UMTS System Architecture
and Protocol Architecture
Overview on overall system architecture
– UMTS network architecture and elements
– Mobile station
– High-level functions
– UMTS domains and strata
– UMTS/GPRS protocol architecture
References:
• Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks – Architecture, Mobility and
Services. 2nd edition, Wiley 2005
• Ch 5.1: Core Network Architecture Release 3
• Ch 5.4&5.5: Core Network Architecture Release 4 and 5
• Ch 6: UMTS Terminal
• Walke, Althoff, Seidenberg: UMTS – Ein Kurs. J. Schlembach Fachverlag, 2001
• 3GPP TS 23.002: UMTS network architecture (CN and AN entities) and procedures
• 3GPP TS 23.101: General UMTS architecture
• 3GPP TS 23.060: GPRS, Service Description
• 3GPP TS 21.101/21.102/21.103: List of standards for Release 3, 4 and 5, respectively
• 3GPP TR 21.905: UMTS vocabulary and abbreviations
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
1
UMTS/GSM Network Architecture
Base station
Base station
ISDN
Base station
controller
Base station
MSC
GSM Core
(Circuit
switched)
GSM
RAN
GMSC
HLR
AuC
EIR
node B
node B
node B
UMTS Networks
Radio network
controller
UTRAN
Oliver Waldhorst, Jens Mückenheim
SGSN
Internet
GPRS Core
(Packet
Switched)
Oct-11
GGSN
2
UMTS System Architecture
Mobile Station (MS):
• radio interface
• service control and user interface
Radio Access Network (RAN):
• radio-specific functions
data
networks
ISDN
network
USIM
mobile
network
UMTS Subscriber Identity Module (USIM):
• subscriber-specific data
• support of authorized access to network
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Core Network (CN):
radio-independent functions
• transport
• mobility management
• subscriber data
• service control
Oct-11
3
Gi
Circuit switched CN
GGSN
AuC
C
PSTN
H
VLR
B
Gr
Gf
Gs
B
MSC
Gn
EIR
F
G
Gc
HLR
PSTN
D
VLR
SGSN
MSC
E
CN
Source: 3GPP 23.002-3.4.0
Basic Configuration, Release 3
GMSC
Gp
Packet switched CN
UMTS Network Architecture
PSTN
A
GSM
RAN
Gb
RNS
BSS
Iur
BSC
RNC
Abis
BTS
RNC
Iub
BTS
Node B
cell
Um
UMTS Networks
IuPS
IuCS
Oliver Waldhorst, Jens Mückenheim
Uu
Oct-11
Node B
UTRAN
4
Mobile-services Switching Centre (MSC)
Source: 3GPP 23.002-3.5.0
An exchange performing all the switching and signalling functions (CS
only) for mobile stations
MSC controls mobile-originated and mobile-terminated CS calls
Functions
–
–
–
–
–
–
–
call management
mobility management (handling attach and authentication)
subscriber administration
maintenance of charging data (for radio network usage)
CS data services (FAX, modem)
supplementary call services (call forwarding, etc.)
SS7-based signaling
Main difference to an exchange in a fixed network: deal with mobility (e.g.
