agilent nov2008 signalling and analysis

Moving into New Era of Wireless

3GPP Long Term Evolution

(LTE)

Signaling and control in 45m

Presented by:Sandy Fraser

November, 2008

LTE signaling and control in 45m

November 2008

This presentation could quickly go out of date

Using this presentation after

March 2009 could seriously

reduce your credibility

The next revision of the std’s in

Dec 2008 could already cause

some of the content in the

paper to be incorrect

This presentation reflects

solely LTE frame type 1 (FDD)


November 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


November 2008

LTE major features

Feature Capability

Access 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 diversity

Single-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


November 2008

Agenda







– RRC controls

– Paging, (P)RACH




– HARQ, CQI



November 2008

Diagram of the various UE states

Idle Mode

Cell selection

System Information

Call/data setup

Paging

RACH

Connected

Call/data control

Data flow

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

Connection


Connection


CCO,

Reselection

CCO with

NACC

CELL_FACH

CCO, Reselection


November 2008

Agenda







– RRC controls

– Paging, (P)RACH




– HARQ, CQI



November 2008

Idle mode processes

• Switch on

• Scan Channels (EUARFCN)s

• Find Strongest signal

• Read System Information

• Select PLMN

• Location Register

• UE is now camped (idle mode)


November 2008

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.


November 2008

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.


November 2008

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 SIB2-9

Periodicity 40ms 80ms Dynamic

Indicated by

SIB1

Resources Fixed # Fixed *

Scheduling Fixed Fixed

Mapped to BCCH BCCH BCCH

Transport CH BCH DL-SCH DL-SCH

Identifier N/A N/A SI-RNTI


November 2008

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).


November 2008

Agenda







– RRC controls

– Paging, (P)RACH




– HARQ, CQI



November 2008

• 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 Signalling – high level

RRC CONNECTION REQUEST

RRC CONNECTION REJECT

UE EUtranUE EUtran

RRC CONNECTION REQUEST

RRC CONNECTION SETUP

RRC CONNECTION SETUPCOMPLETE


November 2008

• 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

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


November 2008

• 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

RRC Signalling – Mobility control

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


November 2008

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.


November 2008

Random Access

• 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)

• 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

UE eNB

Random Access Preamble1

Random Access Response 2

Scheduled Transmission3

Contention Resolution 4

Figure 10.1.5.1-1: Contention

based Random Access Procedure

UE eNB

RA Preamble assignment0

Random Access Preamble 1

Random Access Response2

Figure 10.1.5.2-1: Non-contention

based Random Access Procedure


November 2008

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

Random Access Timing

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

UE eNB

Random Access Preamble1

Random Access Response 2

Scheduled Transmission3

Contention Resolution 4


November 2008

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 3UE 4


November 2008

Agenda







– RRC controls

– Paging, (P)RACH




– HARQ, CQI



November 2008

• 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)

Information required by UE to transmit/receive

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 to

Transmit new block or re-transmit

NACK’d blocks

Is this new data or re-transmitted data


November 2008

• 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)


November 2008


formats

DCI

Format

Payload Usage

0 UL-SCH assignments RB Assignments, TPC, MCS, PUSCH hopping flag

1 DL-SCH assignments RB Assignments, TPC, HARQ, MCS

1A DL-SCH assignments (compact) RB Assignments, TPC, HARQ, MCS

1B DL-SCH assignments (compact with pre-

coding)

RB Assignments, TPC, HARQ, MCS

TPMI, PMI

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

1D DL-SCH assignments (compact with pre-

coding and power offset)

RB Assignments, TPC, HARQ, MCS

TPMI, 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


November 2008

• 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

• DCI UL scheduling applies to resources 4 sub-frames after the DCI was sent


timing

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


November 2008

• 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

PUSCH Uplink Power Control36.213 sec 5

)}()()()())((log10,min{)( TFO_PUSCHPUSCH10MAXPUSCH ifiPLjjPiMPiP

)(TF i

)(if


November 2008

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 s = 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

• 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


November 2008

UCI on the PUCCH or PUSCH

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

Physical Uplink Control Channel (PUCCH) or Physical Uplink Shared Channel

carries the Uplink Control Information CQI and ACK/NACK, and also scheduling

requests

* For normal CP only

The number and position of Demodulation Reference Signal symbols will vary

depending on format


November 2008

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.


