all-ip in UMTS

7/29/2019 all-ip in UMTS

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Wireless and Mobile All-IP NetworksY i-Bing Lin

[email protected]


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From Traditional Telecom to All-IP

Circuit-Switched vsPacket-Switched:

Intellent Network (IN) vs. IP Multimedia CoreNetwork Subsystem (IMS)

Example: Video Phone All-IP Telecom Services : New Technologies vs.

New Services

VoIP: Numbering, Number Portability Service Creation: Dictatorship vs. Democracy

Peer-to-Peer, Web 2.0


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All-IP Architecture


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Issues on Mobile All-IP Network

Short Message Service (SMS) and IP Network

IntegrationSMS is considered as the application level signalingmechanism.

Mobility Management

GSM: Location Area (LA) tracking

GPRS: Routing Area (RA), cell trackingUMTS: RA, UTRAN RA (URA), cell tracking

Session Management

PDP context is introduced.


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Issues on Mobile All-IP Network Mobile Core Networks that Support All-IP:

UMTS: GPRS

cdma2000: PDSN (Packet Data Support Node) UMTS Charging Protocol

On-line Charging System (OCS) Mobile All-IP Network Signaling

Traditional: SS7 is supported by MTP(Message Transfer Part)

All-IP: SS7 is supported by SCTP(Stream Control Transport Protocol)


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Issues on Mobile All-IP Network

UMTS Security and Availability IssuesVirus, fraudulent Usage, RedundantAuthentication

Multicast for Mobile Multimedia MessagingService

UMTS All-IP Network

SIP (Session Initiation Protocol)

IPv6


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Identities in UMTS

Why is identity management important?Billing, Security, Service

ANSI 41: MDN = MIN

GSM MAP: MDN =/= MIN How are identities assigned in UMTS PS

service domain?

Service: APN

MS: IP address


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Access Point Name (APN)

An APN is used in UMTS/GPRS as a referencepoint to external PDN that supports theservices to be accessed by an MS.

The APN information is permanentlydistributed and maintained in the HLR, theGGSN and the Domain Name Server (DNS).


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APN Allocation A set of APN labels is defined in the HLR.

Each mobile user can subscribe to one or more APNsfrom this set.

The labels of these subscribed APNsare then stored inthe MS at the subscription time.

Among the subscribed APNs, there is one default APN. If a user attempts to access a service without specifying

the APN, then the default APN is used.

Additionally, the HLR may also define a wild cardAPN ` *", which allows an MS to access anyunsubscribed APNs.

For each APN, the DNS keeps an IP address list of theGGSNsassociated with this APN label.


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APN Configurations

UTRAN

(3) ISP

GGSN

RADIUSserver

DHCPserver

FW

NAT

(1) INTERNET

(2) WAP

(4) COMPANY

RADIUSserver

RADIUSserver

DHCPserverSignaling

Signaling and data

DHCP: Dynamic Host Configuration ProtocolFW: FirewallGGSN: Gateway GPRS Support Node

MS: Mobile Station

NAT: Network Address translatorRADIUS: Remote Authentication Dial-In User ServiceUMTS: Universal Mobile Telecommunication Service

UTRAN: UMTS Terrestrial Radio Access Network

(5)

(6)(7)

(8)(9) (10)

SGSN

DNS

HLR

(11)

(12) (13)


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IP Address Allocation: Access Modes

Based on the APN setting specified in 3GPP TS29.060, the GGSN provides two access modesfor IP address allocation to an MS

Transparent Non-transparent


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Transparent Access Mode

In the transparent access mode, the mobile

operator acts as an Internet service provider,and an MS is given an IP address from theoperator's IP address space.

The IP address can be allocated statically at thesubscription time or dynamically at theactivation of the PDP context.

The transparent access mode is exercised if therequested APN INTERNET.


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Non-transparent Access Mode

In the non-transparent access mode, the mobile

operator only provides a user the accesschannel to an Internet service provider (if theAPN is ISP) or a company (if the APN is

COMPANY). The IP address pool is owned by the Internet

service provider or the corporate, and the IP

address for an MS is dynamically allocated.


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IP Address Allocation (I)

The IP addresses can be allocated by either theGGSN, a Dynamic Host Configuration Protocol(DHCP) server, or a Remote AuthenticationDial-In User Service (RADIUS) server.

In the transparent access mode, the GGSN mayallocate the IP address for a user by using itsown address pool.

In the current implementation, IPv6 addressescan only be allocated by this alternative.


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IP Address Allocation (II)

In either the transparent or the non-transparent access modes, the GGSN maynegotiate with a DHCP server to allocate an IPaddress from the address pool maintained bythis DHCP server.

