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ITRI LTE RRC software introduction

ITRI LTE RRC software introduction. 資通所 /m200/Jingo ( 葉昌國 ) 2015/08/25. Outline. RRC procedure introduction General concept UE Power-On Procedures Paging procedure Reestablishment procedure Connection release procedure Measurement configuration Handover procedure

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ITRI LTE RRC software introduction

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  1. ITRI LTE RRC software introduction 資通所/m200/Jingo(葉昌國) 2015/08/25

  2. Outline • RRC procedure introduction • General concept • UE Power-On Procedures • Paging procedure • Reestablishment procedure • Connection release procedure • Measurement configuration • Handover procedure • RRC <-> RRM interface introduction

  3. General concept

  4. Functional Split between E-UTRAN & EPC RRM EPC RRM : Radio Resource Management RRC : Radio Resource Control TS 36.300

  5. Radio Protocol Architecture User plane -protocol stack • TS 36.331 • Paging & Broadcast • RRC Connection management • RB control • Mobility functions • UE measurement reporting and control Control - Plane protocol stack TS 36.300

  6. NAS and RRC state NAS layer state EMM State EMM_Registred EMM_Deregistred ECM State ECM_Connected ECM_Idle RRC layer state RRC State EMM : EPS Mobility management ECM : EPS Connection Management RRC_Connected RRC_Idle

  7. EMM ECM State Transitin Registration(Attach) Release due to UE Iactivity Allocate C-RNTI, GUTI Allocate IP address Authentication Establish security context Power On Release RRC connection Release C-RNTI Configure DRX for paging EMM_Registered ECM_Connected EMM_Registered ECM_Idle EMM_Deregistered ECM_Idle Deregistration(Detach) Change PLMN New traffic TAU Release C-RNTI, GUTI Release IP address Establish RRC Connection Allocate C-RNTI Timeout of Periodic TAU Release GUTI Release IP address

  8. Bearer Service DRB context in RRC IE EPS Bearer ID DRB ID Logical Channel Config RLC Config PDCP Config SRB: Signalling Radio Bearer DRB: Data Radio Bearer

  9. UE Power-On Procedures

  10. UE Power-On Procedures UE MME eNB EMM-DEREGISTRED ECM-IDLE EMM-DEREGISTRED ECM-IDLE RRC-IDLE RRC-IDLE Network selection System Information Cell selection Contention based random access RRC connection setup Connection Control RRC-CONNECTED RRC-CONNECTED Attach procedure EMM-REGISTRED ECM-CONNECTED EMM-REGISTRED ECM-CONNECTED

  11. System information

  12. System information

  13. System information

  14. System information

  15. System information

  16. (Source: http://www.lte-bullets.com) RRC connection establishment • eNB obtains the info • Provided by UE NAS • Establishment cause: MT access, MO data, MO signalling, emergency call • initial NAS message: Attach Request, Detach Request, TAU Request, Service Request or Extended Service Request • selected PLMN identity (referred to SIB2) • S-TMSI: optional, provided if UE is registered in the TA of current cell • Registered MME: optional, provided if UE is registered • Provided by eNB MAC • C-RNTI

  17. RRC connection establishment • eNB assigns the context: • Radio resource configuration (Dedicated) • SRB add/mod list: only SRB1 • MAC main configuration • Physical configuration (SRB0) (SRB0) (SRB0) (SRB0) (+ NAS message) (network reject) (SRB1) (successful)

  18. Attach procedure UE MME eNB RRCConnectionSetupComplte (Attach Request) Initial UE Message (Attach Request) Authentication and key Agreement (AKA), NAS SMC InitialContextSetupRequest UECapabilityEnquiry (Attach Accept, Activate Default ESP Bearer) UECapabilityInformation UE Capability Info Indication SecurityModeCommand SecurityModeComplete RRCConnectionReconfiguration (Attach Accept, Activate Default ESP Bearer) RRCConnectionReconfiguration Complete InitialContextSetupResponse UL Information Transfer UL NAS Transport Direct transfer NAS message (Attach Complete, Activate EPS Bearer contest accept) (Attach Complete, Activate EPS Bearer contest accept)

  19. Capability • When NW wants to know UE capability, it sends UE Capability Enquiry specify which information it wants to get • UE-CapabilityRAT-Container • rat-Type • eutra, utra, geran-cs, geran-ps, cdma2000-1XRTT • ueCapabilityRAT-Container • eutra • accessStratumRelease, ue-Category, radio parameters

  20. Security configuration • Initial activation after RRC connection establishment • activate AS security upon RRC connection establishment • Prior to establishment of SRB2 and/or DRBs • Integrity protection and encryption for rrc message (SRB1) (SRB1) (SRB1) (SRB1) (failure) (successful)

  21. Radio resource configuration Optional (SRB1) (SRB1) (successful) Optional (+ NAS message) (SRB1) (failure)

  22. Radio resource configuration • SRB addition/ modification • DRB addition/ modification and release • MAC main reconfiguration • Semi-persistent scheduling reconfiguration • Physical channel reconfiguration

  23. Radio resource configuration: SRB RLC TM mode • SRB2 are configured by E-UTRAN after security activation • NAS messaging on SRB1 only occurs if SRB2 has not yet been established • Operation: add/modify • mandatory in HO to EUTRA (establish SRB1 only) SRB context SRB ID Logical Channel Config RLC Config RLC AM mode

  24. Radio resource configuration: DRB • Operation: add/modify/release • Triggered by S1AP E-RAB setup/modification/release (MME/P-GW initiated) • Not present in RRC connection establishment and re-establishment • PDCP config of DRB: • Mandatory for DRB setup • Optional in HO within eutra without full configuration and first reconfiguration after re-establishment DRB context EPS Bearer ID DRB ID QoS parameters of EPS bearer / E-RAB Logical Channel Config RLC Config PDCP Config discardTimer, rlc-AM, rlc-UM, headerCompression

