1 wireless and mobile all-ip networks yi-bing lin [email protected]

1

Wireless and Mobile All-IP NetworksYi-Bing Lin

[email protected]

2

From Traditional Telecom to All-IP

Circuit-Switched vs Packet-Switched:

Intellient Network (IN) vs. IP Multimedia Core Network 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

3

All-IP Architecture

4

Issues on Mobile All-IP Network

Short Message Service (SMS) and IP Network Integration

SMS is considered as the application level signaling mechanism.

Mobility Management

GSM: Location Area (LA) tracking

GPRS: Routing Area (RA), cell tracking

UMTS: RA, UTRAN RA (URA), cell tracking Session Management

PDP context is introduced.

5

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)

6

Issues on Mobile All-IP Network

UMTS Security and Availability Issues

Virus, fraudulent Usage, Redundant Authentication

Multicast for Mobile Multimedia Messaging Service

UMTS All-IP Network

SIP (Session Initiation Protocol)

IPv6

7

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

8

Access Point Name (APN)

An APN is used in UMTS/GPRS as a reference point to external PDN that supports the services to be accessed by an MS.

The APN information is permanently distributed and maintained in the HLR, the GGSN and the Domain Name Server (DNS).

9

APN Allocation A set of APN labels is defined in the HLR. Each mobile user can subscribe to one or more APNs from

this set. The labels of these subscribed APNs are then stored in the

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 card APN ``

*", which allows an MS to access any unsubscribed APNs. For each APN, the DNS keeps an IP address list of the GG

SNs associated with this APN label.

10

APN Configurations

UTRAN

(3) ISP

GGSN

RADIUSserver

DHCPserver

FW

NAT

(1) INTERNET

(2) WAP

(4) COMPANY

RADIUSserver

RADIUSserver

DHCPserver

SignalingSignaling and data

DHCP: Dynamic Host Configuration ProtocolFW: FirewallGGSN: Gateway GPRS Support NodeMS: Mobile Station

NAT: Network Address translatorRADIUS: Remote Authentication Dial-In User ServiceUMTS: Universal Mobile Telecommunication ServiceUTRAN: UMTS Terrestrial Radio Access Network

(5)

(6)

(7)

(8)

(9) (10)

SGSN

DNS

HLR

(11)

(12) (13)

11

IP Address Allocation: Access Modes

Based on the APN setting specified in 3GPP TS 29.060, the GGSN provides two access modes for IP address allocation to an MS

Transparent Non-transparent

12

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 the operator's IP address space.

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

The transparent access mode is exercised if the requested APN INTERNET.

13

Non-transparent Access Mode

In the non-transparent access mode, the mobile operator only provides a user the access channel to an Internet service provider (if the APN 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.

14

IP Address Allocation (I)

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

In the transparent access mode, the GGSN may allocate the IP address for a user by using its own address pool.

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

15

IP Address Allocation (II)

In either the transparent or the non-transparent access modes, the GGSN may negotiate with a DHCP server to allocate an IP address from the address pool maintained by this DHCP server.

Alternatively, the IP address of an MS may be assigned by a RADIUS server, where the IP address pool is maintained by this RADIUS server.

16

IP Address Allocation (III)

APN label INTERNET WAP ISP COMPANY

GGSN

access mode

Transparent Transparent Non-

transparent

Non-

transparent

IP address allocator

GGSN/ DHCP server

GGSN/ DHCP server

DHCP server

RADIUS

RADIUS

IP address type

IPv6/IPv4 IPv4 IPv4 IPv4

17

PDP Context

Before an MS can access any mobile data service, the Packet Data Protocol (PDP) context for the service must be activated.

The PDP context specifies the application-layer packet data protocol and the routing information used for the communication session.

