Wireless Test World 2009

Transcription

1 Wireless Test World 2009 Agilent, Your Partner in Advancing Agilent, Your Partner in Advancing New New Wireless Wireless Communications Communications LTE Protocol Signaling and Control Presented by: Choi, In-Hwan July 1, 2009 Page 1 Wireless Test World 2009

2 Agenda 1 page Introduction to LTE LTE signalling and control Pre-connection (idle mode) procedures and control Cell Selection, re-selection System information and Master information Connection procedures and control RRC controls Paging, (P)RACH Scheduling, resource allocation Voice/Data transfer (connected mode) processes and control DCI, Power control, Timing control, UCI HARQ, CQI Summary and Agilent LTE solutions Page 2

3 LTE major features Feature Capability Access modes FDD with frame structure 1 TDD with frame structure 2 Variable channel BW Baseline UE capability User Data rates (at baseline capability) Downlink transmission Uplink transmission DL Spatial diversity 1.4, 3, 5, 10, 15, 20 MHz FDD and TDD (1.6 MHz & 3.2 MHz TDD bandwidths now deleted) 20 MHz UL/DL, 2 Rx, one Tx antenna DL Mbps / UL MHz BW (2x2 DL SU-MIMO & SISO on UL) with 64QAM OFDMA using BPSK, QPSK, 16QAM, 64QAM SC-FDMA using BPSK, QPSK,16QAM, 64QAM Open loop TX diversity Single-User MIMO up to 4x4 supportable UL Spatial diversity Bearer services Optional open loop TX diversity, 2x2 MU-MIMO, Optional 2x2 SU-MIMO Packet only no circuit switched voice or data services are supported voice must use VoIP Page 3

4 Agenda 1 page Introduction to LTE LTE signalling and control Pre-connection (idle mode) procedures and control Cell Selection, re-selection System information and Master information Connection procedures and control RRC controls Paging, (P)RACH Scheduling, resource allocation Voice/Data transfer (connected mode) processes and control DCI, Power control, Timing control, UCI HARQ, CQI Summary and Agilent LTE solutions Page 4

5 Diagram of the various UE states CELL_DCH CELL_FACH CELL_PCH URA_PCH Connection establishment/release Handover Reselection E-UTRA RRC CONNECTED Connection establishment/release CCO with optional NACC Handover CCO, Reselection GSM_Connected GPRS Packet transfer mode Connection establishment/release UTRA_Idle Idle Mode Cell selection System Information Reselection E-UTRA RRC IDLE Call/data setup Paging RACH Reselection CCO, Reselection GSM_Idle/GPRS Packet_Idle Connected Call/data control Data flow Page 5

6 Agenda 1 page Introduction to LTE LTE signalling and control Pre-connection (idle mode) procedures and control Cell Selection, re-selection System information and Master information Connection procedures and control RRC controls Paging, (P)RACH Scheduling, resource allocation Voice/Data transfer (connected mode) processes and control DCI, Power control, Timing control, UCI HARQ, CQI Summary and Agilent LTE solutions Page 6

7 Idle mode processes Page 7

8 Idle mode processes Why have a camped idle mode state? 1. It enables the UE to receive system information from the PLMN. The UE will use the System Information to measure suitable candidates for cell reselection/mobility 2. If the UE needs to establish an RRC connection, it initially accesses the network (via RACH) on the control channel of the cell on which it is camped. 3. If the PLMN receives a call for the registered UE, it knows the UE s location. It can then send a Paging Message for the UE on control channels of the cells in this location/area. The UE is monitoring the control channel of the cell on which it is camped. UE will re-register its location should it move from one tracking area to another If a UE was always in a connected state, it would consume more resources. Page 8

