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2 Telecommunication Radio Broadcast

Technology of Personal Mobile Radio
Introduction of PS‑LTE and its Challenges
KATSUYAMA Sakae

At the Olympic and Paralympic Games Tokyo 2020 PS‑LTE was introduced for the first time in the history of the
Olympic and Paralympic Games as one of the technologies for providing Personal Mobile Radio (PMR) service used forcommunication among the Games management personnel and PS‑significantly contributed to the smooth operation of theGames This article outlines the structure of the PS‑LTE system and its construction process for the Olympic andParalympic Games Tokyo 2020 It provides an overview of the use of PS‑LTE during the Olympic and Paralympic GamesTokyo 2020 including the preparation period The post‑Games utilization of the PS‑LTE system is also discussed
Keywords：Personal Mobile Radio (PMR) First time in the history of the Olympic and Paralympic Games PS‑LTE
Post‑Games utilization

1．Introduction
Personal Mobile Radio (PMR) service is a “communication service to support the smooth operation of thenies were provided at Haneda and Narita airports
This article describes PS‑LTE introduced as a PMR
service for the first time in the history of the Olympic
and Paralympic Games

Games” used for communication among the parties
involved in managing the Games to support venue
management competition management medical caresecurity and other event support PMR service provides
an immediate communication means by radio devices totarget devices within a defined area

2．PS‑LTE in the Tokyo 2020 Games
PS‑LTE is a wireless network built on an LTE system
intended for public use
NEC proposed PS‑LTE as a technology for providing

NEC provided PMR service for the Olympic and

PMR service and after evaluation by the Tokyo 2020

Paralympic Games Tokyo 2020 (hereinafter referred toOrganising Committee it was decided to introduce PS‑

as Tokyo 2020 Games) using three technologies : PS‑

LTE as a PMR service

LTE (Terminology) direct communication radio and IP radio

This section describes the PS‑LTE system for the

The areas where PMR service was provided are shownin Table 1
In addition to these three technologies airport MCA
radios serviced by the respective airport radio compa-

Table 1
Technology
PS‑LTEPMR Service Coverage Area
Service area
Tokyo area (within a 10‑km radius of the
Olympic and Paralympic Villages) Musashino Forest Sports Plaza Tokyo Stadium

KATSUYAMA Sakae
City Infrastructure Solution Division NEC Corporation
E‑mail s‑katsuyama@nec com

Direct Communica- Venues outside and surrounding the PS‑tion RadioLTE coverage area

The Journal of The Institute of Electronics Information and Communication Engineers Vol 105 No 8 Supplement pp 104‑109 August 2022

IP Radio© 2022 The Institute of Electronics Information and Communication Engineers

104

Venues outside and surrounding the PS‑
LTE coverage area

THE JOURNAL OF THE INSTITUTE OF ELECTRONICS INFORMATION AND COMMUNICATION ENGINEERS

Tokyo 2020 Games

interfere with the operations of the GamesThe equipment making up the PS‑LTE system for the21

System Overview

Tokyo 2020 Games was the same as that provided to

The PS‑LTE system constructed for the Tokyo 2020
Games consisted of a control station base stations

customers who require continued communication evenduring a disaster

mobile stations and a supervisory and control centre asshown in Figure 1 There were two types of base211

stations : wide‑area stations that covered the area

The control station consists of core network equip-

outside the venues and venue stations that covered thement called EPC (Evolved Packet Core) which has thearea in and around the venues Seven wide‑area stations

function of managing communications for the entire PS‑

and 22 venue stations were installed

LTE system and controls LTE‑based communications a

A redundant backhaul connected the control station
and base stations

Control Station

PTT (Push To Talk) server which controls the PTT
function in which a call is made by pressing a button on

