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2
Contents [1/3]
Chapter 1: Short Message Service and IP Network Integration
Chapter 2: Mobility Management for GPRS and UMTS
Chapter 3: Session Management for Serving GPRS Support Node
Chapter 4: Session Management for Gateway GPRS Support Node
Chapter 5: Serving Radio Network Controller Relocation for UMTS
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Contents [2/3]
Chapter 6: UMTS and cdma2000 Mobile Core Networks
Chapter 7: UMTS Charging Protocol Chapter 8: Mobile All-IP Network Signaling Chapter 9: UMTS Security and Availability Issues Chapter 10: VoIP for the Non-All-IP Mobile Netw
orks Chapter 11: Multicast for Mobile Multimedia Mes
saging Service Chapter 12: Session Initiation Protocol
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Contents [3/3]
Chapter 13: Mobile Number Portability Chapter 14: Integration and WLAN and Cellular
Networks Chapter 15: UMTS All-IP Network Chapter 16: Issues on IP Multimedia Core
Network Subsystem Chapter 17: A Proxy-based Mobile Service
Platform
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Chapter 1: 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
6
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.
7
NCTU-SMS
8
iSMS
9
Mobility and Session Management
Three types of mobility: radio mobility, core network mobility and IP mobility Radio mobility supports handoff of a mobile user during
conversation Core network mobility provides tunnel-related managem
ent for packet re-routing in the core network due to user movement
IP mobility allows the mobile user to change the access point of IP connectivity without losing ongoing sessions.
Session management maintains the routing path for a communication session, and provides packet routing functions including IP address assignment and QoS setting.
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Chapter 2: Mobility Management for GPRS and UMTS
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LAs, RAs, URAs, and Cells
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Chapter 3: Session Management for Serving GPRS Support Node
13
Chapter 4: Session Management for Gateway GPRS Support Node
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, and mobility management.
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Access Point Name (APN)
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)
15
IP Address Allocation
APN label INTERNET WAP ISP COMPANY
Access mode
Transparent Transparent Non-
transparent
Non-
transparent
IP address allocation
GGSN/
DHCP
GGSN/
DHCP
DHCP/
RADIUS
RADIUS
IP address type
IPv6/IPv4 IPv4 IPv4 IPv4
16
17
Lossless SRNC Relocation
In 3GPP TS 23.060, a lossless SRNC relocation procedure was proposed for non-real-time data services.
1. The source RNC first stops transmitting downlink packets to the UE, and then forwards the next packets to the target RNC via a GTP tunnel between the two RNCs.
2. The target RNC stores all IP packets forwarded from the source RNC.
3. After taking over the SRNC role, the target RNC restarts the downlink data transmission to the UE.
No packet is lost during the SRNC switching period. Real-time data transmission is not supported because the IP da
ta traffic will be suspended for a long time during SRNC switching.
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19
20
21
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Chapter 6: UMTS and cdma2000 Mobile Core Networks
UMTS and cdma2000 are two major standards for 3G mobile telecommunication.
Two important functionalities of mobile core network are mobility management and session management.
This chapter describes these two functionalities for UMTS and cdma2000, and compare the design guidelines for these two 3G technologies.
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cdma2000 Architecture
BTS
BTS
Radio Network
HLRMSC/VLR
PDSN
MS
MS
PSTN
PDN
AAA: Authentication, Authorization and AccountingBSC: Base Station Controller BTS: Basestation Transceiver SystemHA: Home Agent HLR: Home Location RegisterMS: Mobile Station MSC: Mobile Switching CenterPCF: Packet Control Function PDSN: Packet Data Seving NodePDN: Packet Data Network PSTN: Public Switched Telephone NetworkSDU: Selection and Distribution Unit VLR: Visitor Location Register
SDU
BSC
PCF
AAA
HA
A1/A2/A5
A8/A9 A10/A11
A3/A7
A1/A2/A5
SDU
BSC
PCFA8/A9
A10/A11
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cdma2000 CS Domain
BSC connects to the core network through the SDU.
The SDU distributes the circuit switched traffic (e.g., voice) to the MSC.
A1 interface supports call control and mobility management between MSC and BSC.
A2 and A5 interfaces support user traffic and circuit switched data traffic between MSC and BSC.
