The technology that enables 5G
The "G" in 5G stands for generation, and the new generation of communication standards established in response to the development of communication technology is called 5G. While 4G represented the communication standards such as LTE and LTE-Advanced, 5G has set A communication standard called NR.In this section, we will introduce the four technologies that made the NR communication standard possible: Carrier Aggregation, Frequency Band Extension, Beamforming, and Massive MIMO, along with the future of 5G.
What is NR (New Radio)?
A new communication standard that replaces 4G LTE is called New Radio. NR is characterized by Ultra-high speed, Ultra-low latency, and Ultra-simultaneous connections.
In 4G LTE-Advanced, high-speed data transmission was achieved by combining up to five frequency bandwidths of up to 20MHz used in 4G LTE, and transmitting over a maximum width of 100MHz. However, 5G NR enables the use of a wider frequency bandwidth of up to 400MHz. This technology is called Carrier Aggregation, and it allows more information to be sent at once by increasing the width of the frequencies sent at once. Therefore, with 5G, the expansion of the frequency bandwidth enables higher capacity communication than was possible with 4G.
Frequencies expected to be used for 5G
The frequency bands used by 5G can be divided into two main ranges. One is the Sub6 band, which has been used since before 4G LTE and is below 6 GHz. The other is the Extremely high frequency band from 30 GHz and up, which has a narrower frequency range due to its very high frequency, but a wider frequency range. In Japan, as of November 2020, the 3.7GHz, 4.5GHz, and 28GHz Extremely high frequency bands have been allocated for 5G, and the frequencies used for 4G and 5G are shown in the figure below.
In normal wireless communication, radio waves of the same output power are sent out in various directions around the antenna. As a result, interference with nearby devices may occur. In contrast, beamforming technology sends out the same radio waves from multiple antennas, and by adjusting the phase and power intensity of each antenna, the waves are strengthened in certain directions and weakened in others. This means it is possible to send radio waves only in one direction. This technology, combined with the technology to recognize the location of the other device and track it, will make it possible to send strong radio waves at all times, thereby stabilizing telecommunications. (Wi-Fi5 and Wi-Fi6, the mainstream Wi-Fi standards as of November 2020, already support this technology.)
5G NR is expected to use a higher frequency band than the 3.5GHz band commonly used in 4G LTE. When using higher frequency bands, the area that can be covered by a single antenna becomes smaller. For this reason, beamforming technology is attracting attention for 5G, which uses high frequencies, because it requires a large number of antennas to be lined up.
In the higher frequency bands used in 5G, the distance that radio waves can reach becomes shorter, and with conventional antennas, the signal strength at the receiving end becomes weaker, resulting in a narrower communication area. Therefore, we decided to compensate for the loss of signal range by applying beamforming technology to Massive MIMO antennas.Massive MIMO uses a "massive" number of antennas (from a few dozen to a thousand) to achieve advanced beamforming and other technologies to assign dedicated radio waves to each individual, enabling comfortable communications even in crowded areas where communication speeds tend to be slow. However, the wavelength of radio waves at frequencies above 30 GHz is less than 1 cm, and the required antenna length is less than 5 mm, so even a large number of antennas can be compactly placed in a box. Therefore, there are plans to improve the communication environment by embedding Extremely high frequency antenna elements in the walls and floors of indoor facilities such as shopping malls and train stations where Extremely high frequency cannot reach.
MIMO is an abbreviation for Multi Input Multi Output, which means multiple inputs and outputs, and is a technology that uses multiple antennas to transmit and receive data. MIMO is one of the key technologies used in LTE-Advanced and Wi-Fi standards, which are currently the mainstream, to speed up data communication. For example, a system that uses two antennas on the transmit and receive sides is called 2×2 MIMO, while one that uses four antennas is called 4×4 MIMO. These are used in LTE, and LTE-Advanced uses the 8×8 MIMO standard, and considering that Massive MIMO uses more than several hundred antennas, you can see how revolutionary 5G technology is.
▪Non-StandAlone (NSA) and StandAlone (SA)
In the early stages of 5G, as of November 2020, the most common network configuration is called non-standalone (NSA), in which 5G NR and 4G LTE-Advanced work together. In NSA, control signals are sent using 4G LTE-Advanced, so it is not possible to realize the advantages of 5G other than ultra-high speed communication. However, since the Extremly high frequency used in NR has a narrow coverage area, 5G can be used in a wide area by using some 4G communications. In addition, since it takes time and costs a lot of money to build NR-compatible base stations all over the country, the NSA can avoid these problems by using the base stations used for 4G.
As 5G becomes more widespread, there will be a shift to a method called StandAlone (SA), in which all base stations are 5G-compatible and do not rely on 4G technology. As of November 2020, the three major mobile carriers are planning to start switching to the SA method by the end of fiscal 2021. As of November 2020, the three major mobile carriers are planning to start switching to the SA method by the end of fiscal year 2021, and the true value of 5G will be demonstrated when the transition to the SA method is complete.
Are you tired of reading all those difficult words? Let's me summarize briefly, 5G is a communication generation that enables high-capacity communication and low latency by applying existing technology and making it available on a large scale. I look forward to the time when we can experience 5G wherever we are.