Alternatively, the IP address of an MS may beassigned by a RADIUS server, where the IPaddress pool is maintained by this RADIUSserver.


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IP Address Allocation (III)

IPv4IPv4IPv4IPv6/IPv4IP addresstype

RADIUSDHCP server

RADIUS

GGSN/ DHCPserver

GGSN/ DHCPserver

IP addressallocator

Non-

transparent

Non-

transparent

TransparentTransparentGGSN

access mode

COMPANYISPWAPINTERNETAPN label


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PDP Context

Before an MS can access any mobile data service, the

Packet Data Protocol (PDP) context for the servicemust be activated.

The PDP context specifies the application-layer packet

data protocol and the routing information used for thecommunication session.

The PDP context is maintained in the MS, the SGSN,and the GGSN.


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During the PDP context activation procedure , theMS specifies a requested APN.

Then the SGSN uses this requested APN to select a

GGSN. If the user does not specify any requested APN in the

activation procedure, the default APN is chosen by

the SGSN.

PDP Context Activation


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MS UTRAN SGSN GGSN

1. Activate PDP Context Request

DNS

The MS specifies the APN in the Activate PDP ContextRequest message and sends it to the SGSN.

PDP Context Activation: Step 1


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MS UTRAN SGSN GGSN


2. Radio Access Bearer Assignment Procedure

DNS

The SGSN negotiates with the UTRAN to allocate the radiobearer bandwidth for the data session.



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MS UTRAN SGSN GGSN



3. APN Query and response

DNS

The SGSN checks if the requested APN (obtained from theActivate PDP Context Request message sent by the MS) is

specified in the APN list of the subscription data for the MS.If not, the default APN is used.

Then the SGSN creates the PDP context for the user,and sends the requested APN to the DNS server. The DNSserver uses this APN to derive the GGSN's IP address.



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MS UTRAN SGSN GGSN




4. Create PDP Context Request

DNS

Based on the GGSN's IP address obtained from the DNS,the SGSN sends the Create PDP Context Request messageto the GGSN to establish a GTP tunnel between the SGSNand the GGSN, which will be used as the packet routing

path between the GGSN and the MS.



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MS UTRAN SGSN GGSN





DNS

5. Create PDP Context Response

Step 5. The GGSN creates a PDP context for the MS.

This PDP context records the requested APN, PDP type,MSISDN, and IP address. The GGSN allocates an IPaddress for the MS by using either transparent or non-transparent access mode, and determines the tunneling

mechanism to the destination external PDN.


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MS UTRAN SGSN GGSN





DNS

5. CreatePDP Context Response6. Activate PDP Context Accept

Step 6. Finally, the SGSN informs the MS that the session

setup is completed


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All-IP Telecom.

Trial in Taiwan

Under the M-Taiwan Program,FarEasToneis

developing IMSService Platform.

APTG is

conductingVoIP ServiceTrial.

Keelung

City

NANKANGSOFTWARE

PARK

Nantou

County

TaichungCounty

HsinchuCounty

TaoyuanCounty

Miaoli

County

MatsuhCounty

NATIONAL

MUSEUMOFHISTORY

TAIPAI

VOIP

Center

TaichungCity

TaitungCounty

YunlinCounty

PenghuCounty

TainanCity

ChiayiCounty

HualienCounty

Chiayi

City

TainanCounty


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Call Setup in APTG Trial

PSTN

APTG IP backbone

(4) Taipei switch

(5) Softswitch

(MGCF/MGW)

Originating switch

IP-PBX (1) AP

(2) Proxy server(CSCF)

(3) Caller


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Performance MeasurementMean Opinion Score (MOS)


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Conclusions

The SIP protocol does not provide all features needed

to implement existing telecommunications services. Forexample, the flash-hook signal for the call waitingservice is implemented proprietarily in the APTG trial.

There are too many kinds of IP CPEs. Some of them

may not be compatible with the networks, and mayshow very poor performance. Furthermore, some CPEsmay be complicate to operate, and cannot be simplyplug-and-play.

Although the cost for deploying All-IP VoIP network islower than traditional PSTN network, it is not clear ifthe same advantages are guaranteed for maintenanceand operations of the VoIP network.


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Appendix A: IPv4 vsIPv6

The above procedure assumes IPv4 IP address allocation.For IPv6, the IP address allocation is different.

Support of public IP address is a major difference forUMTS address allocation between IPv4 and IPv6.

For IPv4, the MS is typically allocated a private addressbecause of limited IPv4 address space.

For IPv6, the MS is always allocated a public address.


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IPv6 Address Allocation

At Step 5 of the PDP context activation procedure, theGGSN allocates a complete IP address for IPv4.

