Engineers are building 5G into Wi-Fi and IoT devices. Frequencies used depend not only on country, but location within a country.
As 5G moves into deployment, engineers are designing it into new products. Some are now beginning to appear on the market and many more will follow. Analog Devices has been leading the way with RF chipsets and participation in standards bodies. To learn more about the state of 5G frequencies and devices, 5G Technology World spoke with Tao Song, business development director in Analog Devices’ Wireless Communications Business Unit.
Song has more than 10 years of design experience in wireless communications RF systems including GSM, CDMA, WCDMA, base station transceivers, active duplexers, tower amplifiers, and other RF modules. He holds a master’s degree in Electromagnetic Fields and Microwave Technology from Nanjing University of Science and Technology in China.
Tao Song
Song: 5G is used for more than cell phones. It will be used for industrial, medical, AI, and automotive for devices to talk to each other. My customers, the OEMs, are building not only macro cells–base stations–but small cells and cell phones. Other customers are developing Wi-Fi and IoT products that will connect to 5G networks.
For the first few years, the most important part of 5G will be the infrastructure. That’s why the OEMs–Huawei, ZTE, Ericsson, Nokia and Samsung–are working on both the micro base stations and mobile devices.
In China, there’s an effort to build out 5G networks as soon as possible. Phase I is already complete and Phase II is underway. Deployment moves very fast because the operators are encouraged by the government.
Song: It very much depends on the market. The OEMs are doing both frequency bands. The priorities for Huawei and ZTE are totally different than Ericsson and Nokia. Ninety percent of the effort is in sub 6 GHz for Huawei and ZTE. Plus, due to certain reasons, it’s hard for Huawei and ZTE to gain market share in the U.S. Ericsson and Nokia are doing more in mmWave: 24 GHz, 28 GHz, and 39 GHz. Huawei and ZTE also made have good progress in mmWave 5G developments. They are not in high volume mass production yet. But both sub-6 GHz and mmWave are important for the OEMs.
Both Sub 6GHz and mmW 5G spectrums have been released in some regions. It varies in each country. For example in China, usually if you get a frequency band, you get it for the entire country. That’s not the case in the U.S. where frequency allocations vary by area. Carriers must join the auctions to get licenses in different cities. A carrier may also have different bandwidths, depending on the area. In China, carriers get a fixed frequency band and signal bandwidth throughout the country. Which band and what bandwidth could be used are determined by field network optimization.
China already released 2.6 GHz, 3.5 GHz and 4.9 GHz Sub-6G spectrums. mmWave bands are still in evaluation. 600MHz low band spectrum was released in 2017 through auction in U.S. 3.5 GHz “golden” spectrum auction was scheduled to June 2020. mmWave 24 GHz, 28 GHz and 39 GHz/47 GHz spectrums auctions were closed in 2019. In general, 3.5 GHz and mmWave 28 GHZ/29 GHz are the most popular spectrums worldwide.
Song: The network build-out must happen first. Applications such as AI, IoT, and automotive need that network buildout. 5G is a high bandwidth, low latency network that will make other applications possible. It’s more than just communications. That’s why the governments are pushing 5G to drive innovations.
Many companies are anticipating the 5G buildout and are developing products that will connect to the network once it’s readily available. Most will initially connect to 5G in the sub- 6 GHz spectrum because of the buildout. mmWave product will come later and the directional characteristics may be an issue connecting devices to each other through the network. For normal coverage, they will use sub-6 GHz. But mmWave products have the advantage of low dollars/bit cost which is a good candidate for the final kilometer access.
Song: Analog Devices covers the whole portion of the RF signal chain. Engineers connect to our RF transceivers at baseband through FPGAs or ASICs. Today in the market 4T4R antenna arrays are popular with 8T8R available. Engineers are designing antenna systems with those arrays but are asking for greater integration and lower power consumption. They ask for 16T16R or even 32T32R. It depends on where the product will be used. In China, for example, I expect 64T64R (128×196 antenna elements) to become popular for densely populated areas while 32T32R has better cost structure in countryside areas. Right now, engineers are asking for 8T8R or higher integration. Most of these designs are being used for sub-6 GHz massive MIMO.
MMIMO RF Signal Chain Typical Block Diagram (1T1R Base)
Song: Yes. Some of that burden falls to chipset providers who need to provide technical support for their products. There are many engineers who need to learn about how to design for 5G and how to use the chipsets successfully. As a chipset provider, we can provide direct support for our products. But, 5G is a big system. Engineers need to learn the basic concepts behind 5G.
