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What Is 5G, the Next Generation Wireless System? [Vol. 1]
Why Aim for 10 Gbps Super-fast Communications at Wi-Fi-level Low Power Consumption?

New technologies in development aiming to be implemented and commercialized by 2020 include 4K/8K TVs in the broadcasting industry, self-driving vehicles in the automobile industry, and the 5G wireless system in the communications industry. It is easy to imagine technological evolutions such as higher definition images enabled by 4K/8K resolution technology and driverless vehicles achieved by self-driving technology. As for 5G, however, people may not have a clear idea of what it enables them to do. This is because 5G has been designed to create a next generation society with new value, rather than simply providing a faster data rate in the manner of "XX times faster than 4G!" Such new value includes 4K/8K television and self-driving vehicles; 5G will support these new features.

To aid in understanding the overall picture of 5G, this series of articles, starting with this article, will introduce the types of value that 5G will create, the types of networks required to create such value, and the types of technologies required to build such networks.

1G: Analog Mobile Phones. 2G: Digitization and Data Communications Services.

The term "5G" should sound familiar because newspapers, magazines, and Internet news websites often discuss it. The letter "G" in terms such as 4G stands for "generation." 4G thus refers to the fourth generation of mobile network technology. Next in line is 5G, the fifth generation of mobile network technology. In Japanese, it is generally called "Dai Go Sedai Ido Tsushin Shisutemu," which means "the fifth generation mobile communications system" in English. The quickest way to understand 5G's characteristics is to learn how mobile networks have developed over time. Let us review the development of mobile communications systems generation by generation.

1G analog mobile phone "mova F" (1991)

The earliest mobile phone technology was independently developed in Japan, the US, and Europe. This led to the establishment of region-specific analog wireless technology specifications and the subsequent release of mobile phones as commercial products. The analog wireless mobile network technology used at this time is called 1G, which made its appearance from the 1980's into the 1990's.

2G i-mode mobile phone "F501i HYPER" (1999)

In the 1990's, wireless technology became digitized. Mobile networks using digital wireless technology were standardized and digital service commenced. Mobile phone systems using such digital wireless technology are called 2G. Digitization of wireless technology made it easier for telecommunications providers to offer data communications services. The result was widespread use of mobile data communications such as email. In Japan, NTT DOCOMO launched i-mode in 1999, which enabled users to obtain information and use Internet email on their mobile phones. This led to an explosive increase in the use of mobile data communications.

As use of mobile data communications became part of daily life, users demanded faster data rates. In response, commercial application of cdmaOne began by employing code-division multiple access (CDMA), which became the core technology of 3G. cdmaOne was called 2.5G because it achieved a faster data rate by taking advantage of such 3G core technology.

3G: The First Global Standard. 4G: Increased Competition over Speed.

Like 1G, 2G services were region-specific and used different technologies. Thus, at that time, mobile phones could only be used in specific areas. Users could not carry a single mobile phone and use it around the world like today. So, to address this issue, the International Telecommunication Union (ITU), a specialized agency of the United Nations, standardized various technologies into 3G.

As a result of research on 3G that started in the 1980's, the ITU set the following three targets: (1) to start provision of 3G service in 2000, (2) to use the 2000 MHz frequency band, and (3) to achieve a maximum speed of 2000 kbps. Since all three targets included the figure "2000," the ITU named 3G "International Mobile Telecommunication 2000" (IMT-2000). In 1999, the ITU established IMT-2000 as a global standard. 3G kicked off the era in which users could carry and use their mobile phones around the world.

In addition to being the first global standard, 3G was also characterized by a continuous, rapid increase in data rates. The initial development target, a maximum data rate of 2 Mbps, was easily met in the 2000's, after which technology to achieve a data rate of 10 to 20 Mbps was implemented.

