L i t e P o i n t C o n f i d e n t i a l © 2 0 1 3 L i t e P o i n t , A T e r a d y n e C o m p a n y . A l l r i g h t s r e s e r v e d .

LitePoint / Sr. FAE Jason Yang (楊則森)

How to test LTE Devices Efficiently

Agenda

•  LTE Overview

•  LTE Test Challenge

•  Testing LTE – Where to Begin?

•  Building a LTE Verification Plan

•  Optimizing a LTE Verification Plan

• 2

Why LTE? – Something for Everyone

For the user.. •  Higher Performance (Data Rate) -  Instantaneous downlink peak data rate:

100 Mbit/s in a 20MHz downlink spectrum (5 bit/s/Hz)

-  Instantaneous uplink peak data rate: 50 Mbit/s in a 20MHz uplink spectrum (2.5 bit/s/Hz)

For the service provider… •  Cell capacity – more users per cell -  up to 200 active users per cell (5 MHz) (i.e., 200 active data clients)

•  1st all-data network: packet-switched -  Simplifies network architecture

• 3

LTE Key Parameters

4

OFDMA Highlights

LTE uses OFDMA for the downlink •  Uses a large number of narrow sub-carriers for

multi-carrier transmission

•  Robustness to multipath fading and interference

•  “Resource blocks” and “elements” - Each resource block and element is defined in

“frequency” and “time” (1 block = 180 kHz; 0.5 ms) - Dynamically assigns these resource blocks to LTE

users, thus improving spectrum utilization - Subcarrier spacing – 15 kHz compared to

312.5 kHz for WLAN

• 5

The basic LTE physical resource can be seen as a time-frequency grid:

LTE-FDD & LTE-TDD

FDD •  downlink and uplink traffic is transmitted simultaneously at separate carrier frequencies •  is the preferred mode by most cellular systems, wherever paired spectrum is available –

easy transition from existing 3G networks

TDD •  transmission in uplink and downlink is at the same carrier frequency •  is a good option where spectrum (carriers) availability is lower •  is necessary when pair spectrum is not available

FDD

TDD fDL

fUL fDL/UL

time time

• 6

•  Intra-band, contiguous channels (up to 100MHz):

•  Intra-band, non-contiguous channels (up to spectrum availability):

•  Inter-band, non-contiguous channels:

LTE-Advanced: Carrier Aggregation

Band A Band B

… Carrier #1 Carrier #2

Band A Band B

… Carrier #1 Carrier #2

Band A Band B

… Carrier #1 Carrier #2

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Carrier CA Type Bands AT&T Inter-band 4 & 17 Verizon Inter-band 4 & 13 Sprint Intra-band 41 SK Telecom Inter-band 3 & 5 Korea Telecom Inter-band 3 & 8 LG Uplus Inter-band 1 & 5 Telstra Inter-band 3 & 8 NTT Docomo Inter-band 1 & 21

LTE Carrier Aggregation Planned Deployments

•  Planned Carrier Aggregation Roll-outs: - Primarily inter-band deployments

DL1 DL2

UL

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Carrier Aggregation: What Does this Mean for Test?

•  Carrier aggregation is primarily a downlink discussion

- Spectrum availability limits intra-band deployment, particularly for non-contiguous

- UE data traffic tends to be asymmetric

- Multiple, simultaneous uplinks (inter-band) requires multiple power amplifiers (reducing battery life)

•  Result is that the UE requires more RX testing, little change to TX testing

DL1 DL2

UL

9

LTE Test Challenges

New Challenges in LTE – More Bands

•  More bands to test: > 40 bands

Band Frequency Range

Channel Bandwidths

Mode

1 to 17 < 2.7 GHz 1.4, 3, 5, 10, 15, 20 MHz FDD

33 to 43 <3.8 GHz 1.4, 3, 5, 10, 15, 20 MHz TDD

More bands means more test time

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New  Challenges  in  LTE  –  More  Bandwidth  •  Spectrum  Emission  Mask  (SEM):  6.6.2.1    

• Adjacent  Channel  Leakage  RaHo  (ACLR):  6.6.2.3  

20 MHz Channel

SE Mask

• 12

New Challenges in LTE – More Configurations

•  LTE has many configurations to test – more test time - Per channel…

• 13

LTE threatens to reduce test throughput… Higher cost test?