9 Master and System Information , System information is divided into the MasterInformationBlock (MIB) and a number of SystemInformationBlocks (SIBs): MasterInformationBlock defines the most essential physical layer information of the cell required to receive further system information, eg System Frame Number, Cell Bandwidth Only the MIB and SIB1 have fixed periodicity and resource allocation SIB2-9 are scheduled within SIB1 which also contains Tracking Area ID, Cell ID, PLMN identities etc The Paging message is used to inform UEs in idle mode and UEs in connected mode about a system information change. System information may also be provided to the UE by means of dedicated signalling e.g. upon handover in this case the dedicated signalling content take precedence. Page 9

10 Master and System Information , Release 7 and earlier Both MIB and SIB s transmitted on the BCH Release 8 i.e. LTE ONLY the MIB is transmitted on the BCH, all other SIB s transmitted on DL-SCH MIB SIB1 SIB2-9 Periodicity 40ms 80ms Resources Fixed # Fixed * Scheduling Fixed Fixed # First MIB in sub-frame #0 for which SFN mod 4=0, subsequently in sub-frame #0 Flexible Indicated by SIB1 Mapped to BCCH BCCH BCCH Transport CH BCH DL-SCH DL-SCH Identifier N/A N/A SI-RNTI * First SIB1 in sub-frame #5 for which SFN mod 8=0, subsequently in sub-frame #5 when SFN mod 2=0 Page 10

11 System Information SystemInformationBlockType1 contains information relevant when evaluating if a UE is allowed to access a cell and defines the scheduling of other system information blocks; SystemInformationBlockType2 contains common and shared channel information; SystemInformationBlockType3 contains cell re-selection information, mainly related to the serving cell; SystemInformationBlockType4 contains information about the serving frequency and intra-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters); SystemInformationBlockType5 contains information about other E-UTRA frequencies and interfrequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters); SystemInformationBlockType6 contains information about UTRA frequencies and UTRA neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters); SystemInformationBlockType7 contains information about GERAN frequencies relevant for cell reselection (including cell re-selection parameters for each frequency); SystemInformationBlockType8 contains information about CDMA2000 frequencies and CDMA2000 neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters); SystemInformationBlockType9 contains a home enb identifier (HNBID). Page 11

12 Agenda 1 page Introduction to LTE LTE signalling and control Pre-connection (idle mode) procedures and control Cell Selection, re-selection System information and Master information Connection procedures and control RRC controls Paging, (P)RACH Scheduling, resource allocation Voice/Data transfer (connected mode) processes and control DCI, Power control, Timing control, UCI HARQ, CQI Summary and Agilent LTE solutions Page 12

13 RRC Signalling high level RRC Connection Establishment RRC Connection Reconfiguration Establish, modify or release user radio bearers, e.g. during handovers RRC Connection Re-establishment Re-activates security (without algorithm change) Only if cell is prepared (maintains context), and security is active Used if coverage temporarily lost, e.g. during Handover UE EUtran UE EUtran RRC CONNECTION REQUEST RRC CONNECTION REQUEST RRC CONNECTION SETUP RRC CONNECTION REJECT RRC CONNECTION SETUP COMPLETE Page 13

14 RRC Signalling bearers RRC Signalling Radio Bearer Control Plane signalling Message contents Priority SRB 0 CCCH Non-UE specific Low SRB 1 DCCH RRC +NAS High SRB 2 DCCH NAS only Low SRB 2 is only setup AFTER security has been enabled NAS messaging on SRB1 only occurs if SRB2 has not yet been established. If piggy backed messaging is used, then these procedures will have joint success/failure criteria Security Overview in , Section 14 Page 14

15 RRC Signalling Mobility control Idle Mode mobility controlled by SIB information Connected Mode use RRC reconfiguration, RRC also configures: Neighbour Cell Measurements dedicated RRC messages over-ride lists sent in SIB s Measurement GAPs Reporting periodic or event triggered UE EUtran Inter-RAT mobility handled by: MOBILITY FROM EUTRA COMMAND Preceded by further messaging if moving to CDMA2000 requires additional preparation for the target network/cell HANDOVER FROM EUTRA PREPARATION REQUEST UL HANDOVER PREPARATION TRANSFER MOBILITY FROM EUTRA COMMAND Handovers to CDMA2000 RAT Only Page 15