  25. DL/UL Information Transfer • Transfer NAS or (tunnelled) non-3GPP dedicated information between E-UTRAN and UE in RRC_CONNECTED

  26. Paging procedure

  27. Paging procedure • To initiate mobile terminated PS call • To initiate mobile terminated CS fallback call • To trigger LTE UE to re-acquire system informations • To provide an Earthquake and Tsunami Warning System(ETWS)/CMAS indication Idle mode Idle / connected mode

  28. Reestablishment procedure

  29. RRC connection re-establishment • Why? One of the events in UE occur: • Radio link failure • Handover failure • Mobility from E-UTRA failure • Integrity check failure from PDCP • RRC connection reconfiguration failure (SRB0) (SRB0) (SRB0) (SRB0) (failure) (SRB1) (successful)

  30. RRC connection re-establishment • eNB only accepts if the valid UE context is present in • the cells of serving eNB • the cells prepared for HO • eNB obtains the info from MAC: C-RNTI • eNB obtains the info from UE • reestablishment cause: reconfiguration failure, handover failure, other failure. • UE Identity: (C-RNTI, PhyCellId, ShortMAC-I), indicate info of • the source cell (handover case) or, • the cell trigger for reestablishment New C-RNTI Old C-RNTI

  31. RRC connection re-establishment • eNB assigns the context for UE: • Radio resource configuration (Dedicated) • SRB add/mod list: only SRB1 resumed • MAC main configuration • Physical configuration • Next Hop Chaining Count: sync AS keys with UE • Also, eNB shall locally • re-establish PDCP/RLC for SRB1 • configure PDCP to re-activate Integrity & Ciphering (use newly-derived AS keys).

  32. First reconfiguration after reestablishment • Resume SRB2 and all DRBs • re-establish PDCP/RLC for SRB2 and all DRBs

  33. Connection release procedure

  34. RRC connection release • Triggered by eNB in case: • S1AP UE Release Command is received • NAS initiated: initial NAS message is rejected, TAU is completed and no user traffic, Detach is accepted, etc • S1AP initiated: Initial Context Setup is failed, S1-HO is completed, X2-HO is completed, etc • UE Inactivity is detected, etc… • All radio resources are released • Release RLC/PDCP entity and MAC config for all RBs (SRB1)

  35. RRC connection release • For the UE leaving RRC_CONNECTED, eNB provide. • release cause: load-balancingTAUrequired, others. • idle mode mobility control info: frequency priority list for cell reselection.

  36. Measurement configuration

  37. Measurement configuration • RRC signaling:RRCConnectionReconfiguration • Types of measurements • Intra-frequency measurements • Inter-frequency measurements • Inter-RAT measurements of UTRA frequencies • Inter-RAT measurements of GERAN frequencies • Inter-RAT measurements of CDMA2000 HRPD or CDMA2000 1xRTT frequencies • Parameters • measurement objects, reporting configurations, measurement identities, quantity configurations, measurement gaps

  38. Measurement configuration • Measurement Object (MO) • In E-UTRA, a MO is a single E-UTRA carrier frequency. • Reporting Configuration (RC) • Reporting criterion: periodically or a single event • Reporting format: the reported quantities, number of cells to report, etc. • Quantity Configuration (QC) • Filtering parameters. One QC is configured per RAT type. • Measurement Identity (MI): • To identify the 1-to-1 link of MO and RC.

  39. Measurement configuration • Example: Measurement identity linking

  40. Measurement reporting RSRP, RSRQ Serving Carrier aggregation : secondary cell related Ex : 3G-> RSCP, EcN0

  41. Handover procedure

  42. Configuration in HO command • Mobility Control Info • Target PhysCellId, Carrier frequency • Carrier bandwidth: from MIB • Radio Resource Config (Common): from SIB2/SIB1/MIB • New UE-Identity: C-RNTI in target eNB • RACH-Config (Dedicated): for non contention based rach • Security Config HO • intra-LTE HO case: KeyChangeIndicator, nextHopChainingCount • inter-RAT HO case: SecurityAlgorithmConfig • Radio Resource Config (Dedicated) • Measurement Config • Full Config flag

  43. Handover Preparation (X2) TS 36.300

  44. Handover Execution (X2) UE Source eNB Target eNB TS 36.300

  45. Handover Completion (X2) SGW UE Source eNB Target eNB MME Source eNB 1 2 3 E Target eNB SGW TS 36.300 4 5 6

  46. RRC<->RRM interface introduction

  47. Socket interface between RRM and RRC RRM (UDP client) RRC (UDP server) RRC (UDP client) RRM (UDP server) Fd = Socket() Fd = Socket() Fd = Socket() Fd = Socket() Sendto() Sendto() bind(5566) bind(13001) While(1) If fd is selected While(1) If fd is selected Data (request) Data (request) Recvfrom() Recvfrom() enbd_config rrc_source_port: 5566 rrc_destination_port: 13001 rrc_cell_address: 127.0.0.1 Oam_rrc_config rrm_src_port: 13001 rrm_dst_port: 5566 Rrmip: 127.0.0.1 Process UDP packet Process UDP packet

  48. rrc_cell_address 127.0.0.1 RRM send message to RRC Port 13001

  49. Port 5566 RRM receive message from RRC

  50. Primitive between RRM and RRC If message part only contains message 0, u8MsgCut should be set to 0 RRC Header u8MsgCnt u16CellIdx Message u8Type Msg 1 Msg 2… Msg m Message 0 L1 L2… Lm Length Additional message part (dynamic) Original data structure of the primitive type defined in RRC Header

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