UMTS Terrestrial Radio Access Network (UTRAN)

Transcription

1 UMTS Terrestrial Radio Access Network (UTRAN) UTRAN Architecture and Protocols UMTS Terrestrial Radio Access (UTRA) UTRAN Procedures (see separate presentation)

2 Important References Books: Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks Architecture, Mobility and Services. 2nd edition, Wiley, 2005 Holma, Toskala: WCDMA for UMTS. 4th edition, Wiley, 2007 Walke, Althoff, Seidenberg: UMTS Ein Kurs. 2. Auflage, J. Schlembach Fachverlag, 2002 T. Benkner, C. Stepping: UMTS Universal Mobile Telecommunications System. J. Schelmbach Fachverlag, Central 3GPP Documents on UTRAN: : UTRAN overview : Radio link protocols (UTRA) : UTRAN procedures 2

3 UTRAN Architecture Components and Interfaces Macro Diversity UTRAN Functions Protocol Architecture RRC connection and signaling connection Access Stratum and Non Access Stratum 3

4 UTRAN Components and Interfaces Core Network Iu Iu UTRAN RNS RNC Iur RNS RNC Iub Iub Iub Iub Node B Node B Node B Node B A Radio Network Subsystem (RNS) consists of a RNC and a number of Node B s Source: 3GPP

5 Macro Diversity: Serving and Drift RNS Source: 3GPP Core Network Drift RNS (DRNS) Iur Iu Serving RNS (SRNS) Cells UE Each RNS is responsible for the resources of its set of cells For each connection between User Equipment (UE) and the UTRAN, one RNS is the Serving RNS (SRNS) Drift RNSs (DRNS) support the Serving RNS by providing radio resources Macro-diversity and handover is jointly supported by Node B(s) and RNC(s) 5

6 Serving, Drift and Controlling RNC Core Network Iu Iu UTRAN RNS DRNC RNC Iur RNS RNC SRNC Iub Iub Iub Iub Node B Node B Node B Node B Softer handover: maximum ratio combining in Node B UE Soft handover: radio frame selection (layer 1) in SRNC (and DRNC) 6

7 Roles of RNSs/RNCs Source: 3GPP Serving RNS (SRNS) A role an RNS can take with respect to a specific connection between a UE and UTRAN There is one Serving RNS for each UE that has a connection to UTRAN The Serving RNS is in charge of the RRC connection between a UE and the UTRAN The Serving RNS terminates the Iu for this UE Drift RNS (DRNS) A role an RNS can take with respect to a specific connection between a UE and UTRAN An RNS that supports the Serving RNS with radio resources when the connection between the UTRAN and the UE need to use cell(s) led by this RNS Controlling RNC (CRNC) A role an RNC can take with respect to a specific set of UTRAN access points (an UTRAN access point is specific to a cell) Exactly one Controlling RNC serves an UTRAN access point (i.e. each cell) The Controlling RNC has the overall of the logical resources of its UTRAN access points 7

8 Distribution of Functions between RNCs Radio resource management: CRNC owns the radio resources of a cell SRNC handles the connection (RRC/RANAP) to one UE, and may borrow radio resources of a certain cell from the CRNC SRNC performs dynamical of power for dedicated channels, within limits admitted by CRNC Inner loop power for some radio links of the UE connection may be done by the Node B Inner loop is led by an outer loop, for which the SRNC has overall responsibility SRNC handles scheduling of data for dedicated channels CRNC handles scheduling of data for common channels (no macro diversity on DL common channels) Source: 3GPP , Ch 6.3 8

9 Serving, Drift and Controlling RNC Core Network Iu Iu UTRAN RNS SRNC RNC DRNC Iub Iub Iur RNS Iub RNC SRNC Iub Node B Node B Node B Node B common/ shared channel UE 2 UE 1 dedicated channel in macro-diversity mode 9

10 Serving and Controlling RNC Example: DCH (Dedicated Channel UL&DL macro diversity) DTCH DCCH Combining/ splitting of phy. channels DCCH DTCH MAC-d MAC-d PHY-upper PHY PHY DchFP DchFP DchFP DchFP PHY PHY AAL2 AAL2 AAL2 AAL2 ATM ATM ATM ATM UE Uu NodeB Iub CRNC cells served by the same node B Combining/splitting is supported for DCH only (no layer 2 processing in Node B and DRNC) Source: 3GPP , sc (see also , sc 5.6.1) cells served by the same CRNC (optional) Iur SRNC cells served by different RNCs 10