November 2008

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 #0 #4#1 #2 #3 #5 #6 #7 #8 #9

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

HARQ

Process n

ACK/NACK from

eNB on PHICHNext HARQ

Process n

Fixed 8 sub-frame (8ms) interval

ACK/NACK from

eNB on PHICH


November 2008

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

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

DL HARQ

Process n

ACK/NACK from UE on

PUCCH or PUSCH

Next HARQ

Process n

Fixed 4 sub-frame interval

ACK/NACK from UE on

PUCCH or PUSCH

Variable

intervalVariable

intervalFixed 4 sub-frame interval

Next HARQ

Process n


November 2008

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.


November 2008

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

CQI

index

modulati

on

coding rate x

1024efficiency

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

36.213 Table 7.2.3-1: 4-bit CQI Table

• 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


November 2008

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 or

Higher Layer Configured wide-band and sub-band CQI, no PMI

Transmit diversity UE selected sub-band CQI + wide-band CQI or


Open-loop spatial

multiplexing

UE selected sub-band CQI + wide-band CQI or


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 + PMI

Closed-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


November 2008

Agenda







– RRC controls

– Paging, (P)RACH




– HARQ, CQI



November 2008

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


November 2008

Agilent and Anite

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.

Industry Leaders Partnering to Deliver

World Class LTE Development Solutions


November 2008

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

Agilent 3GPP LTE Portfolio

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!


November 2008

• 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

Resources

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






November 2008

Appendix


November 2008

LTE Air Interface:

Downlink Physical Signals

BaseStation

(eNB)

UserEquipment

(UE)

P-SS - Primary Synchronization Signal

RS – Reference Signal (Pilot)

P-SS:

- Used in cell search and initial synchronization procedures

- Carries part of the cell ID (one of 3 sequences) and identifies 5 ms timing

- Transmitted on 62 out of the reserved 72 subcarriers (6 RBs) around DC at

OFDMA symbol #6 of slot #0 & #10

- Modulation sequence = One of 3 Zadoff-Chu sequences

S-SS:

- Used to identify cell-identity groups. Also identifies frame timing (10 ms)

- Carries remainder of cell ID (one of 168 binary sequences)

- Transmitted on 62 out of the reserved 72 subcarriers (6 RBs) around DC at

OFDMA symbol #5 of slot #0 & #10

- Modulation sequence = Two 31-bit binary sequences; BPSK

RS:

- Used for DL channel estimation and coherent demodulation

- Transmitted on every 6th subcarrier of OFDMA symbols #0 & #4 of every slot

- Modulation sequence = Pseudo Random Sequence (PRS). Exact sequence

derived from cell ID, (one of 3 * 168 = 504).

S-SS - Secondary Synchronization Signal


November 2008

LTE Air Interface:

Uplink Physical Signals

BaseStation

(eNB)

UserEquipment

(UE)

DM-RS - (Demodulation) Reference Signal

S-RS - (Sounding) Reference Signal

DM-RS: There are two types of DM-RS. PUCCH-DMRS and PUSCH-DMRS

PUSCH-DMRS:

- Used for uplink channel estimation

- Transmitted on SC-FDMA symbol #3 of every PUSCH slot

- Modulation sequence = nth root Zadoff-Chu

PUCCH-DMRS:

- Transmitted on different symbols depending on PUCCH format and cyclic

prefix. For normal cyclic prefix and PUCCH format 1, it is transmitted on

SC-FDMA symbols #2, #3 and # 4 of every PUCCH slot. For PUCCH format

1, it is transmitted on SC-FDMA symbols #1 and 5

- Modulation sequence = Zadoff-Chu

S-RS:

- Used for uplink channel quality estimation when no PUCCH or PUSCH

is scheduled.

