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© 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
Optimize UE Design for Greater Battery Run-Time
© 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
UE Performance Test Challenge
A growing number of complex standards
- operators, UE developers
Long test times
- measured in hours and days
Multiple iterations
- design verification and regression test
Costly to automate in-house
- requires skills, time, adds delay
2
© 2012 Agilent Technologies
Wireless Communications
3 © 2012 Agilent Technologies
Wireless Communications
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DUT Applications
•Voice
•Messaging
•Internet
•Video streaming
•Music
•Social media
•Navigation
•Gaming
•Camera
Real World
Network
Scenarios
•Cell handovers
•Power level
changes
•Interference
•Fading
•Network loading
•Inter-RAT
handover
•Carrier specific
network settings
Innovative battery drain measurement and analysis techniques
coupled with
Innovative methods for exercising all of the capabilities of a wireless device
5 ms/Div 50 mA/Div
Wake up / idle pedestal
Receive activity/RSSI
Baseband activities
Sleep base
User Network
© 2012 Agilent Technologies
Wireless Communications
4 © 2012 Agilent Technologies
Wireless Communications
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Agenda:
1. Importance of effectively measuring and analyzing battery drain of
a wireless device while exercising all of it capabilities
2. Shortcomings of traditional techniques & solutions
3. Description of new techniques & solutions
4. Benefits of using new techniques & solutions
© 2012 Agilent Technologies
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Why is it so important now?
Increasingly power hungry devices
• Multiple radio technologies
• Higher data demands
• Larger displays and touch screens
• “Always-connected” applications
• Limited scope for improving
battery capacity
• Complex interaction of
applications/software/hardware
Inadequate design and analysis methods lead to:
•Shorter device run time
•Unanticipated periods of high battery drain
•Additional design cycles to resolve battery drain issues
•Disappointed customers due to short battery life
A-GPS
WCDMA
GSM
1xEV-DO
CDMA2000
HSPA
FM Radio
802.11
Bluetooth
DAB
WiBro
WiMax
LTE
EGPRS
5
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Server
Voice
Video
Upload
Download
Messaging
Handover
Power changes
DRX
Network User
Fading
UE
Network and user
influences on battery drain
6
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Change from circuit-switched
to packet-switched implementation
Developments such as IMS-SIP allow traditional services to be delivered in new ways. For the same use model, the battery profile may vary depending on the underlying implementation.
IP network
VoIP Voice
Video
SMS Hello world!
DUT
8
© 2012 Agilent Technologies
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9 © 2012 Agilent Technologies
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The Importance of Effectively
Measuring and Analyzing Battery Drain
Optimize battery operating time during HW development:
• Evaluate and optimize overall device and its sub circuits
• Validate and optimize battery power management system
• Identify high peak drain anomalies and their root causes
Validate new code builds In Software Development:
• Run application code regression test suites, impact on battery drain
Quickly run suites of tests in Integration and Validation:
• Current drain for channels & TX power level combinations, & main op modes
• Validate operating time with product’s battery (run-down test)
• Check HW, L1/L2/L3, OS & application interactions on battery drain
© 2012 Agilent Technologies
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Challenges:
• Properly powering the device
• Making accurate, high resolution
current measurements
• Expertise to generate a series of
combinations of simultaneous data-
driven device activities
• Expertise to simulate wireless network
all the way through to the internet
• Massive amounts of data created,
how to best process and manage
• Developing effective visualization
& analysis tools can be difficult
• Software development effort that
yields a flexible & capable system
• Developing takes a large amount of
resources and time
Traditional Solution: Custom RF Stimulus &
Current Drain Logging Setup
Characterizing Battery Drain
under Simulated Network Use
10
© 2012 Agilent Technologies
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.
.
