Radio interface ps_procedures

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  • 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.
  • 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.
  • Radio interface ps_procedures

    1. 1. Signalling Flow: PS Call Establishment For internal use 1 © Nokia Siemens Networks Presentation / Author / Date
    2. 2. Introduction • • This slide set provides a detailed illustration of the message flow observed for an PS call The message flow is focused upon communication with the packet switched core and does not include communication with the circuit switched core. • The UE starts by searching for candidate cells by correlating the RSSI with the code defining the primary SCH • The UE then achieves radio frame synchronisation and reads the BCCH logical channel • The BCCH provides system information including the cell selection criteria • If the cell passes the cell selection criteria then the UE establishes an RRC connection and registers with the core network • Having registered the UE activates the PDP context with the CN using the existing CN (assumption is that follow on request pending is set) • In case of no activity (no data nor signalling For internaldata transmitted between the UE and CN) the use 2 © Nokia Siemens Networks Presentation / Author / Date dedicated channel between the UE and the RNC UE is powered up Cell search Radio frame synchronisation Read BCCH Cell selection Register with core network Originating PS Call Cell State Transitions
    3. 3. Protocol Stacks • Communication between the UE, RNC and packet core makes use of • Uu interface protocol stack • Iub interface protocol stack • Iu,ps interface protocol stack SGSN RNC Node B Uu Iub For internal use 3 © Nokia Siemens Networks Presentation / Author / Date Iu,ps
    4. 4. PS Radio Interface Control Plane • The radio interface protocol control plane allows RRC signalling between the RNC and UE • RRC signalling is communicated across the Iub using the Iub user plane protocol stack i.e. using Frame protocol and AAL2 based ATM • Acknowledged or unacknowledged mode RLC is used between the UE and RNC UE RNC RRC RRC RLC-C RLC-C No de B MAC MAC FP AAL2 WCDMA L1 WCDMA L1 Uu For internal use 4 © Nokia Siemens Networks Presentation / Author / Date FP AAL2 ATM ATM Phy Phy I ub
    5. 5. PS User Plane • The SGSN provides connectivity to the packet switched core and applications • Acknowledged mode RLC (or unacknowledged) is used between the UE and RNC • AAL2 based ATM is used to transfer user plane data across the Iub and AAL5 based ATM across Iu,ps interface UE SG SN RNC RLC-U GTP-U GTP-U MAC UDP UDP FP FP IP IP AAL2 AAL2 AAL5 AAL5 ATM ATM ATM ATM Phy Phy Phy Phy RLC-U No d e B MAC WCDMA L1 WCDMA L1 Uu For internal use 5 © Nokia Siemens Networks I ub Presentation / Author / Date I ps u,
    6. 6. Read BCCH • The BCCH encapsulates the System Information message which includes the Master Information Block (MIB), Scheduling Blocks (SB) and System Information Blocks (SIB) UE is powered up Cell search Radio frame synchronisation Read BCCH Cell selection Register with core network Originating PS Call Cell State Transitions For internal use 6 © Nokia Siemens Networks Presentation / Author / Date
    7. 7. Cell Selection • Cell selection is based upon the S-criteria • UE extracts the S-criteria parameters from SIB 3 • QqualMin UE is powered up • QrxlevMin • UE_TXPWR_MAX_RACH Cell search Radio frame synchronisation Read BCCH Cell selection Register with core network Originating PS Call Cell State Transitions For internal use 7 © Nokia Siemens Networks Presentation / Author / Date
    8. 8. Register with the Core Network • The UE registers with the PS core domain (the UE also registers with the CS core domain but this slide set concerns only the PS domain) • PS domain registering is a GPRS attach procedure • Registering is achieved by establishing an RRC connection and sending non-access stratum messages to the 3G SGSN • RRC Connection Establishment • GPRS Attach UE is powered up Cell search Radio frame synchronisation Read BCCH Cell selection Register with core network Originating PS Call Cell State Transitions For internal use 8 © Nokia Siemens Networks Presentation / Author / Date
