PHS MoU Document
A-GN0.00-01-TS
Title: General Description of Public Personal Handy-phone System
Version: 01
Date: April 21, 1997
PHS MoU Classification: Unrestricted
List of contents:
1.
2.

Introduction
General Objectives of PHS
2.1 Application of Cordless Telephone Concept to Public Mobile
Communication
2.2 Concept of PHS and Existing Public Network Interface
2.3 PHS Feature
2.4 Implementation of Wireless Local Loop Based on PHS Technology
3. Basic Technology of PHS
3.1 PHS Wireless Transmission System
3.2 Network Technology
4. Area of Application of PHS
4.1 Public PHS
4.2 PHS Wireless Local Loop Access System
4.3 Private PHS
4.4 Access System to PLMN
5. Outline of PHS MoU Technical Document
ABBREVIATION

Number of pages: 13

PHS MoU Group
c/o Association of Radio Industries and Businesses (ARIB)
14F, Nittochi Bldg., 4-1, Kasumigaseki 1-choume, Chiyoda-ku, Tokyo 100, Japan
TEL +81-3-5510-8599 FAX +81-3-3592-1103© PHS MoU Group1997

PHS MoU Document
A-GN0.00-01-TS
Version01

History of Revised Versions
Date
OutlineApril 21, 1997 EstablishedA-GN0.00-01-TS

GENERAL DESCRIPTIONOFPERSONAL HANDY-PHONE SYSTEM

Contents

1. Introduction ....................................................................................................................................... 1
2. General Objective of PHS .................................................................................................................2
2.1 Application of Cordless Telephone Concept to Public Mobile Communications .........................2
2.2 Concept of PHS and Existing Public Network Interface............................................................... 2
2.3 PHS Feature ...................................................................................................................................2
2.4 Implementation of Wireless Local Loop Based on PHS Technology............................................3
3. Basic Technology of PHS ..................................................................................................................3
3.1 PHS Wireless Transmission System ..............................................................................................3
3.2 Network Technology ......................................................................................................................6
4. Area of Application of PHS .............................................................................................................10
4.1 Public PHS....................................................................................................................................10
4.2 PHS Wireless Local Loop Access System ...................................................................................10
4.3 Private PHS ..................................................................................................................................11
4.4 Access System to PLMN..............................................................................................................11
5. Outline of PHS MoU Technical Documents ................................................................................... 11
ABBREVIATIONS ...............................................................................................................................13

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1. Introduction
The Personal Handy-phone System (PHS) is a wireless access system of a micro-cell architecture,using 1.9 GHz frequency band. Figure 1-1/A-GNO.00 shows the general concept of PHS. As seenfrom the diagram, PHS can be applied to a public mobile communication system, or to a Wireless
Local Loop (WLL) that substitutes the existing telephone twisted pair to provide subscribers with
telephone services, or to a wireless PBX or a home cordless telephone system, or to transceivers thatenable PSs to communicate directly with each other. A Common Air Interface (CAI) of PHS isstandardized as RCR STD-28 by Association of Radio Industries and Businesses (ARIB). UserNetwork and Network-Network Interfaces (UNI and NNI) are based on ITU-T Q-series standards.
End to end multimedia protocol is standardized as PHS Internet Access Forum Standard (PIAFS).
In order that PHS be used commonly throughout the world, the PHS MOU technical working group,
organized under an international memorandum of understanding is preparing the technicalspecifications for PHS. This document is a general description of the PHS technical specifications
mainly in the areas of objectives, technical features, and application examples.