The equipment used to configure the control stationa mobile station ; and routers to control communication

and base stations was duplicated to provide sufficientwith the base stations All of these devices have a

redundancy Even if a failure occurred the PS‑LTE

redundant configuration of active and standby systems

system would continue to operate and would not

The control station was located in a data centre
managed by NEC had its independent power supply andwas connected to a commercial power supply ensuring
24‑hour operation 365 days a year
212

Base Station

The base station has the function of capturing radio
signals and connecting them to the control station thatmanages communications The base station consists of aBase Band Unit (BBU) (Terminology) that controls the entire
base station and monitors call control protocols and a
Remote Radio Head (RRH) (Terminology) that processes
signals exchanged through the backhaul and signals to
be placed on the radio routers that control communicaFigure 1 The PS‑LTE system configuration
The system
consists of a control station base stations mobile stations and asupervisory and control centretion with the control station

and antennasTheequipment of the base station excluding the antennas
has a redundant configuration of active and standby
systems■

At the Tokyo 2020 Games the base stations were ofTerminology

PS‑LTE
Public‑Safety LTE A radio system built onan LTE system for public use (for example for use by public
safety organizations at disaster sites) At the Tokyo 2020
Games PS‑LTE was built as a dedicated radio system
BBU
Base Band Unit A device performing digital
baseband signal processing connection and termination
processing with control stations call processing andmonitoring and control processing It converts signals
received from control stations into baseband signals andtransmits them to RRH It also transmits the reverse
direction
RRH
Remote Radio Head A device that transmits andreceives radio signals converts and amplifies the processedbaseband signals from the BBU into radio signals andtransmits them to the mobile station and vice versa It alsotransmits in the reverse direction■

two types : wide‑area stations and venue stations The
wide‑area stations were set up to cover the outdoor area
within a 10‑km radius around the Olympic andParalympic Villages The venue stations were set up tocover the indoor and surrounding areas of the venues()

Wide‑area Station

Radio propagation simulations were conducted inadvance to efficiently cover a 10‑km radius around the
Olympic and Paralympic Villages and suitable facilities
were selected for installation

As a result of thesimulation it was decided to install seven base stations
The number of RRHs per base station ranged from 2 to
4 Figure 2 and Figure 3 show a wide‑area stationʼs

Special Issue : Technology and Innovation in the Olympic and Paralympic Games Tokyo 2020

105

Figure 2 Base Station Equipment Configuration
The system
consists of a BBU RRHs antennas and routers The number of
RRHs was 2 to 4 depending on the station

Figure 4

Mobile station

A Smartphone‑type Radio was Usedon the size of the venues and the complexity of theirstructures RRHs were 2 for the Canoe Slalom Centre a
simple structure and 14 for the Olympic Stadium alarge‑scale and complex structure
213

Mobile Station

The mobile station is a device that users hold in theirhands to make and receive calls
The mobile station adopted for the Tokyo 2020 Games
was a smartphone‑type radio shown in Figure 4 unlike
the transceiver‑type radio used in past Games
Figure 3 Appearance of the Wide‑area Stationrouters are installed inside the building

The BBU and

NEC adopted a smartphone‑type model with excellent
shock resistance water resistance and dust resistanceand provided approximately 6 300 units

equipment configuration and appearance

214

Supervisory and Control Centre

The operation status of the PS‑LTE system was()

Venue Station

monitored and remotely controlled in the event ofVenue stations are base stations used to cover indoor

failures etc The centre was located at NECʼs office andand surrounding areas of venues and have the samea 24‑hour monitoring and control system was estab-equipment configuration as that of wide‑area stations

lishedThe difference from wide‑area stations was that a

The PS‑LTE system was operated in close coopera-

configuration in which the antennas were partiallytion with Technology Operation Centre (TOC) during

branched to arrange many antennas for covering

the Games period

complicated indoor areas and the shape of the antennas
While wide‑area stations used large antennas installed215

on steel towers to cover a wide area venue stations used

Core network equipment (e gSystem Performance
EPC) with sufficient

small antennas that could be easily installed The small

processing capacity was installed to handle the approxi-

antennas were adopted for the venue stations because ofmately PS‑LTE 6 300 mobile stations

the less duration required for the installation and

The performance of the core network equipment isremoval and the broadcast cameras would not capture

equivalent to that of the equipment used in telecommuni-

themcation carriers and was sufficient to handle all 6 300

The number of RRHs varied significantly depending
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units even if they were all used simultaneously

