4706 final slides
DESCRIPTION
TelekomunikasiTRANSCRIPT
Presented by:
1 LTE RF Measurements
Martha Zemede
RF Measurements for LTE
Martha Zemede
August 7, 2008
Concepts of 3GPP LTE
9 Oct 2007
Page 2
LTE RF Measurements
Martha Zemede
August 2008
2
Previous Agilent LTE webcastsConcepts of 3GPP LTE TechOnline , September 20, 2007 This webcast will cover what LTE is, where it came from and provide context against the other 3.9G technologies such as HSPA+ and WiMAXTM. There will be a brief introduction to the new OFDM air interface as well as the complimentary changes being planned for the network system architecture evolution or SAE.
Addressing the Design & Verification Challenges of 3GPP LTETechOnline , October 02, 2007 This webcast will investigate system design and verification challenges of 3GPP LTE and show how Agilent’s new design simulation capabilities can help.
Understanding SC-FDMA -- The New LTE UplinkTechOnline , March 20, 2008Everything you wanted to know about SC-FDMA but were afraid to ask! This webcast will provide you with an intuitive understanding of SC-FDMA, LTE's new uplink modulation format. The pros and cons of SC-FDMA vs. OFDMA will be discussed concluding with measurements of typical SC-FDMA distortions using Agilent's industry-leading 89600 Vector Signal Analyzer software
LTE Protocol Primer
TechOnline , June 26, 2008This webcast will introduce the various LTE protocol layers, their functions, interactions, processes and message structures. The various LTE signals will also be discussed. This talk will include comment on the completeness of the relevant standards.
3 LTE RF Measurements
Martha Zemede
August 2008
Agilent LTE Analysis SoftwareThis presentation contains screen images from two separate Agilent LTE signal analysis software
Both of these software share same measurement algorithm and same measurement
features and capabilities. Major differences are:
89600 software works with over 30 different Agilent hardware frontends including X-Series signal
analyzers vs. N9080A LTE application is for X-Series signal analyzers only
89600 software has windows graphical user interface using mouse and keyboard and Microsoft .COM
remote programming vs. N9080A has hardkey/softkey manual user interface and SCPI remote
programming
89600 Vector Signal Analysis Software
LTE Modulation Analysis OptionN9080A LTE Measurement Application
for X-Series Signal Analyzers
LTE RF Measurements
Martha Zemede
August 2008
4
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
5
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
6
Physical Layer definitions
Frame StructureFrame Structure type 1 (FDD) FDD: Uplink and downlink are transmitted separately
#0 #2 #3 #18#1 ………. #19
One subframe = 1ms
One slot = 0.5 ms
One radio frame = 10 ms
Subframe 0 Subframe 1 Subframe 9
Frame Structure type 2 (TDD)One radio frame, Tf = 307200 x Ts = 10 ms
One half-frame, 153600 x Ts = 5 ms
#0 #2 #3 #4 #5
One subframe, 30720 x Ts = 1 ms
DwPTS
Guard period
UpPTS
One slot, Tslot =15360 x Ts = 0.5 ms
#7 #8 #9
DwPTS
Guard period
UpPTS
LTE RF Measurements
Martha Zemede
August 2008
7
Condition (DL) NRBsc NUL
symb
Normal
cyclic prefix∆f=15kHz 12 7
Extended
cyclic prefix
∆f=15kHz 12 6
∆f=7.5kHz 24 3
RB
scN
RB
scN
OFDM symbols
One slot, Tslot
:
:
x subcarriers
Resource block
x
Resource
element
(k, l)
l=0 l= – 1
subcarriers
•A Resource Block (RB) is basic
scheduling unit.
• A RB contains:
• 7 symbols (1 slot) X 12 subcarriers
for normal cyclic prefix
• 6 symbols (1 slot) X 12 subcarriers
for extended cyclic prefix
•Minimum data allocation is 1 ms (2 slots)
and 180 kHz (12 subcarriers).DLRBN RB
scN
DLsy mbN
DLsy mbN
DLsy mbN
RB
scN
Slot structure and physical resource element
Condition (UL) NRBsc NUL
symb
Normal
cyclic prefix12 7
Extended
cyclic prefix12 6
LTE RF Measurements
Martha Zemede
August 2008
8
LTE Physical Layer Overview
LTE air interface consists of two main components:
1. Physical signals
These are generated in Layer 1 and are used for system
synchronization, cell identification and radio channel
estimation
2. Physical channels
These carry data from higher layers including control,
scheduling and user payload
The following is a simplified high-level description of the
essential signals and channels.