11 Serving and Controlling RNC Example: FACH (Forward Access Channel DL, no macro diversity) DTCH DCCH DCCH DTCH CCCH CCCH MAC-d MAC-d MAC-c/ sh MAC-c/ sh FachFP FachFP FachFP FachFP PHY PHY AAL2 AAL2 AAL2 AAL2 ATM ATM ATM ATM UE Uu NodeB Iub CRNC Iur SRNC Physical channel is terminated within node B (no support for combining/splitting) Common MAC (MAC-c/sh) terminates in the CRNC Dedicated MAC (MAC-d) terminates in the SRNC Source: 3GPP , sc (see also , sc 5.6.2) 11

12 Example: BCH (Broadcast Channel DL, system information) RRC MAC RRC MAC RRC PHY UE RRC terminates in PHY NodeB CRNC CRNC: provides broadcast information distributed by node B Node B: handles periodic repetition of broadcast information Splitting of RRC eliminates repetition of broadcast data on Iub interface Source: 3GPP , sc o

13 UTRAN Architecture Principles User Plane radio access bearer SAPs (user plane) Non-Access Stratum Radio protocols (1) Radio protocols (1) Iu proto cols (2) Iu proto cols (2) UE Source: 3GPP Radio (Uu) Access Stratum UTRAN Iu CN Non-Access Stratum: Protocols between UE and CN that are not terminated in the UTRAN Access Stratum: Provides UE-CN transport service to NAS services AS protocols are closely linked to radio technology 13

14 UTRAN Architecture Principles Control Plane signaling connection Non-Access Stratum CM,MM,GMM,SM (3) CM,MM,GMM,SM (3) Radio protocols (1) Radio protocols (1) Iu proto cols (2) Iu proto cols (2) UE Source: 3GPP Radio (Uu) Access Stratum UTRAN CN Iu Non-Access Stratum plane functions: CM: Connection Management MM: Mobility Management GMM: GPRS MM SM: Session Management 14

15 UTRAN Functions (1) - Transfer of User Data - Functions related to overall system access - Admission Control - Congestion Control - System information broadcasting - Radio channel ciphering and deciphering - Integrity protection - Functions related to mobility - Handover - SRNS Relocation - Paging support - Positioning - Synchronisation Source: 3GPP , Ch 7 15

16 UTRAN Functions (2) - Functions related to radio resource management and - Radio resource configuration and operation - Radio environment survey - Combining/splitting - Connection set-up and release - Allocation and deallocation of radio bearers - Radio protocols function - RF power - Radio channel coding and decoding - Channel coding - Initial (random) access detection and handling - CN distribution function for Non Access Stratum messages - Functions related to broadcast and multicast services (broadcast/multicast interworking function BM-IWF) - Broadcast/Multicast Information Distribution - Broadcast/Multicast Flow Control - Cell-based Services (CBS) Status Reporting - Tracing - Volume reporting 16

17 Functions located inside/outside AS Source: 3GPP TS , Release 9 LOCATION\ FUNCTION Outside the Access Stratum Inside the Access Stratum Call set up/release yes no (Connection) Bearer Set-Up Release CN bearer [tbd] Radio Access Bearer [tbd] Supplementary Services yes no Location management yes (IWF/CN related) yes (Radio related) Attach/ Detach yes FFS, Contr expected Resource Management yes (for NAS resource) yes (for AS resource incl. radio) Handover yes* yes Macrodiversity [ffs] yes* yes Encryption yes yes** Authentication yes no compression (non source dependent) yes yes source dependent coding yes no radio channel coding (could be many) no yes (could be many) UE location identification may be supported yes Charging yes no NOTE *: Optionally execution. In some CNs, it may not be present but not full service will be supported (e.g. limited to RLL type of service). NOTE **: Contributions expected to clarify the role between encryption and subscriber data. 17 o

18 UTRAN Architecture: Functional Split Control plane CRNC/DRNC SRNC Mobile Control Core Network Cell Control Paging Node-B Broadcast Com./ Shared Channel Processing Dedicated Channel Processing Bearer plane 18