16 Paging e.g. incoming call or change in SI sec 6.1, sec RRC configures paging message to the UE over PCCH logical channel UE will monitor PCH to received the Paging Message which could also indicate System Information change notifications in Idle mode. Paging information identified by P-RNTI System Information indentified by SI-RNTI When the Paging Message indicates changes to System Information then UE needs to reacquire all System Information. The UE may use Discontinuous Reception (DRX) in idle mode in order to reduce power consumption - When DRX is used the UE needs only to monitor one P-RNTI per DRX cycle. Page 16

17 Random Access Figure : Contention based Random Access Procedure UE enb 5 possible RA events 1.Initial Access 2.Following Radio Link failure 3.Handover 4.DL data arriving during RRC_Connected 5.UL data arriving during RRC_Connected 2 types Contention based (all 5 events) Non-contention based (only applies to 3, 4) 1 3 Random Access Preamble Random Access Response 2 Scheduled Transmission Contention Resolution 4 In the frequency domain, the random access preamble occupies a bandwidth corresponding to 6 resource blocks section Preamble sequence is one of 64 zadoff chu sequences in each cell. The RACH_ROOT_SEQUENCE used by the UE is broadcast as part of the System Information Figure : Non-contention based Random Access Procedure Page 17

18 Random Access Timing 1. UE sends pre-amble, one of 64 randomly selected (listed in SI) 2. UE monitors PDCCH during the Random Access Response Window (variable length) starting 3 sub-frames after the end of the pre-amble, message contents in PDSCH on same sub-frame 3. UE transmits on PUSCH using resources assigned in message 2 on PDSCH Random Access Response window Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 1. PRACH 2. PDCCH Random Access Response 2. PDSCH Random Access Response 3. Scheduled UL resources Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 Page 18

19 LTE 3GPP - MAC Scheduling MAC s main function is the distribution and management of common uplink and downlink resources to multiple UE s UE 1 enb MAC must take account of: Overall traffic volume UE QoS needs for each connection type Buffer reports etc If a UE requests resources via a Scheduling request, the enb may provide a scheduling grant identified by Cell RNTI (C-RNTI) UE 4 UE 3 Page 19

20 Agenda 1 page Introduction to LTE LTE signalling and control Pre-connection (idle mode) procedures and control Cell Selection, re-selection System information and Master information Connection procedures and control RRC controls Paging, (P)RACH Scheduling, resource allocation Voice/Data transfer (connected mode) processes and control DCI, Power control, Timing control, UCI HARQ, CQI Summary and Agilent LTE solutions Page 20

21 Information required by UE to transmit/receive UE s need to know a lot of information before sending or receiving data Uplink When the UE can transmit and on which resources Which modulation, transport block size and redundancy version to use Adjustments to align timing with enb Downlink When the UE should listen for DL data. DL data may not be contiguous in frequency Which modulation, transport block size and redundancy version were used to transmit this data Is this downlink spatially multiplexed Whether to hop the PUSCH or not Power level Transmit new block or re-transmit NACK d blocks For Spatially multiplexed DL what pre-coding has been applied Which HARQ process does this data belong to Is this new data or re-transmitted data ALL of this information is send from the enb to the UE on the Downlink Control Information (DCI) Page 21

22 Downlink Control Information (DCI) Downlink Control Information (DCI) is carried on the Physical Downlink Control Channel enb could send many of these messages per sub-frame using multiple PDCCH s. Each DCI is intended to be received by one or several UE s DCI recipients are distinguished by RNTI, masked into message CRC Only the intended recipient(s) can therefore decode the relevant DCI However the UE still has to attempt to detect all DCI s UE s could have several RNTI s active at any time DCI messages are used for scheduling Paging or System Information, Random Access responses and for control of established UL-SCH or DL-SCH Paging information identified by P-RNTI System Information indentified by SI-RNTI UL Scheduling in response to a Random Access request identified by RA-RNTI Established UL-SCH or DL-SCH identified by UE specific C-RNTI (Cell-RNTI) Page 22