THE JOURNAL OF THE INSTITUTE OF ELECTRONICS INFORMATION AND COMMUNICATION ENGINEERS

Figure 5 PS‑LTE Coverage Area
This is a simulation result for an area within a 10‑km radius of the
Olympic and Paralympic Villages Prepared by NEC based on the Geographical Survey Institute map(https://maps gsi go jp/#12/35 647951/139 766693/&base=std&ls=std&disp=1&vs=c1j0h0k0l0u0t0z0r0s0
m0f1)

22

Service Area

The areas covered by the PS‑LTE system included

stations was determined by repeating the simulation
with antenna positions as a parameteroutdoor areas such as road event courses (marathonsand triathlons) within a 10‑km radius around the23

Olympic and Paralympic Villages 20 venues such as the

The PS‑LTE system construction started in FY2018

Olympic Stadium and the Olympic and Paralympic

and was carried out with preliminary coordination

Villages within a 10‑km radius and Musashino Forest

installation and verification steps

Sports Plaza and Tokyo Stadium outside the 10‑km
radiusSystem Construction

Since the wide‑area stations were constructed outside
the venues the facilities could be rented earlier andadequate time could be ensured for the construction()

Outdoor Areas within a 10‑km Radius of the
Olympic and Paralympic Villages

periodOn the other hand the renting period of facilities at

Figure 5 shows the results of radio propagation

the venues was set at a minimum and construction work

simulation within a 10‑km radius around the Olympic

had to be carried out in multiple venues within a few

and Paralympic Villages

months immediately before the GamesThe locations of the wide‑area stations were deter-

construction resources a challenge

allocating

Howeverthemined based on these simulations In practice even if

construction plan was carefully coordinated with thethe simulation results showed efficient coverage theTokyo 2020 Organising Committee steps and businessselection of the installation site had to be performed

operators in charge of the maintenance at each venue

several times due to the inability to secure (rent) a

The construction was completed before the Games staff

facility

arrived at the venues and started using the PMR
During the construction of the PS‑LTE system()

Venuesadjustments were made for interference from radio to

Simulations were also conducted in advance for

ensure that the operation of communication carriers andvenues such as the Olympic Stadium Olympic andother wireless systems would not be affected As a

Paralympic Villages and outdoors over a 10‑km radius

result the location of the PS‑LTE antennas had to beof the Olympic and Paralympic Villages

changed and additional filters had to be installed at the

The number of devices installed at each of the 22base stations of communication carriers to avoid

Special Issue : Technology and Innovation in the Olympic and Paralympic Games Tokyo 2020107

interferencein the entire PS‑LTE system was 700

After installing the base station radio wave measure-

These groups were defined in a fleet map and thements and call tests were conducted on and aroundmobile stations were configured for these groups based

major roads and venues in Tokyo such as road eventon the fleet map (the configured groups were called

courses and highways designated as Olympic routes“Talk Groups”) and distributed to users

The results confirmed that Reference Signal Received
Power (RSRP) could provide stable calls in all areas

32

except tunnels and that PMR service could be provided

Positions were assigned to TOC and venues to carryas expected

Operational Structureout the operational tasks (Figure 6) The supervisory
and control centre was also staffed 24 hours a day

3．PMR Service Operation
NEC was responsible for constructing the PS‑LTE
system and for operational tasks such as setting up themobile stations delivering to users and responding touser inquiries
NEC handled the PS‑LTE system and other PMR
systems (direct communication radio and IP radio)
Although there were differences in mobile station setup
work depending on the radio technology the operationaltasks were the same
This section describes the operation of the PS‑LTE
system31