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cdma2000 PS Domain
The SDU distributes the packet switched traffic to PCF and then to the PDSN.
Interfaces A8 and A9 support packet switched data and signaling between PCF and SDU, respectively.
Interfaces A10 and A11 (R-P interface) support packet switched data and signaling between PCF and PDSN. GRE tunnel is used for data routing in A10 with standard I
P QoS. MIP is used for signaling routing in A11.
The R-P interface also supports PCF handoff (inter or intra PDSN).
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PDSN Maintaining link-layer sessions to the MSs Supporting packet compression and packet filtering before the
packets are delivered through the air interface Providing IP functionality to the mobile network, which routes
IP datagrams to the PDN with differentiated service support Interacting with AAA to provide IP authentication, authorizati
on and accounting support Acting a MIP FA in the mobile network The interfaces among the PDN nodes (i.e., PDSN, HA, AAA)
follow the IETF standards.
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cdma2000 Control Plane
IP
PPP
LAC
MAC
L1
LAC
MAC
L1 PL PL
Link
Layer
PL
IP
PPP
PL
IP /IPSec
Link
Layer
MS RN PDSN HA
UDP
MIP
IP/IPSec
UDP
IKEMIP MIPIKE
UDP
R-P R-P
IKE: Internet Key Exchange IP: Internet ProtocolIPSec: IP Security HA: Home AgentLAC: Link Access Control MAC: Medium Access ControlMIP: Mobile IP MS: Mobile StationPDSN: Packet Data Serving Node PPP: Point to Point ProtocolPL: Physical Layer RN: Radio NetworkR-P: RN-PDSN Interface UDP: User Datagram Protocol
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UMTS Control Plane
GMM/SM/SMS
RRC
RLC
MAC
L1
RLC
MAC
L1ATM
UTRAN SGSN GGSN
RRC RANAP
AAL5L1
SCCPSignaling
Bearer
GMM/SM/SMS
UDP/IP
L2
MS
ATM
RANAP
AAL5
SCCPSignaling
Bearer
GTP-C
L1
L2
GTP-C
UDP/IP
ATM: Asynchronous Tranfer ModeGGSN: Gateway GPRS Support NodeMS: Mobile StationRLC: Radio Link ControlSGSN: Serving GPRS Support NodeGMM/SM/SMS: GPRS Mobility Management/Session Managemnt/Short Message ServiceGTP-C: GPRS Tunneling Protocol - Control PlaneUTRAN: UMTS Terrestrial Radio Access Network
AAL5: ATM Adaptation Layer Type 5MAC: Medium Access ControlRANAP: Radio Access Network Application ProtocolRRC: Radio Resource ControlSCCP: Signaling Connection Control Part
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cdma2000 User Plane
IP
PPP
LAC
MAC
PL PL
LinkLayer
PPPLinkLayer
PL
IP
LinkLayer
MS RN PDSN HA
PLL1
LACMAC
L1
R-P
PL
R-P
IP/IPSec
IPIP/
IPSec
IP: Internet Protocol IPSec: IP SecurityHA: Home Agent LAC: Link Access ControlMAC: Medium Access Control MS: Mobile StationPDSN: Packet Data Serving Node PPP: Point to Point ProtocolPL: Physical Layer RN: Radio NetworkR-P: RN-PDSN Interface UDP: User Datagram Protocol
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UMTS User Plane
IP,PPP
PDCP
RLC
MAC
L1
RLC
MAC
L1 ATM L1
IP,PPP
MS UTRAN SGSN GGSN
PDCP GTP-U
UDP/IP UDP/IP
L2AAL5 AAL5
GTP-U
UDP/IP
L2
ATM L1
GTP-U
UDP/IP
GTP-U
ATM: Asynchronous Tranfer ModeGGSN: Gateway GPRS Support NodeIP: Internet ProtocolMS: Mobile StationPPP: Point to Point ProtocolSGSN: Serving GPRS Support NodeUTRAN: UMTS Terrestrial Radio Access Network
AAL5: ATM Adaptation Layer Type 5GTP-U: GPRS Tunneling Protocol - User PlaneMAC: Medium Access ControlPDCP: Packet Data Convergence ProtocolRLC: Radio Link ControlUDP: User DatagramProtocol
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Protocol Stacks [1/2]
The control plane carries out tasks for MM/SM/SMS. In cdma2000, the mobility and session tasks are based on the s
ame lower layer protocol (IP based protocols) for user data transportation.
