1 3gpp and ims. 2 gprs operation and pdp contexts ms (mobile station) 는 gprs attach 절차로 sgsn...

1

3GPP and IMS

2

GPRS Operation and PDP Contexts

MS (mobile station) 는 GPRS attach 절차로 SGSN 에 알림 . Attach 되면 , Packet Data Protocol (PDP) context 를 활성화시킴 . GPRS 에서는 PDP Context Activate message 에 있는 QoS profile

과 자원의 가용도 (availability) 에 근거해서 admission control 을 수행함

PDP context: PDP: Network layer protocol, is a virtual connection between the MS and G

GSN Includes an identifier (e.g., IP), QoS parameters etc. Establish a GPRS “tunnel” between GGSN and SGSN using GPRS Tunneli

ng Protocol (GTP) QoS profile (to each PDP context) consists of:

QoS Profile 은 QoS attribute ( 속성 ) 의 집합임 Delay: acceptable transfer time from one edge of GPRS system to the other

edge Service precedence: drop preference during network abnormalities Reliability: tolerance for error rates and need for re-transmission Mean throughput, peak throughput: specify average rate and maximum rate

3

PDP Contexts

PDP Context 는 Parameter 들의 집합으로 , 단대단 접속을 설립하는데 필요한 모든 정보로 구성됨

PDP Type PDP address type (IPv4 or IPv6) QoS profile request ( 이용자가 요청하는 QoS parameters) QoS profile negotiated ( 망과 협약된 QoS parameters ) Authentication type DNS type

PDP Context Activate 가 성공한 경우 : SGSN maps QoS profile into appropriate Radio Link Control (RLC)/Medium

Access Control (MAC) priority level to indicate the use in uplink access SGSN also maps accepted QoS profile into an appropriate IP QoS procedur

e (e.g., marking in Differentiated Services for QoS provisioning over core networks

4

BSS

BTS BSC with PCU

HLR AUC

Public ISP

Corporate

PSTN

ISDN

SCP

GMSC

RADIUS

4. SGSN notifies terminal that it is attached, enters READY state

4

1

1. MS send a requests to the SGSN to be attached to the network. Capabilities are stated multislot, ciphering algorithms, CS and/or PS required

2

2. Authentication between terminal and HLR

3

3

3. Subscriber data downloaded to MSC/VLR and SGSN

GPRS Attach Procedure

5

MT

BSS

BTS BSC with PCU

HLR AUC

Public ISP

PSTN

ISDN

SCP

GMSC

DNS

RADIUS

2

2. SGSN validates request against subscription information downloaded from HLR during GPRS Attach 3

3. APN sent to DNS, IP address(s) of suitable GGSNs returned

4

4. Logical connection using GTP created between SGSN and GGSN.

5

Juniper.net

1

1. MS requests PDP context activation type, APN, QoS

juniper.net

5. IP address allocated to Mobile via local pools, RADIUS or DHCP- from operators own address range, or other- fixed addresses held in HLR- Proxy to RADIUS server in ISP or corporate domain

Juniper.net

PDP Context Activationaka “how is the connection set up?”

6

PDP Context Procedures

MS initiated

GGSN initiated

MS BSS SGSN GGSN

Activate PDP Context Request Create PDP Context Request

Create PDP Context Response

Activate PDP Context Accept

Activate PDP Context RequestCreate PDP Context Request

Create PDP Context ResponseActivate PDP Context Accept

Packets from ext. nw.

PDU notification req.

PDU notification resp.

Request PDP Context activation

7

…

…

PDP Context Activation

8

Transport of IP packets

ApplicationServer

GGSNTerminal SGSNUTRAN

GTP-UGTP-U

User IP (v4 or v6)

Radio Bearer

IP tackets are tunnelled through the UMTS/GPRS network (GTP – GPRS tunneling protocol)

L1

RLC

PDCP

MAC

IPv4 or v6

응용

L1

RLC

PDCP

MAC

ATM

UDP/IPv4 or v6

GTP‑U

AAL5

Relay

L1

UDP/IPv4 or v6

L2

GTP‑U

IPv4 or v6

Iu-PSUu Gn Gi

ATM

UDP/IPv4 or v6

GTP‑U

AAL5

L1

UDP/IPv4 or v6

GTP‑U

L2

Relay

L1

L2

IPv4 or v6

[Source: 3GPP]

9

IP Transport: Concepts

PDP contexts activation 데이터 전송전에 UE 에 의해서 수행됨 APN 사양과 traffic parameters GGSN 은 IP 주소를 UE 에 전달 set-up of bearers in SGSN and GGSN activation of multiple PDP contexts possible

