03 01 rn33023en10gla00 ps call setup

1 © Nokia Siemens Networks RN33022EN10GLA00 PS Call Setup

Radio Access Network SignallingPS Call Setup


Content

• Attach and Detach• PDP Context Activation• Iu-CS vs Iu-PS• Encryption


PMM and SM State

Detached

Connect

Idle

Inactive

Active

SM StatePMM State

ONAttach

OFFDetach

“Iu Release”Command Message

PDP Context

Activation

PDP Context

Deactivation

An MS shall perform a GPRS Attach to the SGSN in order to obtain access to the GPRS services. If the MS is connected via a UMTS radio access network, it shall perform a UMTS GPRS Attach procedure.In the attach procedure, the MS shall provide its identity and an indication of which type of attach that is to be executed. The identity provided to the network shall be the MS's Packet TMSI (P-TMSI) or IMSI. P-TMSI and the RAI associated with the P-TMSI shall be provided if the MS has a valid P-TMSI. If the MS does not have a valid P-TMSI, the MS shall provide its IMSI.

A GPRS-attached MS makes an IMSI attach via the SGSN with the combined RA / LA update procedure if the network operates in mode I (Gs interface is present.). If the network operates in mode II ( Gs interface is not present.), or if the MS is not GPRS-attached, the MS makes a normal IMSI attach. An IMSI-attached MS engaged in a CS connection shall use the (non-combined) GPRS Attach procedure when it performs a GPRS attach.

After having executed the GPRS attach, the MS is in the PMM-CONNECTED state and MM contexts are established in the MS and the SGSN. The MS may then activate PDP contexts as described in subclause "Activation Procedures".

An IMSI-attached MS that cannot operate in CS/PS mode of operation shall follow the normal IMSI detach procedure before it makes a GPRS attach. A GPRS-attached MS that cannot operate in CS/PS mode of operation shall perform a GPRS detach before it makes an IMSI attach.


GPRS Attach

UEATTACH REQUEST ( )

(Identification Procedure)

Authentication and Ciphering Procedure

ATTACH ACCEPT ( )e.g. new TMSI

or P-TMSI

ATTACH COMPLETE ( )

3G-SGSN

Registration and Routing Area Update

In the CS mode of operation, we use the Location Updating Request both for the initial registration and for location updates. This is different in the PS mode of operation:

GPRS AttachA GPRS Attach is used to establish a GMM context between the UE and the 3G-SGSN. It can be used for a - normal GPRS attach, which is an IMSI attach for ps services, or a- combined GPRS attach for a combined cs and ps IMSI attach. This is only possible with NMO I.


UE Initiated PDP Context Activation

Radio Bearer Setup

UE

3G-SGSN

GGSNACTIVATE PDP CONTEXT REQUEST ( )

ACTIVATE PDP CONTEXT ACCEPT ( )

CREATE PDP CONTEXT REQUEST

CREATE PDP CONTEXT RESPONSE

UPDATE PDP CONTEXT REQUEST

UPDATE PDP CONTEXT RESPONSE

GPRS Session Management

Session management is only possible after the establishment of the GMM context between the UE and the network. The session management is then responsible to handle PDP contexts. This incorporates PDP context activation, PDP context modification, and PDP context deactivation procedures. In the TS24.008 you can find all session management messages, which are transmitted over the radio interface. The peer entities are the UE and the SGSN.

The UE send the session management message ACTIVATE PDP CONTEXT REQUEST to the SGSN to activate a PDP context. In parallel, it starts the timer T3380 (30 = seconds). The IE contained in this message are sketched in the figure on the right hand side. The SGSN is analysing the message. The APN is analysed to determine a suitable GGSN. The QoS requested by the UE may be modified. The SGSN may even reject the subscriber‘s request. If the SGSN accepts the UE‘s request, it has to establish a GTP tunnel to the selected GGSN by sending the message CREATE PDP CONTEXT REQUEST. The GGSN analysis the message in order to establish a connection to the external PDN. It returns the message CREATE PDP CONTEXT RESPONSE to the SGSN. This message holds among others the Negotiated QoS and the GPRS Charging Identifier. Based on the Negotiated QoS, the SGSN determines the a radio priority level for the UE. The SGSN returns the message ACTIVATE PDP CONTEXT ACCEPT. Upon its reception, the UE stops the timer T3380. If the QoS requested derivates from the Negotiated QoS, the UE either accepts it, or initiates the PDP context deactivation procedure. Upon expiry of T3380, the UE transmits the ACTIVATE PDP CONTEXT REQUEST message again. Retransmission is possible up to four times.


