8 receiving 8 transmissions to 64 receiving 64 transmissions, so for the mobile phone side, the number of antennas has also been increased to 4 receiving 2 transmitting.
Two-way transmission corresponds to four transmitting antennas. There is no master-slave relationship between the two-way transmission. Instead, SRS (Sounding Reference Signal) is used to detect the signal strength of the two antennas.
The NSA network requires mobile phones to be connected to 4G and 5G base stations at the same time, so two antennas transmit at the same time, one 4G and one 5G.
For the SA network, only the 5G base station is connected, and the SRs judge which signal is strong and uses which antenna to transmit, or two antennas are transmitted simultaneously to achieve the purpose of intelligent transmission in more application scenarios.
The 4 channels of receiving correspond to 4 receiving antennas respectively to ensure the stable reception of the receiving channel and the maximum throughput capacity of the user’s traffic.
The size of mobile phones has become larger due to the larger display screens, but various manufacturers are pursuing the ultimate screen-to-body ratio, and 5G requires more radio frequency devices (4 sets of receiving circuits, 2 sets of transmitting circuits), which is larger. (The average battery capacity has been upgraded from 3500mAh in the 4G era to at least 4500mAh), the mobile phone has become larger, and the net space for antenna design has not increased but has decreased.
At present, most of the middle frames of mobile phones are made of metal, and there is relatively good headroom from the middle frame to the mainboard, so everyone unanimously chose to use the middle frame of the mobile phone as the antenna.
The exponential increase in the number of antennas and the limited area of the middle frame has brought unprecedented challenges to antenna design. This requires dividing the middle frame into many sections, each of which is a set of antennas.
A group of antennas must cover three frequency bands: low frequency, intermediate frequency, and high frequency. Then Bluetooth, GPS, Wifi, and NFC all need antennas. 5G mobile phone antenna design has become the focus of various technological breakthroughs.
The length of the antenna is 1/4 of the wavelength to receive the signal well. But a low-frequency antenna also covers a bandwidth of 600MHZ-960MHZ, about 300MHZ, so how can it satisfy that each wavelength has a good resonant frequency point at the same time?
The antenna design reasonably uses the combination of tuner and SWITCH to achieve good coverage of all frequency bands and optimal signal strength and good isolation between the antennas.
This tuner is a variable and non-polar LC combination matrix. By changing the LC value to correspond to a fixed length of the antenna, the highest receiving performance of the antenna under different frequencies can be achieved.
After the antenna is received, the signal must be transmitted to the motherboard for modulation and demodulation. On the Internet, Apple first adopted the LCP (liquid crystal polymer) antenna, which uses the low dielectric and low loss characteristics of the material to minimize the signal during transmission.
In fact, as early as Apple a few years ago, a domestic mobile phone manufacturer had already adopted LCP material. The use of LCP material can make the transmission line into a flat line, but the diameter of the cable line was still 0.8mm at that time, which was too thick to fit in an ultra-compact space.
Because the LCP material is too expensive, Apple finally compromised. The 2019 Apple 11 uses MPI (Improved Polyimide (PI) material instead of LCP.
MPI also has a very low path loss. However, some manufacturers use traditional cable lines (up to 0.4mm in diameter) for transmission. But if millimeter waves are used, you can only choose MPI or LCP materials. A cable line can only transmit one set of signal lines, while a millimeter wave needs to transmit several sets of signal lines at the same time. A bunch of cable lines will definitely not fit into the phone.
5G Sub 6G VS mmWave
The 5G millimeter-wave frequency band has a large bandwidth ranging from 24GHz to 100GHz, which makes it have unique advantages such as higher uplink and downlink rates, lower latency, and flexible air interface configuration, which can effectively meet the future wireless communication for system capacity and transmission rate And differentiated applications. However, 5G millimeter waves also have some disadvantages. For example, millimeter-wave signal propagation in the atmosphere is easily affected by oxygen absorption, air humidity, rain, snow, and fog. The signal is easily attenuated. At the same time, millimeter-wave signals have poor penetration and are easily affected by object blocking, and these factors have further led to problems such as the small coverage of millimeter-wave signals.
Compared with the 5G millimeter wave, although sub-6GHz is weaker than the 5G millimeter wave band in terms of high speed, low latency, and massive connections, it has more advantages in signal attenuation, penetration, and coverage. This also means that to achieve the same wide range of 5G signal coverage, the deployment density of sub-6GHz 5G base stations must be lower, and the required base station costs can also be lower.
In short, the sub-6GHz frequency band can be used to achieve longer transmission distances and wider coverage of the 5G network, while the 5G millimeter-wave frequency is suitable for characteristics such as high uplink and downlink rates, low latency, and massive connection fields demands in demanding situations.
Sub 6G VS mmWave’s maturity difference of millimeter-wave devices
The millimeter-wave belongs to the high-frequency band and has higher requirements for the corresponding 5G baseband chips, radiofrequency devices, and processes. Compared with the United States, China has been lagging in the medium and high-frequency devices.
Sub 6G VS mmWave’s 5G millimeter wave technology continues to evolve
At present, 5G millimeter wave technology is still evolving, and it is gradually overcoming the shortcomings of 5G millimeter wave technology.
For example, in terms of signal range, space diversity technology, adding relay nodes, and other extended-range technologies can be used to increase the coverage of 5G millimeter-wave signals.
In addition, the 5G millimeter-wave network can realize self-backhauling without the need to rely on the connection of the optical fiber network to the core network.
At present, the 5G network based on Sub-6GHz still needs to rely on the traditional optical fiber backhaul scheme, that is, each 5G base station and the core network need to be connected by optical fiber, which also greatly increases the deployment cost.
The IAB base station (Integrated Access and Backhaul) based on 5G millimeter wave technology can use other 5G millimeter-wave base stations as relay nodes in the form of wireless, through multi-hop function, and finally, the wireless form of transmission is transmitted back to the core network, which will greatly save the cost of optical fiber deployment. This also enables 5G millimeter-wave IAB base stations to support more cost-effective intensive deployment.
5G millimeter-wave and Sub-6GHz technology is not a competitive relationship, but a complementary relationship. At present, while China’s construction of the Sub-6GHz network has become more and more perfect, the research and early deployment of 5G millimeter waves have also begun.
Similarly, the United States is also preparing for the construction of the Sub-6GHz network. Last year, the U.S. FCC voted and approved a plan that the U.S. government spent $9.7 billion to buy back the 3.7GHz-4.2GHz spectrum used by satellite companies, and re-auctioned telecom companies for the construction of 5G networks based on the sub-6GHz frequency band.
In addition, with the application of dynamic spectrum sharing (DSS) technology, network operators can dynamically share spectrum between two different technologies (such as 4G and 5G), allowing operators to dynamically change part of the existing 4G LTE spectrum. Assigned to 5G.
Operators only need to upgrade the software to convert the current 4G signal tower into a 4G/5G mixed-signal tower.
This also makes some US operators with limited spectrum resources, such as AT&T and Verizon, more willing to implement Sub-6GHz 5G network deployment in this way.