Agilent Nov2008 Signalling and Analysis
Transcript of Agilent Nov2008 Signalling and Analysis
Moving into New Era of Wireless
Page 1
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This presentation could quickly go out of date
Page 2
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)
LTE signaling and control in 45m
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
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LTE signaling and control in 45m
November 2008Page 4
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
LTE signaling and control in 45m
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
Page 5
LTE signaling and control in 45m
November 2008Page 6
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
establishment/release
Connection
establishment/release
CCO,
Reselection
CCO with
NACC
CELL_FACH
CCO, Reselection
LTE signaling and control in 45m
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
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LTE signaling and control in 45m
November 2008Page 8
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)
LTE signaling and control in 45m
November 2008Page 9
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.
LTE signaling and control in 45m
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.
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LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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).
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LTE signaling and control in 45m
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
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LTE signaling and control in 45m
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
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RRC Signalling – high level
RRC CONNECTION REQUEST
RRC CONNECTION REJECT
UE EUtranUE EUtran
RRC CONNECTION REQUEST
RRC CONNECTION SETUP
RRC CONNECTION SETUPCOMPLETE
LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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.
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LTE signaling and control in 45m
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
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LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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
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LTE signaling and control in 45m
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
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LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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)
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Downlink Control Information (DCI)
LTE signaling and control in 45m
November 2008
Downlink Control Information (DCI)
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
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LTE signaling and control in 45m
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
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Downlink Control Information (DCI)
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
LTE signaling and control in 45m
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
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PUSCH Uplink Power Control36.213 sec 5
)}()()()())((log10,min{)( TFO_PUSCHPUSCH10MAXPUSCH ifiPLjjPiMPiP
)(TF i
)(if
LTE signaling and control in 45m
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
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LTE signaling and control in 45m
November 2008
UCI on the PUCCH or PUSCH
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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
LTE signaling and control in 45m
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.
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LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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
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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
LTE signaling and control in 45m
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.
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LTE signaling and control in 45m
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
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LTE signaling and control in 45m
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
Higher Layer Configured wide-band and sub-band CQI, no PMI
Open-loop spatial
multiplexing
UE selected sub-band CQI + wide-band CQI or
Higher 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 + 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
Page 34
LTE signaling and control in 45m
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
Page 35
LTE signaling and control in 45m
November 2008
LTE signalling and control in 45m Summary
Page 36
• 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
LTE signaling and control in 45m
November 2008
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Page 37
LTE signaling and control in 45m
November 2008
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LTE signaling and control in 45m
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
Page 39
LTE signaling and control in 45m
November 2008
Appendix
Page 40
LTE signaling and control in 45m
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
Page 41
LTE signaling and control in 45m
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
Page 42
LTE signaling and control in 45m
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
- Modulation scheme = QPSK
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
Page 43
LTE signaling and control in 45m
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
- Modulation scheme = QPSK
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
Page 44
LTE signaling and control in 45m
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
Page 45
LTE signaling and control in 45m
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
Page 46
LTE signaling and control in 45m
November 2008
Channel and Signal definition
Page 47
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
LTE signaling and control in 45m
November 2008Page 48
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
LTE signaling and control in 45m
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
LTE signaling and control in 45m
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
LTE signaling and control in 45m
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
PDSCH - Physical Downlink Shared 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)
Page 51
LTE signaling and control in 45m
November 2008
LTE Protocol Primer
Web presentation 25th June
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
PDSCH - Physical Downlink Shared Channel
Reference Signal – (Pilot)
Page 52
LTE signaling and control in 45m
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
Page 53
LTE signaling and control in 45m
November 2008
LTE Protocol Primer
Web presentation 25th June
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
Page 54
LTE signaling and control in 45m
November 2008
LTE Protocol Primer
Web presentation 25th June
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
Page 55
LTE signaling and control in 45m
November 2008
LTE Protocol Primer
Web presentation 25th June
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
Page 56
LTE signaling and control in 45m
November 2008
PUCCH Uplink Power Control36.213 sec 5
Page 57
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