In UMTS, the lower layer protocols supporting MM/SM tasks in the control plane are different from the lower layer protocols in the user plane. The signaling path between MS and SGSN consists of an R
RC connection between MS and UTRAN, and an Iu connection between UTRAN and SGSN.
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Protocol Stacks [2/2]
In UMTS, the PS domain services are supported by PDCP in the user plane. PDCP contains compression methods, which provide better
spectral efficiency for IP packets transmission over the radio.
In cdma2000, the header and payload compression mechanism is provided by PPP between MS and PDSN.
Both UMTS RLC and cdma2000 LAC provide segmentation and retransmission services for user and control data. cdma2000 LAC supports authentication functionality for
wireless access, which is equivalent to GPRS transport layer authentication in UMTS.
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PPP
In both control and user planes for cdma2000, PPP is carried over the LAC/MAC, and R-P tunnels are utilized to establish the connection between an MS and the PDSN.
In cdma2000, a PPP connection is equivalent to a packet data session, which is comparable to the UMTS PDP context.
In the UMTS control plane, no PPP/IP connection is established between MS and SGSN. Signaling is carried over the RRC and Iu connections.
UMTS user plane provides two alternatives for IP services. IP is supported by non-PPP lower layer protocols. IP is supported by PPP.
Dial-up application Mobile IP is introduced to UMTS
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Chapter 7: UMTS Charging Protocol
The GTP’ protocol is used for communications between a GSN and a CG, which can be implemented over UDP/IP or TCP/IP.
Above the GTP’ protocol, a Charging Agent (or CDR sender) is implemented in the GSN and a Charging Server is implemented in the CG.
Node B
Node B
RNC
RNC
UTRAN
HLR
SGSN GGSN
Core Network
MS
MS
CG : Charging Gateway UTRAN : UMTS Terrestrial Radio Access NetworkGGSN : Gateway GPRS Support Node RNC : Radio Network ControllerHLR : Home Location Register SGSN : Serving GPRS Support Node
MS : Mobile Station Node B : Base StationPDN : Packet Data Network
PDN
signalingsignaling and data
gd
e
a b c
CG
Gn
Ga
Gi
f
signaling
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The GTP’ Service Model
Our GTP’ service model follows the GSM Mobile Application Part (MAP) service model.
A GSN communicates with a CG through a dialog by invoking GTP’ service primitives.
A service primitive can be one of four types: Request (REQ) Indication (IND) Response (RSP) Confirm (CNF) Service
(Confirm)Service
(Request)
GTP' Service User(Charging Agent)
GTP' Service Provider
UDP/IP
Dialog Initiator (GSN)
Service(Indication)
Service(Response)
GTP' Service User(Charging Server)
GTP' Service Provider
UDP/IP
Dialog Responder (CG)
GTP' Message(Response)
GTP' Message(Request)
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GTP’ Connection Setup
Before a GSN can send CDRs to a CG, a GTP’ connection must be established between the charging agent in the GSN and the charging server in the CG.
ChargingAgent
GTP' Service Provider
Charging Server
(2) Node Alive Request
(5) Node Alive Response
(1) CONNECT (REQ)
GSN CG
GTP' Service Provider
(3) CONNECT (IND)
(4) CONNECT (RSP)
(6) CONNECT (CNF)
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GTP’ CDR Transfer
The charging agent is responsible for CDR generation in a GSN. The CDRs are encoded using, for example, the ASN.1 format defined in 3GPP 32.215. The charging server is responsible for decoding the CDRs and returns the processing results to the GSN.
