[20th anniversary of au] Connect with high quality anywhere! au area countermeasures and communication quality challenges

In July 2020, au celebrated its 20th anniversary. Also in 2020, the provision of 5G (5th generation mobile communication system) services began. If NTT started its mobile phone service in 1987 as 1G, there have been four generational changes so far, and it has become possible to carry out high-quality communications over a wider area.

Let's look back on au's 20 years, focusing on expanding the communication area and improving communication quality.

First, we will introduce the communication services that au has provided from 1G to 5G. The table below briefly summarizes the mobile phone network generations and communication standards/communication services.

DDI, KDD, IDO, and 7 cellular group companies merged to form au as a unified brand in 2000. The communication service introduced by each group since 1998 is "cdmaOne."

With this service, it became possible to use mobile phone data communication, which had been mainly for telephone calls until then, and it became possible to view news and weather forecasts on the Internet (EZweb), and to download ringtones and standby images.

By the way, as of 2020, the 4G LTE (800MHz compatible device) service area exceeds 99% of the population, but in fact, as of January 2000, the cdmaOne service area also has a population coverage of 98%. was achieved (*). * "Population coverage rate" is the percentage of people who can use mobile phones in places where people live. Calculated based on areas where communication is possible in 50% or more of the approximately 500m section used for the national census.

Looking only at the numbers, it may seem that the area has expanded slightly over the past 20 years, but if you have been using a mobile phone for more than 10 years, it is probably an underground mall or a rush hour train. Among them, there are many people who have the impression that they have become able to communicate more comfortably than before in places where it was difficult to connect, such as mountains and campsites.

In the 20 years since the birth of au, what has been done behind the scenes to ensure that mobile phones can be connected "anywhere" and "high quality", and to improve au's area measures and communication quality? We asked Tomohiro Nishimura and Takashi Eguchi of KDDI, who have been involved in expanding service areas and improving communication quality, about their memorable episodes from each era.

At the time of 2000, Tomohiro Nishimura belonged to Kansai Cellular's operation department (currently Osaka Technical Center), and he often visited customers' homes to ensure the stability of communications.

"The area painted in orange on the service area map is the area where mobile phones can be connected. At that time, there were many inquiries from customers saying

With the PHS boom after 1995, mobile phones became popular as a communication tool, especially among young people, and at that time, the number of subscribers was increasing steadily. In January 1999, a year and a half before the birth of au, mobile phone numbers were changed from 10 digits to 11 digits.

This is the website of the Ministry of Posts and Telecommunications (at that time) that announced the shift to 11 digits. The conversion to 11 digits was a countermeasure against the shortage of phone numbers. The number of new subscribers was increasing.

And in 2000, when au was born, the number of mobile phone contracts, including PHS, reached 60 million, surpassing landline phones.

With the increase in the number of mobile phone subscribers, the number of inquiries has also increased even in areas with service areas. At that time, Nishimura said that he was responding individually to such customers who were difficult to connect with.

Currently, we have a system that can collect and analyze area data in-house, so we check in advance how much radio wave strength is covered for each frequency in each area, and if there is a problem We can go to the site after assuming the approximate cause and countermeasures.Although we will also conduct a survey at the site, we are working to improve the signal by installing special equipment.

At the time, there were simulators that could measure the strength of radio waves, but they weren't very accurate compared to today, partly because data such as traffic volume in the area hadn't been accumulated yet. Therefore, when I receive an inquiry from a customer, I go to the site anyway. Measure radio waves at the site and search for the cause while staring at the numbers.

At that time, we were mainly trying to improve communication by making it easier for radio waves to reach us, but sometimes we even considered changing the direction of the antenna of the base station that sends radio waves to the area. One by one, we found the affected areas on the spot and treated them as if we were applying a band-aid.”

At present, au has a service called "Radio Support 24", which enables it to effectively provide measures to improve radio waves for customers who have difficulty connecting, but since the birth of au, this kind of detailed support for each customer is related to the accumulation of data.

Since around 2003, Takashi Eguchi has been in the development department of cellular systems and has been engaged in the task of "tuning base stations" for a long time.

"In order to expand the area where mobile phones can connect, the first thing is to build a base station in a place where there is no connection, but after that, tuning is necessary. Tuning is to match the characteristics of the area. Then, in what direction, at what frequency, and at what strength, we adjust the numerical values.”

Radio waves emitted from one base station will be shared and used by all users in the corresponding area.

"If only a certain number of customers live in the area and the amount of communication does not change much, the base station can be operated as it is built. However, depending on the location, usage within the area The number of users fluctuates, and the biggest impact was the increase in traffic.

At the beginning of the year 2000, cdmaOne was used for voice calls and light internet, but after that, as the services provided by au diversified and communication services became faster, customer demand increased, and the amount of communication increased explosively. Did. In order to respond to this, tuning is necessary to properly deliver the radio waves emitted by the base station to customers.”

Let's touch on the state of mobile phones and services at the time.

"CDMA2000 1X" started in April 2002. The downlink communication speed has doubled from the previous maximum of 64kbps to 144kbps. It became possible to exchange photos and movies by e-mail, and the music download service "EZ Chaku-Uta" started in December of the same year. In November 2003, we started offering a new communication standard, "CDMA 1X WIN." The downlink communication speed has increased 16 times to a maximum of 2.4 Mbps.

We have provided a lot of content that makes daily life more convenient and enjoyable, and people are using their mobile phones for more than calling and emailing. Services such as "EZ Chaku-Uta Full", which allows you to download an entire song from a CD sound source, and "EZ Navi Walk," which provides directions like a car navigation system using the GPS function, have also started.