LTE RF Measurements
Martha Zemede
August 2008
9
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
LTE RF Measurements
Martha Zemede
August 2008
10
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
LTE RF Measurements
Martha Zemede
August 2008
11
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
LTE RF Measurements
Martha Zemede
August 2008
12
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
- 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
LTE RF Measurements
Martha Zemede
August 2008
13
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
LTE RF Measurements
Martha Zemede
August 2008
14
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
DL
symbN
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 ARQ Indicator Channel
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)
15 LTE RF Measurements
Martha Zemede
August 2008
RS + PCFICH + PHICH + PDCCH
Downlink frame structure analysis
Slot#0 Symbol#0
RS - Reference Signal (Pilot)
P-SS - Primary Synchronization Signal
S-SS - Secondary Synchronization Signal
PBCH - Physical Broadcast Channel
PCFICH – Physical Control Format Indicator Channel
PHICH – Physical Hybrid ARQ Indicator Channel
PDCCH - Physical Downlink Control Channel
PDSCH - Physical Downlink Shared Channel
10 2 3 4 5 610 3 4 5 62
Time (Symbol)
Fre
qu
en
cy
(Su
b-C
arr
ier
or
RB
)
16 LTE RF Measurements
Martha Zemede
August 2008
Downlink frame structure analysis
Slot#0 Symbol #6:
P-SS + PDSCH
RS - Reference Signal (Pilot)
P-SS - Primary Synchronization Signal
S-SS - Secondary Synchronization Signal
PBCH - Physical Broadcast Channel
PCFICH – Physical Control Format Indicator Channel
PHICH – Physical Hybrid ARQ Indicator Channel
PDCCH - Physical Downlink Control Channel
PDSCH - Physical Downlink Shared Channel
10 2 3 4 5 610 3 4 5 62
Time (Symbol)
Fre
qu
en
cy
(Su
b-C
arr
ier
or
RB
)
LTE RF Measurements
Martha Zemede
August 2008
17
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
LTE RF Measurements
Martha Zemede
August 2008
18
Uplink frame structure analysis
PUSCH - Physical Uplink Shared Channel
PUSCH-DMRS – Demodulation Reference Signal (pilot)
10 2 3 4 5 6 10 2 3 4 5 6
Slot #0 Symbol #0: PUSCH
Time (Symbol)
Fre
qu
en
cy
(Su
b-C
arr
ier
or
RB
)
LTE RF Measurements
Martha Zemede
August 2008
19
Uplink frame structure analysis
10 2 3 4 5 6 10 2 3 4 5 6
Slot #0 Symbol #3: PUSCH-DMRS
Time (Symbol)
Fre
qu
en
cy
(Su
b-C
arr
ier
or
RB
)
PUSCH - Physical Uplink Shared Channel
PUSCH-DMRS – Demodulation Reference Signal (pilot)
LTE RF Measurements
Martha Zemede
August 2008
20
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
21
Transmitter Characteristics – eNB
•6.2 Base Station Output Power
•6.3 Output Power Dynamics
•6.4 Transmit ON/OFF Power
•6.5 Transmit Signal Quality
–6.5.1 Frequency Error
–6.5.2 Error Vector Magnitude
–6.5.3 Time alignment between transmitter branches
–6.5.4 DL RS power
•6.6 Unwanted Emissions
–6.6.1 Occupied bandwidth
–6.6.2 Adjacent Channel Leakage Power Ratio (ACLR)
–6.6.3 Operating band unwanted emissions ( same as SEM)
–6.6.4 Transmitter spurious emission
•6.7 Transmit Intermodulation
These transmitter tests are work
in progress and the definitions
and requirements covered in this
presentation are working
assumptions per TS 36.104
V8.2.0 (2008-05)
Test models (E-TMs) are under
discussion. These various eNB
Tx tests will be mapped to
various E-TMs once finalized.