CS

PS

PS

Transceiver
PS

CS

PS

CS

Home

PSTN/ISDN

Public Mobile Communication
WAC

CS

WCS

CS

WSU

PS

Wireless PBX

Wireless Local Loop
: Personal Station•

PS

PBX

WPS

PS

Cordless

CS : Cell Station•

WSU : WLL Subscriber Unit

WPS : WLL Personal Station

WCS : WLL Cell Station

WAC : WLL Access Controller

PSTN : Public Switched Telephone Network•

ISDN : Integrated Services Digital Network

Figure 1-1/A-GN0.00 Basic Concept of PHS

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2. General Objectives of PHS
The full duplex wireless communication system of PHS employs a micro-cell architecture, has muchlarger per unit traffic coverage for an area than existing cellular telephone systems. PHS can
implement a high-quality voice equivalent to that of existing wired telephone through the employmentof 32 kbps ADPCM voice coding, and it can also provide high-speed multimedia services.
2.1 Application of Cordless Telephone Concept to Public Mobile Communications
PHS is a second generation cordless telephone system proposed as a successor to the conventional
analog cordless telephones. Conventional analog cordless telephony has been applied to small-scale
private communication systems for use in homes or office buildings. PHS does not simply digitize its
wireless transmission system but also employs a wireless access system to attain high traffic
performance. PHS handles incoming and outgoing calls during traveling through the use of handoverand location registration features during talking to provide services equivalent to those of existing
cellular telephone systems.
There features enable using PHS not only as a cordless telephone system inside homes or offices but
also to enjoy public mobile communication services widely outdoors. Although the micro-cell system
has high traffic performance, it is not applicable to high speed mobile communications because
handover is frequently required. PHS is designed mainly for mobile communications in urban areas atwalking speeds.
2.2 Concept of PHS and Existing Public Network Interface
Conventional mobile communications require an exclusive network. Although this complex network
allows communication while traveling at a high speed, there is much complexity in the location
registration, handover and other features. In addition, conventional mobile communications require asignaling system that is delegated to perform complicated control operations.
On the other hand, PHS is designed to be directly used and operated in an ISDN network that
accommodates ordinary wired telephones, since PHS is considered an extension of the conventional
cordless telephone for home use. The location registration and other mobile features are controlled byusing the ordinary ISDN signaling system. The control is implemented by the Intelligent Network(IN) features incorporated in the network. This concept allows establishing a large-scale mobile
communication network with a smaller initial investment.
2.3 PHS Features(1) Sharing the PS by different applications
PHS allows both outdoor public communications and indoor private communications in homes andoffices through a single CAI. The dynamic channel assignment of PHS enables sharing a single
frequency band for a variety of purposes. The use of the same PS for many different applications is
not only a great big advantage for users but also reduces the manufacturing cost because the numberof PS product types is decreased. The PS sharing feature is expected to implement future services
including the one-number service for different applications.
(2) Frequency sharing among multiple common carriers
Another feature of the dynamic channel assignment function allowed by PHS is that a single
frequency band can be shared by several operators (common carriers). The feature enables highly

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efficient use of frequencies. Frequency sharing eliminates maldistribution of frequency usage due tothe scale difference of each operator's operations or the difference of service areas among operators.
PHS employs a full Time Division Duplex (TDD) system to facilitate frequency band expansion as
the demand for the future traffic increases.
(3) Multimedia communications
PHS employing the 32 kbps ADPCM voice coding technology can transmit 9.6 kbps modem signals
similarly to the regular wired telephone system. PHS can also perform 32 kbps bearer communication
via the regular ISDN. In addition, 64 kbps bearer communication is being standardized by ARIB.
2.4 Implementation of Wireless Local Loop Based on PHS Technology
The demand is increasing for a wireless local loop to connect calls to the fixed telephone terminal in a
subscriber's premises using a wireless access system instead of the normal wired subscriber line. The
particularly high traffic performance of PHS is an ideal system for a wireless local loop to substitutethe drop wire portion of the subscriber cable. Implementing a wireless local loop requires providing anormal fixed telephone terminal with an interface similar to that provided by the wired subscriber
communication system. The PHS MOU technology working group is defining the interface suitable
for the wireless local loop.
3. Basic Technology of PHS
3.1 PHS Wireless Transmission System
Table 3-1/A-GNO.00 outlines the PHS wireless transmission system. The PHS MOU TechnicalDocument B-IF 1.00 Series will detail the contents of this section.

Table 3-1/A-GN0.00 PHS Air Interface
Item
Frequency Band
Carrier Spacing
Access Method
Time Slots / RF Carrier
Modulation Method
Transmission Rate
Voice Coding
Transmit Power

PHS Air Interface Specifications
1895.15-1917.95MHz(77channels)
300kHz
TDMA-TDD
4
S/4 shift QPSK
384kbps
32kbps/ADPCM
PS:10mW or less, CS:500mW or less

(1) Micro-cell system
PHS employs a micro-cell system with a cell area limited by the CS transmission output of up to 500
mW and PS output of up to 10 mW. The purpose of the micro-cell system is to provide sufficienttraffic performance with fewer frequency bands by increasing the frequency reuse. The employmentof the micro-cell system assures voice quality equivalent to that of the wired telephone system byusing a wide band channel capacity of 32 kbps. The wireless section employs a 4-channel Time

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3

Division Multiple Access/Time Division Duplex (TDMA/TDD) system, and a physical bit rate of 384kbps. This secures satisfactory transmission quality without the provision of the automatic equalizer,
so that the costs of the PS and the CS can be reduced. The modulation system is •/4 shifted
Quadruple Phase Shift Keying (QPSK) for highly efficient use of frequencies.