19 UTRAN Protocol Architecture: Summary Core Network Node-B RRC-b N B A P Iub N B A P paging (idle) CRNC DRNC RANAP RRC-c/sh SABP Iu BM-IWF BMC R N S A P paging (connected) Iur paging (connected, R PCCH) N S A P SRNC RANAP RRC-d Iu-PS FP PDCP Iu Iu-CS FP LOGICAL CHANNELS TRANSPORT CHANNELS BCCH BCH -b MAC-b Softer Handover Splitting / Combining Iub CCH FP Iub/Iur DCH FP Iub CCH FP Iub/Iur DCH FP PCCH BCCH PCH -c/sh CCCH MAC-c/sh CTCH RACH FACH DSCH CPCH optional Soft Handover Splitting / Combining Iur CCH FP Iub/Iur DCH FP Iur CCH FP Iub/Iur DCH FP DCCH -d MAC-d DCH DTCH Soft Handover Splitting / Combining PHY User plane Control plane 19 o

20 Wrap-up: Why is UTRAN so complicated? Some answers: Limitation of radio resources and last-mile transport resources CDMA macro-diversity mode Single /MAC entity required for synchronous delivery of radio frames over all SHO legs Splitting/combining of radio frames (multicast) Tight handover requirements esp. for voice Need for proactive handover initiation requires interaction between radio layers Designed for maximum functionality and flexibility Overdimensioned from the viewpoint of a single application 20

21 Side note: modes, states and hierarchy (PS mode, AS and NAS) UE SGSN SM: PDP context (active, inactive) HLR PMM state (detached, idle, connected) RNC Signaling connection GGSN RRC connection UE mode 21

22 Radio Link, RRC Connection, Signaling Connection Core Network Iu Iu UTRAN RNS RNC Iur RNS SRNC RNC signaling connection Iub Iub Iub Iub Node B Node B Node B Node B UE RRC connection -> connected mode radio link RRC connections and signaling connections are logical links 22

23 Radio Link, RRC Connection & Signaling Connection Core Network Iu Iu UTRAN RNS DRNC RNC Iur RNS SRNC RNC signaling connection Iub Iub Iub Iub Node B Node B Node B Node B RRC connection UE radio link 23

24 RRC Connection and Signaling Connection UE Higher layer SRNC MSC/VLR or SGSN Higher layer RRC RRC RANAP RANAP Signaling Radio Bearer Iu Signaling Bearer RRC Connection RANAP Connection Radio Access Bearer Signaling Connection 24

25 RRC Connection Connected mode Cell Connected Enter connected state Enter cell connected state Connected RRC connection establishment RRC connection release Idle mode UTRAN Registration Area (): area covered by a number of cells is only internally known in the UTRAN RRC state machine exists as two peer entities, one in the MS and one in UTRAN (SRNC) Apart from transient situations and error cases the two peer entities are synchronized 25

26 Signaling Connection No signaling connection exist (idle state) UE has no relation to UTRAN, only to CN no data transfer paging identification by IMSI, TMSI, P-TMSI Signaling connection exist (connected state) UE position can be known on different levels: - level (UTRAN registration area): is a specified set of cells, which can be identified on the BCCH. - Cell level: Different channel types can be used for data transfer: - Common transport channels (RACH, FACH, DSCH, USCH) - Dedicated transport channels (DCH) Source: 3GPP , ch

27 Recap on Important Vocabulary Source: 3GPP TR RRC connection point-to-point bi-directional connection between RRC peer entities on the UE and the UTRAN sides UE has either zero or one RRC connection Signaling connection an acknowledged-mode link between the UE and the CN to transfer higher layer information between the entities in the non-access stratum (via RRC and RANAP) Radio link a logical association between a single UE and a single UTRAN access point (cell) its physical realization comprises one or more radio bearer transmissions Radio bearer (compare signaling radio bearer) service provided by the layer for transfer of user data between UE and SRNC Radio interface interface between UE and a UTRAN access point radio interface encompasses all the functionality required to maintain the interface 27

28 Access Stratum Services Non-Access Stratum (NAS) GC Nt DC GC Nt DC Access Stratum (AS) end AS entity end AS entity Relay/RNC functions GC Nt DC GC Nt DC GC Nt DC GC Nt DC L2/L1 RRC Uu Stratum (UuS) RRC L2/L1 Iu Stratum UE Source: 3GPP (see also 3GPP ) Radio (Uu) UTRAN Iu Core Network Services of Access Stratum: General Control (GC) idle mode Notification (Nt) idle mode Dedicated Control (DC) connected mode User data transfer (RAB) connected mode Note: NAS signaling services are provided by RANAP 28