- Modulation sequence = Based on Zadoff-Chu


November 2008

LTE Air Interface:

Downlink Physical Channels (1 of 2)

BaseStation

(eNB)

UserEquipment

(UE)

PBCH – Physical Broadcast Channel

Broadcast Channel

PBCH: - Carries cell specific information such as system bandwidth, number of Tx

antennas etc…

- Transmitted in the centre 72 subcarriers (6 RB) around DC at OFDMA symbol #0 to

#3 of Slot #1 of sub-frame #0

- Modulation scheme = QPSK

PCFICH:

- Carries information on the number of OFDM symbols used for transmission of

PDCCH’s in a sub-frame

- Transmitted on symbol #0 of slot 0 in a sub-frame


PHICH:- Carries the hybrid-ARQ ACK/NACK feedback to the UE for the blocks received

- Transmitted on symbol #0 of every sub-frame (Normal duration) and symbols #0, 1

& 2 of every sub-frame (Extended duration) if the number of PDCCH symbols = 3

- Modulation scheme = BPSK (CDM)

PCFICH – Physical Control Format Indicator Channel

PHICH –Physical Hybrid-ARQ Indicator Channel

Indicator Channels


November 2008

LTE Air Interface

Downlink Physical Channels (2 of 2)

BaseStation

(eNB)

UserEquipment

(UE)

PDCCH – Physical Downlink Control Channel

Control Channel

PDCCH

- Carries uplink and downlink scheduling assignments and other

control information depending on format type (there are 4 formats)

- Transmitted on the first 1, 2 or 3 symbols of every subframe


PDSCH

- Carries downlink user data and Paging Channel (PCH)

- Transmitted on sub-carriers and symbols not occupied by

the rest of downlink channels and signals

- Modulation scheme = QPSK, 16QAM, 64 QAM

PDSCH - Physical Downlink Shared Channel

Shared (Payload) Channel


November 2008

LTE Air Interface:

Uplink Physical Channels

BaseStation

(eNB)

UserEquipment

(UE)

PRACH - Physical Random Access Channel

Random Access Channel

PRACH:- Used for call setup

- Modulation scheme = uth root Zadoff-Chu

PUCCH:- Carries ACK/NACK for downlink packets, CQI information and scheduling

requests

- Never transmitted at same time as PUSCH from the same UE

- Two RBs per sub-frame, the outer RB regions, are reserved for PUCCH

- Modulation scheme = On/Off keying, BPSK and QPSK

PUSCH:- Carries uplink user data

- Modulation scheme = QPSK, 16QAM, 64QAM

PUCCH – Physical Uplink Control Channel

Control Channel

PUSCH - Physical Uplink Shared Channel

Shared (Payload) Channel


November 2008

LTE 3GPP CQI reporting

PUCCH

Report

Type

Reported

PUCCH Reporting Modes

Mode 1-1 Mode 2-1 Mode 1-0 Mode 2-0

(bits/BP) (bits/BP) (bits/BP) (bits/BP)

1Sub-band

CQI

RI = 1 NA 4+L NA 4+L

RI > 1 NA 7+L NA 4+L

2Wideband

CQI/PMI

2 TX Antennas RI = 1 NA NA

4 TX Antennas RI = 1 8 8 NA NA

2 TX Antennas RI > 1 NA NA

4 TX Antennas RI > 1 11 11 NA NA

3 RI2-layer spatial multiplexing 1 1 1 1

4-layer spatial multiplexing 2 2 2 2

4Wideband

CQIRI = 1 NA NA 4 4

36.213-820 Table 7.2.2-3: PUCCH Report Type Payload size per Reporting Mode


November 2008

Channel and Signal definition

Logical Channels

Logical Channels are the service access points (SAP) provided by MAC to

RLC. Logical channels are distinguished by “what” information is transferred

over these channels.