    9. 9. UTRAN Specific Signalling Protocols RNS Node B UE I ub :N B RNC AP A RA N -CS: Iu P 3G-MSC/VLR RRC I uPS :R AN AP 3G-SGSN Iur: RNSA P RNC RNS For internal use 9 © Nokia Siemens Networks Presentation / Author / Date
    10. 10. RRC Connection Setup Node-B UE RRC RNC RRC Connection Setup Request ( CCCH on RACH) NBAP Signalling Bearer NBAP Radio Link Setup Request Radio Link Setup Response RRC NBAP NBAP establishment ALCAP ALCAP RRC RRC For internal use 10 © Nokia Siemens Networks Establish Request Establish Response RRC Connection Setup (CCCH on FACH) RRC Connection Setup Complete (DCCH on DCH) Presentation / Author / Date ALCAP ALCAP RRC RRC CN
    11. 11. GPRS Attach UE ATTACH REQUEST ( ) (Identification Procedure) Authentication and Ciphering Procedure ATTACH ACCEPT ( ) e.g. new TMSI or P-TMSI ATTACH COMPLETE ( ) For internal use 11 © Nokia Siemens Networks Presentation / Author / Date 3G-SGSN
    12. 12. Initial Direct Transfer UE Node-B MSC RNC RRC Connection Setup RRC Initial Direct Transfer CM Service Request RRC RANAP UE Node-B Initial UE Message CM Service Request RANAP SGSN RNC RRC Connection Setup RRC Initial Direct Transfer Attach Request GMM RRC RANAP For internal use 13 © Nokia Siemens Networks Presentation / Author / Date Initial UE Message Attach Request GMM RANAP
    13. 13. PS Call UE is powered up • The PS call can be either mobile originated or Cell search mobile terminated • The following slides present a mobile originated call • The first step is to establish an RRC connection, however if the “follow on request” is SET in NAS Message – ‘GPRS Attach Request’ -> there is no Iu release as CN is waiting for additional signalling using the same RRC (e.g. PDP context Activation) • This means that RRC Connections for PS calls are initiated with cause : registration Radio frame synchronisation Read BCCH Cell selection Register with core network Originating PS Call Cell State Transitions For internal use 14 © Nokia Siemens Networks Presentation / Author / Date
    14. 14. Activate PDP Context Request UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request • Having attached with the PS Core NW, UE sends Activate PDP context request DCCH ->DCH -> DPCH • By sending this message UE requests a service for the packet switched connection establishment • DCCH contains the RRC: Uplink Direct Transfer message • Message is sent using acknowledged mode RLC For internal use 15 © Nokia Siemens Networks Presentation / Author / Date
    15. 15. NAS: Activate PDP Context Request IEI Information Element Protocol discriminator Transaction identifier Activate PDP context request message identity Requested NSAPI Requested LLC SAPI Requested QoS Requested PDP address 28 Access point name 27 Protocol configuration options For internal use 16 © Nokia Siemens Networks Type/Reference Protocol discriminator 10.2 Transaction identifier 10.3.2 Message type 10.4 Network service access point identifier 10.5.6.2 LLC service access point identifier 10.5.6.9 Quality of service 10.5.6.5 Packet data protocol address 10.5.6.4 Access point name 10.5.6.1 Protocol configuration options 10.5.6.3 Presentation / Author / Date Presence M Format V Length 1/2 M V 1/2– 3/2 M V 1 M V 1 M V 1 M LV 12 M LV 3 - 19 O TLV 3 - 102 O TLV 3 - 253
    16. 16. RAB Assignment Request UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RAB Assignment Request • Having received the Activate PDP Context Request message the PS core sends the RANAP: RAB Assignment Resuest message to the RNC • The RANAP: RAB Assignment Resuest message requests the RNC to establish a RAB with a specified set of QoS parameters • The PS core requests these QoS parameters based upon the subscription and the service being requested (as seen from Activate PDP Context Request message the QoS is based entirely on the subscription) For internal use 17 © Nokia Siemens Networks Presentation / Author / Date
    17. 17. Radio Bearer Setup UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup • Once the RANAP: RAB Assignment Request message has been received from PS CN and RNC has resources to setup the 0/0 kbps RB the RNC sends a RRC: Radio Bearer Setup message to the UE For internal use 18 © Nokia Siemens Networks Presentation / Author / Date
    18. 18. Radio Bearer Setup Complete UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete • The UE acknowledges the RRC: Radio Bearer Setup message with a RRC: Radio Bearer Setup Complete message For internal use 19 © Nokia Siemens Networks Presentation / Author / Date