ChargingAgent
GTP' Service Provider
Charging Server
(2) Data Record Transfer Request
(1) CDR_TRANSFER (REQ)
GSN CG
GTP' Service Provider
(3) CDR_TRANSFER (IND)
(4) CDR_TRANSFER (RSP)
(6) CDR_TRANSFER (CNF)
(5) Data Record Transfer Response
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GTP’ Failure Detection
In a GSN, an entry in the CG list represents a GTP' connection to a CG. The CG Address attribute identifies the CG connected to the GSN. The Status attribute indicates if the connection is “active” or “inactive”. The Charging Packet Ack Wait Time Tr is the maximum elapsed time the GSN is allow
ed to wait for the acknowledgement of a charging packet. The Maximum Number of Charging Packet Tries L is the number of attempts (includin
g the first attempt and the retries) the GSN is allowed to send a charging packet. The Maximum Number of Unsuccessful Deliveries K is the maximum number of consec
utive failed deliveries that are attempted before the GSN considers a connection failure occurs.
The Unsuccessful Delivery Counter NK attribute records the number of the consecutive failed delivery attempts.
The Unacknowledged Buffer stores a copy of each GTP' message that has been sent to the CG but has not been acknowledged.
A record in the unacknowledged buffer consists of an Expiry Timestamp te , the Charging Packet Try Counter NL and an unacknowledged GTP' message.
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Path Failure Detection Algorithm
Step 1. After the connection setup procedure is complete, both NL and NK are set to 0, and the Status is set to “active”. At this point, the GSN can send GTP’ messages to the CG.
Step 2. When a GTP’ message is sent from the GSN to the CG at time t , a copy of the message is stored in the unacknowledged buffer, where the expiry timestamp is set to te=t + Tr.
Step 3. If the GSN has received the acknowledgement from the CG before te , both NL and NK are set to 0.
Step 4. If the GSN has not received the acknowledgement from the CG before te , NL is incremented by 1. If NL =L, then the charging packet delivery is considered failed. NK is incremented by 1.
Step 5. If NK =K, then the GTP’ connection is considered failed. The Status is set to “inactive”.
The Path Failure Detection Algorithm (PFDA) detects path failure between the GSN and the CG. PFDA works as follows:
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Chapter 8: Mobile All-IP Network Signaling
Traditional SS7 signaling is implemented in MTP-based network, which is utilized in the existing mobile networks including GSM and GPRS.
In UMTS all-IP architecture, the SS7 signaling will be carried by IP-based network.
The low costs and the efficiencies for carriers to maintain a single, unified telecommunications network, guarantee that all telephony services will eventually be delivered over IP.
This chapter describes design and implementation of the IP-based network signaling for mobile all-IP network.
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SS7 Architecture
STP pair STP pair
SCP
STP pair
A-link
B-linkC-link
D-link
E-link
F-linkSSP SSP
A-linkA-link
Trunk
NETWORK 1NETWORK 2
Voice/Data Trunk
SS7 Signaling Link
Service Switching Point (SSP) is a telephony switch that performs call processing.
Service Control Point (SCP) contains databases for providing enhanced services.
Signal Transfer Point (STP) is a switch that relays SS7 messages between SSPs and SCPs.
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Access Links (A-links) connect the SSP/STP or the SCP/STP pairs.
Bridge Links (B-links) connect STPs in different pairs. Cross Links (C-links) connect mated STPs in a pair. Diagonal Links (D-links) are the same as the B-links except t
hat the connected STPs belong to different SS7 networks. Extended Links (E-links) provide extra connectivity between
an SSP and the STPs other than its home STP. Fully-Associated Links (F-links) connect SSPs directly.
SS7 Link Types
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Message Transfer Part (MTP) consists of three levels corresponding to the OSI physical layer, data link layer, and network layer, respectively.
The MTP level 1 (MTP1) defines the physical, electrical, and functional characteristics of the signaling links connecting SS7 components.
The MTP level 2 (MTP2) provides reliable transfer of signaling messages between two directly connected signaling points.
The MTP level 3 (MTP3) provides the functions and procedures related to message routing and network management.
Signaling Connection Control Part (SCCP) provides additional functions such as Global Title Translation (GTT) to the MTP.
SS7 Protocol Stack: MTP & SCCP
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Integrated Services Digital Network User Part (ISUP) establishes circuit-switched network connections (e.g., for call setup).
Transaction Capabilities Application Part (TCAP) provides the capability to exchange information between applications using non-circuit-related signaling.
Operations, Maintenance, and Administration Part (OMAP) is a TCAP application for network management.