For IPv6, there are two alternatives for dynamic addressallocation: statelessaddress allocation andstateful address

allocation. Like IPv4, the stateful IPv6 address is allocated by DHCP

server at Step 5.

On the other hand, in stateless address auto-configuration,

the GGSN allocates a part of the IPv6 address called link-local address for the MS by using its own IPv6 addresspool at Step 5.

Then the MS generates the public IP address by combining

the link-local address and a network-prefix address.

IP 6St t l A t


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MS UTRAN SGSN

1. PDP Context Activation Procedure

2. Router Solicitation

3. Router Advertisement

GGSN

4. GGSN-Initiated PDP Context Modification Procedure

IPv6 Stateless Auto-

configuration Procedure


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Stateless Address Auto-configuration (I)

Step 1: the MS first obtains the link-local address in the PDPcontext activation procedure.

Step 2: the MS activates the IPv6 address auto-configurationby sending theRouter Solicitationmessage to the GGSN.

Step 3:The GGSN replies with the Router Advertisementmessage, which includes the network-prefix address.

After the MS has received the Router Advertisement message,it obtains the IPv6 address by concatenating the link-local

address and the network-prefix address.Step 4:Then the GGSN updates the IPv6 address of the PDP

contexts in the SGSN and the MS.


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Stateless Address Auto-configuration (I I) To avoid conflict of link-local address assignment, the

GGSN shall exercise neighbor discovery with otherGGSNs.

Note that in traditional IPv6 stateless address allocation,neighbor discovering is conducted by the mobile host. In

UMTS, neighbor discovery is exercised by the GGSNs. Also note that existing UMTS core network is developed

based on the IPv4 transport network.

Therefore, IPv6 packets are carried on top of the IPv4-based GTP tunnel, which are invisible to the UMTS corenetwork.


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UMTS and External PDN Interworking

The GGSN interworksthe external data network throughthe Gi interface. The interworkingmechanisms may bedifferent for various APN configurations.

For the INTERNET and WAP APNs, the GGSN connectsto the external PDN directly through Ethernet or leased

lines. For the ISP APN, the external PDN can be connected to

the GGSN either through the leased lines or the VPN. Ifthe Internet service provider connects to the GGSN

through VPN, then tunneling is required. For the COMPANY APN, tunneling is always required for

interworkingbetween the GGSN and the corporate intranet.


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Tunneling Methods

Three tunneling methods have been proposed forUMTS.

IP-in-IP tunneling.

Generic Routing Encapsulation (GRE) tunneling Layer 2 Tunneling Protocol (L2TP) tunneling


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IP-in-IP Tunneling

InternetMS GGSN

(1) IP(2) IPApplication

VPNGateway

ApplicationServer

Intranet ofa corporate


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InternetMS GGSN

(1) IP(2) GRE(3) PPPApplication

VPN

Gateway

Application

Server


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InternetMS GGSN

(1) IP(2) UDP(3) L2TP(4) PPP

ApplicationVPN

Gateway

Application

Server

(5) IP


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IPIP/UDP,

FR, ATM

yeshighL2TP

PPPIPyesmediumGRE(PPTP)IPIPnolowIP-in-IP

MSsupport

Transportsupport

Multiprotocolsupport

OverheadTunnelingmethod


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Each of the above three methods can be usedtogether with IPsecto provide protection for packetdelivery.

If an MS supports both PPP and IP, then all thesethree tunneling methods can be used to provide datasessions to this MS.


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Quality of Service

UMTS defines four QoSclasses for user data traffic:conversational, streaming, interactive, background

The conversational and the streaming classes support real-time traffic for services such as voice and streaming video.

The interactive and the background classes support nonreal-time traffic for services such as web browsing andemail.

Each class defines parameters including maximum bit rate,guaranteed bit rate, bit error ratio, transfer delay, etc.


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QoS: VoIP and Internet Access

unguaranteed100 msTransferdelay

10-6104Bit errorratio

100 Kbps12.2 KbpsGuaranteedbit rate

128 Kbps16 KbpsMaximumbit rate

Internet access

(Interactive )

VoIP

(conversational)

QoS

parameter


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End-to-end IP QoS Models (I)

DS

SBLP

DS

RSVP

DS

RSVP

DSDSRemote

host

DSDSRSVP

DSDSDSExternalPDN

DSSBLP

DSRSVP

DSDSDSGGSN

SBLPRSVPDSRSVPDS--MS

54321Scenario

RSVP: Resource Reservation ProtocolSBLP: Service-Based Local Policy


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End-to-end IP QoS Models (II)

The end-to-end QoS for packet switched service isnegotiated among the MS, the GGSN and the remote hostlocated in the external PDN.