29 Services provided at AS SAPs GC and Nt (UE in idle mode) General Control SAPs (GC) information broadcast service Enable CN to provide information and to give commands that do not relate to specific users or specific sessions (group calls, conference) Typically one GC SAP per AN/CN connection point (Iu) Typically one GC SAP in MS Notification SAPs (Nt) paging and notification broadcast services SAPs are used to broadcast data to identified users Typical use is for initiating paging in the AN Typically one Nt SAP per AN/CN connection point (Iu) Typically one Nt SAP (a Paging SAP) in MS Source: 3GPP , ch. 6; see also , ch o

30 Services provided at AS SAPs DC (conn. mode) Dedicated Control SAPs (DC) connection establishment/release and message transfer SAPs are used to establish and release connections with specific UEs, and to transfer information on these connections Several types of connections are identified, point connections (single user) and group connections SAPs are identified by a SAPI at the AS boundary SAPI is valid for the lifetime of a connection SAPI is used as a unambiguous connection identifier of the associated SAP Typically a great number of DC SAPs per AN/CN connection point Typically a single DC SAP in MS Source: 3GPP o

31 Radio Interface Protocols UMTS Terrestrial Radio Access (UTRA) Air interface protocol architecture Layer 1, 2 and 3 protocols Mapping between logical, transport and physical channels 31

32 Radio Protocols Overview GMM / SM / SMS RRC MAC L1 Application MS E.g., IP, PPP PDCP Control plane Uu User plane RRC MAC L1 PDCP Relay RNS Relay RANAP SCCP Signalling Bearer AAL5 ATM GTP-U Iu-Ps GMM / SM / SMS RANAP SCCP Signalling Bearer AAL5 ATM 3G SGSN GTP-U Relay GTP-U Layer 3 IP, PPP (user plane) RRC ( plane) Layer 2 PDCP (user plane) BMC (user plane) MAC Layer 1 PHY E.g., IP, PPP GTP-U UDP/IP UDP/IP UDP/IP UDP/IP MAC MAC AAL5 AAL5 L2 L2 L1 MS L1 ATM ATM L1See 3GPP and L1 Uu Iu-PS UMTS Networks Gn book, ch. 9 Gi UTRAN 3G-SGSN 3G-GGSN 32

33 Radio Protocol Architecture C-plane signalling GC Nt DC U-plane information Radio Access Bearers AS plane SAPs RRC L3 PDCP PDCP Radio Bearers L2/PDCP BMC L2/BMC L2/ Logical Channels Source: 3GPP Transport Channels 35 MAC PHY L2/MAC L1

34 Physical Layer Services GC Nt DC Duplication avoidance Radio Access Bearers AS plane SAPs GC Nt DC Physical layer offers information transfer services (transport channels) to UuS boundary MAC and higher layers C-plane signalling Physical layer transport services define how and RRC U-plane information with what characteristics data are transferred over the radio interface Transport channels do not define what is transported (which is defined by logical channels) Example: DCH offers the same type of service for and user traffic 36 MAC PHY PDCP PDCP BMC L3 Radio Bearers L2/PDCP L2/BMC L2/ Logical Channel L2/MAC Transport Channels L1

35 Physical Layer Channel Types GC Nt DC Duplication avoidance Radio Access Bearers AS plane SAPs GC Nt DC common transport channels (there is a need for inband UuS boundary identification of the UEs when C-plane signalling particular UEs are U-plane addressed) information dedicated transport channels (the UEs are identified by the physical channel, i.e. code and frequency for FDD (code, time slot and frequency for TDD)) RRC L3 PDCP PDCP Radio Bearers L2/PDCP BMC L2/BMC L2/ Logical Channel Transport Channels L1 37 MAC PHY L2/MAC

36 Physical Layer Common Transport Channels (1) Random Access Channel (RACH) Contention based uplink channel used for transmission of relatively small amounts of data, e.g. for initial access or non-real-time dedicated or traffic data Forward Access Channel (FACH) Common downlink channel for relatively small amount of data no closed-loop power Downlink Shared Channel (DSCH) TDD only Downlink channel shared by several UEs carrying dedicated or traffic data Uplink Shared Channel (USCH) TDD only Uplink channel shared by several UEs carrying dedicated or traffic data 38

37 Physical Layer Common Transport Channels (2) Broadcast Channel (BCH) Downlink channel used for broadcast of system information into an entire cell Paging Channel (PCH) A downlink channel used for broadcast of information into an entire cell allowing efficient UE sleep mode procedures Currently identified information types are paging and notification Another use could be UTRAN notification of change of BCCH information High-Speed Downlink Shared Channel (HS-DSCH) Rel. 5 High-speed downlink channel shared by several UEs 39