Mobile Application Part is a TCAP application that supports mobile roaming management.
SS7 Protocol: ISUP, TCAP, MAP
46
IETF Signaling Transport (SIGTRAN) working group addresses the issues regarding the transport of packet-based SS7 signaling over IP networks.
SIGTRAN defines not only the architecture but also a suite of protocols, including the SCTP and a set of user adaptation layers (e.g. M3UA), which provides the same services of the lower layers of the traditional SS7.
Why not TCP ? TCP provides strict order-of-transmission which causes head-of-line block
ing problem. The TCP socket does not support multi-homing. TCP is vulnerable to blind Denial-of-Service (DoS) attacks such as floodi
ng SYN attacks.
Stream Control Transmission Protocol (SCTP)
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Like TCP To provide reliable IP connection. To employ TCP-friendly congestion control (including slow-start,
congestion avoidance, and fast retransmit)
Unlike TCP To provide message-oriented data delivery service and new delivery
options (ordered or unordered) To provide selective acknowledgments for packet loss recovery To use a four-way handshake procedure to establish an association (i.e., a
connection). To offer new features that are particularly for SS7 signaling
Multi-homing Multi-streaming
SCTP Features
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Chapter 11: 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.
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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.
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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
MMS Multicast [1/2]
RA1 0
RA2 1
RA3 0
RA4 2
RA5 0
RA6 0
MCc (CBC)
53
MMS Multicast [2/2] Step 1. The multimedia message is first delivered from the message send
er to the Cell Broadcast Entity (CBE). Step 2. The CBE forwards the message to the Cell Broadcast Center (CB
C). Step 3. The CBC searches the multicast table MCC to identify the routing
areas RAi where the multicast members currently reside (i.e., MCC [RAi] > 0 in the CBC). In Figure 1.7, i = 2 and 4.
Step 4. The CBC sends the multicast message to the destination RNCs (i.e., RNC1 and RNC2 in Figure 1.7) through the Write Replace message defined in 3GPP TS 23.041.
Step 5. The RNCs deliver the multimedia messages to the multicast members in the RAs following the standard UMTS cell broadcast procedure.
Like SMS multicast, a multicast table MCC is implemented in the CBC to maintain the identities of the RAs and the numbers of the multicast members in these RAs.
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Chapter 12: Session Initiation Protocol
SIP is an application-layer signaling protocol over the IP network.
SIP is designed for creating, modifying and terminating multimedia sessions or calls.
SIP message specifies the Real-Time Transport Protocol / Real-Time Transport Control Protocol (RTP/RTCP) that deliver the data in the multimedia sessions.
RTP is a transport protocol on top of UDP, which detects packet loss and ensures ordered delivery.
A RTP packet also indicates the packet sampling time from the source media stream. The destination application can use this timestamp to calculate delay and jitter.
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Network Elements: User Agent The user agent resides at SIP endpoints (or phones). A user agent
contains both a User Agent Client (UAC) and a User Agent Server (UAS).
The UAC (or calling user agent) is responsible for issuing SIP requests The UAS (or called user agent) receives the SIP request and responds to
the request.
(a) SIP UA Developed in the National Chiao Tung University
(b) Windows Messenger 4.7-based SIP UA (with phone number 0944021500)
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Network Elements: Network Servers
Registrar: A UA can periodically register its SIP URI and contact information (which includes the IP address and the transport port accepting the SIP messages) to the registrar.
Proxy Server: A proxy server processes the SIP requests. The proxy server either handles the request or forwards it to other servers, perhaps after performing some translation.
Redirect Server: A redirect server accepts the INVITE requests from a UAC, and returns a new address to that UAC.
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SIP Registration and Call Setup
1. REGISTER
2. Store
3. OK
4. INVITE
5. Query
6. INVITE
7. Trying
8. Ringing
10. ACK10. ACK
SIP UAS SIP UACRegistrar SIP Proxy
LocationService
9. OK9. OK
Registration
Callsetup 8. Ringing
7. Trying
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Chapter 13: Mobile Number Portability
Number Portability (NP) is a network function that allows a subscriber to keep a unique telephone number.
NP is an important mechanism to enhance fair competition among telecommunication operators
and to improve customer service quality.