LTE RF Measurements
Martha Zemede
August 2008
22
Transmitter Characteristics – UE• 6.2 Transmit Power
• 6.3 Output Power Dynamics
• 6.4 Control and Monitoring Functions
• 6.5 Transmit Signal Quality
– 6.5.1 Frequency error
– 6.5.2 Transmit modulation
• 6.5.2.1 Error Vector Magnitude (EVM)
• 6.5.2.2 IQ-Component
• 6.5.2.3 In-band Emissions
• 6.5.2.4 Spectrum Flatness
• 6.6 Output RF Spectrum Emissions
– 6.6.1 Occupied bandwidth
– 6.6.2 Out of band emission
• 6.6.2.1 Spectrum emission mask (SEM)
• 6.6.2.3 Adjacent channel leakage power ratio (ACLR)
– 6.6.3 Spurious emissions
• 6.7 Transmit Intermodulation
These transmitter tests are work
in progress and the definitions
and requirements covered in this
presentation are working
assumptions per TS 36.101
v8.2.0 (2008-05) + CR from June
RAN WG47 meeting
LTE RF Measurements
Martha Zemede
August 2008
23
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
24
Transmitted Signal Quality –
eNB (Downlink)
Currently there are four requirements under the
transmitted signal quality category for an eNB:
• Frequency error
• EVM
• Time alignment between transmitter
branches
• DL RS Power
LTE RF Measurements
Martha Zemede
August 2008
25
eNB Transmitted Signal Quality:Frequency Error
• A quick test is use the
Occupied BW measurement
• An accurate measurement
can then be made using the
demodulation process
•Minimum Requirement (observed over 1 ms):
±0.05 PPM
If the frequency error is larger than a
few sub-carriers, the receiver demod
may not operate, and could cause
network interference
LTE RF Measurements
Martha Zemede
August 2008
26
eNB Transmitted Signal Quality:
EVM Measurement Block
TS 36.104 V8.2.0 FigureE.1-1: Reference point for EVM measurement
Pre-/post FFT
time/frequency
synchronization
BS TXRemove
CPFFT
Per-subcarrier
Amplitude/phase
correction
Symbol
detection
/decoding
Reference point
for EVM
measurement
Measurement Block: EVM is
measured after the FFT and a
zero-forcing (ZF) constrained
equalizer in the receiver
EVM measurement is defined over one sub-frame
(1ms) in the time domain and 12 subcarriers
(180kHz) in the frequency domain. However
equalizer is calculated over full frame (10 sub-frames)
LTE RF Measurements
Martha Zemede
August 2008
27
eNB Transmitted Signal Quality:
Error Vector Magnitude (EVM)
EVM measurement requires the signal
to be correctly demodulated
EVM specification differs for each
modulation scheme
Minimum Requirement:
Parameter Unit Level
QPSK % 17.5
16QAM % 12.5
64QAM % 8
Signal BW 89650S
(typ)
MXA
(typ)
5 MHz 0.35 % 0.45 %
10 MHz 0.40 % 0.45 %
20 MHz 0.45 % 0.50 %
Agilent Signal Analyzer EVM Performance – DL
LTE RF Measurements
Martha Zemede
August 2008
28
eNB Transmitted Signal Quality:Time alignment between transmitter branches
• This test is required for eNB supporting TX diversity or spatial
multiplexing transmission
• Purpose is to measure time delay between the signals from two
transmit antennas
Minimum requirement:
< [65] ns
It is RS based measurement.
Measures relative timing error
between RS on antenna port
0 and RS on antenna port 1.
It is one of the many metrics
reported under MIMO Info
trace.
LTE RF Measurements
Martha Zemede
August 2008
29
eNB Transmitted Signal Quality:DL RS Power
Measures RS transmitted power
Test requirement:
DL RS power shall be within [+/- 2.1]
dB of the DL RS power indicated on
the BCH
RS power, as well as EVM,
measured at base station RF
output is reported under
Frame Summary trace
LTE RF Measurements
Martha Zemede
August 2008
30
Downlink EVM Equalizer Definition
The subsequent 7 subcarriers are averaged over 5, 7 .. 17 subcarriers
From the 10th
subcarrier onwards the window size is 19 until the upper edge of the channel is reached and the window size reduces back to 1
The first reference subcarrier is not averaged
The second reference subcarrier is the average of the first three subcarriers
Reference subcarriers TS 36.104 V8.2.0 Figure E.6-1: Reference subcarrier
smoothing in the frequency domain
Rather than use all the RS data to correct the received signal a moving average is performed in the frequency domain across the channel which limits the rate of change of correction
For the downlink, the EVM equalizer has been constrained
Agilent 89600 VSA EVM Setting
LTE RF Measurements
Martha Zemede
August 2008
31
Important notes on EVM
No transmit/receive filter will be defined
• In UMTS a transmit/receive filter was defined– Root raised cosine α = 0.22
• This filter was also used to make EVM measurements– Deviations from the ideal filter increased the measured EVM
• In LTE with OFDMA/SC-FDMA no filter is defined
• The lack of a filter creates opportunities and problems:– Signal generation can be optimized to meet in-channel and out
of channel requirements
– Signal reception and measurement have no standard reference
• It is expected that real receivers will use the downlink reference signals (pilots) to correct for frequency and phase
Concepts of 3GPP LTE
9 Oct 2007
Page 32
LTE RF Measurements
Martha Zemede
August 2008
2
• The lack of a defined transmit filter means that trade-offs can be made between in-channel performance and out of channel performance (ACLR, Spectrum emission mask)
• But applying too aggressive filtering can introduce delays to the signal which appear like multipath and reduce the effective length of the CP
• For this reason EVM is defined across a window at two points in time either side of the nominal symbol centre
Important notes on EVM
EVM vs. time – impact on CP reduction
Usable ISI free period
CP length
EV
M
Impact of time domain
distortion induced by shaping
of the transmit signal in the
frequency domain
LTE RF Measurements
Martha Zemede
August 2008
33
CP Len FFT Size
EVM Window
FFT Size aligned with EVM Window End
EVM is measured at two locations in time and
the maximum of the two EVM is reported. i.e.
