Numbering, Addressing
and Location Identities
References:
• Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks – Architecture, Mobility
and Services. Wiley 2001, Ch. 5.2
• 3GPP TS 23.003: Numbering, Addressing and Identification
• 3GPP TS 23.002: Network Architecture (including location area definitions)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
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Numbering and Addressing – Summary
Unique subscriber identity:
– IMSI
Security: temporary subscriber identity
– TMSI
– P-TMSI
Service address and service separation:
– CS: MSISDN (voice or FAX)
– PS: PDP context address (IP address)
Routing:
– MSRN (same format as MSISDN)
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Oliver Waldhorst, Jens Mückenheim
Oct-11
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User Identity:
International Mobile Subscriber Identity (IMSI)
IMSI is the unique identity for the mobile subscriber
Maximum of 15 digits
3 digits
MCC
IMSI consists of 3 parts:
2 or 3 digits
MNC
MSIN
NMSI
IMSI
IMSI serves as unique search key in the
HLR, VLR, AuC and SGSN
IMSI follows the ITU-T E.214 numbering plan
IMSI is stored in the SIM card (USIM)
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Oliver Waldhorst, Jens Mückenheim
• Mobile Country Code (MCC)
identifies uniquely the country
of domicile of the mobile
subscriber (three digits)
• Mobile Network Code (MNC)
identifies the home PLMN of the
mobile subscriber (two or three
digits)
• Mobile Subscriber
Identification Number
(MSIN)
identifies the mobile subscriber
within a PLMN (9-10 digits)
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Service Address and Service Separation:
Mobile Subscriber ISDN Number (MSISDN)
MSISDN is used for service separation
e.g. to separate numbers for voice and FAX
CC
NDC
SN
National (significant)
mobile number
Mobile station international
ISDN number
MSISDN consists of:
• Country Code (CC)
1-3 digits
• National Destination Code (NDC)
1-3 digits
• Subscriber Number (SN)
MSISDN is the directory number or subscriber number
MSISDN numbers are allocated from the ITU-T E.164 numbering plan
Packet Data Protocol (PDP) context address is the counterpart of the
MSISDN in the PS domain, e.g. an (static or dynamic) IP address
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Oliver Waldhorst, Jens Mückenheim
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Subscriber Identities
MSISDN
ISDN
Base station
Base station
controller
MSC
• IMSI
• MSISDN
• PDP context
address
GMSC
HLR
AuC
EIR
Node B
Radio network
controller
• IMSI
• MSISDN
SGSN
Internet
GGSN
PDP context
address
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Oliver Waldhorst, Jens Mückenheim
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Security: Temporary Mobile Subscriber Identity
Number (TMSI)
For security reasons, the IMSI should be transfered in non-ciphered mode
as seldom as possible
 TMSI is used in CS mode instead of the original IMSI
 P-TMSI (Packet TMSI) is used in PS mode
TMSI and P-TMSI are random numbers with limited validity time and
validity area
• TMSI is allocated by the VLR (changed with each UE transaction)
• P-TMSI is allocated by the SGSN and valid in the SGSN area
(changed when UE performs a RA update)
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Oliver Waldhorst, Jens Mückenheim
Oct-11
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Routing:
Mobile Subscriber Roaming Number (MSRN)
• Used for routing purposes
• Follows E.164 specification (similar to MSISDN number)
specifies country code (CC), network (NDC), network element and
subscriber number (SN)
Equipment:
International Mobile Equipment Identity (IMEI)
• Unique identification of the terminal hardware
• IMEI is provided by UE with transaction establishment request
• Use of IMEI by EIR is optional
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Oliver Waldhorst, Jens Mückenheim
Oct-11
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Numbering and Addressing – Summary
Unique subscriber identity:
– IMSI
Security: temporary subscriber identity
– TMSI
– P-TMSI
Service address and service separation:
– CS: MSISDN (voice or FAX)
– PS: PDP context address (IP address)
Routing:
– MSRN (same format as MSISDN)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
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Location-related Areas
Location Area (LA)
– area in which a mobile
station may move freely
without updating the VLR
Routing Area (RA)
– area in which a mobile
station, in PS mode, may
move freely without
updating the SGSN
– a RA is always contained
within a location area
Source: 3GPP 23.002-5.5.0
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LA
RA
RA
LA/RARA
Update
RA
RA
RA
RA
Update
RA
RA RA
Update
LA/RA
Update
Oliver Waldhorst, Jens Mückenheim
RA
RA
Update
Oct-11
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Location-related Areas – Details
MSC area
– part of the network covered by an MSC
– an MSC area may consist of one or several LAs
VLR area
– part of the network controlled by a VLR
– a VLR area may consist of one or several MSC areas
SGSN area
– part of the network served by an SGSN
– an SGSN area may consist of one or several RAs
– an SGSN area may also consist of one or several BSC areas
– there need not be a one to one relationship between SGSN area and MSC/VLR
area
Base Station Controller (BSC) area
– radio coverage area (cells) controlled by a BSC
– the boundaries of a BSC area and a LA are independent
Radio Network Controller (RNC) area
– radio coverage are (cells) controlled by a RNC
– the boundaries of a RNC area and a LA are independent
Cell
– area of radio coverage identified by a Base station identification
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MSC area, VLR area and SGSN area
VLR
SGSN
MSC
SGSN
MSC
LA
LA
RA
RA
RA
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RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
RA
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Location Area Identifications
Location Area Identification (LAI)
MCC
MNC
LAC
LA
RA
RA
RA
RA
RA
RA
RA
RA
RA
Location Area Identification
LAI elements:
• Mobile Country Code (MCC) identifies the country in which the PLMN is located
• Mobile Network Code (MNC) identifies the PLMN in that country
• Location Area Code (LAC) identifies a location area within the PLMN (2 octets)
Routing Area Identification (RAI)
LAI
RAC
Routing Area Identification
RAI elements:
• A valid Location Area Identity (LAI)
• Routing Area Code (RAC) identifies a routing area within a location area (1 octet)
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
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Location Area Identifications
UTRAN Registration Area (URA)
• Location area for PS domain
• RA contains a set of URAs
• URA is maintained by the UTRAN
URA
URA
LA
URA
URA
RA URA
RA URA
URA
URA
URA
URA
URA
URA
URA
URA
 see UTRAN part for details
Cell Global Identity (CGI)
MCC
MNC
LAC
RA URA
RA URA
CI
Cell Global Identity
URA
URA
URA
URA
URA
URA
URA
URA
CGI elements:
• Mobile Country Code (MCC) identifies the country in which the PLMN is located
• Mobile Network Code (MNC) identifies the PLMN in that country
• Location Area Code (LAC) identifies a location area within the PLMN (2 octets)
• Cell ID (CI)
CGI is distributed to the UE by the UTRAN
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Summary: Location Registers in UMTS Core Netw.
Home Location Register (HLR)
location register to which a mobile subscriber is assigned for record
purposes such as subscriber information
Visitor Location Register (VLR)
location register for Circuit Switched (CS) services, other than the HLR,
used by an MSC to retrieve information, e.g. to handle calls to or from
a roaming mobile station currently located in the VLR area
Location register function in the SGSN
stores subscription information and location information for Packet
Switched (PS) services for each subscriber registered in the SGSN
(similar to VLR for CS domain)
Location register function in the GGSN
stores subscription information and routing information (needed to
tunnel packet data traffic to the SGSN where the MS is registered) for
each subscriber for which the GGSN has at least one PDP context active
UMTS Networks
Oliver Waldhorst, Jens Mückenheim
Oct-11
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