38 Physical Layer Dedicated Transport Channels & Transport Formats Dedicated Channel (DCH) Channel dedicated to one UE used in uplink or downlink Enhanced Dedicated Channel (E-DCH) Channel dedicated to one UE used in uplink only Subject to Node-B led scheduling and HARQ Transport Formats and Transport Format Sets A Transport Format or a Transport Format Set is associated with each transport channel A Transport Format defines the format offered by L1 to MAC (encodings, interleaving, bit rate and mapping onto physical channels) A Transport Format Set is a set of Transport Formats Example: a variable rate DCH has a Transport Format Set (one Transport Format for each rate), whereas a fixed rate DCH has a single Transport Format See 3GPP , ch. 7 and Walke, ch 5.10, for details on Transport Formats and Transport Format Sets 40

39 Physical Layer Processing Data Data Data Transport Block Set Data Transport Block DCH DCH DCH Data Data Transport Block Set Note: Functional blocks which implement concatenation, segmentation, interleaving, discontinuous transmission (DTX) and macrodiversity distirbution/combining have been suppressed. CRC attachment Channel Coding Rate Matching CRC attachment Channel Coding Rate Matching CRC attachment Channel Coding Rate Matching Transport Channel Multiplexing Note: Physical Channel Mapping is used to implement multicoding (more than one DPCH). This will usually only be used for high data rates Physical Channel Mapping Coded Composite Transport Channel (CCTrCH) DPCH DPCH See 3GPP for details 41 o

40 Physical Layer Functions Macrodiversity distribution/combining and soft handover execution Error detection on transport channels and indication to higher layers (CRC) FEC encoding/decoding and interleaving/deinterleaving of transport channels Multiplexing of transport channels and demultiplexing of coded composite transport channels Rate matching (fit bits into physical channel) Mapping of coded composite transport channel on multiple physical channels Power weighting and combining of physical channels Modulation and spreading/demodulation and despreading of physical channels Frequency and time (chip, bit, slot, frame) synchronisation Measurements and indication to higher layers (e.g. frame error rate, signal-tointerference ratio, interference power, transmit power, etc.) Closed-loop power RF processing Support of timing advance on uplink channels (TDD only) Support of Uplink Synchronisation (TDD only) 43

41 Medium Access Control (MAC) Services Data transfer (logical channels SAPs) GC Nt DC UuS boundary Unacknowledged transfer C-plane of signalling MAC SDUs between U-plane information peer MAC entities Duplication avoidance No data segmentation (performed by higher layers) in R.99 Reallocation of radio resources RRC and MAC parameters (combination) sets, change of transport channel PDCP type PDCP 44 GC Nt MAC PHY DC Radio Access Bearers AS plane SAPs Execution of radio resource reallocation and change of MAC parameters by request of RRC, i.e. change of transport format Autonomously resource allocation in TDD mode Reporting of measurements Local measurements such as traffic volume and quality indication (reported to RRC) BMC L3 Radio Bearers L2/PDCP L2/BMC L2/ Logical Channel L2/MAC Transport Channels L1

42 MAC Logical Channels Logical channels define what information is transported (transport channels (PHY SAP) define how data are transported) Control Channels (transfer of plane information) Broadcast Control Channel (BCCH) DL Paging Control Channel (PCCH) DL Common Control Channel (CCCH) DL/UL Dedicated Control Channel (DCCH) DL/UL Shared Channel Control Channel (SHCCH) DL/UL (TDD) Traffic Channels (transfer of user plane information) Dedicated Traffic Channel (DTCH) DL/UL Common Traffic Channel (CTCH) DL/UL 45 o

43 MAC Functions (1) Mapping between logical channels and transport channels Selection of appropriate Transport Format for each Transport Channel depending on instantaneous source rate Priority handling (multiplexing) between data flows of one UE (MAC-d) Priority handling (scheduling) between different UEs (MAC-c/sh) Identification of UEs on common transport channels Example: DTCH/DCCH mapped on DSCH (TDD only) DTCH DCCH DCCH DTCH MAC-d MAC-d MAC-c/sh MAC-c/sh DschFP DschFP DschFP DschFP PHY PHY AAL2 AAL2 AAL2 AAL2 ATM ATM ATM ATM UE Uu NodeB Iub CRNC Iur SRNC 46