location registration, handover)
Gateway MSC (GMSC)
– Provides interconnection between the UMTS core network and external
PSTN/ISDN networks
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
5
GPRS Support Node (GSN)
Source: 3GPP 23.002-3.5.0
GSNs constitute the interface between the radio access network and the
fixed networks for packet switched services (similar to MSC for CS calls)
Serving GSN (SGSN)
–
–
–
–
–
–
session management
mobility management
subscriber database management (interface with HLR)
maintenance of charging data (for radio network usage)
IP-based transport of user data between SGSN and the UTRAN
IP- or SS7-based signaling transport
Gateway GSN (GGSN)
– gateway for UMTS packet service to external data networks (e.g. the
Internet)
– IP interface towards SGSN
– performs user data screening and security
– maintenance of charging data (for external data network usage)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
6
Home Location Register (HLR)
Source: 3GPP 23.002-3.5.0
Home (primary) data base in charge of the management of
mobile subscribers
Basic information:
• International Mobile Subscriber Identity (IMSI)
• CS subscription information
– one or more Mobile Subscriber International ISDN number(s)
(MSISDN)
• PS subscription information
– zero or more Packet Data Protocol (PDP) address(es)
– permission for GGSN to dynamically allocate PDP addresses for a
subscriber
• location information enabling the charging and routing of calls towards
the MSC or SGSN where the MS is registered (e.g. VLR Number)
Other information:
• teleservices and bearer services subscription information
• service restrictions (e.g. roaming limitation)
• parameters attached to supplementary services
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
7
Visitor Location Register (VLR)
Source: 3GPP 23.002-3.5.0
(Secondary) data base supporting the management of mobile
subscribers currently located within its VLR area
Motivation: minimize load for HLR (i.e. of the primary data base)
Tasks:
• control MSs roaming in an MSC assigned to it
• exchange information with HLR to allow the proper handling of calls
Information maintained by VLR (for call handling):
–
–
–
–
–
–
–
International Mobile Subscriber Identity (IMSI)
Mobile Station International ISDN number (MSISDN)
Mobile Station Roaming Number (MSRN)
Temporary Mobile Station Identity (TMSI), if applicable
location area where the mobile station has been registered
the last known location and the initial location of the MS
supplementary service parameters attached to the mobile subscriber
(received from the HLR)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
8
Authentication Centre (AuC)
Source: 3GPP 23.002-3.5.0
Stores data for each mobile subscriber
– to authenticate the International Mobile Subscriber Identity (IMSI)
– to support ciphering of the communication over the radio path
The AuC transmits the data needed for authentication and ciphering via
the HLR to the VLR, MSC and SGSN which need to authenticate a mobile
station
AuC is associated with an HLR, and stores an identity key for each mobile
subscriber
The AuC communicates solely with its associated HLR (H-interface)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
9
Equipment Identity Register (EIR)
Source: 3GPP 23.002-3.5.0
Logical entity storing the International Mobile Equipment Identities (IMEIs)
Equipment is classified as
– white listed: serie number of equipment
– grey listed: equipment tracked by network
– black listed: barred equipment
– unknown to EIR
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
10
Other CN entities
Source: 3GPP 23.002-3.5.0
SMS Gateway MSC (SMS-GMSC)
– gateway between Short Message Service Center and PLMN
– deliver SMSs from service center to MS
SMS Interworking MSC (SMS-IWMSC)
– gateway between PLMN and Short Message Service Center
– deliver SMSs from MS to service center
Interworking Function (IWF)
– associated with MSC
– supports interworking of PLMN with fixed networks, e.g. ISDN, PSTN,
PDN (protocol conversion)
Border Gateway (BG)
– PS gateway to other PLMNs
– firewall functionality
Charging Gateway Functionality (CGF)
– collects charging records from SGSNs and GGSNs
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
11 o
Radio Network System (RNS)
Provide access to the UMTS terrestrial radio interface
Radio Network Controller (RNC)
• (Radio) mobility management