Challenges When Powering
a Mobile Phone
Actual battery response to a GSM
pulse load
Battery voltage drops proportionally
with current
• Battery resistance is 150 mΩ
GP power supply response to a GSM
pulse load
Voltage response and current drain
does not match battery
• Instability & overshoot
• 10% higher drain experienced
11
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The Need for Accurate
Current Drain Measurement
50 mA/Div 500 ms/Div
Receive current pulses
sleep current 500 mA/Div
2 ms/Div
Transmit current pulses
Receive current pulses
idle current
GPRS Smart Phone Battery Drain for Talk… and Standby
Digital wireless devices operate in short bursts of activity to conserve power: •Long periods of sleep or idle between bursts of activity
•Resulting current drain is pulsed; high peak and low average
•Currents span up to 4 decades over range of operation
•Engineers need to observe and measure current drain details to optimize battery life.
Problem: Traditional solutions do not have the dynamic measurement range needed to accurately measure current drain of mobile wireless devices.
12
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Most common: Shunt + DAQ
Typical Performance:
~12 to16 bits resolution
~ 50K to 1M samples/sec
~ 0.2 to 1.0% gain error (both shunt and DAQ)
~ 0.05 to 0.2% offset error (mainly DAQ)
Commonly Encountered Challenges:
– Large effort to configure and program
– Peak voltage drop on shunt may be
excessive
– Multiple shunts needed to span wider range
– Greater measurement BW = lower DC
accuracy
– Offset error and noise floor limits
dynamic range of measurement to about
2 decades to assure reasonable accuracy
for minimum (floor) level of a dynamic
signal
Challenges With Traditional
Measurement Solutions
DC source or battery
Shunt
+ +
- - DUT current
Diff Amp MUX Gain Amp ADC
Data Acquisition Equipment Data
out +
-
PC to log long-term data
DUT
13
© 2012 Agilent Technologies
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New Solution for Battery Drain
Characterization
N6705 DC Power Analyzer Mainframe N6781A 2-Quadrant SMU for Battery Drain Analysis
Integrates multiple instrument functions into a single box:
• 1 to 4 advanced power supplies; >22 different models available
• Digital voltmeter and ammeter
• Arbitrary waveform generator
• Oscilloscope
• Long term data logger
• Full functionality from front panel
• Gain insights in minutes, not days!
Specialized DC power supply module for battery drain testing:
• For use in the N6705 mainframe
• Settable battery emulation characteristics
• Fast transient response for pulsed loads
• Zero-burden current measurement and auxiliary DVM for battery run-down testing
• Up to 200 KSa/sec digitizing rate
• Innovation: Seamless ranging spans over 7 decades for accurate measurement of battery drain over wide dynamic range
14
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Comparing a Battery to a Battery
Emulator SMU Powering a GSM Handset
Actual battery response to a GSM
pulse load
Battery voltage drops proportionally
with current
• Battery resistance is 150 mΩ
N6781A Battery emulator SMU
response to a GSM pulse load
Voltage response and current
drain comparable to the battery
• SMU set to 150 mΩ
BE-SMU Voltage
BE-SMU Current Battery Current
Battery Voltage
15
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N6781A SMU Measurement
Ranging Performance
Range 3 A 100 mA 1 mA 10 µA Measurement
Accuracy ±(0.03% + 250 µA) ±(0.025% + 10µA) ±(0.025% + 100 nA) ±(0.025% + 8 nA)
Seamless measurement between these 3 ranges
Parameter Fixed Range Seamless Improvement
Overall DC accuracy (2.97 mA avg) 8.5% 0.4% 21 X
Sleep base current DC accuracy (1.22 mA avg) 20.5% 0.8% 25.6 X
Measuring DRX Standby Current Drain
50 mA/Div
500 ms/Div Sleep current base (1.22 mA)
Receive current pulses (up to 291 mA)
High digitizing rate, resolution, and DC accuracy are needed for standby operation
• 1.22 mA sleep base current
• Peak pulses up to 291 mA, complex shape
• Low average current of 2.97 mA, determines standby battery life
• High crest factor makes accurate measurement difficult
• N6781A seamless measurement ranging greatly extends dynamic range of accurate measurement, spanning to up to 7 decades
• Improvement depends on signal, shown below for this example
16
© 2012 Agilent Technologies
Wireless Communications
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N6781A Time Resolution Performance
for Detailed Insights
High level of time resolution provides greater insights details for optimizing run time:
• Able to correlate specific activities to current drain duration and level
• N6781A provides down to 5.12 µsec sample interval in scope mode and down to 20.48 µsec in long-term data log mode to gain greater insight on details
GPRS Smart Phone Battery Drain for DRX Standby
• 1.22 mA sleep current during 1.25 s paging interval
50 mA/Div
500 ms/Div Sleep current base
Receive current pulses
DRX Burst Current pulse details
• 23 ms pulse: 239 mA peak & 92 mA ave.