23 Downlink Control Information (DCI) formats DCI Format Payload Usage 0 UL-SCH assignments RB Assignments, TPC, MCS, PUSCH hopping flag, CQI request 1 DL-SCH assignments RB Assignments, TPC, HARQ, MCS 1A DL-SCH assignments (compact) RB Assignments, TPC, HARQ, MCS, RA 1B DL-SCH assignments (compact with precoding) 1C DL-SCH assignments (VERY compact) RB Assignments 1D DL-SCH assignments (compact with precoding and power offset) RB Assignments, TPC, HARQ, MCS TPMI, PMI RB Assignments, TPC, HARQ, MCS TPMI, DL Power offset 2 DL-SCH assignments for closed loop MIMO RB Assignments, TPC, HARQ, MCS, pre-coding 2A DL-SCH assignments for open loop MIMO RB Assignments, TPC, HARQ, MCS, pre-coding 3 TPC commands for PUSCH and PUCCH with 2 bit power adjustments 3A TPC commands for PUSCH and PUCCH with single bit power adjustments Power control, e.g. USER1, USER2, USER.etc using TPC-PUCCH-RNTI and TPC-PUSCH-RNTI Power control, e.g. USER1, USER2, USER.etc using TPC-PUCCH-RNTI and TPC-PUSCH-RNTI Page 23

24 Downlink Control Information (DCI) timing DCI for DL scheduling Sent to many UE s DCI DL scheduling applies to resources on the same sub-frame as the DCI Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 DCI received for DL assignment Scheduled DL resources DCI received for UL assignment Scheduled UL resources Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 DCI for UL scheduling Only ever sent to a single UE, identified by RNTI masked into CRC DCI UL scheduling applies to resources 4 sub-frames after the DCI was sent Page 24

25 PUSCH Uplink Power Control sec 5 The setting of the UE Transmit power for the physical uplink shared channel (PUSCH) transmission in sub-frame i is defined in dbm by: P i) = min{ P,10 log ( M ( i)) + P ( j) + α( j) PL + ( i) + PUSCH ( MAX 10 PUSCH O_PUSCH TF f ( i)} When the number of resource blocks increases, the overall available integrated power level increases Essentially this is a single calculation which is transformed from open loop to closed loop (enb) control with the α component. When α =0 we have closed loop control and the MS calculated open loop component is eliminated ( i TF ) is a cell specific boosting factor which increases with data rate so that S/N can be improved when using the higher modulation schemes Power control is adjusted with increments: f (i) includes the TPC command TPC values are carried in the DCI and depend on DCI format PUCCH has a similar, but different equation, as does PRACH Page 25

26 Other controls on DL - MAC Control Elements Several controls are multiplexed into MAC messaging The Timing Advance field indicates the timing adjustment (granularity 0.52 µs = 16 T s ) that a UE has to apply. The value is derived from the timing of uplink transmissions as measured by the enb. UE adjusts timing 6 sub-frames after receipt of command. The Buffer Size field identifies the total amount of data available across all logical channels of a logical channel group after the MAC PDU has been built. Indicated in number of bytes, and includes: All data that is available for transmission (and any re-transmissions) in the RLC layer and in the PDCP layer The size of the RLC and MAC headers are not considered in the buffer size computation The Power Headroom reporting procedure is used to provide the serving enb with information about the difference between the UE TX power and the maximum UE TX power Discontinuous Reception (DRx). The UE may be configured by RRC with a DRx functionality that allows it to monitor the PDCCH discontinuously to save battery life Contention resolution information Page 26