• Management of radio resources
Core Network
Iu
Iu
RNS
RNS
UTRAN
Iur
RNC
Iub
Node B
RNC
Iub
Iub
Node B
Node B
Iub
Node B
Base Station (Node B)
• Radio coverage of cells
• Physical layer processing
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
12
Mobile Station (MS)
Mobile station (MS)/
User Equipment (UE)
physical equipment used by
a PLMN subscriber
Mobile Equipment (ME)
radio transmission
and application
Mobile Termination (MT)
functions for radio transmission
and management of the radio
interface, e.g. the handset
ITU-T Recommendyer
Terminal Equipment (TE)
support for end-to-end
application
functions necessary for
the operation of the
access protocols by the
user, e.g. a laptop
UE
Mobile Equipment (ME)
Terminal
Equipment
(TE)
R
Mobile
Termination
(MT)
Uu
T
A
F
Access
Network
Cu
UMTS Subscriber Identity
Module (USIM)
user identity
contains data and procedures
to unambiguously and securely
identify itself
UMTS Networks
USIM
Oliver Waldhorst, Jens Mückenheim
Terminal Adaptation Functions (TAF)
(service dependent)
• mapping of terminal requests on
network capabilities
• flow control/rate adaptations
Oct-11
13 o
UMTS High-level Functions (PS Domain)
Network Access Control
Provide means by which a user is
connected to a telecommunication
network
• Registration
Association of Mobile ID with the
user's packet data protocol(s) and
address(es) within the PLMN, and
with the user's access point(s) to the
external PDP network
• Authentication and Authorisation
Identification and authentication of
the service requester, and the
validation of the service request type
• Admission Control
Check available network resources
required to provide the quality of
service (QoS)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
•
•
•
•
Message Screening
A screening function with filtering out
unauthorised or unsolicited messages
(firewall)
Packet Terminal Adaptation
Adaptation of data packets suitable
for transmission across the packet
domain network
Charging Data Collection
Collection of data necessary to
support subscription and/or traffic
fees
Operator Determined Barring
Limitation of the service provider's
financial risk with respect to new
subscribers or to those who have not
promptly paid their bills by restricting
a particular packet-switched service
Oct-11
14
UMTS High-level Functions (PS Domain)
Packet Routing and Transfer
Determining and using the route
for transmission of a message
within and between the PLMN(s)
• Relay
Forwarding of data received from
one node to the next node in the
route
• Routing
Selection of the transmission path
for the "next hop" in the route
using the destination address of
the message
• Address Translation and Mapping
Conversion of one address to
another address of the same or
different type, i.e. to convert an
external network protocol
address into an internal network
address
UMTS Networks
•
•
•
•
Encapsulation/Decapsulation
Addition/removal of address and control
information to a data unit for routing
packets within and between the PLMN(s)
and between the SGSN and the MS
Tunneling
Transfer of encapsulated data units
within and between the PLMN(s) from
the point of encapsulation to the point of
decapsulation
A tunnel is a two-way point-to-point path
Compression
Optimisation of radio path capacity
Ciphering
Preservation of the confidentiality of user
data and signalling across the radio
channels
Mobility Management
• Keep track of location of MS
Radio Resource Management
• Management of radio resources
Oliver Waldhorst, Jens Mückenheim
Oct-11
15
UMTS Functional Entities: Domains
Domain: grouping of physical entities of the system
Air Interface
Radio Access
Network (RAN)
Home
Network
Domain
[Zu]
Cu
Uu
Iu
[Yu]
Serving Network
(SN) Domain
USIM
Domain
Mobile
Equipment
Domain
Access Network
(AN) Domain
User Equipment (UE) Domain
Transit
Network
Domain
Core Network
(CN) Domain
Infrastructure Domain
Source: 3GPP 23.101-4.0.0
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
16
Functions of the UMTS Domains
Infrastructure domain
– Access network (AN) domain: functions specific to access technique
– Core network (CN) domain: functions independent of access technique
Access network domain
– physical entities managing the resources of the access network
– provides the user with a mechanism to access the core network domain
Serving network (SN) domain
– part of the CN domain to which the AN domain that provides the user’s