5 ms/Div 50 mA/Div
Wake up / idle pedestal
Receive activity / RSSI
Baseband activities
Sleep base
17
© 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
N6781A Measure Only Mode: Zero
Burden Ammeter for Battery Run-down
Using actual battery gives most realistic assessment of DUT performance
N6781A regulates zero volts at output while measuring current, acting as a zero burden ammeter, eliminating voltage drop problem of using a shunt
N6781A Aux DVM input simultaneously measures battery voltage
Application note 5990-7370EN provides details on setting up
+ _
0 Volts
A
DUT
battery
Aux in voltage measurement
Zero burden ammeter
Battery current drain
_
+ +
_
N6781A source/measure unit
+
_
Vout + Vout -
DUT
18
© 2012 Agilent Technologies
Wireless Communications
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Battery Run-down Test
Example Results and Insights
•Results
• Logged min, avg & max volts, amps, & watts
• Markers at start and shutdown determine:
I avg = 233 mA
V avg voltage = 3.82 V
Charge = 843 mA-h
Energy = 3.19 W-h
Run time = 3 hr 38 min
V shutdown = 3.44 V
Insights:
• Delivered charge (843 mA-h) less than spec’d (1000 mA-h)
• V shutdown high (target 3V)
• Often energy (unspec’d) is more related to actual run-time than Charge (spec’d)
Voltage
Current
Power
24 min/div
N6781A SMU and 14585A Software Measuring
Battery Run-down on a GSM/GPRS Mobile Phone
20
© 2012 Agilent Technologies
Wireless Communications
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DUT
Battery In RF
N6705B DC Power Analyzer
with N6781A SMU emulates
the DUT battery
PXT Wireless
Communications Test Set
PC running 14585A
Battery Drain
Analysis software
Analyzing & Optimizing LTE DRX,
Example System Setup
DRX (Discontinuous Receive) power savings mode
High speed digitizing measurement system captures DUT current drain
Base station emulation, maintains standby with DUT for DRX-off and DRX-on modes
21
© 2012 Agilent Technologies
Wireless Communications
22 © 2012 Agilent Technologies
Wireless Communications
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Effects of DRX on Battery Drain
LTE example
The UE may use Discontinuous Reception (DRX) in idle or connected mode
in order to reduce power consumption.
No DRX – High constant current drain in either Idle or Connected Mode
Idle DRX – dramatically reduce current drain, but lengthen re-action times
• 4 DRX settings, 320, 640, 1280, 2560 sub-frames
Connected DRX – multiple settings
• If only long cycle configured, UE could be “asleep” in Connected mode for
more than 2 seconds, dramatically changing current drain, but leaving a
very slow reaction time.
• If both long and short cycles are used, UE may be able to react a little
faster, current drain will be slightly higher than if only long cycle used.
System settings such as DRX can have a significant effect on battery drain.
