4706 final slides

Presented by:

1 LTE RF Measurements

Martha Zemede

RF Measurements for LTE

Martha Zemede

August 7, 2008

Concepts of 3GPP LTE

9 Oct 2007

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.

http://www.techonline.com/learning/webinar/201801263?queryText=agilent+lte



http://www.techonline.com/learning/webinar/206101979?queryText=LTE+uplink







http://www.techonline.com/learning/webinar/207800310?queryText=LTE+protocol+primer

http://www.techonline.com/learning/webinar/207800310?queryText=LTE+protocol+primer


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

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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

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– Downlink

– Uplink





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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

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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

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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.

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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

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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

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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

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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

- 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

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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

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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)



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


#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)


Martha Zemede

August 2008

RS + PCFICH + PHICH + PDCCH

Downlink frame structure analysis

Slot#0 Symbol#0






PHICH – Physical Hybrid ARQ Indicator Channel

PDCCH - Physical Downlink Control Channel


10 2 3 4 5 610 3 4 5 62

Time (Symbol)

Fre

qu

en

cy

(Su

b-C

arr

ier

or

RB

)


Martha Zemede

August 2008

Downlink frame structure analysis

Slot#0 Symbol #6:

P-SS + PDSCH






PHICH – Physical Hybrid ARQ Indicator Channel

PDCCH - Physical Downlink Control Channel


10 2 3 4 5 610 3 4 5 62

Time (Symbol)

Fre

qu

en

cy

(Su

b-C

arr

ier

or

RB

)

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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

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Uplink frame structure analysis


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

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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-DMRS – Demodulation Reference Signal (pilot)

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– Downlink

– Uplink





LTE RF Measurements

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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.

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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

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– Downlink

– Uplink





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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

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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

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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)

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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

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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

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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

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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

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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


9 Oct 2007

LTE RF Measurements

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• 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


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

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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)


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

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– Downlink

– Uplink





LTE RF Measurements

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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

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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

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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

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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

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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

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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.


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

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Spectrum flatness

The spectrum flatness is defined as a relative power variation

across the subcarrier of all RB of the allocated UL block


TBD

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42





– Downlink

– Uplink

• Modulation quality signal analysis and troubleshooting

techniques




LTE RF Measurements

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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

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Basic Demodulation

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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

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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

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Advanced Demodulation:Measure EVM in Time, Frequency, Slot and RB domain

EVM per Sub-CarrierEVM per Symbol

EVM per RB EVM per Slot

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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

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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

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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

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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


9 Oct 2007

LTE RF Measurements

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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

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53





– Downlink

– Uplink





LTE RF Measurements

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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

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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)

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

LTE RF Measurements

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– Downlink

– Uplink


– Downlink

– Uplink




LTE RF Measurements

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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

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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

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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

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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

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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

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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

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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

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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

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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

4706 final slides

Documents

gpp lte techonline

various lte signals

new lte uplinktechonline

n9080a lte application

various lte protocol

brief introduction

measurement algorithm

measurement features