access is currently connected
– responsible for routing calls and transport user data/information from source
to destination
– provides CN functions that are local to the user’s access point (i.e. SN
changes when the user moves)
Home network (HN) domain
– provides CN functions that are conducted at a permanent location regardless
of the location of the user’s access point (i.e. does not change due to user
mobility)
– contains user-specific data and is responsible for management of
subscription information
– handle home-specific services, not offered by the serving network domain
User Services Identity Module domain (USIM)
– related to the home network domain by subscription
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
17
Functional Communication between
UMTS domains
Protocols and functions related to the
handling and storage of
subscription data and
possibly home network
specific services
“Home Stratum”
USIM - HN
USIM - MT
MT - SN
SN - HN
Protocols and functions to
“Serving Stratum”
USIM - MT
route and transmit
data/information (user
MT - SN
or network generated) from
source to destination
Transport of user data and
network control signalling
“Transport Stratum”
“Access Stratum”
MT - AN
USIM
MT/ME
AN - SN
Access
Network
Domain
Strata concept:
• grouping of functions
• grouping of
respective protocols
UMTS Networks
• functions related to subscription
data management, customer care,
including billing and charging,
mobility management and
authentication
• functions to allow domains other
than the home network domain to
act on behalf of the home network
Serving
Network
Domain
Home
Network
Domain
• error correction and recovery
• encrypt data over the radio interface
and in the infrastructure part
• adaptation of data to use the supported
physical format
• transcoding of data to make efficient
use of, e.g. the radio interface
Parts of infrastructure, user equipment and
protocols specific to the access technique
• provides services related to the transmission
of data over the radio interface and
the management of the radio
interface
Oliver Waldhorst, Jens Mückenheim
Source: 3GPP 23.101-4.0.0
Oct-11
18 o
ow1
Functional Communication between
UMTS domains
End-to-end protocols and
Application Stratum
functions which make use of services
provided by the home, serving and
transport strata and infrastructure to
support services and/or value added
services.
Application
The functions and protocols within the
application stratum may adhere to
GSM/UMTS standards such as MExE or
may be outside the scope of the UMTS
standards.
“Serving Stratum”
TE - MT
MT - SN
“Transport Stratum”
“Access Stratum”
MT - AN
AN - SN
MT
TE
Mobile
Equipment
Domain
Access
Network
Domain
Serving
Network
Domain
Transit
Network
Domain
Remote
Party
Source: 3GPP 23.101-4.0.0
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
19 o
Folie 19
ow1
Hier ist das Serving Stratum seltsam!
Oliver Waldhorst; 17.10.2011
UMTS Protocol Architecture
We will focus on the packet switched mode here
References:
• Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks – Architecture, Mobility
and Services. Wiley 2001, Ch. 5.1
• Walke, et al: UMTS – ein Kurs, Ch. 5 (air interface only)
• 3G TS 23.060: GPRS, Service Description
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
20
User Plane Bearer Services – Overview
UMTS
TE
MT
UTRAN
CN
Gateway
CN Iu
EDGE
NODE
TE
End-to-End Service
TE/MT Local
Bearer Service
Radio Access Bearer Service
UMTS Networks
External Bearer
Service
UMTS Bearer Service
Radio Bearer
Service
Iu Bearer
Service
UTRA
FDD/TDD
Service
Physical
Bearer Service
Oliver Waldhorst, Jens Mückenheim
CN Bearer
Service
Backbone
Bearer Service
Oct-11
21
Bearer Services – Analogy with Public
Transportation
UMTS
TE
MT
UTRAN
CNtaxi
Iu
Combo ticket:
bus and
EDGE
NODE
Taxi, bus and train combo:
singleCNticket, single
TE reservation,
Gateway
same
service everywhere
End-to-End Service
TE/MT Local
Bearer Service
External Bearer
Service
UMTS Bearer Service
Radio Access Bearer Service
CN Bearer
Service
Walk to taxi
Taxi:
Flat – bus stop
Radio Bearer
Service
Iu Bearer
Service
UTRA
FDD/TDD
Service
Physical
Bearer Service
Taxi with driver
UMTS Networks
Backbone
Bearer Service
Bus:
Bus stop – railway station
Bus with driver
Oliver Waldhorst, Jens Mückenheim
Train:
Station – station
For each bearer:
• specific attributes (delay,
bandwidth, guarantees, etc.