Access Point Names (APN) APN 은 외부망의 식별자 (logical Gi interface of GGSN) PDP context activation 과정에서 , SGSN 은 DNS 에 문의하여 , 단말이 요청한 APN

을 지원하는 GGSN 을 찾아냄 . DNS 응답은 GGSN 주소 목록을 갖고 있으며 , SGSN 은 이들 중에서 라운드 로빈

방식에 의해 하나의 주소를 선택함 . Traffic Flow Templates (TFTs)

A set of packet filters (source address, subnet mask, destination port range, source port range, TOS (IPv4), Traffic Class (v6), Flow Label (v6)

GGSN 이 사용하는 것으로서 , 외부 망에서 입력되는 IP 패킷에 적절한 PDP context 를 할당하는데 사용됨 .

GPRS Tunnelling protocol (GTP) 모든 UE 에 대해서 , 신호를 위해서 한 개의 GTP-C tunnel 이 , 이용자 데이터

전송을 위해서 복수개의 GTP-U tunnels 이 설립되는데 , GTP-U 는 PDP context (i.e., session) 마다 하나임 .

10

GGSN

IP Transport: PDP Context & APNs

Terminal SGSNGGSN

PDP Context X 2 (APN X, IP address X, QoS 2)

PDP Context X 1 (APN X, IP address X, QoS 1)

ISP X

ISP Z

ISP Y

PDP Context Z (APN Z, IP address Z, QoS)

PDP Context Y (APN Y, IP address Y, QoS)

AP

N Y

AP

N Z

AP

N X

Same PDP (IP) address and APN

PDP Context selectionbased on TFT (downstream)

[Source: 3GPP]

11

IP Backbone DiffServ 망

GTP TunnelingOver IP

DiffServ orATM AAL5

GTP TunnelingOver IPDiffServ

QoS Framework in UMTS R5/R6

AF PDF

UMTS BSRAB Iu BS Backbone BS

IP BS Manager

UMTS IP QoS Domain

Policy-based Framework

IP QoSParameters

QoSEnforcement

GateFunction

Service RequestAuthorization Token Service Provision with QoS

PDP QoS 로 변환IP BS Manager

Gq

Go

외부 IP QoS Domain

RNC

UTRAN

GERAN

12

3GPP Releases

Release '99 1999 년 12 월에 제정완료 UTRA 정의 및 많은 초기 기능들이 정의됨 .( 초기 3G 의 기본이 됨 )

Release 4 2001 년 3 월에 제정 . R99 의 개선과 핵심망에서 제어평면과 이용자

평면이 분리됨 . low chip rate TDD mode (TD-SCDMA) 정의됨 .

Release 5 2002. 년 3 월 제정 R4 의 개선과 함께 ,

• IMS - IP-based Multimedia Services

• HSDPA - High Speed Downlink Packet Access

Release 6 2004 년 제정 IMS 의 2 단계로서 , 멀티미디어 통신을 위한 다양한 기능을 포함함 .

13

3GPP 패킷도메인 진화 과정 요약

Release 4 Release 5 Release 6

CapabilityExchange

NONE UAProf UAProf

Video Codecs

H.263 P0L10 (M), P3L10 (O)MPEG-4 VSP L0 (O)

As in Release 4 As in Release 4H.263 P0 L45 (O)MPEG-4 VSP L 0b (0)H.264 Full Baseline (O)

Audio & Speech Codecs

AMR-NB & WB (M)MPEG-4 AAC LC, LTP (O)

As in Release 4 As in Release 4AMR-WB+ or AACPlus (O)

Media File Format

3GPP File Format (.3gp).amr

As in Release 4ISO Base Format Conformance (M)Timed-text (O)

As in Release 5Different 3GP file profiles (server, MMS, progr. downloadable, generic)(O)DRM (O)

Session Establishment

RTSP (M)SDP (M)HTTP (O)

As in Release 4 As in Release 4Media Alternatives in SDPMetadata signalling in SDP (O)MBMS - FLUTE (M)

Data Transport

RTP/RTCP (M) As in Release 4Progressive Download (O)

As in Release 5MBMS Download (M)DRM (O)SRTP(O)

QoS NONE (only if network provied QoS)

As in Release 4 Additional RTSP & SDP level signalling (O)QoE Protocol (O)RTCP extentions (O)

Rate Control

NONE Annex.G (video only)

As in Release 53GPP Rate Adaptation (O)

14

IMS 에 의한 음성통신서비스 사례

비교 :R99 인 경우 회선교환방식으로 음성제공

IMS:

12.2kbps AMR speech3.4kbps Signalling

SF-128

Uu

Uu

UTRAN PSDomain

IMS PSDomain

UTRAN

Session control Signaling (SIP / SDP)

Media ( RTP)

Real Time Media Control (RTCP)

UE UE

RRC+NAS

SF-??

