wireless test world 2009 - · pdf filelte signaling and control in 45m november 2008 agenda...

Agilent, Your Partner in AdvancingNew Wireless Communications

Wireless Test World 2009 Agilent, Your Partner in AdvancingNew Wireless Communications

Wireless Test World 2009

LTE Protocol Signaling andControl

Presented by:Choi, In-Hwan

July 1, 2009

LTE signaling and control in 45mNovember 2008

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


LTE major features

Feature CapabilityAccess modes FDD with frame structure 1

TDD with frame structure 2

Variable channel BW 1.4, 3, 5, 10, 15, 20 MHz FDD and TDD(1.6 MHz & 3.2 MHz TDD bandwidths now deleted)

Baseline UE capability 20 MHz UL/DL, 2 Rx, one Tx antenna

User Data rates(at baseline capability)

DL 172.8 Mbps / UL 86.4 Mbps @ 20 MHz BW(2x2 DL SU-MIMO & SISO on UL) with 64QAM

Downlink transmission OFDMA using BPSK, QPSK, 16QAM, 64QAM

Uplink transmission SC-FDMA using BPSK, QPSK,16QAM, 64QAM

DL Spatial diversity Open loop TX diversitySingle-User MIMO up to 4x4 supportable

UL Spatial diversity Optional open loop TX diversity, 2x2 MU-MIMO, Optional 2x2 SU-MIMO

Bearer services Packet only – no circuit switched voice or data services are supported voice must use VoIP


Agenda







Diagram of the various UE states

Handover

CELL_PCH URA_PCH

CELL_DCH

UTRA_Idle

E-UTRA RRC CONNECTED

E-UTRA RRC IDLE

GSM_Idle/GPRS Packet_Idle

GPRS Packet transfer mode

GSM_Connected Handover

Reselection Reselection

Reselection

Connection establishment/release



CCO, Reselection

CCO with optional

NACC

CELL_FACH

CCO, Reselection

Idle ModeCell selectionSystem Information

Call/data setupPagingRACH

ConnectedCall/data control Data flow


Agenda







Idle mode processes


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 re-

selection/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.


Master and System Information36.300 7.4, 36.331 5.2

• 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.


Master and System Information36.300 7.4, 36.331 5.2

• 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

# First MIB in sub-frame #0 for which SFN mod 4=0, subsequently in sub-frame #0

* First SIB1 in sub-frame #5 for which SFN mod 8=0, subsequently in sub-frame #5 when SFN mod 2=0

MIB SIB1 SIB2-9Periodicity 40ms 80msResources Fixed # Fixed *Scheduling Fixed Fixed

Flexible Indicated by

SIB1

Mapped to BCCH BCCH BCCHTransport CH BCH DL-SCH DL-SCHIdentifier N/A N/A SI-RNTI


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 inter-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);

• 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 re-selection (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).


Agenda







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

RRC CONNECTION REQUEST

RRC CONNECTION REJECT

UE EUtranUE EUtran

RRC CONNECTION REQUEST

RRC CONNECTION SETUP

RRC CONNECTION SETUPCOMPLETE


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 36-300, Section 14


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

HANDOVER FROM EUTRA PREPARATION REQUEST

UL HANDOVER PREPARATION TRANSFER

MOBILITY FROM EUTRA COMMAND

Handovers to CDMA2000 RAT Only

• 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


Paging – e.g. incoming call or change in SI36.304 sec 6.1, 36.331 sec 5.3.2.3

• 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.


Random AccessUE eNB

Random Access Preamble1

Random Access Response 2

Scheduled Transmission3

Contention Resolution 4

Figure 10.1.5.1-1: Contention based Random Access Procedure

Figure 10.1.5.2-1: Non-contention based Random Access Procedure

• 5 possible RA events1.Initial Access2.Following Radio Link failure3.Handover4.DL data arriving during RRC_Connected5.UL data arriving during RRC_Connected

• 2 types• Contention based (all 5 events)• Non-contention based (only applies to 3, 4)

• In the frequency domain, the random access preamble occupies a bandwidth corresponding to 6 resource blocks 36.211 section 5.7.1

• 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


Random Access Timing

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

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

1. PRACH

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

2. PDCCH Random Access Response

Random Access Response window

3. Scheduled UL resources

2. PDSCH Random Access Response


LTE 3GPP - MAC Scheduling

• MAC’s main function is the distribution and management of common uplink and downlink resources to multiple UE’s

• 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 1

UE 4 UE 3


Agenda







Information required by UE to transmit/receive

• UE’s need to know a lot of information before sending or receiving data

• ALL of this information is send from the eNB to the UE on the Downlink Control Information (DCI)

Uplink Downlink

When the UE can transmit and on which resources

When the UE should “listen” for DL data. DL data may not be contiguous in frequency

Which modulation, transport block size and redundancy version to use

Which modulation, transport block size and redundancy version were used to transmit this data

Adjustments to align timing with eNB Is this downlink spatially multiplexed

Whether to hop the PUSCH or not For Spatially multiplexed DL what pre-coding has been applied

Power level Which HARQ process does this data belong toTransmit new block or re-transmit NACK’d blocks

Is this new data or re-transmitted data


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)


Downlink Control Information (DCI) formatsDCIFormat

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 pre-coding)