Modulation RB Config PWR Levels QPSK 50,0 4 QPSK 12,0 4 QPSK 12,38 2 QPSK 1,0 1 QPSK 1,24 1 QPSK 1,49 1

16 QAM 50,0 2 16 QAM 12,38 2 16 QAM 12,0 2 16 QAM 50,0 1 64 QAM 50,0 1

Testing LTE: Key Requirements

RF Frequency Range •  The test equipment must support the frequency bands 698 MHz - 3800 MHz •  The test equipment must handsets with an increasing number of antennas

VSA / VSG Bandwidth •  The test equipment must have at least 20 MHz VSA/VSG bandwidth -  LTE requires support for six channel bandwidths (from 1.4 to 20 MHz) -  With LTE-Advanced, this requirement will become 100 MHz -  >70 MHz required for single-shot LTE ACLR & Spectrum Emission Mask testing

MIMO Technology •  Support for accurate MIMO testing is necessary in both R&D and MFG •  In particular, it is essential to have multiple VSA / VSG ports for DL / UL MIMO signal

Transmission Schemes •  Support two transmission schemes for downlink and uplink (OFDMA, SC-FDMA) •  Support two transmission modes (FDD and TDD)

• 14

Testing LTE: Where to Begin?

•  The production floor is not the place to be verifying millions of lines of firmware nor HW functionality associated with a million gate DSP/ASIC design.

•  LTE complexity introduces more than 10x configurations to test - Testing every scenario is not practical

•  In production, we are looking to validate manufacturing quality

•  Goal is to exercise the mobile as much as possible to identify manufacturing defects while minimizing test time.

• 15

Testing LTE: Where to Begin?

•  What to test in mobile manufacturing verification: - Physical layer RF measurements - TX power - TX modulation quality - TX frequency - RX sensitivity (min / max)

•  What NOT to test in mobile manufacturing verification - Software - Digital Design - Redundant (overlapping) tests or configurations

• 16

LTE UE Transmitter Tests

• 17 3GPP Measurements

Measurement Why is this Important?

TX Power LTE network performance is highly dependent on accurate power control

Error Vector Magnitude Primary TX quality measurement – detects distortions that will ultimately degrade accurate transmission of data

Frequency Error Critically important to avoid communication interference

ACLR Ensures that transmission does not interfere with neighboring channels

Occupied Bandwidth Confirms that signal is contained within channel allocation

Spectrum Emissions Mask Ensures that signal in adjacent channels rolls off to minimize interference

Carrier Leakage An indication of mismatch in the I/Q modulator

Transmit Time Mask Verifies UE timing accuracy – particularly important for LTE TDD since the UL/DL are on the same frequency

In-Band Emissions for non-allocated RBs

Ensures that a UE’s assigned RBs (within a channel) do not interfere with the unassigned RBs in the channel

LTE Signal seen by LitePoint Tester - IQxstream

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•  LTE Transmitter characteristic – 10MHz as an example.

LTE UE Receiver Tests

Measurement Notes

RX Bit Error Rate (BER) Fundamental test of a receiver’s ability to decode the inbound signal. Typically performed at both min & max RX input power

RX Sensitivity (RSSI)

Receive signal strength is a parameter often measured as part of calibration. Since the initial TX power level is calculated per the measured RSSI, accuracy of this measurement directly impacts UE power transmission

• 19

•  TX measurements give direct access to the signal via the UE antenna. •  Unlike TX measurements, RX signal quality issues remain buried within

the DUT until the signal is fully decoded.

• 3GPP Measurements

Building a LTE Verification Plan

LTE Test Plan Development

•  Several different approaches to develop a test plan:

- Use the 3GPP standard’s recommendations

- Use the IC manufacturer’s recommendations

- Use historical data from similar devices

- Looking for likely failure modes in the design

• 21

LTE Test Configurations Concept

•  Transmitter signal differs with WCDMA, the Resource block concept introduced here which makes lots of configuration for LTE testing.

22

6.2.2 Max Output Power

•  Take 10MHz as an example : RB number: 1, 12 / Modulation: QPSK

23

Target power 24 24 24 24 24

Modulation QPSK QPSK QPSK QPSK QPSK

number RB 1 1 1 12 12

RB offset 0 24 49 0 38

Test Parameters for Channel Bandwidths 　� Downlink Configuration Uplink Configuration

Ch BW N/A for Max UE output power testing Mod'n RB allocation 　� 　� FDD TDD

1.4MHz QPSK 1 1 1.4MHz QPSK 5 5 3MHz QPSK 1 1 3MHz QPSK 4 4 5MHz QPSK 1 1 5MHz QPSK 8 8

10MHz QPSK 1 1 10MHz QPSK 12 12 15MHz QPSK 1 1 15MHz QPSK 16 16 20MHz QPSK 1 1 20MHz QPSK 18 18

Source:

6.5.2.1 EVM

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Target power 24 -36.8 24 -36.8 24 -36.8 24 -36.8 24 -36.8 24 36.8

Modulation QPSK QPSK 16QAM 16QAM QPSK QPSK 16QAM 16QAM QPSK QPSK 16QAM 16QAM

number RB 50 50 50 50 12 12 12 12 12 12 12 12

RB offset 0 0 0 0 0 0 0 0 38 38 38 38

Test Parameters for Channel Bandwidths 　� Downlink Configuration Uplink Configuration

Ch BW N/A for PUSCH EVM testing Mod'n RB allocation 　� 　� FDD TDD

1.4MHz QPSK 6 6 1.4MHz QPSK 1 1 1.4MHz 16QAM 6 6 1.4MHz 16QAM 1 1 3MHz QPSK 15 15 3MHz QPSK 4 4 3MHz 16QAM 15 15 3MHz 16QAM 4 4 5MHz QPSK 25 25 5MHz QPSK 8 8 5MHz 16QAM 25 25 5MHz 16QAM 8 8

10MHz QPSK 50 50 10MHz QPSK 12 12

10MHz 16QAM 50 (Note 3)

50 (Note 3)

10MHz 16QAM 12 12 15MHz QPSK 75 75 15MHz QPSK 16 16

15MHz 16QAM 75 (Note 3)

75 (Note 3)

15MHz 16QAM 16 16 20MHz QPSK 100 100 20MHz QPSK 18 18

20MHz 16QAM 100 (Note 3)

100 (Note 3)

20MHz 16QAM 18 18

6.6.2.3 ACLR

25

Target power 24 24 24 24 24 24 Modulation QPSK 16QAM QPSK QPSK 16QAM 16QAM number RB 50 50 12 12 12 12 RB offset 0 0 0 38 0 38

Test Parameters for Channel Bandwidths 　� Downlink Configuration Uplink Configuration

Ch BW Mod'n RB allocation Mod'n RB allocation 　� 　� FDD TDD 　� FDD TDD

1.4MHz N/A FOR ACLR testing QPSK 6 6 1.4MHz QPSK 5 5 1.4MHz 16QAM 6 6 1.4MHz 16QAM 5 5 3MHz QPSK 15 15 3MHz QPSK 4 4 3MHz 16QAM 15 15 3MHz 16QAM 4 4 5MHz QPSK 25 25 5MHz QPSK 8 8 5MHz 16QAM 25 25 5MHz 16QAM 8 8

10MHz QPSK 50 50 10MHz QPSK 12 12

10MHz 16QAM 50 (Note 3)

50 (Note 3)

10MHz 16QAM 12 12 15MHz QPSK 75 75 15MHz QPSK 16 16

15MHz 16QAM 75 (Note 3)

75 (Note 3)

15MHz 16QAM 16 16 20MHz QPSK 100 100 20MHz QPSK 18 18

20MHz 16QAM 100 (Note 3)

100 (Note 3)

20MHz 16QAM 18 18

6.6.2.3 LitePoint IQxstream – ACLR Measurement 6.5.2.3 LitePoint IQxstream – Spectrum Emission Mask Measurement

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12RB with 0 RB offset:

Building a LTE TX Verification Test Plan Per-Band / Per-Channel Derived from 3GPP Test Specification A “reasonable” LTE test plan covered in 21 configurations Showing config 1-11

• 27

Parameters 1 2 3 4 5 6 7 8 9 10 11TX Power +23 +23 +23 +23 +3.2 -26.8 -36.8 +23 +3.2 -26.8 -36.8Modulation QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSKRB 1 1 1 12 12 12 12 12 12 12 12RB Offset 0 24 49 0 0 0 0 38 38 38 38DL Power -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57Measurements 1 2 3 4 5 6 7 8 9 10 11PowerEVMEVM FlatnessFrequency AccuracyCarrier FeedthroughOccupied BandwidthACLRSEMIn-Band Emissions forNon-Allocated RBs

Test Configuration

• Varies RB Offset for RB = 1

• Varies TX Power for RB = 12

• RB Offset Extremes

Building a LTE TX Verification Test Plan Per-Band / Per-Channel A “reasonable” LTE test plan covered in 21 configurations Showing config 12-21