    19. 19. RAB Assignment Response UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response • Once the radio bearer establishment has been acknowledged, the RNC indicates to the PS core that the RAB has been established using the RANAP: RAB Assignment Response message For internal use 20 © Nokia Siemens Networks Presentation / Author / Date
    20. 20. Measurement Control UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control • Once the RAB has been established the RNC sends a measurement control messages •For traffic volume measurements (UE internal) •For intra and inter frequency measurements • Prior to receiving this message, the UE uses the measurement control information from the SIBs (inter and intra freq. Measurements – traffic volume measurements are not performed prior to measurement control) • Measurement control defines the reporting thresholds for traffic Presentation / Author / Date For internal use 21 © Nokia Siemens Networks
    21. 21. Activate PDP Context Accept UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control Downlink Direct Transfer : Activate PDP Context Accept (DCH) Direct Transfer: Activate PDP Context Accept • Once the radio access bearer establishment has been acknowledged, (measurement control messages can be sent before or after the Activate PDP Context Accept) the PS CN indicates to the UE that the PDP Context Ativation has been successfully established using the RANAP: Activate PDP Context Accept message • RNC receives the Direct Transfer : Activate PDP Context Accept message and forwards it as Downlink Direct Transfer : Activate PDP Context AcceptAuthor / Date message to the UE Presentation / For internal use 22 © Nokia Siemens Networks
    22. 22. PS call established UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control Downlink Direct Transfer : Activate PDP Context Accept (DCH) Direct Transfer: Activate PDP Context Accept Call Established • PS data call Established, but 0 / 0 kbps RB For internal use 23 © Nokia Siemens Networks Presentation / Author / Date
    23. 23. UE Initiated PDP Context Activation 3GSGSN UE GGSN ACTIVATE PDP CONTEXT REQUEST ( ) CREATE PDP CONTEXT REQUEST CREATE PDP CONTEXT RESPONSE Radio Bearer Setup UPDATE PDP CONTEXT REQUEST UPDATE PDP CONTEXT RESPONSE ACTIVATE PDP CONTEXT ACCEPT ( ) For internal use 24 © Nokia Siemens Networks Presentation / Author / Date
    24. 24. Traffic Volume Measurements Reporting event: 4A: Transport Channel Traffic Volume becomes larger than an absolute threshold 4B: Transport Channel Traffic Volume becomes smaller than an absolute threshold Transport Channel Traffic Volume (TCTV) 4A 4A 4A Threshold time 4B For internal use 26 © Nokia Siemens Networks 4B Presentation / Author / Date 4B
    25. 25. Reporting Event 4a UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control Downlink Direct Transfer : Activate PDP Context Accept (DCH) Direct Transfer: Activate PDP Context Accept Packet Call Established Measurement Report : e4a • Once the UE determines that an event 4a has occurred it sends a measurement report to the RNC. This is done using the RRC: Measurement Report message • As instructed, the UE sends measurement report when the RLC buffer absolute payload exceeds the threshold • The measurement identity reflects that provided within the measurement control message For internal use 27 © Nokia Siemens Networks Presentation / Author / Date
    26. 26. Radio Bearer Reconfiguration UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control Downlink Direct Transfer : Activate PDP Context Accept (DCH) Direct Transfer: Activate PDP Context Accept Call Established Measurement Report : e4a NBAP: Radio Link Reconfigure Prepare Radio Link Reconfigure Ready RRC: Radio Bearer Reconfiguration (DCH) • Once the reconfiguration of radio link at Node-B is done the RNC sends a RRC: RRC: Radio Bearer Reconfiguration message to UE For internal use 28 © Nokia Siemens Networks Presentation / Author / Date