44 MAC Functions (2) Multiplexing/demultiplexing of upper layer PDUs on common transport channels Multiplexing/demultiplexing of upper layer PDUs on dedicated transport channels Traffic volume measurement Transport channel type switching (led by RRC) Ciphering for transparent mode Example: DTCH/DCCH mapped on DSCH (TDD only) DTCH DCCH DCCH DTCH MAC-d MAC-d MAC-c/sh MAC-c/sh DschFP DschFP DschFP DschFP PHY PHY AAL2 AAL2 AAL2 AAL2 ATM ATM ATM ATM UE Uu NodeB Iub CRNC Iur SRNC 47

45 Logical/ Transport/ Physical Channels Mapping (excerpt, FDD) Logical Channels Transport Channels Physical Channels P-SCH Control Ch Traffic Ch Common Ch (no FPC) Common Ch (FPC) S-SCH Fixed Channels Dedicated Ch (FPC) P-CPICH S-CPICH Info Channels Assoc Channels BCCH BCH P-CCPCH PCCH PCH PICH CCCH FACH S-CCPCH CTCH RACH PRACH DCCH AICH DTCH Key: Uplink Downlink Bidirectional Data Transfer Association DCH DPDCH DPCCH DPCH Notes: Figure deschribes a subset of the possible mappings only! See , sc. 5.6 or following slides for the complete list of possible mappings. FPC denotes Fast Power Control 48 o

46 Logical/Transport Channels Mapping UE side (all possibilities) BCCH- SAP PCCH- SAP DCCH- SAP CCCH- SAP SHCCH- CTCH- SAP SAP (TDD only) DTCH- SAP Logical Channels (MAC SAPs) BCH PCH RACH FACH USCH DSCH (TDD only) (TDD only) DCH Transport Channels 49 o

47 Logical/Transport Channels Mapping UTRAN side (all possibilities) BCCH- SAP PCCH- SAP DCCH- SAP CCCH- SAP SHCCH- SAP (TDD only) CTCH- SAP DTCH- SAP Logical Channels (MAC SAPs) BCH PCH RACH FACH USCH (TDD only) DSCH (TDD only) DCH Transport Channels 50 o

48 Radio Link Control () Transparent data transfer (TM) GC Unacknowledged data transfer (UM) C-plane signalling Acknowledged data transfer (AM) GC Nt DC Duplication avoidance Nt DC U-plane information UuS boundary RRC L3 PDCP PDCP Radio Bearers L2/PDCP BMC L2/BMC L2/ Logical Channel Transport Channels L1 51 MAC PHY L2/MAC

49 Services (1) Transparent data transfer (TM) Transmission of upper layer PDUs without adding any protocol information (no header) Possibly including segmentation/reassembly functionality Unacknowledged data transfer (UM) Transmission of upper layer PDUs without guaranteeing delivery to the peer entity Error detection: The sublayer shall deliver only those SDUs to the receiving upper layer that are free of transmission errors by using the sequence-number check function Immediate delivery: The receiving sublayer entity shall deliver a SDU to the upper layer receiving entity as soon as it arrives at the receiver Acknowledged data transfer (AM) Transmission of upper layer PDUs and guaranteed delivery to the peer entity Notification of user at transmitting side in case is unable to deliver the data correctly in-sequence and out-of-sequence delivery error-free delivery (by means of retransmission) duplication detection 52

50 Services (2) Maintenance of QoS as defined by upper layers retransmission protocol shall be configurable by layer 3 to provide different levels of QoS Notification of unrecoverable errors notifies the upper layer of errors that cannot be resolved by itself by normal exception handling procedures There is a single connection per Radio Bearer 53

51 Functions Transfer of user data (AM, UM, TM) Segmentation and reassembly ( PDU size adapted to transport format) Concatenation Padding Sequence number check (UM mode) Duplicate PDUs detection In-sequence delivery of upper layer PDUs Error correction (selective-repeat ARQ) Convert variable-size higher layer PDUs into fixed-size PDUs (TBs) Convert radio link errors into packet loss and delay Flow between peers Avoid Tx and Rx SDU discard buffer overflows or Protocol error detection and recovery protocol stalling Exchange of status information between peer entities Ciphering (non-transparent mode) Suspend/resume and stop/continue of data transfer Re-establishment of AM/UM entity 54