EVM1 measured at EVM Window Start
EVM2 measured at EVM Window End
Reported EVM = max(EVM1, EVM2)
Important notes on EVM
EVM Window (Downlink and Uplink)
Agilent 89600 VSA EVM SettingFFT Size aligned with EVM Window Center
FFT Size aligned with EVM Window Start
LTE RF Measurements
Martha Zemede
August 2008
34
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
35
Transmitted Signal Quality –
UE (Uplink)
Frequency error
Transmit modulation
Currently there are four requirements under the
transmit modulation category for a UE:1. EVM for allocated resource blocks
2. I/Q Component (also known as carrier leakage power or
I/Q origin offset)
3. In-Band Emission for non-allocated resource blocks
4. Spectrum flatness for allocated RB
LTE RF Measurements
Martha Zemede
August 2008
36
UE Transmitted Signal Quality:Frequency Error
• A quick test is use the
Occupied BW measurement
• An accurate measurement
can then be made using the
demodulation process
•Minimum Requirement (observed over 1 ms):
UE: ±0.1 PPM
If the frequency error is larger than a
few sub-carriers, the receiver demod
may not operate
LTE RF Measurements
Martha Zemede
August 2008
37
UE Transmit Modulation:
Measurement Block
Modulated
symbolsDFT
FFTTX
Front-endChannel
RF
correction FFT
Tx-Rx chain
equalizer
In-band
emissions
Meas.
IDFTEVM
meas.
DUT Test equipment
0
0
In-band emissions
measurement is made in
frequency domain, after
FFT, with no equalizer filter.
This is “OFDM Freq Meas”
trace in 89601A & N9080A
LTE application
EVM is made after ZF
equalization filter and IDFT.
This is “OFDM Meas” trace
in 89601A and N9080A LTE
application
I/Q origin offset (LO Leakage) must
be removed from the evaluated
signal before calculating EVM and
In-band emissions.
LTE RF Measurements
Martha Zemede
August 2008
38
UE Transmit Modulation:
EVM – For allocated resource blocks
Minimum Requirement
For signals > -40 dBm,
Parameter Unit Level
QPSK % 17.5
16QAM % 12.5
64QAM % [tbd]
•It is not expected that 64QAM will be allocated at the edge of the signal
TS 36.101 v8.2.0 Table 6.5.2.1.1-1:
Minimum requirements for Error Vector Magnitude
Signal BW 89650S
(typ)
MXA
(typ)
5 MHz 0.35 % 0.56 %
10 MHz 0.40 % 0.56 %
20 MHz 0.45 % 0.63 %
Agilent Signal Analyzer EVM Performance – UL
EVM for individual
channels & signals
Composite
EVM plus
Data only and
RS only EVM
LTE RF Measurements
Martha Zemede
August 2008
39
UE Transmit Modulation:
I/Q Component
LO Leakage Parameters Relative Limit (dBc)
Output power >0 dBm -25
- 30 dBm ≤ Output power ≤0 dBm -20
-40 dBm Output power < -30 dBm -10
TS 36.101 v8.2.0 Table 6.5.2.2.1-1: Minimum requirements for Relative Carrier Leakage Power
I/Q Component (LO Leakage or IQ
Offset) revels the magnitude of the
carrier feedthrough present in the
signal
I/Q Component is removed from
EVM result
Minimum requirements
LTE RF Measurements
Martha Zemede
August 2008
40
UE Transmit Modulation:
In-band Emission – For non-allocated RBsThe in-band emission is measured as the
relative UE output power of any non –allocated
RB(s) and the total UE output power of all the
allocated RB(s)
It is defined as an average across 12 sub-
carriers and as a function of the RB offset from
the edge of the allocated UL block.