Three types of NP are discussed: location portability, service portability, and operator portability.
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Terminologies Number range holder (NRH) network : the network which the
number is assigned Subscription network: the network with which the customer’s
mobile operator has a contract to implement services for a specific mobile phone number
Donor (release) network: subscription network from which a number is ported in the porting process
Recipient network: network that receives the number in the porting process
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MDN vs MIN An MS is associated with two number.
Mobile directory number (MDN) is dialed to reach the MS (e.g., MSISDN in GSM).
Mobile identification number (MIN) is a confidential number that uniquely identifies an MS in Mobile Network (e.g., IMSI in GSM).
When mobile number portability is introduced, a porting mobile user would keep the MSISDN (the ported number) while being issued a new IMSI in GSM.
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Simplified GSM Call Termination Procedure without NP
Step 1: After calling party dials the MSISDN of MS2, the call route to the GMSC of MS2.
Step 2: GMSC query HLR to query the location of MS2.
Step 3: The call is routed to the destination MSC and eventually set up.
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Call Routing Mechanism with NP
In 3GPP TS 23.066, two approaches are proposed to support number portability call routing: Signaling Relay Function (SRF)-based solution, and Intelligent Network (IN)-based solution.
Both approaches utilize the Number Portability Database (NPDB) that stores the recodes for the ported numbers.
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SRF-based Approach
The SRF node is typically implemented on the Signal Transfer Point (STP).
Three call setup scenarios have been proposed for SRF-based approach: direct routing (DR) and indirect routing (IR). DR: The mobile number portability query is
performed in the originating network. IR: The mobile number portability query is
performed in the NRH.
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DR Call Setup Scenario 1Step 1: After calling party dials the MSISDN of MS2, the call is routed to the GMSC of
the originating network.
Step 2: The GMSC queries SRF for the subscription network information of MS2.
Step 3: By consulting the NPDB, the SRF obtains the subscription network information, and forwards it to the originating GMSC.
Step 4: The originating GMSC routes the call to the subscription GMSC (i.e., GMSC of MS2). The call is then set up following the standard GSM procedure.
65
DR Call Setup Scenario 2
Step 1: After calling party dials the MSISDN of MS2, the call is routed to the GMSC of the originating network.
Step 2: The GMSC queries SRF for the subscription network information of MS2.
Step 3: By consulting the NPDB, the SRF obtains the subscription network information. If the originating network is the subscription network of MS2, then SRF forward message to query HLR to obtain the routing information of MS2.
Step 4: The information will then be returned to the originating GMSC. Then call is set up following the standard GSM procedure.
66
Chapter 14: Integration and WLAN and Cellular Networks
Service aspects Access control aspects Security aspects Roaming aspects Terminal aspects Naming and address
aspects Charging and billing
aspects
UMTS: Universal Mobile telecommunication System HLR: Home Location RegisterUTRAN: UMTS Terrestrial Radio Access Network PDN: Packet Data NetworkRNC: Radio Network Controller WGSN: WLAN-based GPRS Support NodeSGSN: Serving GPRS Support Node AP: AccessGGSN: Gateway GPRS Support Node MS: Mobile Station
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WLAN/Cellular Integration Scenarios
Service Capabilities Scenario 1 2 3 4 5 6
Common Billing ○ ○ ○ ○ ○ ○
Common Customer Care ○ ○ ○ ○ ○ ○
Cellular-based Access Control ╳ ○ ○ ○ ○ ○
Cellular-based Access Charging ╳ ○ ○ ○ ○ ○
Access to Mobile PS Services ╳ ╳ ○ ○ ○ ○
Service Continuity ╳ ╳ ╳ ○ ○ ○
Seamless Service Continuity ╳ ╳ ╳ ╳ ○ ○
Access to Mobile CS Service with Seamless Mobility ╳ ╳ ╳ ╳ ╳ ○
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The MS Architecture
Retrieve the SIM information.
Perform MS Attach and detach procedure.(The authentication action is included in the attach procedure.)
Set up network Configuration.