(2) Multiple access (TDMA/TDD) system
Figure 3-1/A-GNO.00 shows an overview of the PHS wireless transmission frame.
The PHS wireless transmission frame is structured by a 4-channel TDMA system. The frame isimplemented in full duplex communication by the downward link from the CS to the PS and the
upward link in the opposite direction that are multiplexed by the TDD system. The first channel of
the TDMA frame is used as the control channel. A particular frequency is assigned as for the control
channel of a particular public communication operator, and the same channel is used at all the Cell
Stations (CSs) and Personal Stations (PSs) accommodated in this operator's network. In the callprocessing of this system, the control information is first exchanged over the control channel, andthen one of the remaining three traffic channels (time slots) is assigned for user communication.
Which one of the traffic channels, and which frequency channel should be used is specified over thecontrol channel. The TDD system may complicate communication control such as CS synchronization but it reduces the problems of handling increased traffic in the future, since the PHS service
frequency band can be easily expanded to both up- and down-ward even after inauguration of service.

TDMA Frame
TX

CS

CCH

RX
TCH2

TCH1

TCH3

PS2
PS3

RX
TCH1

TCH2

TCH1

CCH

TCH1

TX

CCH
CCH

CCH

TCH2

TCH2
CCH

CCH

TCH3

TDMA-TDD:Time Division Multiple Access-Time Division Duplex
CCH:Control Channel , TCH:Traffic Channel , TX:Transmit , RX:Reception

Figure 3-1/A-GN0.00 Air Interface Physical Frame Structure

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TCH3

Upward Link

Downward
Li k
PS1

CCH

TCH3

(3) Fixed Frequency Control channel
Communication control such as incoming/outgoing call notification, number information delivery,
and authentication is required before commencing actual talk in the wireless communication system.
In PHS, particular frequency channels used exclusively for communication control are specified, andthe frequencies are shared by all the CSs and PSs within the same system. This enables the PS toeasily exchange the control information with the CS. This eliminates the need for searching for acontrol channel frequency each time the PS moves from a cell to another adjoining cell. This in turnfacilitates handover control and drastically reduces battery consumption for waiting for a call.
Sharing the same frequency band by different operators, or by different private and public
communication applications requires independent control channel frequencies to be assigned forparticular applications.
(4) Dynamic channel assignment system
The control channel designates a traffic channel with the least interference after checking the usage
conditions of traffic channel time slots and frequencies when assigning a time slot and a frequency.
Thus, the actual traffic channel time slot and frequency vary with each call. This system, referred toas the dynamic channel assignment system, eliminates the need of prior assignment of frequencies
used by the CS unlike the ordinary cellular system, enabling the frequencies to be used extremely
efficiently. This system features not only the increased efficiency but also increased flexibility andexpandability in the system design through installation of an overlapped new cell on the existing cellto meet increased traffic demand. Terminal sharing by multiple operators and PS sharing for public
and private communications can only be implemented by the application of the dynamic channel
assignment technology.

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5

3.2 Network Technology
3.2.1 Network Configuration
The PHS network employs ISDN signaling for network interface and utilizes the IN functions in the
network. These features enable the use of sophisticated functions such as location registration,
paging, handover, authentication, and roaming that PHS services require. The contents of this section
are detailed in the PHS MOU Technical Documents B-NWO.00 Series. Figure 3-2/A-GNO.00 showsa configuration of the PHS network integrated with IN-structured PSTN/ISDN. The functions of its
components are outlined below.
(1) Transit Switch: Has the connecting and switching functions with the other network to allow all
the communications with the other network to be performed through the transit switch.
(2) PHS Switching Center (PSC): Performs the processing functions such as paging, mobile
switching, and handover in addition to the normal switching functions.
(3) Service Control Point (SCP): Uses the database to perform location registration, authentication,and location search of call receiving PS. The SCP is connected with Toll Switch through Common
Channel Signaling (CCS) Network.
(4) CS: Provided with the digital wireless communications functions with the mobile PS, and the
ISDN interface with the network.
(5) PS: The terminal possessed by the subscriber to perform digital wireless communications with
the CS.

