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WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 1
Course Overview• Motivation• Standardization issues• UMTS architecture basics• UMTS radio link
– Accessing the network– Transferring data– Detaching from the network– Information storage
• Mobility• QoS• Security• Charging
• IMS
• Example signaling flows
• UMTS Evolution: from R99 to Rel7
• Beyond UMTS
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 2
• Functionality overview• Accessing the network• Transferring data• Detaching from the network• Identities• Information storage
cf. TS 23.003 „Numbering, addressing and identification“TS 23.060 "General Packet Radio Service (GPRS)“TS 23.107 „Quality of Service (QoS) concept and architecture”TS 25.331 “Radio Resource Control (RRC) Protocol Specification”
Basic Functionalities
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 3
Functionality overview• Accessing the network
– Finding the access point– Localizing UE – Establishing connectivity for signaling– Registration
• Authentication and authorization (-> security)
– Establishing connectivity for data transfer• Admission control (-> QoS)
– Paging (-> Mobility)
• Transferring data – Routing, encapsulating and tunneling– Address translation– Ciphering and encryption (-> security)– Compression– Charging– Resource management (-> QoS)
• Mobility Handling• Detaching from the network
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 4
• Functionality overview• Accessing the network
– Finding the access point– Localizing the UE – Establishing connectivity for signaling (RRC connection set-up)– Registration (GPRS Attach)– Establishing connectivity for data transfer (PDP context activation)
• Transferring data• Detaching from the network• Identities• Information storage
cf. TS 23.003 „Numbering, addressing and identification“TS 23.060 "General Packet Radio Service (GPRS)“TS 23.107 „Quality of Service (QoS) concept and architecture”TS 25.331 “Radio Resource Control (RRC) Protocol Specification”
Basic Functionalities
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 5
Accessing the network -Finding the access point I
Upon being switched on the UE…
• …scans all possible frequencies (time slots), in order to find elegible cells
– elegible = UMTS technologie, e.g. UTRA FDD
• …synchronizes, and finds scrambling code
– As described in lecture on UTRA
– Now it is able to receive cell-specific broadcast information• Sent by RNC on BCCH
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 6
Accessing the network -Finding the access point II
• …prioritizes PLMNs(if more than one is available)– PLMN „Public Land Mobile Network“
mobile telecommunication network under the control of a single operator
– PLMN identity broadcasted on P-CCPCH• in regular intervals
– PLMN identified by MCC-MNCMobile Country Code – Mobile Network Code
– UE prioritizes PLMNs according to a preference list stored on the USIM
• Always prefer „home PLMN“• Availability of better PLMN is checked on a regular basis
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 7
Accessing the network -Finding the access point III
• …looks for suitable cells– Suitable = acceptable radio conditions
• Signal to noise ratio is above threshold both uplink and downlink
• …finally picks cell– Listens on the BCCH for general
cell configuration information, e.g. localization• UE is responsible for tracking its location
– Only now UE makes its presence known to the network
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 8
Accessing the network - Localization of the UE I
• Hierarchical organization
…not exchanging data in CS („idle“)…several RAsLA – LocationArea
Accuracy with which location of UE is knownwhen. . .