Measurement is made at the output of the front-
end FFT, prior to equalization.
Minimum requirements
In-band emission
Relative emissions (dB)
TS 36.101 v8.2.0 Table 6.5.2.3.1-1: Minimum requirements for in-band emissions
[ ])/)1(103)log20(,25max 10 RBRB NEVM -D---
In-band
emission
LTE RF Measurements
Martha Zemede
August 2008
41
UE Transmit Modulation:
Spectrum flatness
The spectrum flatness is defined as a relative power variation
across the subcarrier of all RB of the allocated UL block
Minimum requirements
TBD
LTE RF Measurements
Martha Zemede
August 2008
42
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting
techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
43
Spectrogram
Tim
e
RS transmitted every 6 sub-carrier
P-SS,S-SS occupying
center 6 RBs
RS sub-carriers as selected by
the spectrogram marker
The Spectrogram
shows how the
spectrum varies with
time
See entire LTE
frame in frequency
and time
simultaneously
Find subtle
patterns, errors
Spectrogram
marker
Frequency
LTE RF Measurements
Martha Zemede
August 2008
44
Basic Demodulation
LTE RF Measurements
Martha Zemede
August 2008
45
Basic Demodulation – Constellation DiagramConstellation DiagramDemodulates and displays all active channels and signals within the measurement interval. Color coded by channel type
Only control channels
and signals are
included. (QPSK, 16
QAM and 64QAM data
channels are disabled)
All active
channels and
signals are
included
LTE RF Measurements
Martha Zemede
August 2008
46
Basic Demodulation: Error Summary
EVM parameters: composite, peak, data and
RS EVM
Auto detects CP Length, Cell ID, Cell ID
Group/Sector and RS sequence
I/Q impairments
Sync correlation: How well the signal is
synchronized to either RS or P-SS (user selected)
EVM of individual active channels and
signals
LTE RF Measurements
Martha Zemede
August 2008
47
Advanced Demodulation:Measure EVM in Time, Frequency, Slot and RB domain
EVM per Sub-CarrierEVM per Symbol
EVM per RB EVM per Slot
LTE RF Measurements
Martha Zemede
August 2008
48
Normal view
Zoomed on 72 Center Sub-Carriers (6 RB) to show
P-SS, S-SS & PBCH
EV
M
Sub-Carrier
DC sub-carrier
not used for DL
Error Vector Spectrum:
Shows error in %EVM for each of 300 subcarriers (excluding DC) of 5MHz DL BW.
X-Axis is sub-carrier vertical bars show EVM for
individual symbols contained In each sub-carrier
Y-Axis is EVM in %
Color code relates EVM reading to channel/signal type
Error Vector Spectrum :
EVM vs. Time and Frequency
RMS EVM
LTE RF Measurements
Martha Zemede
August 2008
49
Error Vector Time:
EVM vs. Time and Frequency
Turned off the PDSCH (user data) channel
Error Vector Time:
Shows error in %EVM for each of 140 OFDM symbols (Normal CP) of radio frame
• X-Axis is symbol
vertical bars show EVM for individual sub-carriers contained in each symbol
• Y-Axis is EVM in %
Color coding makes it easy to
visualize which channels/ signals
have high EVM. In this example, S-
SS and P-SS transmitted on symbols
5 and 6 of slots #1& #10 have the
highest EVM (Marker can also be
used to identify the channel type as
well as EVM values)
EV
M
OFDM Symbol
LTE RF Measurements
Martha Zemede
August 2008
50
RB Error Magnitude Spectrum:
EVM vs. RB and Slot
BB Filter characteristics
RB Error Magnitude Spectrum
Shows error in %EVM for each of 25 RB of 5MHz DL BW.
X-Axis is RB
vertical bars show EVM for individual slots contained in each RB
Y-Axis is EVM in %
Best EVM trace to view the characteristics of transmit filter or any other impairment that affect the edges of the band.
Since data is allocated to each user based on RB, best way to look at performance per each RB.