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CCS No.7
INAP
(IF4)

SCP

Other
serviceprovider

SCP
LI

LI
CCS Network(STP)

Other
Network

Transit
SWITCHLOCALSWITCHCCS No.7
ISUP
(IF3)

LOCAL
SWITCH
PSC

O&M

BC

CSC

DSS1
(IF2)

CS

CS

CS

CS

CS

RCR STD-28
(IF1)
PS

PS
Public PHS service area

PSC
LI
CS
PS
BC
CSC
O&M
STP
SCP

: PHS Switching Center: Location Information: Cell Station: Personal Station: Billing Center: Customer Service Center: Operation and Maintenance Center: Signal Transfer Point: Service Control Point

Figure 3-2/A-GN0.00 PHS Network Configuration

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3.2.2 Function Allocation
Implementing the mobile communications requires the switching functions particular to mobile
communications that were not possessed by the conventional wired telephony. The following
describes these functions briefly.
(1) Location Registration
Location registration means the processing of the constantly maintaining and updating the moving PS
location information. The purpose of this processing is to inform the network database of the location
information on the called PS in advance because it is necessary to search for the called PS and ring it
up when a call is terminating at the particular PS.
(2) Paging
An incoming call message is sent to all the CSs in the paging area having the area code included in
the called PS location information. Then the incoming call message is sent from each CS to its served
PSs.
(3) Handover
The handover means the processing of maintaining a call in the talking state as the talking PS moves
from a radio zone to another using a new CS in the visited zone. The handover function isparticularly important for PHS since it uses a micro-cell system.
(4) Authentication
Authentication means the function of preventing an unauthorized user from using communication
services illegally. Authentication determines whether or not a PS has subscribed to the requested
communications service provider when the terminal makes a connection request such as callorigination, call termination, location registration, or handover.
(5) Roaming
Roaming is the service that enables a PHS PS to obtain an incoming or outgoing connection inanother network in the same manner as if it was in the original network.
3.2.3 Network Interface
Detailed information can be sent and received between the CS and the network through the use of acontrol channel to a CS to be connected via the ISDN interface. This provides sophisticated functions
required for implementing PHS services, such as location registration, paging, handover,authentication, and roaming as well as the supplemental services inherent to ISDN.
The following outlines the major functions that the ISDN interface provides.
(1) Terminal number notification
This function is to send and receive the PS identification numbers between the digital network and theCSs when originating and terminating a call. It is implemented by designating the PS numbers forcalling and called number information elements.
(2) Multiple interface call termination
An area of multiple CSs is used generally as the unit of location registration in order to reduce the8

A-GN0.00-01-TS

traffic load of location registration information transfer. It is therefore necessary for the network sideto perform incoming call processing simultaneously for multiple interfaces for an incoming call.
(3) D-channel sharing
D-channel sharing means the function of performing call control on the information channels (Bchannels) of multiple physical circuits with a signaling channel (D-channel) of a single physicalcircuit. This function reduces the CS cost and group CS installation in the case of installing multiple
physical circuits to the same CS.

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4. Areas of Application of PHS
4.1 Public PHS
This section outlines public PHS applications. The PHS MoU Technical Document B-GNO.00
details the contents of the section.
Although PHS may not be suitable for mobile communication while traveling at high speed, it does
have high traffic performance per unit area as described before. It is more suited for application to theservices for pedestrians walking in dense populated areas in large cities. In Japan, PHS has
penetrated into user groups such as students and housewives whose daily traveling range is relatively
limited. Newly subscribers seem to purchase PHS PSs instead of fixed telephone terminals to usethem not only during traveling but also in their homes.
Public PHS is classified by its system configuration into the type such as the public network utilizing
type and the independent network type. Figure 4-1/A-GN0.00 shows a conceptual diagram of them.
The public network utilizing type will utilize the existing PSTN switching functions and the IN
functions on a nationwide scale to provide such functions as location registration, mobile management, authentication, and message accounting that are required for PHS control. In some case, thePHS operator may accommodate their own database or management facilities. In this case, two database are used with functional sharing depending to managing items. On the other hand, theindependent network type will implement PHS in an independent switching network to connect theexisting network via Inter-Network Interface. All of database and management facilities are
implemented within the independent network.