• 28

Parameters 12 13 14 15 16 17 18 19 20 21TX Power +23 -50 +6.4 -5.6 +23 -36.8 +23 -36.8 +23 -36.8Modulation QPSK QPSK QPSK QPSK 16QAM 16QAM 16QAM 16QAM 16QAM 16QAMRB 50 50 50 50 12 12 12 12 50 50RB Offset 0 0 0 0 0 0 38 38 0 0DL Power -57 -57 -57 -57 -57 -57 -57 -57 -57 -57Measurements 12 13 14 15 16 17 18 19 20 21PowerEVMEVM FlatnessFrequency AccuracyCarrier FeedthroughOccupied BandwidthACLRSEMIn-Band Emissions forNon-Allocated RBs

Test Configuration

• Min / Max Power • for QPSK RB = 50

• Tests Absolute Power Setting

• Min / Max Power for 16 QAM • RB = 12

• Min / Max Power for 16 QAM • RB = 50

• RB Offset Extremes

LTE TX Verification Test Plan Analysis How well did we do?

• 29

Parameters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21TX Power +23 +23 +23 +23 +3.2 -30 -40 +23 +3.2 -30 -40 +23 -40 +6.4 -5.6 +23 -40 +23 -40 +23 -40Modulation QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK 16QAM 16QAM 16QAM 16QAM 16QAM 16QAMRB 1 1 1 1 12 12 12 12 12 12 12 50 50 50 50 12 12 12 12 50 50RB Offset 0 24 49 0 0 0 0 38 38 38 38 0 0 0 0 0 0 38 38 0 0DL Power -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57Measurements 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21PowerEVMEVM FlatnessFrequency AccuracyCarrier FeedthroughTX Time MaskOccupied BandwidthACLRSEMIn-Band Emissions for Non-Allocated RBs

Test Configuration

• Provides  good  test  coverage  - Min  /  max  RB  allocaHons  - Min  /  max  modulaHon  rates  - Min  /  max  power  - Checks  variaHon  across  the  channel  

• What  about  from  a  test  throughput  point  of  view?  - The  table  is  sparse…Significant  number  of  configuraHons  - LitePoint  IQxstream  S/W  architecture  efficiently  enables  more  test  per  configuraHon  - OpportuniHes  to  condense  the  test  list  

Parameters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21TX Power +23 +23 +23 +23 +3.2 -30 -40 +23 +3.2 -30 -40 +23 -40 +6.4 -5.6 +23 -40 +23 -40 +23 -40Modulation QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK QPSK 16QAM 16QAM 16QAM 16QAM 16QAM 16QAMRB 1 1 1 12 12 12 12 12 12 12 12 50 50 50 50 12 12 12 12 50 50RB Offset 0 24 49 0 0 0 0 38 38 38 38 0 0 0 0 0 0 38 38 0 0DL Power -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57 -57Measurements 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21PowerEVMEVM FlatnessFrequency AccuracyCarrier FeedthroughTX Time MaskOccupied BandwidthACLRSEMIn-Band Emissions for Non-Allocated RBs

Test Configuration

Optimizing the LTE TX Test Plan

• 30

• No Need for Mid-Channel Offset

• Already Tested Band Edges in Configs 1 & 3

• Covered by Config 21

• Can be covered by any absolute power setting

• Covered by Config 20 & 21, do not need mid-RB

• Configurations 1, 3, 12, & 20 test the extremes of modulation and RB allocations / offsets • Configuration 12 would be expected to have the most issues with signal quality measurements (QPSK) • Configuration 4 is a “typical” use case, it provides good coverage of overall transmitter performance

Configurations we definitely want to keep

• Covered by Config 21

Condensed Test Plan

• 31

•  Reduced to 7 TX configurations •  Added RX tests •  Increases number of measurements while reducing test time

7.3 Reference Sensitivity Level

•  Uplink configuration for reference sensitivity differs with LTE bands.

32

7.3 Reference Sensitivity Level

33

LitePoint Test Plan easy to configure different settings for BLER uplink RB configuration.

LTE Manufacturing Test

•  LTE increases test complexity 5 to 10X - More measurements, more antennas, wider bandwidth, higher performance - IQxstream’s unique architecture makes LTE test simple and fast

•  Test plan development for LTE needs to focus on exercising the mobile device with the minimum test time

•  A test plan can be created to maximize the coverage of the device by using the test equipment in an efficient manner - Number of configurations take more test time than number of tests - Scale test plan to multi-DUT through turnkey non-signaling solutions - No sacrifice in product quality with shorter per-DUT test times

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Thank You!