27 UCI on the PUCCH or PUSCH Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel carries the Uplink Control Information CQI and ACK/NACK, and also scheduling requests Format Bits per sub-frame Payload Mod n 1 N/A No Ack/Nack, only SR N/A 1a 1 SISO Ack/Nack BPSK 1b 2 MIMO Ack/Nack QPSK 2 20 CQI, no Ack/Nack QPSK 2a * 21 CQI + SISO Ack/Nack B/QPSK 2b * 22 CQI + MIMO Ack/Nack B/QPSK The number and position of Demodulation Reference Signal symbols will vary depending on format * For normal CP only Page 27

28 LTE 3GPP - MAC HARQ N-Process Stop and Wait HARQ similar to that of 3G Downlink Asynchronous Adaptive HARQ (variable turnaround time) PUSCH or PUCCH used for ACK/NACKS for DL (re-)transmissions PDCCH signals the HARQ process number and if re-transmission or transmission Uplink Synchronous HARQ (turnaround time of 8ms) Maximum number of re-transmissions configured per UE PHICH used to transmit ACK/NACKs for non-adaptive UL (re-)transmissions. Adaptive re-transmissions are scheduled through PDCCH 8 UL HARQ processes MAC HARQ can also interact with RLC to provide information to speed up RLC ARQ re-segmentation and re-transmission. Page 28

29 Synchronous H-ARQ (UL transmission) UL LTE utilises synchronous H-ARQ Each H-ARQ processes is always sent at fixed 8 sub-frame intervals Ack/Nacks are sent on DL PHICH 4 frames after receipt of UL frame, i.e. Ack/Nack on subframe 6 for data in sub-frame 2 as shown in the diagram below Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 HARQ Process n ACK/NACK from enb on PHICH Next HARQ Process n ACK/NACK from enb on PHICH Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 Fixed 8 sub-frame (8ms) interval Page 29

30 Asynchronous H-ARQ (DL transmission) DL LTE utilises asynchronous H-ARQ Each H-ARQ process could have variable timing, the enb can transmit as soon as it receives the ACK/NACK from the UE on the uplink PUCCH DL HARQ Process n Next HARQ Process n Next HARQ Process n Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 Fixed 4 sub-frame interval Variable interval Fixed 4 sub-frame interval Variable interval Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 Sub-frame #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 ACK/NACK from UE on PUCCH or PUSCH ACK/NACK from UE on PUCCH or PUSCH Page 30

31 HARQ Link Adaptation Retransmissions of a particular HARQ process use the same modulation and coding scheme as the initial transmission. Each subsequent retransmission simply reduces the effective code rate through incremental redundancy there are 4 redundancy versions for LTE Link adaptation (AMC: adaptive modulation and coding) with various modulation schemes and channel coding rates is applied to the shared data channel. AMC optimises the transmission performance of each UE while maximizing the system throughput. If we use too low a modulation depth e.g. QPSK during good radio conditions, then we are utilizing more bandwidth (for a given desired data rate) than we need to If we use too high a modulation depth in poor conditions, we end up with too many retransmissions Either way we are not making efficient use of the resources available Channel Quality Indicator (CQI) is the means by which the channel conditions are reported to the enb to optimise AMC process. Page 31

32 LTE 3GPP Channel Quality Indictor (CQI) section 7.2 CQI reports can be Wideband or per sub-band Semi static, Higher Layer Configured or UE selected single or multiple sub-bands CQI only, or CQI plus Pre-coding Matrix Indicator (PMI) Transmitted on PUCCH for sub-frames with no PUSCH allocation or PUSCH with or without scheduling grant or if no UL-SCH Depends on spatial multiplexing Reports can be periodic or aperiodic (when signaled by DCI format 0 with CQI request field set to 1) The enb need not necessarily use the CQI reported from the UE CQI index modulati on coding rate x out of range efficiency 1 QPSK QPSK QPSK QPSK QPSK QPSK QAM QAM QAM QAM QAM QAM QAM QAM QAM Table : 4-bit CQI Table Page 32

