PTT : PushPTT : Push--ToTo--TalkTalk(Push to talk over Cellular)(Push to talk over Cellular)

전영희전영희 ((yhjeon@xener.comyhjeon@xener.com))

제너시스템즈제너시스템즈 기술연구소기술연구소

CONTENTSCONTENTS

l PTT 개요l 시장 동향

l OMA (Open Mobile Alliance)l PoC (Push to talk over Cellular)l References

What is PTT ?What is PTT ?

PTT PTT 개요개요 (1)(1)

Wireless Network

Member B

Member A

Member C

Member D

Member E

PTT PTT 개요개요 (2)(2)

n Push-To-Talk (PTT)l 휴대폰 + 무전기

l 단방향음성메시징서비스

l 특정버튼을누른채로일대일혹은일대다그룹통화가능

n Key Featuresl Half-duplex Voice Communicationl Rapid call setup§ 1 to 1 § 1 to many

l Easy to Usel Instant Communication & Presencel Will be a early application in VoIP technology

시장시장 동향동향 (1)(1)

n 해외사업자 (미국)

n도입검토중2004 ?AT&T Wireless

n Ready-Linkn Motorola PoC + Core Mobility + Dynamicsoftn CDMA 1xRTT Network

2003.10Sprint PCS

n Push to Talkn Motorola PoCn CDMA 1xRTT Network

2003.8Verizon

n도입검토중2004 ?Cingular

n Direct Connect n Motorola iDENn가입자 1,200 만

1996Nextel

관련사항도입시기사업자

시장시장 동향동향 (2)(2)

n 해외사업자 (유럽)

l PTT 서비스에대한시각§ 음성서비스수익감소우려

§ SMS 서비스대체가능성여부§ PTT 단말확보

n PTT 시범서비스예정2004 ?mmO2n서비스시험중?Vodafone

n Talk Nown올해 100만명목표

2004 .1Orange

관련사항도입시기사업자

시장시장 동향동향 (3)(3)

n 국내사업자l TRS 사업자§ KT 파워텔, 서울 TRS 등을포함 6개사업자§ 가입자 30만정도

l CDMA-PTT§ 2004.3, SK텔레콤, KTF, LG 텔레콤이 PTT 도입을위한공동협의체구성실무협의

– 공동기술표준마련을통환호환성확보– 상호망연동– 과금및정산체계마련

§ 각사업자별로서비스도입검토중

§ 기존 TRS사업자와의역무조율필요

시장시장 동향동향 (4)(4)

n PTT 사용자예측l 출처: IMS Research, October 2003l 단위: 천명

370,091141,331104,07554,56329,73216,32712,51411,548Worldwide Total

88,45912,78112,92513,00713,00812,82512,36511548iDEN

85,05236,45425,83013,9236,9231,7731490cdma2000 1xRTT / 1xEVDO

196,58192,09665,32027,6339,8011,73000GSM / GRPS / EDGE / W-CDMA

SUM2008200720062005200420032002

OMAOMA(Open Mobile Alliance)(Open Mobile Alliance)

What is OMA ?What is OMA ?

n Open Mobile Alliancel In June 2002, the mobile industry set up OMAl Integrated organizations into OMA§ Location Interoperability Forum (LIF)§ SyncML Initiative§ Multimedia Messaging Interoperability Process (MMSIOP)§ Wireless Village§ Mobile Gaming Interoperability Forum (MGIF)§ Mobile Wireless Internet Forum (MWIF)

n OMA’s Visionl “No matter what device or operating system you have, no

matter what service you have, no matter what carrier you use, you can communicate, access and exchange information.”

OMA in the industryOMA in the industry

Others

3GPP 3GPP2

IETF

W3C

OMA

CDG

GSMAOthers

RequirementsStandardizationMobile DomainWireline Domain

Tran

spor

t Le

vel

(Cor

e, R

adio

, Te

rm)

App

licat

ion

Leve

l

(Ser

vice

, En

able

s)

Desire common boundaries and clarity of roles

Various candidatetechnologies to

consider

Need to harmonizedisparate

requirements

OMA OrganizationOMA Organization

Board of Directors

Operations andProcess

Committee

Release Planning &ManagementCommittee

Interoperability

DeviceManagement

Location

Browser andContent

Requirements

DevelopersInterest Group

Mobile WebServices

Presence andAvailability

Security

Game Services

MobileCommerce and

Charging

Push to TalkOver Cellular

Architecture

DataSynchronization

Messaging

Technical Plenary

P o CP o C

PoCPoC SpecificationSpecification

n Push to talk over Cellular (PoC)l defines the implementation of Push-to-talk servicesl assures operability between infrastructure and handsets from

different vendors

n PoC is divided in 6 main areasl User Requirementsl Architecturel Signaling Flowsl Group/List Managementl User-plane specification – Transportl User-plane specification – (E)GPRS / UMTS