DB

Functional
Share

PSTN/ISDN

PSTN/ISDNDBInter-Network Interface
PHS
Operator
CS

CS

Independent
Switching
NetworkCS

Public Network Utilizing Type

CS

DB

PHS
Operator

Independent Network Type

Figure 4-1/A-GN0.00 Public PHS Network Type

4.2 PHS Wireless Local Loop Access System
This section outlines the applications of the wireless local loop based on PHS. The PHS MOU
Technical Document C-GNO.00 details the contents of this section. Figure 4-2/A-GN0.00 illustrates awireless local loop configuration using PHS. The wireless local loop connects a conventional

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A-GN0.00-01-TS

telephone terminal or FAX, as Terminal Equipment (TE), to provide its user with the same ease ofoperation as before. Interface between TE and WLL Subscriber Unit (WSU) is almost equivalent toconventional wired telephone interface. At the same time, PHS WLL can accommodate WLL
Personal Station (WPS) for limited mobile application as well. Interface between WLL Cell Station(WCS) and WSU or WPS (WIF2) is based on RCR STD-28 CAI. The wireless local loop connectswith the existing Public Switched Telephone Network (PSTN) or ISDN via WLL Access Controller(WAC), which implements the functions including location registration and authentication that are
required for the wireless section of PHS WLL. PHS WLL will use a standard interface such as V5.2
to work with the existing network at WIF3.

WIF2

WIF1

PSTN/ISDN

WSU

TE
WIF2

WCS

WAC

TE
WSU
WPS
WAC
SN

WPS

WIF3

SN

: Terminal Equipment: WLL Subscriber Unit
: WLL Personal Station: WLL Access Controller: Service Node

Figure 4-2/A-GN0.00 PHS WLL Architecture

4.3 Private PHS
For further study
4.4 Access System to PLMN
For further study
5. Outline of PHS MoU Technical Documents
This section outlines PHS MoU technical documents. PHS MoU technical documents consist ofTechnical Specifications (TSs) and Technical Reports (TRs). Technical Specifications are documents
which provide specifications related to PHS. On the other hand, Technical Reports are document
which provides technical information related to PHS.
Document number structure of PHS MoU technical documents and the meaning of each element are
as follows.

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Document number structure : A-BBX.XX-CC-DD
A : Segmentation of documents
A:
PHS General Description
B:
PHS Public systemC:
PHS Wireless Local Loop System (PHS-WLL System)
BB : Sub-segmentation of documents
GN : General
SV: Service
IF : Interface
IW : Internetworking
HI : Human Interface
X.XX : Numeral number
CC : Version number
DD : Document TypeTS : Technical Specification (TS)TR : Technical Report (TR)The elaborated Technical Specifications and Technical Reports are listed in A-GN2.00-cc-TR“Document List of PHS MoU Technical Specifications and Technical Reports”.

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ABBREVIATIONS
ADPCM
ARIB
CAI
CCS
CS
IN
NNI
PIAFS
PHS
PS
PSC
PSTN
SCP
TDD
TDMA
TE
UNI
WAC
WCS
WLL
WPS
WSU

Adaptive Differential Pulse Code Modulation
Association of Radio Industries and Businesses
Common Air Interface
Common Channel Signaling
Cell Station
Intelligent Network
Network-Network Interfaces
PHS Internet Access Forum Standard
Personal Handy-phone System
Personal Stations
PHS Switching Center
Public Switched Telephone Network
Service Control PointTime Division Duplex
Time Division Multiple Access
Terminal Equipment
User-Network Interface
WLL Access Controller
WLL Cell Station
Wireless Local LoopWLL Personal Station
WLL Subscriber Unit

Note
Each group of terms written below as an example is used in this document without strict definition.
The terminology is to be discussed by the TWG (Technical Working Group) under the PHS MoUGroup.
1. Digital cordless Telephone (System)
Mobile Communication System
2. PBX WirelessWireless PBX
3. Home Cordless
Home Cordless Telephone (System)

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