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

18

During the PDP context activation procedure , the MS 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

19

MS UTRAN SGSN GGSN

1. Activate PDP Context Request

DNS

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

PDP Context Activation: Step 1

20

MS UTRAN SGSN GGSN


2. Radio Access Bearer Assignment Procedure

DNS

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


21

MS UTRAN SGSN GGSN



3. APN Query and response

DNS

The SGSN checks if the requested APN (obtained from the Activate 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 DNS server uses this APN to derive the GGSN's IP address.


22

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 message to the GGSN to establish a GTP tunnel between the SGSN and the GGSN, which will be used as the packet routing path between the GGSN and the MS.


23

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 IP address for the MS by using either transparent or non-transparent access mode, and determines the tunneling mechanism to the destination external PDN.

24

MS UTRAN SGSN GGSN





DNS

5. Create PDP Context Response

6. Activate PDP Context Accept

Step 6. Finally, the SGSN informs the MS that the session setup is completed

25

All-IP Telecom. Trial in Taiwan

Under the M-Taiwan Program, FarEasTone is developing IMS Service Platform.

APTG is conducting VoIP Service Trial.

Keelung City

NANKANGSOFTWAREPARK

Nantou County

Taichung County

Hsinchu County

Taoyuan County

Miaoli County

Matsuh County

NATIONALMUSEUM OFHISTORY

TAIPAIVOIPCenter

Taichung City

Taitung County

Yunlin County

Penghu County

TainanCity

Chiayi County

Hualien County

Chiayi City

TainanCounty

26

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

27

Performance Measurement

Mean Opinion Score (MOS)

28

Conclusions

The SIP protocol does not provide all features needed to implement existing telecommunications services. For example, the flash-hook signal for the call waiting service 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 may show very poor performance. Furthermore, some CPEs may be complicate to operate, and cannot be simply “plug-and-play”.

Although the cost for deploying All-IP VoIP network is lower than traditional PSTN network, it is not clear if the same advantages are guaranteed for maintenance and operations of the VoIP network.

29

Appendix A: IPv4 vs IPv6

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 for UMTS address allocation between IPv4 and IPv6.

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

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

30

IPv6 Address Allocation

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

For IPv6, there are two alternatives for dynamic address allocation: stateless address allocation and stateful 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 address pool at Step 5.

Then the MS generates the public IP address by combining the link-local address and a network-prefix address.

31

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

32

Stateless Address Auto-configuration (I)

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

Step 2: the MS activates the IPv6 address auto-configuration by sending the Router Solicitation message to the GGSN.

Step 3: The GGSN replies with the Router Advertisement message, 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.

33

Stateless Address Auto-configuration (II)

To avoid conflict of link-local address assignment, the GGSN shall exercise neighbor discovery with other GGSNs.

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 core network.

34

UMTS and External PDN Interworking

The GGSN interworks the external data network through the Gi interface. The interworking mechanisms may be different for various APN configurations.

For the INTERNET and WAP APNs, the GGSN connects to 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. If the Internet service provider connects to the GGSN through VPN, then tunneling is required.

For the COMPANY APN, tunneling is always required for interworking between the GGSN and the corporate intranet.

35

Tunneling Methods

Three tunneling methods have been proposed for UMTS.

IP-in-IP tunneling. Generic Routing Encapsulation (GRE) tunneling Layer 2 Tunneling Protocol (L2TP) tunneling

36

IP-in-IP Tunneling

InternetMS GGSN

(1) IP

(2) IP

Application

VPNGateway

ApplicationServer

Intranet ofa corporate

37


InternetMS GGSN

(1) IP

(2) GRE

(3) PPP

Application

VPNGateway

ApplicationServer

38


InternetMS GGSN

(1) IP

(2) UDP

(3) L2TP

(4) PPP

Application

VPNGateway

ApplicationServer

(5) IP

39

Tunneling method

Overhead Multiprotocol support

Transport support

MS support

IP-in-IP low no IP IP

GRE(PPTP) medium yes IP PPP

L2TP high yes IP/UDP, FR, ATM

IP

40

Each of the above three methods can be used together with IPsec to provide protection for packet delivery.