Source: R2-032164

15

IMS 의 음성통신 프로토콜 스택

Source: R2-032166

ROHC Comp

ROHC Decomp

PDCP Entity#1 PDCP - SAP

RAB/RB #1

UDP

SIP/SDP

IP

PDCP

RLC UM

MAC - D

Physical Layer

RLC AM

MAC - D

RTCP1 RTP

DTCH#1

DCH#1

RAB/RB #3

RLC UM

MAC - D

RLC AM RLC AM RLC AM

SRB#1 SRB#2 SRB#3 SRB#4

DCH#3 DCH#4

DTCH#3 DCCH

RLC UM

MAC - D

RLC AM RLC AM RLC AM

SRB#1 SRB#2 SRB#3 SRB#4

DCH#3 DCH#4

DTCH#3 DCCH

ROHC Comp

ROHC Decomp

PDCP Entity#2

RAB/RB #2

RLC UM

MAC - D

DTCH#2

DCH#2

PDCP - SAP

UDP

IP

UDP

IP

AMR

16

R5 참조구조

SIP

IM SubsystemApplicationsand

ServicesMultimedia

IPNetworks

CS Domain-or-

PSTN-or-

Legacy-or-

External

PS Domain

HSS

R-SGW

CSCF

CSCF

GGSN

MRF-CSCP

MGCF

MGW

SGSN

Cx

Sh

Sc

Gr

Mm

Mw

Mc

Gc

Mg

Gn

BGCF

T-SGW

BGCFMi

GoGm

SLF

Dx

AS

AlternativeAccess Networks

„Gi-Cloud“

PCF

OSA-SCS

IM-SSF

MRF-PMp

Sr

ISC

SIP

SIP

?

?

Dia

met

er

H248

SIP

H248

CO

PS

TCP/IP/UDP/RTP/…

SIP

?

MAP

CAP SIP

SIP

Mj

SIP TCP UDP

HTTP Others

? ?

SIP

?

R-SGW

CA

PO

SA

UE

UTRANMT TE

Uu IuR

GERAN

Mr

SIP Mk

17

3G Release 6

PSTN

InternetCorporate

IP/AAL5USIM

NodeB

BICC Circuit switchedcall control server

H.248

TDMATMIP

SIP IP MultimediaCSCF

IMS enhancements for conversational

UDP/IP or AAL2

Iu b

Iu ps

Iu cs

RTPor

AAL2

UMTS/GPRS - WLAN Interworking

Definition in R6, implementation sooner

TS 23.221

Multimedia Broadcast/Multicast Service (MBMS) – conferencing etc

Service charging enhancements

18

Establishing IP-CAN for IMS Signalling

PDP Context Activation

Local P-CSCF Discovery

Application Level Registration

Ready for IMS Session

GPRS Attach

Ready for Internet Access and SIP signalling - UE GGSN link setup - UE’s IP address allocation

Find a local SIP server

User-network authenticationand location registration

19

Local CSCF (P-CSCF) DiscoveryDHCP/DNS Procedure

DHCP Server

DHCP query

pcscf.visit1.net, IP addr of DNS

DNS Server

pcscf.visit1.net NAPTR ?

_sip._udp.pcscf.visit1.net

_sip._udp.pcscf.visit1.net SRV ?

pcscf1.visited1.net , port 5060, 5555::aba:dab:aaa:daa

5555::aaa:bbb:ccc:dddvisit1.netvisit1.net

PDP Context Activation ProcedureP-CSCF

???

pcscf1.visited1.netUDP port 5060

5555::aba:dab:aaa:daa

20

Local CSCF (P-CSCF) DiscoveryDHCP Procedure with DHCPv6 options for SIP servers

DHCP Server

DHCP query

P-CSCFs IP address list


PDP Context Activation Procedure

DHCPv6 options for SIP Servers

21

Local CSCF (P-CSCF) DiscoveryGPRS Procedure

Activate PDP Context Request


Obtain IP addressesof P-CSCF

Create PDP Context Request

Create PDP Context ResponseActivate PDP Context Reponse

22

AKA: Authentication and Key AgreementUE SN HE

VLR/SGSN

Authentication data requestMAP Request

Parameter{IMSI or TMSI/P-TMSI}

Generate Authentciation vectors on the

AuC side

HLR/AuC

Authentication data responseMAP Response

Parameter AV[1..n] = {RAND, AUTN, XRES, CK, IK}

Store Authentication vectors AV[1..n]