• specific reservation
mechanism
22
Oct-11
MS-RNS-SGSN-GGSN – User Plane
Application
E.g., IP,
PPP
E.g., IP,
PPP
Relay
Relay
PDCP
PDCP
GTP-U
GTP-U
GTP-U
GTP-U
RLC
RLC
UDP/IP
UDP/IP
UDP/IP
UDP/IP
MAC
MAC
AAL5
AAL5
L2
L2
L1
L1
ATM
ATM
L1
L1
Uu
MS
Iu-PS
UTRAN
Gn
Gi
3G-GGSN
3G-SGSN
Source: 3GPP 23.060-4.1.0
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
23
MS-RNS-SGSN-GGSN – User Plane
Application
E.g., IP,
PPP
E.g., IP,
PPP
Relay
Relay
PDCP
PDCP
GTP-U
GTP-U
GTP-U
GTP-U
RLC
RLC
UDP/IP
UDP/IP
UDP/IP
UDP/IP
MAC
MAC
AAL5
AAL5
L2
L2
L1
L1
ATM
ATM
L1
L1
Uu
Iu-PS
GTP-U
(GPRS Tunneling
plane):
MS
UTRAN Protocol for User
3G-SGSN
• tunneling of user data between UTRAN and the 3G-SGSN
• tunneling between the GSNs in the backbone network
Source: 3GPP 23.060-4.1.0
• encapsulation of all PDP PDUs
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
Gn
Gi
3G-GGSN
24
MS-RNS-SGSN-GGSN – User Plane
Application
E.g., IP,
PPP
Relay
PDCP
PDCP
GTP-U
RLC
RLC
UDP/IP
MAC
MAC
AAL5
L1
L1
ATM
Uu
MS
UTRAN
PDCP (Packet Data Convergence
Protocol):
E.g., IP,
PPP(wrt
• provides protocol transparency
the underlying radio-interface
Relay
protocols)
for higher-layer protocols
• support
forGTP-U
e.g., IPv4, PPP and
IPv6
GTP-U
GTP-U
(easy introduction of new higherlayer protocols)
UDP/IP UDP/IP
UDP/IP
• compression of control information
L2
AAL5 compression)
L2
(header
• no ATM
user data L1
compression in Iu
L1 mode
Iu-PS (because the data compression
Gn
Gi
3G-GGSN
3G-SGSN
efficiency
depends on the type
of
user data)
Source: 3GPP 23.060-4.1.0
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
25
MS-RNS-SGSN-GGSN – User Plane
Application
E.g., IP,
PPP
E.g., IP,
PPP
RelayControl):
RLC (Radio Link
RLC GTP-U
protocol GTP-U
provides logical GTP-U
link
GTP-U
control over the radio interface
There may be several simultaneous
UDP/IP
UDP/IP UDP/IP
UDP/IP
RLC links per MS; each link is identified
L2
AAL5
by a AAL5
Bearer Id L2
Relay
PDCP
PDCP
RLC
RLC
MAC
MAC
L1
L1
ATM
Uu
MS
Source: 3GPP 23.060-4.1.0
UMTS Networks
UTRAN
ATM
L1
L1
Iu-PS
Gn
MAC
(Medium Access Control):
3G-GGSN
3G-SGSN
MAC protocol controls the access
signaling (request and grant)
procedures for the radio channel
Oliver Waldhorst, Jens Mückenheim
Oct-11
Gi
26
MS-RNS-SGSN-GGSN – Control Plane
GMM /
SM / SMS
GMM /
SM / SMS
Relay
RRC
RRC
RANAP
RANAP
GTP-C
GTP-C
RLC
RLC
SCCP
SCCP
UDP
UDP
MAC
MAC
Signalling
Bearer
Signalling
Bearer
IP
IP
AAL5
AAL5
L2
L2
ATM
ATM
L1
L1
L1
L1
Uu
MS
UMTS Networks
Gn or Gp
Iu-Ps
RNS
3G SGSN
Oliver Waldhorst, Jens Mückenheim
GSN
Oct-11
GSN
27 o