PDP Context Activation

Protocol discriminator

Requested QoS

Requested LLC SAPI

Transaction indicatorActivate PDP contextrequest message ID

Requested PDP address

Access Point Name OP

Requested NSAPI

Protocol configurationoptions OP

1010: GPRS session management messages

01000001: Activate PDP context request

• Delay class• Reliability class• Precedence class• Mean and peak throughput

class• Maximum UL/DL bit rate• Transfer delay• Guaranteed UL/DL bit rate• Residual BER• Delivery order• etc.

UE 3G-SGSNACTIVATE PDP CONTEXT REQUEST ( )

The RAB establishment is initiated by the SGSN at the reception of the CREATE PDP CONTEXT RESPONSE. The QoSattributes may be downgraded during the RAB establishment process. If so, the GGSN may be informed about it by the sending the UPDATE PDP CONTEXT REQUEST message to the GGSN. Please note, that the radio priority level and the LLC parameters are not used in UMTS. They are only transmitted to support cell re-selection between UMTS and GSM.

In the PDP Context Activation Request message, we again find a list of parameters, which need further explanation. A basic idea here is, that the mobile has the chance to request certain features, values or qualities, which might be conceded or downgraded or even rejected by the PDP Context Activation Response. The PDP Context Activation Request contains:Network Serv. Access Point Id.The purpose of the Network Service Access Point Identifier information element is to identify the service access point that is used for the GPRS data transfer at layer 3. An NSAPI is assigned when the MS initiates the PDP Context Activation function.LLC Service Access point Id The purpose of the LLC Service Access Point Identifier information element is to identify the service access point that is used for the GPRS data transfer at LLC layer.SAPI identifies a point at which LLC services are provided by an Logical Link Entity (LLE) to a layer-3 entity. Consequently, SAPI identifies an LLE that should process an LLC frame and also a layer-3 entity that is to receive information carried by the LLC frame.SAPI is a four bit field. Possible values are:SAPI Related Service 1 GPRS Mobility Management3 User data 15 User data 27 SMS9 User data 3 11 User data 4 Other values are reserved



Protocol discriminator

Negotiated QoS

Negotiated LLC SAPI

Transaction indicatorActivate PDP contextrequest message ID

PDP address

Packet Flow Identifier

OPProtocol configuration

optionsOP

Radio prioritySpare half octet

OP

1010: GPRS session management messages

01000010: Activate PDP context accept

Not required in UMTS, but transmitted tosupport UMTS – GPRS cell reselection

UE 3G-SGSNACTIVATE PDP CONTEXT ACCEPT ( )

In UMTS, both the network and the MS shall store the LLC SAPI and the radio priority in the PDP context. If a UMTS to GSM system change is performed, the new SGSN shall initiate establishment of the logical link using the negotiated QoS profile, the negotiated LLC SAPI, and selected radio priority level stored in the PDP context as in a GSM to GSM Routing Area Update.

An MS, which is capable of operating in both GSM and UMTS, shall use a valid LLC SAPI, while an MS which is capable of operating only in UMTS shall indicate the LLC SAPI value as "LLC SAPI not assigned" in order to avoid unnecessary value range checking and any other possible confusion in the network. When the MS uses a valid LLC SAPI, the network shall return a valid LLC SAPI. However, in this version of the protocol, if the network does not support handover to GSM, it may return the "LLC SAPI not assigned" value.

NOTE: The radio priority level and the LLC SAPI parameters, though not used in UMTS, shall be included in the messages, in order to support handover between UMTS and GSM networks.