If an MS supports both PPP and IP, then all these three tunneling methods can be used to provide data sessions to this MS.

41

Quality of Service

UMTS defines four QoS classes 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 non real-time traffic for services such as web browsing and email.

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

42

QoS: VoIP and Internet Access

QoS parameter

VoIP (conversational)

Internet access (Interactive )

Maximum bit rate

16 Kbps 128 Kbps

Guaranteed bit rate

12.2 Kbps 100 Kbps

Bit error ratio

104 10-6

Transfer delay

100 ms unguaranteed

43

End-to-end IP QoS Models (I)

Scenario 1 2 3 4 5

MS -- DS DS RSVP

RSVP SBLP

GGSN DS DS DS DS RSVP

DS SBLP

External PDN

DS DS DS DS RSVP

DS

Remote host

DS DS DS RSVP

DS RSVP

DS SBLP

RSVP: Resource Reservation ProtocolSBLP: Service-Based Local Policy

44

End-to-end IP QoS Models (II)

The end-to-end QoS for packet switched service is negotiated among the MS, the GGSN and the remote host located in the external PDN.

3GPP TS 23.207 assumes that the external PDN supports Diffserv QoS mechanism, and the GGSN is required to perform 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 QoS mechanism where the QoS parameters are set in the PDP contexts.

45

GGSN QoS Architecture

SGSN

incoming GTP packets

outgoing GTP packets

GGSNOutgoing IP packets

Resource Manager

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

46

UMTS QoS vs DSCP

UMTS QoS class

DSCP codepoint Delivery Priority

Conversational Expedited Forward 1 (high)

Streaming Assured Forward class 1

2

Interactive Assured Forward class 2

3

Background Best Forward 4 (low)

47

Remarks on GGSN QoS

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

The Packet Classifier, Traffic Conditioner, Packet Mapper and Packet Scheduler are involved in packet delivery.

48

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 to deliver 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.

49

MMS Architecture [1/2]

50

MMS Architecture [2/2]

The MMS 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 the MMS value added service applications (b) connected to the mobile networks or by the external servers (d) (e.g., email server, fax server) in the IP network.

The MMS server (c) stores and processes incoming and outgoing multimedia messages.

The MMS relay (e) transfers messages between different messaging systems, and adapts messages to the capabilities of the receiving devices. It also generates charging data for the billing purpose. The MMS server and the relay can be separated or combined.

The MMS user database (f) contains user subscriber data and configuration information.

The mobile network (g) can be a WAP (Wireless Application Protocol) based 2G, 2.5G or 3G system. Connectivity between different mobile networks is provided by the Internet protocol.

51

Short Message Multicast Architecture

VLR1 1

VLR2 2

VLR3 0

MCH (HLR)

LA1 0

LA2 1

MCV (VLR1)

LA3 0

LA4 2

MCV (VLR2)

LA5 0

LA6 0

MCV (VLR3)

52

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

53

SMS-IP Integration: SM-SC-based

Mobile Network

Mobile Network

SM-SC Gateway

IP Network

IP Network

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

54

NCTU-SMS

55

iSMS

56

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)+

where style is 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)

57

STL Representation for a Taiwanese Song

Notes: STL: t13 3e 3f 5 3e 3f 5 3e 5f 5e 6f 5 5e 6f 5e 3f 3

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

58

Appendix C: GGSN Functionalities

The GGSN plays the role as a gateway, which controls user data sessions and transfers the data packets between the UMTS network and the external PDN.

The meta functions implemented in the GGSN are described as follows:

Network access control Packet routing and transfer Mobility management

59

Functions of UMTS Network Elements

1 wireless and mobile all-ip networks yi-bing lin [email protected]

Documents

ip address slide

allip architecture slide

allip circuit

ip address allocation

apn ms

apn configurations slide

ip address list

apn allocation