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The WGSN Node Architecture
70
Chapter 15: UMTS All-IP Network
Mobile system history
The advantages of evolution from UMTS R99 to all-IP network Mobile network will benefit from all existing Internet applications. The telecommunications operators will deploy a command backbone for
all type of access, and thus to reduce capital and operating cost. New applications will be developed in an all-IP environment, which
guarantees optimal synergy between the mobile network and Internet.
GSM GPRSUMTS R99
UMTS R00
UMTSR4
UMTSR5
(CS domain)
(IMS on top of PS domain)
2G 2.5G 3G
71
All-IP Architecture
Option 1 Support PS-domain multimedia and data service.
Option 2 Extend option 1 network by accommodating CS-
domain voice service over a packet switched core network.
72
All-IP Architecture (option 1)
73
All-IP Architecture (option 1)
Radio Network Can be GERAN or UTRAN.
Home Subscriber Server Act as master database containing all 3G user-related subscriber da
ta. GPRS Network
Support mobility management and session management. IP Multimedia Core Network Subsystem
Provide mobility management and session management. Application and Service Networks
Support flexible services through service plateform.
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Call Session Control Function (CSCF)
Function Communicate with HSS for location information Handle control-layer functions related to application level
registration and SIP-based multimedia session. Logical components
Incoming Call Gateway Communicate with HSS to
perform routing of incoming calls. Call Control Function
Handle call setup and call-event
report for billing and auditing.
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CSCF (cont.) Serving Profile Database
Interact with HSS in the home network to obtain profile information. Address Handing
Analyze, translate, and may modify address. Three types of CSCF
P-CSCF Be assigned to a UE while it attaches to the network. Forward the requests to the I-CSCF at home network.
I-CSCF Contact point for the home network of the destination UE. Route the request towards the S-CSCF.
S-CSCF Be assigned to a UE after successful application level registration. Support signing interactions with the UE for call setup and
supplementary services control.
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HSS, BGCF, and MGCF Home Subscriber Server (HSS)
Keep a list of features and services associated with users, and maintain the location of the users.
Provide the HLR functionality required by the PC and CS domain, and the IM functionality required by the IMS.
Breakout Gateway Control Function (BGCF) Select appropriate PSTN breakout point (another BGCF or an MGCF).
Media Gateway Control Function (MGCF)
Acts as the media gateway controller in a VoIP network.
Control the media channels in an MGW.
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T-SGW, MRF, and MGW Transport Signaling Gateway Function (T-SGW)
Map call related signing from/to the PSTN on an IP bearer and send it to/from the MGCF.
Media Resource Function (MRF) Perform multiparty call, multimedia conference, tones and announcements
functionalities.
Media Gateway (MGW) Provide user plane data transport between
UMTS core network and PSTN. Interact with MGCF for resource
control.
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All-IP Architecture (option 2)
Two control elements are introduced: MSC server and GMSC server. Support Media Gateway Control Protocol (MGCP) or H.248 to handle
control layer functions related to CS domain. MSC server + MGW = MSC (in UMTS R99)
Control planeUser plane
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Application Level RegistrationStep 1. UE sends SIP REGISTER to P-CSCF.Step 2. P-CSCF performs address translation of UE’s home domain name to find I-CSCF address.
Step 3. I-CSCF determines the HSS address, and queries the HSS about the registration status of the UE.Step 4. I-CSCF obtains the required S-CSCF capability information and selects an appropriate S-CSCF.Step 5. I-CSCF forwards SIP REGISTER to S-CSCF.Step 6. S-CSCF presents its name and subscriber identity to HSS.Step 7. S-CSCF obtains the UE’s subscriber data from HSS.Step 8. SIP 200 OK is replied. Step 9. P-CSCF stores the home contact name and forwards SIP 200 OK.
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Author Biography
Yi-Bing Lin is Chair Professor of College of Computer Science, National Chiao Tung University.
His current research interests include mobile computing and cellular telecommunications services. Dr. Lin has published over 200 journal articles and more than 200 conference papers.
He is the co-author of the books Wireless and Mobile Network Architecture (with Imrich Chlamtac; published by Wiley, 2001) and Wireless and Mobile All-IP Networks (with Ai-Chun Pang; published by Wiley, 2005).
Dr. Lin is an IEEE Fellow, ACM Fellow, AAAS Fellow, and IEE Fellow.
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