Transport Channels

Transport Channels are the service access points (SAP) used by MAC and

provided by PHY to achieve data transfer. Transport channels are

distinguished by “how” the data is transferred - MAC provides a Transport

Format that specifies to the physical layer the processing to be applied to

each transmission

Physical Channels

Are the actual resources used to transmit the Logical/Transport channels

Reference signals, are used for synchronization and link estimation


November 2008

Reference Signals

Downlink only

Uplink only

P-SS S-SS RS SRS DMRS

P-SS – Primary Synchronisation Signal

• Contains the Cell ID one of 3 sequences

S-SS – Secondary Synchronisation Signal

• Combines with the P-SS to provide one of 168 sequence ID’s

• Contained in the 6 RB’s around DC

RS – Reference Signal

• Pilot used for channel equalisation and DL channel estimation. Exact sequence

derived from Cell ID (one from 3x168 = 504 possibilities

DMRS – Demodulation Reference Signal

• Used for synchronisation to the UE and UL channel estimation. Only used

when there is an active transport channel on EITHER PUCCH or PUSCH

SRS – Sounding Reference Signal

• Used for synchronisation to the UE and providing an estimation of the UL

channel . Only used when there is NO active PUSCH or PUCCH channel


November 2008

Channel Mapping UL/DL

Logical

Channels

UL/DL

Transport

Channels

UL/DL

Physical

Channels

DL Equivalent

Uplink only

DTCHDCCHCCCH

UL-SCH

PUCCH PUSCH

RACH

PRACH

Uplink Logical to Transport Channel Mapping

Logical Channel Purpose of Logical Channel Transport Channel

CCCHCarries RRC signaling before UE

has been identified – e.g. for

connection setup

UL-SCH

DCCH Carries signaling from RRC UL-SCH

DTCH Carries user data (speech etc) UL-SCH


November 2008

Channel Mapping

UL Equivalent

Downlink only

Downlink Logical to Transport Channel Mapping

Logical Channel Purpose of Logical Channel Transport Channel

BCCH Carries Master Information Block BCH

BCCH Broadcast of System Information

messagesDL-SCH

PCCH Carries paging messages PCH

CCCH Carries RRC signaling before UE has been

identified – e.g. for connection setupDL-SCH

DCCH Carries signaling from RRC DL-SCH

DTCH Carries user data (speech etc) DL-SCH

UL/DL

Transport

Channels

UL/DL

Physical

Channels

UL/DL

Logical

Channels

DTCHDCCHCCCH

BCHPCH DL-SCH

PBCHPDCCH PDSCHPHICHPCFICH

BCCHPCCH


November 2008

LTE Protocol Primer

Web presentation 25th June

2008

OFDM symbols (= 7 OFDM symbols @ Normal CP)

The Cyclic Prefix is created by prepending each

symbol with a copy of the end of the symbol

160 2048 144 2048 144 2048 144 2048 144 2048 144 2048 144 2048 (x Ts)

1 frame= 10 sub-frames

= 10 ms

1 sub-frame= 2 slots

= 1 ms

1 slot= 15360 Ts

= 0.5 ms

0 1 2 3 4 5 6

etc.