RB Assignments, TPC, HARQ, MCSTPMI, PMI

1C DL-SCH assignments (VERY compact) RB Assignments

1D DL-SCH assignments (compact with pre-coding and power offset)

RB Assignments, TPC, HARQ, MCSTPMI, 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

Power control, e.g. USER1, USER2, USER….etc using TPC-PUCCH-RNTI and TPC-PUSCH-RNTI

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


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

• 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

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

DCI received for DL assignment

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

Scheduled DL resources

DCI received for UL assignment

Scheduled UL resources


PUSCH Uplink Power Control36.213 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:

• 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

• 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: 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

)}()()()())((log10,min{)( TFO_PUSCHPUSCH10MAXPUSCH ifiPLjjPiMPiP +∆+⋅++= α

)(TF i∆

)(if


Other controls on DL - MAC Control Elements36.321

• Several controls are multiplexed into MAC messaging

• The Timing Advance field indicates the timing adjustment (granularity 0.52 µs = 16×Ts) 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


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/A1a 1 SISO Ack/Nack BPSK1b 2 MIMO Ack/Nack QPSK2 20 CQI, no Ack/Nack QPSK2a * 21 CQI + SISO Ack/Nack B/QPSK2b * 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


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.


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 sub-frame 6 for data in sub-frame 2 as shown in the diagram below

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9 Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9 #0 #4#1 #2 #3 #5 #6 #7 #8 #9

ACK/NACK from eNB on PHICH

ACK/NACK from eNB on PHICH

HARQ Process n

Next HARQ Process n

Fixed 8 sub-frame (8ms) interval


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

Next HARQ Process n

Next HARQ Process n

DL HARQ Process n

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9 Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

Sub-frame #0 #4#1 #2 #3 #5 #6 #7 #8 #9

Fixed 4 sub-frame intervalVariable interval

Variable intervalFixed 4 sub-frame interval

ACK/NACK from UE on PUCCH or PUSCH

ACK/NACK from UE on PUCCH or PUSCH


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 re-transmissions

• 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.


LTE 3GPP Channel Quality Indictor (CQI) 36.213 section 7.2

CQI index

modulation

coding rate x 1024 efficiency

0 out of range

1 QPSK 78 0.1523

2 QPSK 120 0.2344

3 QPSK 193 0.3770

4 QPSK 308 0.6016

5 QPSK 449 0.8770

6 QPSK 602 1.1758

7 16QAM 378 1.4766

8 16QAM 490 1.9141

9 16QAM 616 2.4063

10 64QAM 466 2.7305

11 64QAM 567 3.3223

12 64QAM 666 3.9023

13 64QAM 772 4.5234

14 64QAM 873 5.1152

15 64QAM 948 5.5547

• 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

36.213 Table 7.2.3-1: 4-bit CQI Table


Channel Quality Indication CQI on Uplink Channel Information (UCI) 36.213 Section 7.2

Transmission Mode Payload

Single-antenna port; port 0

UE selected sub-band CQI + wide-band CQI orHigher Layer Configured wide-band and sub-band CQI, no PMI

Transmit diversity UE selected sub-band CQI + wide-band CQI orHigher Layer Configured wide-band and sub-band CQI, no PMI

Open-loop spatial multiplexing

UE selected sub-band CQI + wide-band CQI orHigher Layer Configured wide-band and sub-band CQI, no PMI

Closed-loop spatial multiplexing

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

Multi-user MIMO Higher Layer Configured wide-band and sub-band CQI + PMIClosed-loop Rank=1 pre-coding

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

Single-antenna port; port 5

Not yet defined


Agenda







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


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 andinteroperability 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.


Agilent 3GPP LTE Portfolio

Coming Soon!

Software Solutions

• ADS LTE Design Libraries

• N7624B Signal Studio

• 89601A VSA Software

Distributed Network

Analyzers

Conformance Network

Digital VSA

VSA, PSA, ESG, Scope, Logic

R&D

Network Analyzers, Power supplies, and More!

MXA/MXG R&D

Signalling

Agilent/Anite SAT LTE –Protocol Development Toolset

Agilent/Anite SAT LTE – UE Protocol Conformance Development Toolset

E6620A Wireless Communications Platform

Drive Test

Coming Soon!

Coming Soon!

PXB R&D

NEW!


Resources

• Agilent LTE Page: www.agilent.com/find/lte

• Wall chart (poster)

• E6620A Page: www.agilent.com/find/e6620a

• E6620A Photo Card• LTE Brochure

• Anite web site: www.anite.com• http://www.anite.com/images/userdocuments/AniteLTE.PDF

• Other Agilent LTE Webcasts:• Concepts of LTE: http://www.techonline.com/learning/webinar/201801263• LTE Protocol Primer: http://www.techonline.com/learning/webinar/207800310• LTE Measurements: http://www.techonline.com/learning/webinar/208403979• SC-FDMA: http://www.techonline.com/learning/webinar/206101979• Mimo: http://www.techonline.com/learning/webinar/210102164

http://www.agilent.com/find/lte

http://www.agilent.com/find/e6620a

http://www.anite.com/

http://www.anite.com/images/userdocuments/AniteLTE.PDF

http://www.techonline.com/learning/webinar/201801263






Q&A

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