© 2012 Agilent Technologies
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Analyzing & Optimizing
LTE DRX Power Savings
LTE Data Modem
Idle DRX rate set to 320 sub-frames
Highest level of activity for standby
Found average current was 180mA and peak was 466mA
23
© 2012 Agilent Technologies
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Analyzing & Optimizing
LTE DRX Power Savings
LTE Data Modem
Idle DRX rate set to 640 sub-frames
High level of activity for standby
Found average current was 150mA and peak was 467mA
24
© 2012 Agilent Technologies
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Analyzing & Optimizing
LTE DRX Power Savings
LTE Data Modem
Idle DRX rate set to 1280 sub-frames
Lower level of activity for standby
Found average current was 143mA and peak was 465mA
25
© 2012 Agilent Technologies
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Analyzing & Optimizing
LTE DRX Power Savings
LTE Data Modem
Idle DRX rate set to 2560 sub-frames
Lowest level of activity for standby
Found average current was 135mA and peak was 462mA
26
© 2012 Agilent Technologies
Wireless Communications
27 © 2012 Agilent Technologies
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LTE Long and Short Cycle DRX 36.321, 36.331
Page 27
drx-InactivityTimer
onDurationTimer
longDRX-Cycle
drx-InactivityTimer
longDRX-Cycle
onDurationTimer
drxStartOffset
SF0
drxStartOffset
SF0
drxShortCycleTimer
(number of short cycles)
shortDRX-Cycle
If both short and long cycles are configured, the UE will (if no activity during
the drx-inactivityTimer), drop to the short cycle. This will allow the UE to be
more reactive to data reception. After the number short cycles defined in the
drxShortCycleTimer, if there remains no activity, the UE reverts to the long
cycle.
© 2012 Agilent Technologies
Wireless Communications
28 © 2012 Agilent Technologies
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Battery Drain Influences
LTE examples
© 2012 Agilent Technologies
Wireless Communications
29 © 2012 Agilent Technologies
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Battery Drain Influences
LTE examples
What influences LTE Current Drain Tx Power has VERY high influence in LTE Tx Allocations (number of RB’s), Rx much less so Connected Mode DRX settings Paging Cycle setting MIMO Many applications which use SatNAV / Location services do not switch off Touch Screen use, constant backlighting What does not influence LTE Current Drain significantly BSE Tx level – causing adjustments in UE Rx, gain etc. BUT open loop Tx will be influenced Some strange effects with non-contiguous DL allocations. Unacknowledged Vs Acknowledged mode RLC Ciphering What MIGHT influent LTE Current Drain – untested SPS and TTI Bundling Voice Vs Data
© 2012 Agilent Technologies
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Challenge:
Easily Exercise UE Capabilities
Requirements
• Exercise All Applications (Voice, Video, Messaging, e-Mail, Download, Upload etc)
• Exercise All Network Conditions (Handovers, Power Level Changes, DRX)
• Flexibility to quickly setup, change, and re-run tests
Traditional Solutions
• Custom software for application
• Use a general purpose graphical test executive program environment
• Test mode operation of device
Specialized Approach
• Simultaneous and multi-threaded exercising of device under defined network conditions
Challenges
• Custom software is a huge programming effort
• Learning curve for test implementation and measurement methods
• Tests a limited subset of UE features
35
© 2012 Agilent Technologies
Wireless Communications
37 © 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
N5972A
Interactive Functional Test Software
• Multiple radio access technologies
• LTE using PXT and associated protocol logging
• UMTS and CDMA with 8960 and associated protocol logging
• Voice, video, messaging with IMS-SIP emulator (E6966A)
• Battery drain test with DC power source, modules and analysis software
(66319B/D or 66321B/D DC source with 14565B device characterization
s/w & now supporting N6705B DC power analyzer, N6781A source and
14585A s/w)
© 2012 Agilent Technologies
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Protocol Log
Simultaneous and Multi-threaded Exercising of Devices
Simultaneous activities (SMS/MMS, FTP, battery profile etc.)
Predictably or randomly changing over short or long periods of time
– Enables user-experience testing scenarios
– Stresses phones and finds issues earlier, vs. sequential testing
38
FTP
SMS
Cell
Power
Failure caused
by unique
combination of
Activities
Failure due to
SMS buffer
limitations in
DUT
Failure
© 2012 Agilent Technologies
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DUT
DC Supply RF
Control interface
N6705B DC Power Analyzer
with N6781A SMU in
battery emulation mode
PXT Wireless
Communications Test Set DUT
PC running N5972A
Interactive Functional
Test (IFT) SW, and
14585A Battery Drain
Analysis SW
Optional PC or internet
connection for running
server applications
LAN
Example System Setup For
Automated Operation
39
© 2012 Agilent Technologies
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Remote or Local Server Interfaces
Device Automation Tools
• Parallel activity
execution.