Mobile Station Setup

The PS‑LTE system supported approximately 6 300
mobile stations or about 6 300 users

Users gave

instructions through PMRs in units of operational groups
such as venue management

security

and medical

services Groups ranged from 20 to 45 people dependingon the size of the venues and the total number of groups

Figure 7
figure108

PS‑LTE traffic

Figure 6 PMR‑related Operational Positions
positions in TOC and 2 positions at venues

NEC deployed 3

The total daily talk time of the Talk Group is shown in the

THE JOURNAL OF THE INSTITUTE OF ELECTRONICS INFORMATION AND COMMUNICATION ENGINEERS

During the Tokyo 2020 Games more than 300 personnel
were mobilized
In principle TOC was staffed 24 hours a day during
the Olympic Games and 19 hours a day during theParalympic Games while the venues were staffed forcompetition hours and several hours before and after
33

Operational Status

The PMR service was provided stably during theGames period including the preparation period with nosystem outages or other problems
The traffic generated during the Tokyo 2020 Games
was also within the performance range of the PS‑LTE

Figure 8 Utilization Rate of the Wireless Band over Time on July
24 2021
The figure shows the utilization rate of the wirelessband over time when the utilization rate was the highest

systemFigure 7 shows the total talk time for each Talk Group
from July 1 to September 8 2021 organized per day
The horizontal axis is the date and the vertical axis is
the total talk time in each Talk Group If Person A

4．Utilization of the PS‑LTE System after
the Games

speaks for 5 seconds in one Talk Group to call Person B

NEC worked to utilize the PS‑LTE system introduced

and then Person B responds for 3 seconds the callat the Tokyo 2020 Games as a legacy after the Games
NEC proposed that the PS‑LTE system be used as

duration is recorded as 8 seconds
The traffic generated (Talk Group calls) tended to bepart of MCA Advance provided by MRC (Mobile Radio
Center Inc ) and after the Tokyo 2020 Games the usedsimilar to past Games
Traffic increased from the time when preparations for
the Games began in earnest and reached their maximum

equipment was diverted to be used to build MCA
Advanceon the day after the opening ceremony of the Olympic
Games The day after the opening ceremony was thefirst day of the competitions in many venues There

5．Conclusion

which

NEC was able to provide a stable PMR service on astimulated the use of radios Subsequently the number

large scale Thanks to the efforts of NEC and the Tokyo

of calls decreased and it is assumed that users got used2020 Organising Committee and all related organiza-

to their work

tions institutions business operators and volunteers I

were many interactions between personnel

Traffic decreased during the transition period but

want to take this opportunity to express my gratitudetraffic increased as the Paralympic Games approachedand preparations began in earnest
Traffic during the Paralympic Games was less thanduring the Olympics Games due to the smaller scale(number of venues etc ) and fewer users
Figure 8 shows the transition of the utilization rate of
the wireless band where the utilization rate was thehighest on July 24

2021

when traffic was at its

maximum The utilization rate of the wireless band was
34% at the maximum and there was enough capacity
The PMR service could be provided without the
restriction of low‑priority Talk Groups which had been

(Received February 28 2022 ; Revised March 17 2022)

KATSUYAMA Sakae
He graduated from Nagoya University in1994 with a Bachelorʼs degree in Electronics
and Information Technology and completed thefirst half of a Doctoral course at the same
university in 1996 He joined NEC in the same
year and has been engaged in designing
developing and maintaining defense communication networks Since 2017 he has beenworking in the PMR service development for
the Tokyo 2020 Games Currently he is theradio solution project manager of the City
Infrastructure Solutions Division of NEC Corporationconsidered in advance㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇㍇

Special Issue : Technology and Innovation in the Olympic and Paralympic Games Tokyo 2020109