EVM Window set to “Center”
EVM Window set to “Max of EVM
Window Start/End”
EV
M
RB
LTE RF Measurements
Martha Zemede
August 2008
51
Marker table showing
all the marker readings
(up to 12 markers)
Coupled markers
track problem
between
measurements
Marker Coupling - Multiple Signal ViewsSearch Peak Error, Link to Other Measurements
Link error peaks to
constellation points,
symbols, amplitude
values, specific
carriers, as a way to
pinpoint error
mechanism
Concepts of 3GPP LTE
9 Oct 2007
Page 52
LTE RF Measurements
Martha Zemede
August 2008
2
Analyzing the equalizer results:
SC-FDMA Example
Transition from RS unity circle to 16QAM
Amplitude flatness ± 0.1 dB
Phase flatness ± 0.5 degrees
Amplitude flatness for outer 10 RB
Subcarrier relative flatness for outer 10 RB
10 MHz IQ
constellation
LTE RF Measurements
Martha Zemede
August 2008
53
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
54
LTE Signal Analysis -
89601A Vector Signal Analysis Software
LTE downlink (OFDMA) and uplink (SC-
FDMA) analysis in a single option
Industry leading performance: EVM of
< 0.35% (-50 dB) - hardware dependent
FDD mode, Type 1 generic frame
structure
All LTE bandwidths: 1.4 MHz to 20 MHz
All LTE modulation formats and
sequences: BPSK, QPSK, 16 QAM, 64
QAM, CAZAC (Zadoff-Chu)
Supports Agilent signal analyzers: PSA,
MXA, EXA, 89600 as well as Agilent
logic analyzers and scopes
Connectivity with Agilent’s Advance
Design System (ADS) LTE wireless
library
Features/Capabilities Summary
LTE RF Measurements
Martha Zemede
August 2008
55
Consistent Measurement SW =
Correlation of results across the block diagram
ADS connectivityDirect connection to ADS LTE signal simulation
output using ADS 89600 instrument sink.
+
DUT
DSP
Digital (SSI) BB/IF/RF BB (I-Q)
Logic Analyzer Oscilloscope Signal Analyzer
89601A VSA
LTE RF Measurements
Martha Zemede
August 2008
56
N9080A LTE Measurement Application
For Agilent’s X-Series Signal Analyzers
In-depth LTE modulation analysis capability
based on the same algorithm and feature
set as the 89600 VSA software’s option BHD
LTE modulation analysis
Embedded solution with Hard-key/Soft-key
MUI and SCPI RUI
LTE downlink (OFDMA) and uplink (SC-
FDMA) analysis in a single option
LTE FDD frame structure signal according
to March 2008 release of 3GPP LTE
standard docs (v.8.2.0)
All LTE bandwidths: 1.4 MHz to 20 MHz
All LTE modulation formats and sequences:
BPSK, QPSK, 16 QAM and 64 QAM, CAZAC
(Zadoff-Chu)
Color coding by channel type to highlights
signal errors
Features/Capabilities Summary
LTE RF Measurements
Martha Zemede
August 2008
57
Generate uplink / downlink LTE signals
• Create physical layer coded signals for amplifier test
• Create transport layer coded signals for BLER test
Supports March 2008 Version of 3GPP Standard
– System bandwidths up to 20MHz
– Selectable modulation - QPSK, 16QAM, or 64QAM
– User definable data payload or PN sequences
– Downlink Channels: Reference signals, sync signals, PDSCH, PDCCH, PBCH, PCFICH, PHICH
– Uplink Channels – Demodulation Reference Signal, PUSCH, PUCCH, UCI coding, PRACH and Sounding Reference Signal
Create Multi-carrier signals
• Add multiple uplink / downlink LTE carriers
• Add multiple uplink / downlink W-CDMA / HSPA carriers
MIMO Pre-coding with Multipath Fading Profile
– MIMO configuration up to 4x4
– Tx diversity
– Spatial multiplexing with Cyclic Delay Diversity
N7624B Signal Studio for 3GPP LTE
LTE RF Measurements
Martha Zemede
August 2008
58
Software Solutions
• E8895 ADS LTE Library
• N7624B LTE Signal Studio
• 89601A LTE VSA Software
•N9080A LTE Measurement Application
Distributed
Network
Analyzers
Conformance & IOT Deployment
Digital VSA
Analyzers, Sources, Scopes, Logic Analyzers
Product development
Network Analyzers, Power supplies, and More!
MXA/MXG
R&D
Agilent 3GPP LTE Portfolio
Agilent/Anite SAT LTE –
Protocol Development
Toolset
Agilent/Anite Signalling and RF
conformance test systems
E6620A Wireless
Communications
Platform
Drive TestNEW!
NEW!
NEW!Coming Soon!