52 Logical/Transport Channels Mapping Details UTRAN side D D U/D U/D D U/D Broadcast Control Channel (BCCH) Paging Control Channel (PCCH) Dedicated Control Channel (DCCH) Common Control Channel (CCCH) Control Plane User Plane Common Traffic Channel (CTCH) Dedicated Traffic Channel (DTCH) Logical Channels BCCH- SAP PCCH- SAP DCCH- SAP CCCH- SAP CTCH- SAP DTCH- SAP MAC SAPs Tr UM UM Tr Tr UM AM UM AM Tr UM AM UM AM UM AM Tr UM AM Tr Modes Tr Transparent UM Unacknowledged AM Acknowledged Broadcast Channel D (BCH) Paging Channel (PCH) U Uplink D Downlink U/D Uplink / Downlink D Random Access Channel (RACH) Forward Access Channel (FACH) To / From Physical Channels U D Transport Dedicated Channels Channel (DCH) U/D 55 o

53 Control Plane Relationships Call signalling: Entities / Channels / Signaling Radio Bearers (SRB) Relationships SRB1 SRB2 SRB3/4 UM Entity Entity AM Entity AM Entity DCCH DCCH DCCH DCCH Logical Channels MAC DCH DCH LAYER 1 CCTrCH CCTrCH DPDCH DPDCH Abbr. Mode Entities Tr Transparent mode 2 (one Tx and one Rx) UM Unacknowleged Mode 2 (one Tx and one Rx) AM Acknowleged Mode 1 (bi-directional for ARQ) Notes: This is for a single user and only shows the plane. SRB0 is not shown as this is for the CCCH - i.e. not used for a dedicated call, only for establishment. 56 o

54 Circuit Switched Voice Call Relations Call signalling: Entities / Channels / Radio Bearers (RB) Relationships Control Plane SRB1 SRB2 SRB3/4 AMR VOICE CODEC Class A (81bits) DL Class B (103bits) Class C (60bits) AMR VOICE CODEC Class A (81bits) UL Class B (103bits) Class C (60bits) UM Entity Entity AM Entity AM Entity Tr RB RB RB RB RB RB User Plane DCCH DCCH DCCH DCCH DTCH DTCH MAC DCH DCH DCH DCH LAYER 1 Physical Channels CCTrCH DPDCH CCTrCH DPDCH Abbr. Mode Entities Tr. Transparent mode 2 (one tx. and one rx.) UM Unacknowleged Mode 2 (one tx. and one rx.) AM Acknowleged Mode 1 (bi-directional for ARQ) Notes: This is for a single user. SRB0 is not shown as this is for the CCCH - i.e. not used for a dedicated call, only for establishment. 57 o

55 Mapping of Layers to Network Elements Logical Channels Control Ch Traffic Ch Transport Channels Common Ch (no fast power ) Common Ch (fast power ) Dedicated Ch (fast power ) CCCH DCCH, DTCH PHY MAC MAC-c/sh PCH FACH RACH DSCH USCH DCH MAC-d FACH, etc. RACH DSCH USCH MAC-d, etc., etc. PHY-upper DCH I ub I ur Node B Controlling RNC Serving RNC 58 o

56 Packet Data Convergence Protocol (PDCP) Service: PDCP SDU delivery C-plane signalling GC Nt DC Duplication avoidance U-plane information Radio Access Bearers AS plane SAPs GC Nt DC PDCP is defined for PS domain only! UuS boundary RRC L3 PDCP PDCP Radio Bearers L2/PDCP BMC L2/BMC L2/ Logical Channel Transport Channels L1 63 MAC PHY L2/MAC

57 PDCP Functions Header compression and decompression Header compression and decompression of IP data streams (e.g. TCP/IP and RTP/UDP/IP headers) Header compression method is specific to the upper layer protocol combinations, e.g. TCP/IP or RTP/UDP/IP (RFC 2507 & RFC 3095) Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the layer and vice versa Support for lossless SRNS relocation Maintenance of PDCP sequence numbers for radio bearers that are configured to support lossless SRNS relocation 64

58 GC Nt DC Broadcast/Multicast Control Duplication (BMC) avoidance Service: GC Nt DC broadcast/multicast transmission C-plane signalling service in the user plane for common user data in unacknowledged mode U-plane information UuS boundary RRC L3 PDCP PDCP Radio Bearers L2/PDCP Functions: Storage of Cell Broadcast Messages Traffic volume monitoring and radio resource request for CBS Scheduling of BMC messages Transmission of BMC messages to UE Delivery of Cell Broadcast messages to upper layer (NAS) in the UE MAC PHY BMC L2/BMC L2/ Logical Channel L2/MAC Transport Channels L1 66 o

59 Radio Resource Control (RRC) GC Nt DC Duplication avoidance GC Nt DC UuS boundary C-plane signalling U-plane information RRC L3 PDCP PDCP Radio Bearers L2/PDCP BMC L2/BMC Services Provided to Upper Layers General Control (GC) information broadcast service Logical Channel Transport Channels L1 67 MAC Notification (Nt) paging and notification broadcast services Dedicated Control (DC) connection management and message transfer PHY L2/ L2/MAC