3GPP TS 23.207 assumes that the external PDN supports

Diffserv QoS mechanism, and the GGSN is required toperform the Diffserv edge function in all scenarios.

Within the UMTS network (MS-UTRAN-SGSN-GGSN),

the IP QoS is translated and maintained by the UMTS QoSmechanism where the QoS parameters are set in the PDPcontexts.


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GGSN QoS Architecture

SGSN

incoming GTP packets

outgoing GTP packets

GGSNOutgoing IP packets

ResourceManager

AdmissionController

PacketScheduler

Packet Mapper

TrafficConditioner

PacketClassifier External

Data Network

Incoming IPpackets

1

2

3

4

5

6

Step 1

Step 2

Step 3

Step 4

Step 5Step 6

Step 7

Step 8

Step 9

GTP/IP PacketConverter

7

QoS Control Signaling

User data


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UMTS QoS vsDSCP

4 (low)Best ForwardBackground

3Assured Forwardclass 2

Interactive

2Assured Forwardclass 1

Streaming

1 (high)Expedited ForwardConversational

Delivery PriorityDSCP codepointUMTS QoS

class


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Remarks on GGSN QoS

The Resource Manager and the AdmissionController are involved in PDP context activation.

The Packet Classifier, Traffic Conditioner, Packet

Mapper and Packet Scheduler are involved inpacket delivery.

Appendix B: Multicast for Mobile


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Appendix B: Multicast for Mobile

Multimedia Messaging Service

Short Message Service (SMS) allows mobile subscribers to

send and receive simple text message in 2G systems (e.g.GSM).

Multimedia Message Service (MMS) is introduced todeliver messages of sizes ranging from 30K bytes to 100K

bytes in 2.5G systems (e.g. GPRS) and 3G systems (e.g.UMTS)

The content of an MMS can be text (just like SMS),graphics (e.g., graphs, tables, charts, diagrams, maps,

sketches, plans and layouts), audio samples (e.g., MP3 files),images (e.g., photos), video (e.g., 30-second video clips),and so on.


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MMS Architecture [1/2]


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MMS Architecture [2/2] TheMMS user agent (a) resides in a Mobile Station (MS) or an

external device connected to the MS, which has an application layer

function to receive the MMS. The MMS can be provided by theMMS value added service

applications (b) connected to the mobile networks or by theexternalservers (d) (e.g., email server, fax server) in the IP network.

TheMMS server (c) stores and processes incoming and outgoing

multimedia messages. TheMMS relay (e) transfers messages between different messaging

systems, and adapts messages to the capabilities of the receivingdevices. It also generates charging data for the billing purpose. TheMMS server and the relay can be separated or combined.

TheMMS user database (f) contains user subscriber data andconfiguration information. Themobile network (g) can be a WAP (Wireless Application Protocol)

based 2G, 2.5G or 3G system. Connectivity between different mobilenetworks is provided by the Internet protocol.


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Short Message Multicast Architecture

2VLR2

0VLR3

1VLR1

MCH (HLR)

1LA2

0LA1

MCV

(VLR1)

2LA4

0LA3

MCV (VLR2)

0LA60LA5

MCV (VLR3)

Appendix C: Short MessageServiceand IP


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Appendix C: Short Message Service and IP

Network Integration

BTS

BTS

BSC IWMSC

SM-SC

SMSGMSC

BTS

BTS BSC MSC

(1) (2)

(3)

(4)

(5)(6)

GSM SMS Network Architecture


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SMS-IP Integration: SM-SC-based

MobileNetworkMobileNetwork

SM-SC Gateway

IPNetwork

IPNetwork

In most commercial implementations, SMS and IP networksare integrated through SM-SC.


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NCTU-SMS


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iSMS


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Simple Tone Language (STL)The regular expressions are used for the STL grammar. In STL,

a music tone is defined as

tone= [style] [tempo] [volume] [repeat] (note-expression)+

wherestyleis of the format

style= S 0 (0 | 1 | 2)

S00: Natural Style (rest between notes)

S01: Continuous Style (no rest between notes)

S02: Staccato Style (shorter notes and longer rest period)


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STL Representation for a Taiwanese Song

Notes:

STL: t 13 3e 3f 5 3e 3f 5 3e 5f 5e 6f 5 5e 6f 5e 3f 3

2z 3f 1c 2z 3f 1c


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Appendix C: GGSN FunctionalitiesThe GGSN plays the role as a gateway, which controls user

data sessions and transfers the data packets between theUMTS network and the external PDN.

The meta functions implemented in the GGSN are describedas follows:

Network access control Packet routing and transfer

Mobility management


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Functions of UMTS Network Elements

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