Coming Soon!
LTE RF Measurements
Martha Zemede
August 2008
59
NEW LTE Literature
www.agilent.com/find/lte
Poster (5989-7646EN)
Brochure (5989-7817EN)
Application Note
(5989-8139EN)
LTE RF Measurements
Martha Zemede
August 2008
60
Agenda• Brief overview of LTE FDD frame structure
• Brief overview of LTE physical layer channels and signals
• List of LTE physical layer transmitter tests
• LTE modulation quality test requirements
– Downlink
– Uplink
• Modulation quality signal analysis and troubleshooting techniques
– Downlink
– Uplink
• Agilent LTE signal analysis solutions
• Agilent LTE measurement solutions overview
• Appendix – LTE physical layer RF measurements
LTE RF Measurements
Martha Zemede
August 2008
61
Transmit Power – UE“Does the UE transmit too much or too little?”
• MOP (Maximum Output Power)
– Method: broadband power
measurement (No change from UMTS)
• MPR (Maximum Power Reduction)– Definition: Power reduction due to higher
order modulation and transmit bandwidth
(RB) – this is for UE power class 3
• A-MPR (Additional MPR)– Definition: Power reduction capability to
meet ACLR and SEM requirements
Power measurement for each active
channel after demodulation
Channel power measurement using
swept spectrum analyzer
LTE RF Measurements
Martha Zemede
August 2008
62
Output RF Spectrum Emissions
Unwanted emissions consist of:
1. Occupied Bandwidth: Emission within the occupied
bandwidth
2. Out-of-Band (OOB) Emissions
– Adjacent Channel Leakage Power Ratio (ACLR)
– Spectrum Emission Mask (SEM)
3. Spurious Emissions: Far out emissions
LTE RF Measurements
Martha Zemede
August 2008
63
Occupied Bandwidth Requirement“Does most UE energy reside within its channel BW?”
Occupied bandwidthMeasure the bandwidth of the LTE
signal that contains 99% of the
channel power
Occupied channel bandwidth
Channel Bandwidth [MHz] 1.4 3.0 5 10 15 20
Occupied Bandwidth
(MHZ)
1.08
(6 RB)
2.7
(15 RB)
4.5
(25 RB)
9.0 MHz
(50 RB)
13.5 MHz
(75 RB)
18 MHz
(100 RB)
Minimum Requirement: The
occupied bandwidth shall be less than
the channel bandwidth specified in the
table below
LTE RF Measurements
Martha Zemede
August 2008
64
ACLR Requirements – eNB case“Does the eNB transmit in adjacent channels?”
ACLR (Adjacent Channel Leakage Ratio) measurement:
- Measure the channel power at the carrier frequency
- Measure the channel power at the required adjacent channels
- Ensure the eNB power at adjacent channels meets specs
ACLR defined for two cases
• E-UTRA (LTE) ACLR 1 and ACLR 2 with square measurement filter
• UTRA (W-CDMA) ACLR 1 and ACLR 2 with 3.84 MHz RRC measurement filter with
roll-off factor =0.22.
ACLR limits defined
for adjacent LTE
carriers
ACLR limits defined
for adjacent UTRA
carriers
LTE RF Measurements
Martha Zemede
August 2008
65
ACLR Limits – eNB case
E-UTRA Tx signal
channel BW
E-UTRA adjacent
channel carrier
E-UTRA channel measurement
filter BW (Square filter)
ACLR Limit
1.4 MHz 1.4 MHz 1.08 MHz 45 dB
3.0 MHz 3.0 MHz 3.0 MHz 45 dB
5 MHz 5 MHz 4.5 MHz 45 dB
10 MHz 10 MHz 9.0 MHz 45 dB
15 MHz 15 MHz 13.5 MHz 45 dB
20 MHz 20 MHz 18 MHz 45 dB
E-UTRA Tx signal
channel BW
UTRA adjacent
channel carrier
UTRA channel measurement
filter BW (RRC filter with 0.22
ACLR Limit
1.4 MHz 3.84 MHz 3.84 MHz 45 dB
3.0 MHz 3.84 MHz 3.84 MHz 45 dB
5 MHz 3.84 MHz 3.84 MHz 45 dB
10 MHz 3.84 MHz 3.84 MHz 45 dB
15 MHz 3.84 MHz 3.84 MHz 45 dB
20 MHz 3.84 MHz 3.84 MHz 45 dB
In the case of E-UTRA (LTE) adjacent carrier:
In the case of UTRA (W-CDMA) adjacent carriers:
LTE RF Measurements
Martha Zemede
August 2008
66
ACLR Requirements – UE case
“Does the UE transmit in adjacent channels?”