    27. 27. Radio Bearer Reconfiguration Complete UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control Downlink Direct Transfer : Activate PDP Context Accept (DCH) Direct Transfer: Activate PDP Context Accept Call Established Measurement Report : e4a NBAP: Radio Link Reconfigure Prepare Radio Link Reconfigure Ready RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (DCH) • The UE acknowledges the RRC: Radio Bearer Reconfiguration message with a RRC: Radio Bearer Reconfiguration Complete message For internal use 29 © Nokia Siemens Networks Presentation / Author / Date
    28. 28. UL: 64kbps DL: 64 kbps Connection Established UE Node B SGSN RNC GPRS Attach Uplink Direct Transfer : Activate PDP context request (DCH) Direct Transfer : Activate PDP context request RANAP: RAB Assignment Request RRC: Radio Bearer Setup Radio Bearer Setup Complete RAB Assignment Response Measurement Control Measurement Control Downlink Direct Transfer : Activate PDP Context Accept (DCH) Call Established Measurement Report : e4a NBAP: Radio Link Reconfigure Prepare Radio Link Reconfigure Ready RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (DCH) 64 kbps service established For internal use 30 © Nokia Siemens Networks Presentation / Author / Date Direct Transfer: Activate PDP Context Accept
    29. 29. Cell State Transitions • When the RNC notices that there is nothing being transmitted between UE and RNC, inactivity timers will start to run and in case of expiry of those timers the UE is moved to use common channels i.e. cell state transition from Cell_DCH to Cell_FACH occurs • In order to save some UE battery power (as in Cell_FACH the UE has to read FACH channel all the time) in case of further inactivity i.e. no capacity requests from UE nor RNC the UE is further moved to Cell_PCH where the UE only listens to PCH (paging channel) UE is powered up Cell search Radio frame synchronisation Read BCCH Cell selection Register with core network Originating PS Call Cell State Transitions For internal use 31 © Nokia Siemens Networks Presentation / Author / Date
    30. 30. Radio Bearer Reconfiguration UE Node B RNC GPRS Attach Call Established Measurement Report : e4a NBAP: Radio Link Reconfigure Prepare Radio Link Reconfigure Ready AAL2SIG:ERQ AAL2SIG:ECF FP: Downlink Sync FP: Uplink Sync Radio Link Reconfiguration Commit RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (DCH) Measurement Control Data Flow RRC: Radio Bearer Reconfiguration (DCH) • In case the RNC decides to move the UE to Cell_FACH state it sends RRC: Radio Bearer Reconfiguration For internal use 32 © Nokia Siemens Networks Presentation / Author / Date SGSN
    31. 31. Radio Bearer Reconfiguration Complete UE Node B RNC GPRS Attach Call Established Measurement Report : e4a NBAP: Radio Link Reconfigure Prepare Radio Link Reconfigure Ready AAL2SIG:ERQ AAL2SIG:ECF FP: Downlink Sync FP: Uplink Sync Radio Link Reconfiguration Commit RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (DCH) Measurement Control Data Flow RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (RACH) • The UE acknowledges the RRC: Radio Bearer Reconfiguration message with a RRC: Radio Bearer Reconfiguration Complete message on RACH For internal use 33 © Nokia Siemens Networks Presentation / Author / Date SGSN
    32. 32. UE in Cell_FACH UE Node B RNC GPRS Attach Call Established Measurement Report : e4a NBAP: Radio Link Reconfigure Prepare Radio Link Reconfigure Ready AAL2SIG:ERQ AAL2SIG:ECF FP: Downlink Sync FP: Uplink Sync Radio Link Reconfiguration Commit RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (DCH) Measurement Control Data Flow RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (RACH) Measurement Control (FACH) NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response ALCAP: Release Request ALCAP: Release Confirm UE in Cell_FACH, PDP Context Active and GPRS Attached For internal use 34 © Nokia Siemens Networks Presentation / Author / Date SGSN
    33. 33. Physical Channel Reconfiguration UE Node B RNC GPRS Attach Call Established Data Flow RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (RACH) Measurement Control (FACH) NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response ALCAP: Release Request ALCAP: Release Confirm UE in Cell_FACH, PDP Context Active and GPRS Attached RRC: Physical Channel Reconfiguration (FACH) RRC: Physical Channel Reconfiguration Complete (RACH) • RNC sends RRC: Physical Channel Reconfiguration message to the UE to move the UE to Cell_PCH state For internal use 35 © Nokia Siemens Networks Presentation / Author / Date SGSN