CP CP CP CPCPCP

DLsymbN

Downlink frame structure type 1

RS - Reference Signal (Pilot)

P-SS - Primary Synchronization Signal

S-SS - Secondary Synchronization Signal

PBCH - Physical Broadcast Channel

PCFICH – Physical Control Channel Format Indicator Channel

PHICH (Normal)– Physical Hybrid Indicator Channel (HARQ)

PDCCH (L=3) - Physical Downlink Control Channel


#0 #1 #8#2 #3 #4 #5 #6 #7 #9 #10 #11 #12 #19#13 #14 #15 #16 #17 #18

10 2 3 4 5 610 3 4 5 62

Su

b-C

arr

ier

(RB

)

Time (Symbol)


November 2008

LTE Protocol Primer


2008

64QAM16QAM QPSK

Frequency

Time

Downlink mapping

P-SS - Primary Synchronization Channel

S-SS - Secondary Synchronization Channel

PBCH - Physical Broadcast Channel

PDCCH -Physical Downlink Control Channel


Reference Signal – (Pilot)


November 2008

Slot structure and physical resource elementDownlink – OFDMA

Condition

Normal

cyclic prefix∆f=15kHz 12 7

Extended

cyclic prefix

∆f=15kHz 12 6

∆f=7.5kHz 24 3

RBscN

RBscN

OFDM symbols

One downlink slot, Tslot

:

:

xsubcarriers

Resource block

x

Resource

element

(k, l)

l=0 l= – 1

subcarriers

A Resource Block is the

minimum allocation of

resource which can be

allocated

An RB is 0.5 ms long and 180

kHz wide

An RB may contain different

numbers of symbols

depending on the CP length

and subcarrier spacingDLRBN RB

scN

DLsymbN

DLsymbN

DLRBN DL

symbN

DLsymbN RB

scN


November 2008

LTE Protocol Primer


2008

#0 #1 #8#2 #3 #4 #5 #6 #7 #9 #10 #11 #12 #19#13 #14 #15 #16 #17 #18

10 2 3 4 5 6 10 2 3 4 5 6

PUSCH - Physical Uplink shared Channel

Reference Signal – (Demodulation)

OFDM symbols (= 7 OFDM symbols @ Normal CP)

The Cyclic Prefix is created by prepending each

symbol with a copy of the end of the symbol

160 2048 144 2048 144 2048 144 2048 144 2048 144 2048 144 2048 (x Ts)

1 slot= 15360 Ts

= 0.5 ms

0 1 2 3 4 5 6CP CP CP CP CPCPCP

DLsymbN

1 sub-frame= 2 slots

= 1 ms

1 frame= 10 sub-frames

= 10 ms

Ts = 1/(15000 x 2048) = 32.6 ns

Uplink frame structure type 1PUSCH mapping


November 2008

LTE Protocol Primer


2008

Uplink mapping

PUSCH

Demodulation Reference Signal

for PUSCH

PUCCH

Demodulation Reference Signal

for PUCCH format 1

64QAM

16QAM

or QPSK

64QAM16QAM QPSKRotated

QPSK

Zadoff-Chu


November 2008

LTE Protocol Primer


2008

Slot structure and physical resource elementUplink – SC-FDMA

:

:

Resource element

(k, l)

l=NULsymb – 1

Condition NRBsc NUL

symb

Normal

cyclic prefix12 7

Extended

cyclic prefix12 6

Resource Block =

0.5 ms x 180 kHz

RBscN subcarriers

ULRBN RB

scNx subcarriers

Resource block

x ULsymbN

RBscN

SC-FDMA

symbols

ULsymbN

One uplink slot, Tslot


November 2008

PUCCH Uplink Power Control36.213 sec 5

igFnnhPLPPiP HARQCQI F_PUCCH0_PUCCHMAXPUCCH ,,min

• The setting of the UE Transmit power for the physical uplink control channel

(PUCCH) transmission in sub-frame i is defined in dBm by:

• Depends on PUCCH format (the number of CQI and HARQ bits)

• Power control is adjusted with cumulative increments, there is no absolute

value setting.

• The setting of the UE Sounding Reference Signal (SRS) is defined in dBm by:

• Similar to the PUSCH definition - Depends on current PUSCH power setting

and the number of resource blocks (bandwidth)

)}()()(log10,min{)( O_PUSCHSRS10SRS_OFFSETMAXSRS ifPLjPMPPiP

SRSM)(if

agilent nov2008 signalling and analysis

Documents