60 RRC Interaction with Lower Layers Measurement Report Control R R C Radio Resource Assignment [Code, Frequency, TS, TF Set, Mapping, etc.] R R C Control R L C R L C Measurements Control retransmission Control Measurements Control Measurements M A C M A C Control Measurements L 1 L 1 U T R A N U E 68

61 RRC Functions RRC handles the plane signaling of layer 3 between the UEs and UTRAN: - Broadcast of information provided by the non-access stratum (Core Network) - Broadcast of information related to the access stratum - Establishment, re-establishment, maintenance and release of RRC connections - Establishment, reconfiguration and release of Radio Bearers - Assignment, reconfiguration and release of radio resources for the RRC connection - RRC connection mobility functions - Paging/notification - Routing of higher layer PDUs - Control of requested QoS - UE measurement reporting and of the reporting - Outer loop power - Control of ciphering - Slow DCA (TDD) - Arbitration of radio resources on uplink DCH - Initial cell selection and re-selection in idle mode - Integrity protection (message authentication for sensitive data) - Control of Cell Broadcast Service (CBS) - Timing advance (TDD) 69

62 RRC State Machine Connected mode Cell Connected RRC connection establishment RRC connection release Enter connected state Enter cell connected state Connected Idle mode RRC state machine exists as two peer entities (MS and UTRAN) The two peer entities are synchronized (apart from transient situations and error cases) 70

63 UTRAN Registration Area () is known to the UTRAN only RA RA RA is established in RRC connected mode LA is independent of RNC area may cover part of an RNC area RA RA RA parts of several RNC areas s may overlap RA RA RA 71

64 RRC State Machine RRC Idle mode: no connection established between the MS and UTRAN no signalling between UTRAN and the MS except for system information sent from UTRAN on a broadcast channel to the MS MS can only receive paging messages with a CN identity on the PCH no information of the MS is stored in UTRAN Cell Connected Connected mode Enter connected state Enter cell connected state Connected RRC connection establishment RRC connection release Idle mode 72

65 RRC State Machine Cell Connected Connected mode Enter connected state Enter cell connected state Connected RRC connection establishment RRC connection release RRC Connected mode: Idle mode two main states Cell Connected: MS position is known at the cell level; RRC connection mobility is handled by handover and cell update procedures Connected: MS position is known at the level; updating procedures provide the mobility functionality; no dedicated radio resources are used in the state. there is one RNC that is acting as serving RNC, and an RRC connection is established between the MS and this SRNC An UE has either zero or one RRC connection 73

66 RRC State Machine: Details of connected mode Release RRC Connection _PCH out of service UTRA RRC Connected Mode in service CELL_DCH Establish RRC Connection Release RRC Connection CELL_PCH out of service out of service in service CELL_FACH in service Establish RRC Connection UTRA: Inter-RAT Handover Cell reselection _PCH or CELL_PCH state Release of temporary block flow GPRS Packet Transfer Mode GSM: Handover GSM Connected Mode Neither DCCH nor DTCH are available in these states CELL_FACH state Release RR Connection Establish RR Connection DCCH and, if configured, Initiation of temporary DTCH are available in this block flow state Camping on a UTRAN cell Idle Mode GPRS Packet Idle Mode CELL_DCH state Camping on a GSM / GPRS cell DCCH and DTCH are available in this state 74

67 UMTS RRC State Optimization (PS mode) idle T 3 _PCH T 2 cell_pch T 1 cell_dch Goal: Minimization of Radio Resource Consumption during Idle Times Tradeoff for idle periods retaining in state => continuous state cost or move to cheaper state => one time transition cost Limited resources radio resources (transmit power) channelization codes processing cost (signaling) power consumption transport resources (Iu, Iub, ) Find optimal timeout settings depending on traffic model (distribution of idle times) cost per state cost per transition user mobility 75

68 UMTS RRC State Optimization Optimization of Timeout Values sum state cost transition cost 76

69 Radio Interface Control Plane Summary UE Higher layer SRNC MSC/VLR or SGSN Higher layer RRC RRC RANAP RANAP AS Signaling Radio Bearer 2 Iu Signaling Bearer RRC Connection RANAP Connection NAS Signaling Radio Bearer Radio Access Bearer Signaling Connection (GC, Nt, DC) 77