Distribution of authentication vectors

from HE to SN

Select one Authentication vector AV[i]

User Authentication requestAuthentication Request

Parameter {RAND, AUTN}

Verify AUTN (MAC = XMAC) and generate RES, CK & IK

User Authentication responseAuthentication Response

Parameter {RES}

Compare RES (from UE) with XRES (from AV vector) and select CK & IK

Authentication and Key establishment

23

Application Level (SIP) Registration ProcedureInitial Registration

S-CSCF

P-CSCF

I-CSCF

HSS

Home Network

Visited Network

visit1.net

home1.net

[email protected][email protected]

P-CSCF discovery(pcscf1.visited1.net

UDP port 50605555::aba:dab:aaa:daa )

5555::aaa:bbb:ccc:ddd

PDP Context

DNS Server

REGISTER sip:registrar.home1.net SIP/2.0Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]; From: <sip:[email protected]>;tag=4fa3To: <sip:[email protected]>Contact: <sip:[5555::aaa:bbb:ccc:ddd];comp=sigcomp>;expires=600000Authorization: Digest username="[email protected]", realm="registrar.home1.net", nonce="", uri="sip:registrar.home1.net", response=""Security-Client: ipsec-3gpp; alg=hmac-sha-1-96; spi-c=23456789; spi-s=12345678; port-c=2468; port-s=1357Require: sec-agreeProxy-Require: sec-agree

pcscf1.visit1.net

icscf1_p.home1.net

scscf1.home1.net

DNS:

Cx: User reg. status REGISTER sip:registrar.home1.net SIP/2.0Via: SIP/2.0/UDP pcscf1.visited1.net; SIP/2.0/UDP [5555::aaa:bbb:ccc:dddPath: <sip:[email protected];lr>

REGISTER sip:scscf1.home1.net SIP/2.0Via: SIP/2.0/UDP icscf1_p.home1.net; SIP/2.0/UDP pcscf1.visit1.net; SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]Path: <sip:[email protected];lr>

UE#1

Query: Public User Identity Private User Identity Visited Network IdentifierResponse: S-CSCF list

24

Application Level (SIP) Registration ProcedureChallenge

S-CSCF

P-CSCF

I-CSCF

HSS

Home Network

Visited Network

visit1.net

home1.net


PDP Context

DNS Server

pcscf1.visit1.net

icscf1_p.home1.net

scscf1.home1.netSIP/2.0 401 UnauthorizedFrom: <sip:[email protected]>;tag=4fa3To: <sip:[email protected]>; tag=5ef4Call-ID: apb03a0s09dkjdfglkj49111WWW-Authenticate: Digest realm="registrar.home1.net", nonce=base64(RAND + AUTN + server specific data), algorithm=AKAv1-MD5, ik="00112233445566778899aabbccddeeff", ck="ffeeddccbbaa11223344556677889900"

SIP/2.0 401 UnauthorizedWWW-Authenticate: Digest realm="registrar.home1.net", nonce=base64(RAND + AUTN + server specific data), algorithm=AKAv1-MD5Security-Server: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531


UE#1

Querry: Public User Identity Private User Identity S-CSCF nameResponse: AV list AV=RAND | AUTN | XRES | CK | IK

Cx: authentication

AV selection

25

Application Level (SIP) Registration ProcedureRegistration with Response (Integrity Protected)

S-CSCF

P-CSCF

I-CSCF

HSS

Home Network

Visited Network

visit1.net

home1.net



PDP Context

DNS Server

REGISTER sip:registrar.home1.net SIP/2.0Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]; From: <sip:[email protected]>;tag=4fa3To: <sip:[email protected]>Contact: <sip:[5555::aaa:bbb:ccc:ddd];comp=sigcomp>;expires=600000Authorization: Digest username="[email protected]", realm="registrar.home1.net", nonce=base64(RAND + AUTN + server specific data), algorithm=AKAv1-MD5, uri="sip:registrar.home1.net", response="6629fae49393a05397450978507c4ef1"Security-Client: ipsec-3gpp; alg=hmac-sha-1-96; spi-c=23456789; spi-s=12345678; port-c=2468; port-s=1357Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531Require: sec-agree

Proxy-Require: sec-agree

pcscf1.visit1.net

icscf1_p.home1.net

scscf1.home1.net

DNS:

Cx: User reg. statusREGISTER sip:registrar.home1.net SIP/2.0

REGISTER sip:scscf1.home1.net SIP/2.0Authorization: Digest username="[email protected]", realm="registrar.home1.net", nonce=base64(RAND + AUTN + server specific data), algorithm=AKAv1-MD5, uri="sip:registrar.home1.net", response="6629fae49393a05397450978507c4ef1", integrity-protected="yes"

Cx: Reg. notification

UE#1

Query: Public User Identity Private User Identity Visited Network IdentifierResponse: S-CSCF list

Generation of Responseand Session Key

Authentication

Querry: Public User Identity Private User Identity S-CSCF nameResponse: User Profile

26

Application Level (SIP) Registration Procedure200 OK response

S-CSCF

P-CSCF

I-CSCF

HSS

Home Network

Visited Network

visit1.net

home1.net


PDP Context

DNS Server

pcscf1.visit1.net

icscf1_p.home1.net

scscf1.home1.netSIP/2.0 200 OKVia: SIP/2.0/UDP icscf1_p.home1.net; SIP/2.0/UDP pcscf1.visited1.net; SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357Path: <sip:icscf1_p.home1.net;lr>, <sip:[email protected];lr>Service-Route: <sip:icscf1_p.home1.net;lr>, <sip:[email protected];lr>P-Associated-URI: <sip:[email protected]>, <sip:[email protected]>, <sip:[email protected];user=phone>

SIP/2.0 200 OKVia: SIP/2.0/UDP pcscf1.visited1.net; SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357Service-Route: <sip:icscf1_p.home1.net;lr>, <sip:token([email protected];lr)@home1.net;tokenized-by=home1.net>


UE#1

27

Assigning CSCF for a User

Criteria for assigning a S-CSCF for a User Required capabilities for user services (provided by the HSS) Operator preference on a per-user basis (provided by the HSS) Capabilities of individual S-CSCFs in the home network (internal

information) Topological (i.e. P-CSCF) information of where the user is located (internal

information) Topological information of where the S-CSCF is located

(internal information) Availability of S-CSCFs (internal information)

Assignment of I-CSCF DNS-based mechanism

28

IMS Session Setup: 1. Initial SDP Offer

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS

Service controlLocation Query/Response Service control

Originating Home Network Terminating Home Network

Originating Visited Network Terminating Visited Network

visit1.net

home1.net home2.net

visit2.netUE#2

[email protected]

5555::eee:fff:aaa:bbb

INVITE sip:[email protected]: precondition, sec-agreeVideo codec H.263 or MPEG-4Audio codec AMR

INVITE sip:[5555::eee:fff:aaa:bbb]:8805



UE#1

(pcscf1.visited1.netUDP port 5060

5555::aba:dab:aaa:daa )

29

IMS Session Setup: 2. Offer Response

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2

AuthorizeQoS ResourcesAuthorize

QoS Resources 183 Session ProgressVideo codec H.263 or MPEG-4Audio codec AMR

30

IMS Session Setup: 3. Response Conf (Opt SDP)

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2GPRS: Activate

PDP ContextGPRS: CreatePDP Context

COPS: REQ

ResourceReservation

PRACK sip:[email protected] codec H.263Audio codec AMR

COPS:DEC

COPS:RPTGPRS: CreatePDP response

GPRS: ActivatePDP Context accept

31

IMS Session Setup: 4. Conf ACK (Opt SDP)

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS

Terminating Home Network


visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2ResourceReservation

Originating Visited Network

GPRS: ActivatePDP Context

COPS: REQCOPS:DEC

COPS:RPT

GPRS: CreatePDP response

GPRS: ActivatePDP Context accept

GPRS: CreatePDP Context

200 OK (PRACK)

Secondary PDP Context

32

IMS Session Setup: 5. Reservation Conf

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2

UPDATEAlertUser

Secondary PDP Context Secondary PDP Context

33

IMS Session Setup: 6. Reservation Conf

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2

200 OK (UPDATE)


34

IMS Session Setup: 7. Ringing

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2

180 RingingAlertUser


35

IMS Session Setup: 8. 200 OK (INVITE)

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

home1.net home2.net

visit2.net

UE#1 UE#2

200 OKStartMedia

Approval ofQoS Commit

COPS:RPTCOPS: DEC(Open gate)

Approval ofQoS Commit

COPS: DEC(Open gate)COPS:RPT

StartMedia


36

IMS Session Setup: 9. ACK

I-CSCFS-CSCF

P-CSCF

I-CSCF

HSS

I-CSCF S-CSCF

I-CSCF

P-CSCF

AS AS



visit1.net

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ACK

1 3gpp and ims. 2 gprs operation and pdp contexts ms (mobile station) 는 gprs attach 절차로 sgsn...

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