PoCPoC PhasePhase

n PoC 1 – detailed multi-vendor specificationl Prepared by: Ericsson, Motorola, Nokia and Siemens,

submitted to OMA August 2003l Contains : architecture, group and list management, signaling

flows, GPRS user plane & transport protocols and user requirement

n PoC 2 – additions to the PoC 1 specificationl Contains : Network to network interconnect, presence

n Ratificationl Contains : Final adjustments

PoC phase 1

PoC phase 2

OMA PoC workgroup

2003 (Aug) 2004 2005

OMA-PoCRatification

PoCPoC(Specification)(Specification)

Network ArchitectureNetwork Architecture

PoC

Client

PoC

Serv

er

A C

E S

S

N E

T W

O R

KGLMS

SIP/

IP C

ore

Im

IsIf

It

IkPresence

Server

Ipl

Ips

Rem

ote

PoC

Net

wor

k

In

Itn

GLMS Management/Administration

Ie

Igs

Interface ProtocolsInterface Protocols

PoC

Clie

nt

Group List Management Server

SIP/IP Core (CSCF/HSS)

PoC Server

XML/HTTP/TCP

SIP/UDP

RTP/RTCP/UDP

Im: manage groups and lists

Is: manage call setup andsession control

It: transport talk bursts and implement floor control

Functional Entities (1)Functional Entities (1)

PoC ClientPoC Client

- Session Initiation, Participation & Termination

- Registration & Authentication in Service Infra

- Generates talk bursts / Reproduces received talk bursts

- Support floor control procedures

- Provides access to PoC group lists

- Provides access to service entity on presence conditions

Functional Entities (2)Functional Entities (2)

PoC ServerPoC Server

- Centralized session handling & media distribution

- Centralized floor control functionality

- Policy enforcement for participation in group sessions

- Provides participants information

- Collects & provides centralized media quality info.

- Centralized charging reports

Functional Entities (3)Functional Entities (3)

GLMSGLMS

- List management operation to create, modify,

retrieve and delete groups & lists

- Storage for groups & lists

- Notification of modification to lists

Functional Entities (4)Functional Entities (4)

SIP/IP CoreSIP/IP Core

- Routes the SIP signaling between PoC Client & Server

- Discovery and address resolution services

- Supports SIP compression

- Performs authentication & authorization of PoC Client

- Maintains the registration state

- Provides charging information

Functional Entities (5)Functional Entities (5)

Presence ServerPresence Server

- Maintains the Presence Status of PoC Clients

- Publication of Presence Information on PoC Clients

- Watching & Fetching of Presence Information

- Authorization for watchers of PoC Client Presence Info.

- Authorization of presence list subscriptions

- reachable, busy, do not disturb, unreachable, offline

List Management & DNDList Management & DND

n List Managementl Contact lists§ addressable entities (PoC Clients)§ attributes : id, display name, type, URI, …

l Access lists§ Controlling the session requests from other users of groups§ types : reject lists & accept lists§ attributes : URI/wildcard(*), display name, …

l Group list§ PoC specific groups§ attributes : id, display name, talk session type, membership, …

n Do-not-Disturbl block all incoming talk session requestsl no effect on the sending and delivery of the talk alerts

List Management FlowList Management Flow

n Protocol : HTTP Version 1.1l Objects § DnD flag § Answer mode flag § Contact lists § Access lists § Groups

UE#1 GLMS

HTTP GET(get_list_of_buddy_list)

HTTP 200 OK

List Management FlowList Management Flow

GET http://glms.operator.com/script?action=get_list_of_buddy_list&owner=sip%3Aronald.underwood%40umts.uk HTTP/1.1

Authorization: Digest username="u29502566", realm="glms.umts.uk", nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093",uri="http://glms.operator.com/script?action=get_list_of_buddy_list&owner=sip%3Aronald.underwood%40umts.uk",response="e966c932a9242554e42c8ee200cec7f6",cnonce="dcd99agsfgfsa8b7102dd2f0e8b1",opaque="5ccc069c403ebaf9f0171e9517f40e41",qop=auth-int,nc=00000001

HTTP/1.1 200 OKContent-Type: application/buddylists+xml;charset=UTF-8

<?xml version="1.0" encoding="UTF-8"?><buddylists><buddylist uri="sip:ronald.underwood@umts.uk;contact-list=Colleagues" displayname="Colleagues" default="N" type=”user”/>

<buddylist uri="sip:ronald.underwood@umts.uk;contact-list=Family"displayname="Family" default="Y" type=”user”/>