33 Channel Quality Indication CQI on Uplink Channel Information (UCI) Section 7.2 Transmission Mode Single-antenna port; port 0 Transmit diversity Open-loop spatial multiplexing Closed-loop spatial multiplexing Multi-user MIMO Closed-loop Rank=1 pre-coding Single-antenna port; port 5 Payload UE selected sub-band CQI + wide-band CQI or Higher Layer Configured wide-band and sub-band CQI, no PMI UE selected sub-band CQI + wide-band CQI or Higher Layer Configured wide-band and sub-band CQI, no PMI UE selected sub-band CQI + wide-band CQI or Higher Layer Configured wide-band and sub-band CQI, no PMI Wide-band CQI per codeword + PMI for each sub-band or UE selected sub-band and wide-band CQI per codeword + PMI or Higher Layer Configured wide-band and sub-band CQI + PMI Higher Layer Configured wide-band and sub-band CQI + PMI Wide-band CQI per codeword + PMI for each sub-band or UE selected sub-band and wide-band CQI per codeword + PMI or Higher Layer Configured wide-band and sub-band CQI + PMI Not yet defined Page 33

34 Agenda 1 page Introduction to LTE LTE signalling and control Pre-connection (idle mode) procedures and control Cell Selection, re-selection System information and Master information Connection procedures and control RRC controls Paging, (P)RACH Scheduling, resource allocation Voice/Data transfer (connected mode) processes and control DCI, Power control, Timing control, UCI HARQ, CQI Summary and Agilent LTE solutions Page 34

35 LTE signalling and control in 45m Summary Signal and Channel mapping - simple but effective only 2 modes connected and idle MIB, SIB s provision of essential cell information, HO cell lists Connection processes - Paging and RACH very similar to 3G processes DCI Carries all the UE control instructions such as power control, scheduling, assignments, pre-coding etc Scheduling controlled by multiple variants of RNTI UCI Carries HARQ, CQI, resource requests UL Power control simple compared with W-CDMA MAC control elements Buffer reporting, Timing Advance etc HARQ very stressful for UE, 8ms Turnaround Time 1ms TTI CQI sub-band and wide-band, plus MIMO - much more complex compared to W-CDMA but essential to optimise the shared channel Page 35

36 Agilent and Anite Industry Leaders Partnering to Deliver World Class LTE Development Solutions Providing scalable test solutions to address the complete R&D life cycle for LTE mobile development. Anite and Agilent are partnering to deliver industry leading UE LTE R&D test solutions. Anite will provide industry leading development, conformance and interoperability protocol test solutions for LTE Agilent will be providing an industry leading RF platform, OBT based solutions and RF conformance solutions for LTE. These solutions will use a common RF hardware platform and a common protocol stack providing a truly scalable solution to address all phases of UE development enabling customers to bring LTE UEs to market faster and more efficiently. Page 36

37 Agilent 3GPP LTE Portfolio Software Solutions Coming Soon! ADS LTE Design Libraries N7624B Signal Studio 89601A VSA Software NEW! E6620A Wireless Communications Platform Agilent/Anite SAT LTE Protocol Development Toolset Drive Test VSA, PSA, ESG, Scope, Logic PXB R&D MXA/MXG R&D Coming Soon! Coming Soon! Digital VSA Network Analyzers, Power supplies, and More! Agilent/Anite SAT LTE UE Protocol Conformance Development Toolset Distributed Network Analyzers R&D Signalling Conformance Network Page 37

38 Resources Agilent LTE Page: Wall chart (poster) E6620A Page: E6620A Photo Card LTE Brochure Anite web site: Other Agilent LTE Webcasts: Concepts of LTE: LTE Protocol Primer: LTE Measurements: SC-FDMA: Mimo: Page 38

39 Q&A Page 39