Quality of Service The purpose of the quality of service information element is to specify the QoSparameters for a PDP context. . The trace shows subfields of which possible values are as follows:

The quality of service is a type 4 information element with a length of 13 octets. The QoSrequested by the MS shall be encoded both in the QoS attributes specified in octets 3-5 and in the QoS attributes specified in octets 6-13.

A QoS IE received without octets 6-13 shall be accepted by a receiving entity.

NOTE: This behavior is required for interworking with entities supporting an earlier version of the protocol.


Overview of Setting Up Call

Mobile Terminated Call (MTC)

ServiceRequest

Radio AccessBearer

Paging

Mobile Originated Call

RRCConnection

L3 Call Setup

In case of a mobile terminated call (MTC), the process starts with paging. Paging is the procedure by which a mobile network attempts to locate the UE within its location area before any other network-initiated procedure can take place.

If the UE originates the call, paging is not needed and the UE directly requests RRC connection setup.

After having established an RRC connection, the UE starts setting up a signallingconnection to the CN. For that, a new radio link is needed.

Finally, the radio access bearer setup procedure builds a radio access bearer service between the UE and the core network (CN), and the call is established.


Iu-CS VS Iu-PS Call Setup

RRC

ServiceReq

Security Mode Command

Non-real-time services (NRT) only involve packet switched data calls. For non-

real time services, the radio access bearer is created without immediately

reserving radio resources. The resources are allocated on demand by using the

signalling link between the UE and the RNC. The following figures illustrate the

process of establishing a packet switched call.


RAB Establishment Iu-CS VS Iu-PS

For non-real time services, the radio access bearer is created without immediately reserving radio resources

RAB

Iu-CS Iu-PS



RAB Assignment Iu-CS VS Iu-PS

Iu-PS RAB-ASSIGNMENT REQUEST

RANAP-PDUinitiatingMessage- procedureCode: 0- criticality: reject

initiatingMessageRAB-AssignmentRequestprotocolIEs

- id: 54- criticality: ignoreRAB-SetupOrModifyList

- id: 53- firstCriticality: rejectfirstValue- rAB-ID: '00000101'BrAB-Parameters- trafficClass: background- rAB-AsymmetryIndicator: symmetric-bidirectionalmaxBitrate- MaxBitrate: 128000- deliveryOrder: delivery-order-not-requested- maxSDU-Size: 12016sDU-ParametersresidualBitErrorRatio- mantissa: 1- exponent: 5

Iu-CS RAB-ASSIGNMENT REQUEST

RANAP-PDUinitiatingMessage- procedureCode: 0- criticality: reject

initiatingMessageRAB-AssignmentRequestprotocolIEs

- id: 54- criticality: ignoreRAB-SetupOrModifyList

- id: 53- firstCriticality: rejectfirstValue- rAB-ID: '00000001'BrAB-Parameters- trafficClass: conversational- rAB-AsymmetryIndicator: symmetric-bidirectionalmaxBitrate- MaxBitrate: 12200

guaranteedBitRate- GuaranteedBitrate: 4750- deliveryOrder: delivery-order-requested- maxSDU-Size: 244sDU-ParameterssDU-ErrorRatio- mantissa: 7- exponent: 3

Bit rate



Iu-PS residualBitErrorRatio

- mantissa: 1- exponent: 5- deliveryOfErroneousSDU: no-error-detection-consideration

allocationOrRetentionPriority- priorityLevel: 2- pre-emptionCapability: shall-not-trigger-pre-emption- pre-emptionVulnerability: pre-emptable- queuingAllowed: queueing-not-allowed- relocationRequirement: none

Iu-CS residualBitErrorRatio

- mantissa: 1- exponent: 6- deliveryOfErroneousSDU: yessDU-FormatInformationParameters

- subflowSDU-Size: 81: :

residualBitErrorRatio- mantissa: 1- exponent: 3- deliveryOfErroneousSDU: no-error-detection-considerationsDU-FormatInformationParameters


residualBitErrorRatio- mantissa: 5- exponent: 3- deliveryOfErroneousSDU: no-error-detection-considerationsDU-FormatInformationParameters