May contain. . .Name
…not exchanging data in PS („idle“)…several URAsRA – Routing Area
…sporadically exchanging data in PS (II)(unless using (I))
…several cellsURA - UTRAN Registration Area
…continuously exchanging data(both CS and PS)…sporadically exchanging data in PS (I)(unless using (II))
Cell
SGSN 2
SGSN 1
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 9
Accessing the network -Localization of the UE II
• Identification of Localization– LAI – Location Area Identity = MCC + MNC + LA Code
– RAI – Routing Area Identity = LAI + RA Code
– URA Identity
– CGI – Cell Global Identity = LAI + cell identity
• Globally unique identifiers
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 10
Now a signaling connection needs to be established in order to perform signaling for registration:
RRC connection set-up• UE sends a RRC Connection Request to RNC
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 19
Establishing connectivity for data transfer Sequence chart for PDP context activation
GGSN
9. Activate PDP Context Accept
4. Create PDP Context Response
4. Create PDP Context Request
1. Activate PDP Context Request
SGSNRANMS
5. Radio Access Bearer Setup
C1
C2
6. Invoke Trace
8. Update PDP Context Response
8. Update PDP Context Request
Fig. 64 from 23.060
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 20
• Functionality overview• Accessing the network• Transferring data
– Routing – Encapsulating and tunneling– Address translation– Compression
• Detaching from the network• Identities• Information storagecf. TS 23.003 „Numbering, addressing and identification“TS 23.060 "General Packet Radio Service (GPRS)“TS 23.107 „Quality of Service (QoS) concept and architecture”TS 25.331 “Radio Resource Control (RRC) Protocol Specification”
Basic Functionalities
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 21
Transferring Data –Routing, Encapsulation and Tunneling
• each user packet is assigned to a PDP context by GGSN / RNC– When more than one PDP context exists for this UE,
pick one based on associated traffic descriptors (TFT)
– Encapsulate packet with • GTP-U header (TEID)
– Allows assigning packets to PDP context at RNC / GSNs
– Masks upper layer protocol (may not be IP)
• “lower” IP header with GGSN as destination address
• Etc
⇒Routing in UMTS network controlled by operator- Using IETF protocols
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 22
Transferring Data –Address Translation; Compression
• PDP address is UE’s externally visible IP address
• Within PLMN, UE may use different IP address
⇒GGSN may perform address translation
• Redundant header information may be compressed in order to save resources on the UTRA
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 23
• Functionality overview• Accessing the network• Transferring data• Detaching from the network• Identities• Information storage
cf. TS 23.003 „Numbering, addressing and identification“TS 23.060 "General Packet Radio Service (GPRS)“TS 23.107 „Quality of Service (QoS) concept and architecture”TS 25.331 “Radio Resource Control (RRC) Protocol Specification”
Basic Functionalities
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 24
Detaching from the network• For example triggered by…
– … UE (e.g. switching it off)– …SGSN, when no Routing Area Update is received from UE (soft state)
• …involves– PDP context deactivation
• PDP State becomes “inactive”• Triggered actively by UE or… • …GSNs
– Triggered by Mobility Management State becoming IDLE (by time-out) or PMM-DETACHED (by performing GPRS Detach)
– Triggered by switching off UE
• Results in deletion of PDP context information at RNC and GSNs
– GPRS Detach• Mobility Management State becomes PMM-Detached• Triggered actively by UE or…• …SGSN when no periodic location update received • Results in deletion of user data in SGSN, and message to HLR
– Release of RRC Connection
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 25
Detaching from the network:Sequence Chart for user-initiated GPRS Detach
3. IMSI Detach Indication
2. Delete PDP Context Response
1. Detach Request 2. Delete PDP Context Request
5. Detach Accept
MS BSS/UTRAN GGSNSGSN MSC/VLR
4. GPRS Detach Indication
6. PS Signalling Connection Release
C2
C1
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 26
• Functionality overview• Accessing the network• Transferring data• Detaching from the network• Identities• Information storage
cf. TS 23.003 „Numbering, addressing and identification“TS 23.060 "General Packet Radio Service (GPRS)“TS 23.107 „Quality of Service (QoS) concept and architecture”TS 25.331 “Radio Resource Control (RRC) Protocol Specification”
Basic Functionalities
WS 04/05, TKN TU Berlin, Cornelia Kappler Course UMTS Networks, IX. Basic Functionalities 27
Identities Summary• Identities concerned with location
– PLMN identity = MCC + MNC– LAI = MCC + MNC + LA Code– RAI = MCC + MNC + LA Code + RA Code– URA identity– CGI = MCC + MNC + LA Code + cell identity