• Creates more
realistic user
experience
Function Test
Activities • Current drain
• SMS (MO, MT)
• MMS(MO,MT)
• ftp,http,UDP
• Call processing
• Network impairments
Current Drain vs. Simultaneous
FTP, SMS, and Power Changes
Current Drain Monitoring
40
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Controls with blue arrow Icons can be “drag & dropped” into the scripting interface, It basically writes the code for you.
• VB.Net “Based” Programming environment (Scripter) allows custom automation of Interactive Activities.
• What ever you create in Interactive mode can easily be programmed and modified in the Scripting Mode.
41
© 2012 Agilent Technologies
Wireless Communications
44 © 2012 Agilent Technologies
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Greater insight. Greater confidence. Accelerate next-generation wireless.
N5972A Interactive Functional
Test Operating Modes
Interactive mode
– User manually sets up and executes activities through easy to use controls
– Use for troubleshooting design issues
– Setup and define test processes that can be saved in the script interface
Script development mode
– Once test process has been defined through the interactive mode, easily save the setup as a script
– Enhance and modify the scripts to include other user defined tasks
Stress test mode
– Setup an automated test plan that runs created scripts
– Combine multiple scripts into a single test plan
– TCP/IP API interface can control test plan execution through other programs
– E-mail notification of test plan status and results
© 2012 Agilent Technologies
Wireless Communications
45 © 2012 Agilent Technologies
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N5974A IFT automation for
AT&T compliance test plan
N5974A-9FP IFT scripts for battery performance test
– example test conditions (UMTS / LTE modes)
• AMR Call
• SMS & MMS
• Idle mode
• FDP
• UDP
• Video streaming
• CSFB
Speaker Note:
Additional details of
this product are
behind this note and
are available only to
companies approved
by AT&T
© 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
Benefits: Bring smaller, longer running, more competitive products to market
Faster time-to-market and at lower expense by reducing development time
In Development, optimize battery
operating time:
• Evaluate and optimize overall device and its
sub circuits
• Validate and optimize battery power
management system
• Identify high peak drain anomalies and their
root causes
In Software Development, validate
new code builds:
• Run application code regression test suites,
impact on battery drain
In Design Integration and Validation:
run suites of benchmark tests:
• Current drain for channels & power level
combinations, & main op modes
• Validate operating time with product’s battery
(run-down test)
• Check impact of HW, L1/L2/L3, OS &
application interactions on battery drain
Summary: A Growing Need for
Real World Tests
46
© 2012 Agilent Technologies
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Some Examples:
In Design Validation:
• Test suite of current drain vs. transmit (TX)
power levels & channels
In Software Development:
• Validate against current drain with
regression test suites
• Timestamp current drain behavior
synchronized to specific DUT activity
In Integration and Verification:
• Stress testing designs to find issues early in
the design cycle
• Perform realistic network testing before
network drive tests
• Ensure Product’s meet published
specifications & industry benchmarks
• Ensure Product’s meet Service provider
sourcing requirement specification
Network Operator compliance plans:
• Focus on testing without having to create
complex code or program test equipment
Why Automate Current
Drain Measurements?
Benefits: Reduce Time-to-market - Get product out more quickly and with less resources
Test early and more thoroughly - Perform tests previously not practical to do
47
© 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
48
The Benefits of Using New Techniques
Bring hardware, protocol and software together, check that it works
Performance verification & regression test of components and integrated devices
More expansive testing of UEs for interoperability and performance against expected use models
Use on real networks
Design Integration
Validation Testing
Operator Deployment
Develop a BETTER product
Achieve test EFFICIENCY
Efficiently and accurately complete necessary iterations of design and verification cycles
Get to market FASTER
© 2012 Agilent Technologies
Wireless Communications
49 © 2012 Agilent Technologies
Wireless Communications
Greater insight. Greater confidence. Accelerate next-generation wireless.
Additional Resources
Interactive functional test software
www.agilent.com/find/N5972A
IFT automation for AT&T compliance test plan
www.agilent.com/find/N5974A
DC Power Analyzer
www.agilent.com/find/N6705B