- transferDelay: 80- sourceStatisticsDescriptor: speech



Iu-PSuserPlaneInformation- userPlaneMode: transparent-mode- uP-ModeVersions: '0000000000000001'B

transportLayerInformation- transportLayerAddress: '00001010001110100001010100000101'B

- -extension range: 0

- length (in bits): 00011111 - padding: 00000 - contents: 0A 3A 52 0C

iuTransportAssociation- gTP-TEI: '3C000000'H- service-Handover: handover-to-GSM-should-not-be-performed- secondCriticality: ignoresecondValuepDP-TypeInformation- PDP-Type: ipv4- PDP-Type: ipv4- dataVolumeReportingIndication: do-not-report

Iu-CS

userPlaneInformation- userPlaneMode: support-mode-for-predefined-SDU-sizes- uP-ModeVersions: '0000000000000001'B

transportLayerInformation- transportLayerAddress:

'01000101000000000000000000000110011000011000000110010000000100010001111100000000000

0000000000000000000000000000000000000000000000000000000000000000000000000000 0'B

- extension range: 0 - length (in bits): 10011111 - padding: 000000 - contents

45 00 00 06 61 81 90 11 1F 00 00 00 00 00 00 00 00 00 00 00

iuTransportAssociation- bindingID: '01025550'H

- secondCriticality: ignoresecondValue

Tunnel Unit (TU) of SGSNi.e. 10.58.82.12

Tunnel EndpointMGW A2EA


RAB Assignment on IP transport (1/2)

Frame 49 (182 bytes on wire, 182 bytes captured)Ethernet II, Src: EmersonN_13:ce:1a (00:80:42:13:ce:1a), Dst: Cisco_a9:fa:4d (00:1b:2a:a9:fa:4d)Internet Protocol, Src: 10.2.60.88 (10.2.60.88), Dst: 10.2.80.130 (10.2.80.130)Stream Control Transmission Protocol, Src Port: 2906 (2906), Dst Port: m3ua (2905)

Source port: 2906Destination port: 2905Verification tag: 0x64722d39Checksum: 0x58d7f7ed (not verified)SACK chunk (Cumulative TSN: 3641121891, a_rwnd: 192000, gaps: 0, duplicate TSNs: 0)DATA chunk(ordered, complete segment, TSN: 2507691165, SID: 12, SSN: 2, PPID: 3, payload length: 104 bytes)

Chunk type: DATA (0)Chunk flags: 0x03Chunk length: 120TSN: 2507691165Stream Identifier: 0x000cStream sequence number: 2Payload protocol identifier: M3UA (3)

MTP 3 User Adaptation LayerSignalling Connection Control PartRadio Access Network Application Part

RANAP-PDU: initiatingMessage (0)initiatingMessage

procedureCode: id-RAB-Assignment (0)criticality: reject (0)value

RAB-AssignmentRequest

Frame 49 (182 bytes on wire, 182 bytes captured)Ethernet II, Src: EmersonN_13:ce:1a (00:80:42:13:ce:1a), Dst: Cisco_a9:fa:4d (00:1b:2a:a9:fa:4d)Internet Protocol, Src: 10.2.60.88 (10.2.60.88), Dst: 10.2.80.130 (10.2.80.130)Stream Control Transmission Protocol, Src Port: 2906 (2906), Dst Port: m3ua (2905)

Source port: 2906Destination port: 2905Verification tag: 0x64722d39Checksum: 0x58d7f7ed (not verified)SACK chunk (Cumulative TSN: 3641121891, a_rwnd: 192000, gaps: 0, duplicate TSNs: 0)DATA chunk(ordered, complete segment, TSN: 2507691165, SID: 12, SSN: 2, PPID: 3, payload length: 104 bytes)

Chunk type: DATA (0)Chunk flags: 0x03Chunk length: 120TSN: 2507691165Stream Identifier: 0x000cStream sequence number: 2Payload protocol identifier: M3UA (3)

MTP 3 User Adaptation LayerSignalling Connection Control PartRadio Access Network Application Part

RANAP-PDU: initiatingMessage (0)initiatingMessage

procedureCode: id-RAB-Assignment (0)criticality: reject (0)value

RAB-AssignmentRequest…

Source and destination IP Address

Source and destination SCTP port

SCTP Stream ID

RAB Assignment Request Message


RAB Assignment on IP transport (2/2)

RAB-AssignmentRequest...