Here is the service area page of the same catalog. Areas painted in orange on the map indicate areas where au mobile phones can be used.

“Nowadays, in addition to expanding the connection area, in order to use various services, it is important to consider how much radio waves can be stably delivered to that area. New elements have been added."

Eguchi was also involved in the "tuning of base stations" that showed his power there.

"In addition to the increase in the number of users, the amount of communication for each has also increased, so there was inevitably a shortage of radio waves. Building a new base station would solve the problem, but it would take time. Therefore, we are working on optimizing the performance so that the maximum performance can be demonstrated according to which area of ​​the existing base station and how much mobile phone is using what amount of communication. We reviewed the direction and strength of the radio waves, and adjusted the 'handover'."

Handover refers to the smooth switching of radio waves to a nearby base station in the most suitable area when using a mobile phone while moving and leaving the area of ​​a certain base station.

Including this work, Eguchi repeatedly fine-tuned the base station so that the quality of calls could be stabilized and radio waves could be used efficiently.

au launched its first smartphone in 2010. The communication service at that time was CDMA 1x EV-DO Rev.A, with a maximum download speed of 9.2 Mbps.

In 2012, we introduced 4G LTE, which suddenly realized high-speed data communication with a maximum reception speed of 75 Mbps, which is about eight times that of conventional communication services. Furthermore, in 2013, the speed was increased to a maximum of 112.5 Mbps when receiving. It became possible to enjoy higher definition videos and music than 3G, and the mainstream of mobile phones shifted to smartphones. Smartphones began to function as transportation tickets and IDs, and 4G LTE was a communication standard that allowed PCs to be connected to the Internet by tethering and used comfortably.

This is the August 2010 au general catalog, and in the page titled "au mobile phone lineup", only the two phones circled in red are smartphones, but...

In the 2012 summer au general catalog, it is written that "smartphones are appearing one after another", and the method of picking up is reversed with the circled mobile phones.

KDDI's Tomohiro Nishimura and Takashi Eguchi decided to work together as a team to solve communication problems during the introduction of 4G LTE and the transition to smartphones, where large-capacity data communication began to take place. became.

Eguchi looks back on the time when 4G LTE was introduced.

"Normally, when a new communication standard is introduced, it is common to install new communication equipment at the base station, but at this time we were particular about making a quick start. We developed a function that allows the new system to operate simply by updating the software, without replacing the equipment of each base station.” (Eguchi)

The introduction of 4G LTE went smoothly, but after that, we started receiving inquiries about communication problems while moving.

Even if the new communication service starts to be provided, we will continue to provide the old communication service in parallel so that it can be used even on terminals that are outside the service area or that do not support it. If you are communicating while moving and go out of the new service area, a handover will be performed and you will automatically switch to the old service. I had a problem with the switch.

"I received information that it was difficult to connect to commuter trains in metropolitan areas, so I often rode crowded trains with Mr. Eguchi during rush hours to confirm 'what and how it was slow'. At that time, we were able to monitor the amount of communication in-house, but we actually got on the commuter train and used it in the same situation as the customer, and measured how many seconds it took to connect to the Internet and how many seconds it took to send an e-mail. By measuring this, I came up with a standard for how long it would take to get connected without feeling frustrated.” (Nishimura)

"In order to meet that standard, we tuned the base station again. It takes a few seconds to connect to the Internet with a smartphone on a crowded train and send an e-mail. Measured, collected data, returned to the office, and fine-tuned how radio waves emitted from the base station could be used comfortably. I tried it, and I went back to the company and tuned it up again.So to speak, it was fieldwork.Similarly, I checked the usage status on the Shinkansen.It was tough to make 10 round trips between Shin-Yokohama and Odawara on the Tokaido Shinkansen (laughs). )” (Eguchi)

These steady efforts have led to the current 4G LTE population coverage rate of 99.99%, and will continue to provide 5G services in the future. "We want our customers to take it for granted that mobile phones can be connected anytime, anywhere."

From 2020, the operation of au 5G will begin, and 5G systems are gradually being introduced to base stations nationwide.

"Now is the time to build 5G base stations nationwide. 4G LTE has achieved a population coverage rate of 99.99%, but simply installing a new 5G system on an existing base station However, it is also necessary to consider radio wave characteristics and build new base stations.Due to the characteristics of the radio wave band, 5G is difficult to spread over a wide range, so it will be used in conjunction with 4G LTE for the time being. Although it is far superior to "high speed, large capacity, and multiple connections", as the amount of communication increases and the number of people using it increases, some customers may feel that it is difficult to connect. I think it's necessary to treat each person carefully.I'll do my best to properly deliver radio waves while remembering the days of WIN and 4G LTE." (Nishimura)

These are the records of my work so far. We have constructed base stations and adjusted equipment so that mobile phones can be used comfortably not only in urban areas, but also in mountainous areas, remote islands, and other places throughout Japan. This work will continue as communication standards evolve and services become more diverse.

"Unlike the era when 3G changed to 4G LTE, 5G will be in the form of installing new equipment in base stations. Now, I am leaving the department that expands areas and improves communication quality, We are developing an in-vehicle base station, and we have already released a new 5G in-vehicle base station.In addition to expanding the 5G service area, we will also be able to use 5G for comfortable communication at events. I would like to be able to provide it.” (Eguchi)

Based on the evolution of communication standards, 5G is beginning to be operated in conjunction with the current 4G LTE. The area is still limited and the places where the service can be used are limited, but the construction of base stations is progressing at a rapid pace.

5G communication with "large capacity, low latency, and multiple connections" anytime, anywhere, and with the spread of this new communication standard, au What kind of excitement can we provide? We would like you to continue to pay attention to au, which is entering its 21st year.