MS-RNS-SGSN – Control Plane
GMM (GPRS Mobility Management):
– GMM supports mobility management functionality such as attach, detach,
security, and routing area update
SM (Session Management):
– SM supports PDP context activation and deactivation
SMS supports short message service
GTP-C (GPRS Tunneling Protocol for Control plane):
– establish, manage and release GTP tunnels
RANAP (Radio Access Network Application Protocol):
– transport of higher-layer signalling
– handling of signalling between the 3G-SGSN and UTRAN
– management of the GTP connections on the Iu interface
RRC (Radio Resource Control):
– Information Broadcast (AS and NAS)
– RRC connection management (setup, release, reconfiguration)
– Radio Bearers management (setup, release, reconfiguration)
– Management of radio resources for the RRC connection
– RRC connection mobility functions
– Paging/notification
Source: 3GPP 23.060-4.1.0
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
28
UMTS Protocol Architecture:
The Complete Picture (Packet Switched)
Uu
Node B
Iub
Iups
RNC
SM
SM
SM
MM
IP
PMM
MM
PMM
SM
PDCP
RRC
RRC
RRC
RRC
RLC
codec
RLC
RLC
RLC
MAC
MAC
ALCAP
ALCAP
STC.2
NBAP
ALCAP
NBAP
FP
FP
PHY
PHY
AAL2
AAL2
UDP
Phy-up
Phy-up
STC.2
ALCAP
SSCF-UNI
SSCF
SSCF
SSCOP
SSCOP SSCOP
SSCOP
SSCOP SSCOP
AAL5
AAL5
AAL5
AAL5
AAL5
AAL5
IP
GTP-U
RANAP
FP
RANAP
SCCP
SCCP
GTP-C
Q2150.1
UDP
Q2150.1
GTP-U
GTP-C
UDP
FP
AAL2
AAL2
AAL2
User Plane
MTP3-b
MTP3B
SSCF-N
SSCF
SSCF-N
SSCF
SSCF
SSCOP
SSCOP
SSCOP
SSCOP
AAL5
AAL5
AAL5
Oliver Waldhorst, Jens Mückenheim
MTP3BIP
AAL5
AAL5
AAL5
Q2150.1
Iu UP
MTP3BIP
SSCFQ2150.1
SSCOP
L2
AAL2
AAL5
L2
ATM
ATM
STM-1
E1
Transport Plane
Q2150.1
MTP3-b
IP
FP
SCCP
SCCP
ATM
ATM
E1/ STM-1
E1
UMTS Networks
NBAP
NBAP
SSCF-UNI
SSCF
SSCF
ATM
ATM
Control Plane
GTP-U
GGSN
MAC
MAC
Phy-up
Phy-up
PHY
PHY
PDCP
Gn
SGSN
STM-1
L1
L1
E1
Common
Oct-11
29 o
UMTS Protocol Architecture:
The Complete Picture (Circuit Switched)
Uu
codec
Iub
Node B
CM
SM
MM
MM
RRC
RRC
MM
SM
RANAP
RLC
RLC
MAC
MAC
ALCAP
AA
FP
ALCAP
NBAP
SSCF-UNI
SSCOP
PHY
AAL2
AAL5
SSCF-UNI
SSCF
SSCF
SSCOP
SSCOP SSCOP
AAL5
AAL5
AAL5
STC.1
SCCP
Iu UP
MTP3-b
FP
FP
SSCF-NNI
SSCOP
AAL2
AAL2
AAL2
AAL5
ATM
ATM
STM-1
E1
E1
User Plane
Phy-up
Phy-up
Transport Plane
Oliver Waldhorst, Jens Mückenheim
RANAP
ALCAP
ALCAP
NBAP
STC.2
NBAP ALCAP
ATM
UMTS Networks
codec
RRC
RRC
STC.2
Control Plane
3G-MSC
CM
MM
RLC
codec
RLC
MAC
MAC
Phy-up
Phy-up
PHY
PHY
Iucs
RNC
Iu UP
SCCP STC.1
SCCP Q2150.1 Iu UP
MTP3B
MTP3B
MTP
SSCF-NNI
SSCF
SSCF
SSCOP
SSCOP
AAL5
AAL2
AAL5
AAL5
AAL2
ATM
ATM
STM-1
E1
Common
Oct-11
30 o