ACLR defined for two cases:
•E –UTRA (LTE) ACLR1 with rectangular measurement filter
•UTRA (W-CDMA) ACLR1 and ACLR 2 with 3.84 MHz RRC measurement filter with
roll-off factor =0.22.
E-UTRAACLR1 UTRA ACLR2 UTRAACLR1
RB
E-UTRA channel
Channel
ΔfOOB
TR 36.101 v8.2.0 Figure 6.6.2.3 -1: Adjacent Channel Leakage requirements
LTE RF Measurements
Martha Zemede
August 2008
67
ACLR Limits –UE case
Channel bandwidth / E-UTRAACLR1 / measurement bandwidth
1.4
MHz
3.0
MHz
5
MHz
10
MHz
15
MHz
20
MHz
E-UTRAACLR1 30 dB 30 dB 30 dB 30 dB 30 dB 30 dB
E-UTRA channel
Measurement
bandwidth
4.5 MHz 9.0 MHz 13.5 MHz 18 MHz
In the case of LTE adjacent carrier:
Channel bandwidth / UTRAACLR1/2 / measurement bandwidth
1.4
MHz
3.0
MHz
5
MHz
10
MHz
15
MHz
20
MHz
UTRAACLR1 33 dB 33 dB 33 dB 33 dB 33 dB 33 dB
UTRAACLR2 - - 36 dB 36 dB 36 dB 36 dB
E-UTRA channel
Measurement bandwidth- 4.5 MHz 9.0 MHz 13.5 MHz 18 MHz
UTRA channel
Measurement bandwidth- - 3.84 MHz 3.84 MHz 3.84 MHz 3.84 MHz
In the case of W-CDMA adjacent carriers:
TS 36.101 v8.2.0 Table 6.6.2.3.2-1: Additional requirements
TS 36.101 v8.2.0 Table 6.6.2.3.1-1: General requirements for E-UTRAACLR
LTE RF Measurements
Martha Zemede
August 2008
68
Spectrum Emission Mask (SEM)“Does the eNB/UE leak RF onto neighbor channels?”
Operating Band (BS transmit)
10 MHz 10 MHz
Operating Band Unwanted emissions limit
CarrierLimits in
spurious domain
must be
consistent with
SM.329 [4]
OOB domain
Spectrum emissions mask is also known as “Operating Band Unwanted
emissions”
These unwanted emissions are resulting from the modulation process and non-
linearity in the transmitter but excluding spurious emissions
Measure the Tx power at specific frequency offsets from the carrier frequency
and ensure the power at the offsets is within specifications
TR 36.804 v1.2.0 figure 6.6.2.2-1 Defined frequency range for Operating band unwanted emissions with an
example RF carrier and related mask shape (actual limits are TBD).
eNB example:
Base station SEM limits are
defined from 10 MHz below the
lowest frequency of the BS
transmitter operating band up to
10 MHz above the highest
frequency of the BS transmitter
operating band.
LTE RF Measurements
Martha Zemede
August 2008
69
20MHz Mask
Regulatory Masks + Proposed 20MHz LTE Mask
-50
-40
-30
-20
-10
0
10
-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2
offset (MHz)
level (d
Bm
/100kH
z)
WCDMA
FCC band 5
FCC band 2
FCC band 7
Ofcom
Japan PHS
mask 6/7 RBs
mask 15/16 RBs
mask 25 RBs
mask 50 RBs
mask 75 RBs
mask 100 RBs
Spectrum Emission Mask– UE Example
TR 36.803 v1.1.0 Figure 6.6.2.1 -1: Regulatory mask and proposed E-UTRA masks
LTE RF Measurements
Martha Zemede
August 2008
70
Spurious Emission Requirements“How much power does UE leak well beyond neighbor?”
Frequency Range Maximum Level Measurement
Bandwidth
9 kHz f < 150 kHz -36 dBm 1 kHz
150 kHz f < 30 MHz -36 dBm 10 kHz
30 MHz f < 1000 MHz -36 dBm 100 kHz
1 GHz f < 12.75 GHz -30 dBm 1 MHz
Spurious emissions are emissions caused by unwanted transmitter effects
such as harmonics emission & intermodulation products but exclude out of
band emissions
Example of spurious emissions limit for a UE
TS 36.101 v8.2.0 table 6.6.3.1-2: Spurious emissions limits