    34. 34. UE in Cell_PCH UE Node B RNC GPRS Attach Call Established Data Flow RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (RACH) Measurement Control (FACH) NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response ALCAP: Release Request ALCAP: Release Confirm UE in Cell_FACH, PDP Context Active and GPRS Attached RRC: Physical Channel Reconfiguration (FACH) RRC: Physical Channel Reconfiguration Complete (RACH) UE in Cell_PCH, PDP Context Active and GPRS Attached For internal use 36 © Nokia Siemens Networks Presentation / Author / Date SGSN
    35. 35. Cell Update UE Node B RNC GPRS Attach Call Established Data Flow RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (RACH) Measurement Control (FACH) NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response ALCAP: Release Request ALCAP: Release Confirm UE in Cell_FACH, PDP Context Active and GPRS Attached RRC: Physical Channel Reconfiguration (FACH) RRC: Physical Channel Reconfiguration Complete (RACH) UE in Cell_PCH, PDP Context Active and GPRS Attached RRC: Cell Update (RACH) • In case the UE has something to send it has to send RRC: Cell Update message to the RNC to move the UE to Cell_FACH state to get dedicated resources For internal use 37 © Nokia Siemens Networks Presentation / Author / Date SGSN
    36. 36. Cell Update Confirm UE Node B RNC GPRS Attach Call Established Data Flow RRC: Radio Bearer Reconfiguration (DCH) RRC: Radio Bearer Reconfiguration Complete (RACH) Measurement Control (FACH) NBAP: Radio Link Deletion Request NBAP: Radio Link Deletion Response ALCAP: Release Request ALCAP: Release Confirm UE in Cell_FACH, PDP Context Active and GPRS Attached RRC: Physical Channel Reconfiguration (FACH) RRC: Physical Channel Reconfiguration Complete (RACH) UE in Cell_PCH, PDP Context Active and GPRS Attached RRC: Cell Update (RACH) RRC: Cell Update Confirm (FACH) • RNC acknowledges the UE message RRC: Cell Update with RRC: Cell Update Confirm message and instructs UE to move to Cell_FACH state For internal use 38 © Nokia Siemens Networks Presentation / Author / Date SGSN
    37. 37. Deactivate PDP Context Request UE Node B RNC SGSN GPRS Attach Call Established Data Flow UE in Cell_DCH, PDP Context Active and GPRS Attached UpLink Direct Transfer : Deactivate PDP Context Request (DCH) Direct Transfer : Deactivate PDP Context Request (DCH) • The UE requests deactivation of PDP context by sending the Deactivate PDP Context Request towards the PS core encapsulated within RRC: Uplink Direct Transfer For internal use 39 © Nokia Siemens Networks Presentation / Author / Date
    38. 38. Deactivate PDP Context Accept UE Node B SGSN RNC GPRS Attach Call Established Data Flow UE in Cell_DCH, PDP Context Active and GPRS Attached UpLink Direct Transfer : Deactivate PDP Context Request (DCH) Direct Transfer : Deactivate PDP Context Request Downlink Direct Transfer : Deactivate PDP Context Accept (DCH) Direct Transfer : Deactivate PDP Context Accept • The PS CN acknowledges the deactivation of PDP context by sending Deactivate PDP Context Accept to the UE encapsulated within RRC: Downlink Direct Transfer For internal use 40 © Nokia Siemens Networks Presentation / Author / Date
    39. 39. Radio Bearer Release UE Node B SGSN RNC GPRS Attach Call Established Data Flow UE in Cell_DCH, PDP Context Active and GPRS Attached UpLink Direct Transfer : Deactivate PDP Context Request (DCH) Direct Transfer : Deactivate PDP Context Request Downlink Direct Transfer : Deactivate PDP Context Accept (DCH) Direct Transfer : Deactivate PDP Context Accept RANAP: RAB Assignment Request NBAP: Radio Link Reconfiguration Prepare RANAP: RAB Assignment Response NBAP: Radio Link Reconfiguration Ready NBAP: Radio Link Reconfiguration Commit RRC: Radio Bearer Release (DCH) RRC: Radio Bearer Release Complete (DCH) • Then the RNC is ready to inform the UE about the changes in the RB by sending RRC: Radio Bearer Release • After this there is only signalling link active between the UE and PS CN and the UE can be moved to Cell_FACH and to Cell_PCH still maintaining the signalling link or the signalling link can be deactivated by doing GPRS detach or by releasing For internal use 41 © Nokia Siemens Networks Presentation / Author / Date the RRC connection (and Iu) but still GPRS Attached

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