RAB-SetupOrModifyItemFirstrAB-ID: 05 [bit length 8]rAB-Parameters

trafficClass: background (3)rAB-AsymmetryIndicator: asymmetric-bidirectional (3)maxBitrate: 2 items

Item 0RAB-Parameter-MaxBitrateList: 8640000

Item 1RAB-Parameter-MaxBitrateList: 2048000

deliveryOrder: delivery-order-not-requested (1)maxSDU-Size: 12000sDU-Parameters: 1 item

Item 0SDU-Parameters

sDU-ErrorRatiomantissa: 1exponent: 4

residualBitErrorRatiomantissa: 1exponent: 5

deliveryOfErroneousSDU: no (1)

allocationOrRetentionPrioritypriorityLevel: Unknown (2)pre-emptionCapability: shall-not-trigger-pre-emption (0)pre-emptionVulnerability: pre-emptable (1)queuingAllowed: queueing-not-allowed (0)

relocationRequirement: none (1)userPlaneInformation

userPlaneMode: transparent-mode (0)uP-ModeVersions: 0001 [bit length 16]

transportLayerInformationtransportLayerAddress: 0A 02 3C CA [bit length 32]iuTransportAssociation: gTP-TEI (0)

gTP-TEI: 00000004service-Handover: handover-to-GSM-should-not-be-performed (1)

.

.

.RAB QoS

Transport Layer Address, GTP Tunnel Endpoint ID


Encryption in SGSN

Encryption setting in 3G SGSN


Encryption Off vs. Encryption On

User Data can not be decoded

Encryption OFF Encryption ON


Encryption Off vs. Encryption On

Encryption OFF Encryption ON


Iu-PS Attach (1/2)

UE RNC

RRC Connection Setup

GMM : Identity Request RANAPRANAP

Identity Request (GMM)RRC RRC

SGSN Node-B

Initial Direct TransferAttach Request GMM

RRC RRC

Initial UE MessageAttach Request GMM

RANAPRANAP

Identity Response (GMM)RRC RRC

RANAPRANAPGMM: Identity Response


Iu-PS Attach (2/2)UE RNC

RRC Connection Setup

GMM: Authentication & Ciphering Request RANAPRANAP

GMM: Authentication & Ciphering RequestRRC RRC

SGSN Node-B

RRC RRC

RANAPRANAP

GMM: Authentication & Ciphering Response

GMM: Authentication & Ciphering Response

GMM: Attach Accept RANAPRANAP

GMM: Attach AcceptRRC RRC

RRC RRC

RANAPRANAP

GMM: Attach Complete

GMM: Attach Complete

Security Mode Command

Common ID RANAPRANAP

Common IDThe purpose of the Common ID procedure is to inform the RNC about the permanent NAS UE identity (IMSI) of a user. This is used by the RNC, for example, to create a reference between the permanent NAS UE identity of the user and the Radio Resource Control (RRC) connection of that user for UTRAN paging coordination. The procedure uses connection-oriented signalling. The figure below describes the Common ID procedure.

Security Mode Command The purpose of the Security Mode Control procedure is to allow the CN to pass cipher and integrity mode information to the UTRAN. The UTRAN uses this information to select and load the encryption device for user and signalling data with the appropriate parameters, and also to store the appropriate parameters for the integrity algorithm. The procedure uses connection-oriented signalling

CommonID- extension flag: 0 - preamble: 0

protocolIEs- padding: 000000 - length: 00 01

- id: 23- contents: 00 17

- criticality: ignore- contents (in bits): 01

- padding: 000000 - opentype length: 09

PermanentNAS-UE-ID- extension flag: 0

- iMSI: '62029903000040F1'H- length (in bits): 101 - padding: 0000 - contents: 62 02 99 03 00 00 40 F1

03 01 rn33023en10gla00 ps call setup

Documents

ps imsi attach

gprs attacha gprs attach

normal gprs attach

attach procedure

normal imsi attach

pdp context modification

umts gprs

gprs services