3.5G and LTE (3.9G) smartphone "ARROWS X LTE F-05D" (2011)

Such technology to achieve faster data rates can be divided into two types depending on its technical characteristics. The first type was called 3.5G because it used 3G technology to achieve higher data rates. The second type was called Long Term Evolution (LTE). This LTE name came from the fact that it was developed as a technology for long-term innovation that could also be used in the future 4G era. LTE was sometimes referred to as 3.9G because it was a 3G technology that used 4G technology in advance.

The ITU used the name "IMT-Advanced" for the next version of the IMT-2000 international standard. IMT-Advanced aimed to achieve super-fast communications at a rate of 50 Mbps to 1 Gbps and seamless handovers between fixed and mobile networks. The ITU requested that specifications be created by the IEEE, an organization of engineers, and the standardization project 3GPP, which was launched by regional standardization organizations. The ITU then accredited the achievements of these standardization activities as international standards. More specifically, it approved two specifications--WirelessMAN-Advanced created by the IEEE and LTE-Advanced created by the 3GPP--as IMT-Advanced in 2012. This is 4G.

Meanwhile, on October 6, 2012, the ITU issued a press release that included statements implying permission to use the term 4G for the names of services employing 3.5G or 3.9G technology. The ITU was driven to make such an announcement because data rates had rapidly increased with 3.5G and 3.9G, and service names including the term "4G" had already begun to appear. Japan also had "4G" services that in fact used 3.9G technology.

As described above, there is a slight difference between the technical definition of 4G and the actual services that were called "4G." From the user's perspective, 4G is mobile network technology for smartphones.

Aiming to Realize a Society with Devices Beyond Smartphones, Usage-scenario-specific Technical Development of Devices Has Begun

What remains for 5G then? With 5G, the aim is to achieve the mobile network that will support society in the 2020's. This may sound somewhat vague, but the point is that 5G is being designed to meet a wide variety of needs in diverse situations. If 4G is technology for smartphones, then 5G may be considered to be technology for all kinds of devices and applications.

5G technology is being developed in a unique way. In addition to clear network performance goals specifying targets such as data rates and delays, development themes include communications specifications for specific scenarios and new technologies to meet such specifications.

Take a large sporting event as an example. The service being considered enables the stadium audience to use their smartphones and tablets to watch goals being scored and a live feed from the stadium in high resolution. In this case, a network must be built that enables tens of thousands of devices in a relatively small area to communicate at a rate of a few hundred Mbps.

Building such a network requires new technology that (1) uses a high frequency band not used by current mobile networks to (2) achieve unprecedented, stable super-high-speed wireless communications at a level of 10 Gbps in (3) a location where tens of thousands of devices are in use simultaneously. There is another major task too: since many base stations will be installed within a limited space, it is necessary to reduce their power consumption to the level of Wi-Fi access points (approximately 10 W).

Such scenario-specific technical development has already begun. Fujitsu (1) has developed beam-division multiplexing, a technology to enable efficient communications between base stations and many devices in a small area, and (2) uses the millimeter wave, a high frequency band that has not been used previously, in order to (3) develop technology to increase data rates through beamforming, a method for focusing radio waves in the desired direction by employing many antenna elements.

Image of beam-division multiplexing and the millimeter wave, which are required to realize a high-definition video transmission service for a stadium audience

To reduce base station power consumption, Fujitsu Laboratories developed an inter-subarray encoding technology designed to reduce the power consumption of the antenna arrays used in beamforming. This technology achieved low power consumption for high-speed, high-capacity communications.

Realizing super-high-speed communications of 10 Gbps with power consumption as low as Wi-Fi communication will facilitate network creation, management, and design. As a result, information services that provide a rich lineup of content, including high definition videos at train stations, airports, and event venues as well as stadiums, may become a reality.

This article gave an overview of 5G and introduced the new value it will create in the future by taking the example of a large sporting event. It also described the required network performance and technical specifications for such a scenario. In the next article, we will examine the target values for 5G network performance and the types of value created when such targets are achieved.