<buddylist uri=”sip:ronald.underwood@umst.uk;contact-list=Groups”displayname=”Groups” type=”group”>

</buddylists>

Basic Communication FeaturesBasic Communication Features

n 1-to-1 communicationn 1-to-many communicationll PrePre--arranged arranged PoCPoC GroupGroupll AdAd--hoc hoc PoCPoC GroupGroupll Chat Chat PoCPoC GroupGroup§ Open chat group§ Restricted chat group

n Instant personal alertl Call back service

11--toto--1 Communication Scenario (1)1 Communication Scenario (1)

n UE#11. Presses the PTT button2. Receives a “beeping” signal when a media channel is

established3. The user starts to talk4. Releases the PTT button5. Receives a “beeping” sound that the floor is taken by the

other user6. Receives speech from the other user7. Receives a beeping sound when the floor is idle again

11--toto--1 Communication Scenario (2)1 Communication Scenario (2)

n UE#2 (auto answer mode)1. Receives a “beeping” sound in the loud speaker2. Listens to the user at UE#1 speech phrase3. Presses the PTT button4. Receives a “beeping” sound that the user can start to speak5. The user talk6. The user releases the PTT button

11--toto--1 Communication Scenario (3)1 Communication Scenario (3)

UE#1 UE#2PoC Server

SIP INVITE

SIP INVITE

SIP 100 Trying

SIP 100 Trying

SIP 200 OK

SIP 200 OK

RTCP Floor Granted

SIP ACK

SIP NOTIFY

SIP 200 OK

Speech/Listening, Floor Control(RTP: Talk burst)

SIP BYE

SIP 200 OKSIP BYE

SIP 200 OK

RTCP Floor Taken

Press PoCButton

Listening

indication

Talk

indication

Floor Control Procedures (1)Floor Control Procedures (1)

n Floor Request at Session Initiation

UE#1 PoC Server UE#2

SIP session establishment with UE#1 SIP session establishment

with UE#2

Talker ID Notification

Press PoCButton

①RTCP: Floor Grant

RTP: media streamRTCP: Floor Taken ID#1

RTP: media stream

②Talk ProceedNotification

③

Floor Control Procedures (2)Floor Control Procedures (2)

UE#1 PoC Server UE#2

Floor Idle

Talker ID Notification

Press PoCButton

①

RTCP: Floor Grant

RTCP: Floor Taken ID#1⑤Talk ProceedNotification ④

n Floor Request

RTCP: Floor Request

③

②

Floor Control Procedures (3)Floor Control Procedures (3)

n Floor Release

UE#1 PoC Server UE#2

Floor Granted : UE#1

Floor Idle Notification

Release PoCButton

①

RTCP: Floor Idle

RTCP: Floor Idle

⑤

Floor IdleNotification ④

RTCP: Floor Release③

②

⑥⑦

RTP: Last Burst PacketRTP: Last Burst Packet

Floor Control Procedures (4)Floor Control Procedures (4)

n Floor Revoke

UE#1 PoC Server UE#2

Floor Granted : UE#1

Floor Idle Notification

Floor RevokedNotification ①

RTCP: Floor Idle

RTCP: Floor Idle

⑤

Floor IdleNotification

④

RTCP: Floor Revoke

③②

⑥

n Protocol : RTCP

n Control Methodl Floor Idlel Floor Releasel Floor Request

Floor Control MethodFloor Control Method

0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|V=2|P| subtype | PT=APP=204 | length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| SSRC |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| name (ASCII) |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| application-dependent data ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

l Floor Grantl Floor Takenl Floor Deny

l Floor Revoke

PoCPoC Performance RequirementsPerformance Requirements

MOS>=3 for BER<=2%Voice quality

n Group list / Buddy list / Do not disturb

< 10 secondsto receive Ack

List changes

n From time spoken to time heard

< 1.6 seconds(95% confidence level)

Voice burst delay

< 4 secondsto hear voice

Join a group in progress

n Auto answer< 4 secondsCall setup delay

n For sender to know if delivered< 5 secondsAlert delay

NoteRangeMetric

ReferencesReferences

l PoC User Requirements; PoC Release 1.0l PoC Architecture; PoC Release 1.0l PoC List Management and Do-Not-Disturb; PoC Release 1.0l PoC Signaling Flows; PoC Release 1.0l PoC User Plane; Transport Protocols; PoC Release 1.0l PoC User Plane; (E)GPRS Specification; PoC Release 1.0l OMA-RD_PoC-V1_0-20031204-D, Requirementsl OMA-AD_PoC-V1_0-20040407-D, Architecturel PUSH to TALK World Summit, 29 March ~ 31 March 2004l 김도경, 해외 이동통신업계의 PTT 도입현황및시사점, 정보통신정책제16권 6호통권 344호