S-38.3310 Tietoverkkotekniikan
diplomityöseminaari
09.05.2006
Title: Automatic Bluetooth Radio Frequency Measurement System
Author: Jussi Savolainen
Supervisor: Prof. Sven-Gustav Häggman
Instructor: Petteri Yrjälä, M.Sc.
Work carried out at: Elcoteq Design Center Oy, Salo
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
1
Presentation outline
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Elcoteq Presentation / Jussi Savolainen
Background
Research problem
Research methods
Bluetooth essentials
Bluetooth RF measurements
System setup
Software implementation
Conclusions and further work
Tuesday, May 09, 2006
2
Background
• Bluetooth RF conformance testing by far the most expensive
(time and cost) of the conformance tests, because
– off-the-shelf test systems > 1 M€ (cost)
– response time using external test houses too long (time)
• Projects need a heap of test data in a short amount of time for
statistical analysis, etc.
• Failing in type approval tests is expensive
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
3
Research problem
• How to automatically perform the Bluetooth RF conformance
tests according to Bluetooth Test Specification version 2.0+EDR
in prequalification phase of the design
• How to perform the tests simultaneously for a number of devices
• How to support different Bluetooth products and product types
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Research methods
• Literary study (Bluetooth RF specification, Bluetooth test
specification, measurement device vendor application notes,
etc.)
• Vendor audits/interviews
• HW Designer interviews
• UI usability study
• Data storage study
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Bluetooth essentials
• Bluetooth connects portable or fixed equipment, and it is a cable
replacing technology, which is cheap and robust with low power
consumption
• Technology initially developed at Ericsson in 1994
• Bluetooth SIG established in 1998, first version of specification
out same year
• Most recent version 2.0+EDR came out in 2004 with support to
higher data rates than previously
• Operates on unlicensed (but not unregulated!) 2.4GHz ISM band
p
s
S
S
S
M
M/S
s
b
piconet 2
S
p
s
piconet 1
Scatternet with two piconets
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Bluetooth essentials – protocol stack
• Bluetooth protocol stack is a fuzzy structure
• Controller and Host can be separated using HCI, chipset and
applications implemented separately
• Thesis discusses mainly radio layer
APPLICATIONS
OBEX
twoway
voice
WAP
SDP
TCS
RFCOMM
control
HOST
L2CAP
HOST CONTROLLER INTERFACE
data
LINK MANAGER
CONTROLLER
BASEBAND AND LINK CONTROLLER
RADIO
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Bluetooth essentials – packet structure
• Basic rate 1Mb/s
• Enhanced Data Rate 2Mb/s or 3Mb/s
• in EDR packets modulation is changed during the burst from
2FSK to PSK (backwards compatible)
• EDR mostly affects radio layer
LSB
MSB
ACCESS
CODE
68/72b
HEADER
PAYLOAD
54b
0-2745b
General basic rate packet format
MSB
LSB
ACCESS
CODE
72b
HEADER GUARD SYNC
54b
5 µs
11 µs
2FSK
PAYLOAD
16-8200b
PSK
General enhanced data rate packet format
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Bluetooth RF measurements - basics
• Device Under Test (DUT) can be placed to test mode, which
allows configuration and control of the DUT
• Some tests must be performed under extreme temperature and
voltage conditions
• Tests divided in transmitter (TX), receiver (RX) and transceiver
(TRC) measurements
• TX and RX tests according to Bluetooth RF test specification
• TRC tests according to ETSI EN 300 328
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Bluetooth RF measurements – TX tests
• TX tests either power measurement as function of frequency or
frequency as function of time
Elcoteq Presentation / Jussi Savolainen
Measurement
Description
Output power
Maximum peak and average power of the burst
Power density
Maximum RF-output power density
Power control
Verification of power control
Frequency range
Emissions inside the operating frequency within limits
20dB bandwidth
Emissions inside the operating frequency within limits
Adjacent channel power
Emissions inside the operating frequency within limits
Modulation characteristics
Modulation index
Initial carrier frequency tolerance
Transmitter carrier frequency accuracy
Carrier frequency drift
Transmitter centre frequency drift within a packet
EDR relative transmit power
Difference in power during 2FSK and PSK portions of packet
EDR carrier frequency stability
and modulation accuracy
Carrier frequency stability and modulation accuracy
EDR differential phase encoding
Differential phase encoded data correctness
EDR in-band spurious emissions
Unwanted signal levels on adjacent channels
Tuesday, May 09, 2006
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Bluetooth RF measurements – RX tests
• RX tests are BER measurements performed under different stimulus
conditions
Elcoteq Presentation / Jussi Savolainen
Measurement
Description
Sensitivity – Single slot packets
Required sensitivity with non-ideal signal
Sensitivity – Multi slot packets
Required sensitivity with non-ideal signal
C/I performance
Sensitivity in presence of co-/adjacent channel interference
Blocking performance
Sensitivity in presence of out-of-band interference
Intermodulation performance
Verification of receiver’s intermodulation characteristics
Maximum input level
Receiver performance in presence of high power signal
EDR sensitivity
Required sensitivity with non-ideal signal
EDR BER floor performance
Receiver performance for 10^-5 BER
EDR C/I performance
Sensitivity in presence of co-/adjacent channel interference
EDR maximum input level
Receiver performance in presence of high power signal
Tuesday, May 09, 2006
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Bluetooth RF measurements – TRC tests
• Out-of-band spurious emissions measured according to ETSI EN
300 328
• Does not belong to Bluetooth conformance tests
• Measures harmonics of the carrier signal, cabinet radiation and
modulation products
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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System setup
• All Bluetooth RF conformance tests and out-of-band spurious
emission measurement must be performed automatically with
one setup
• 12 DUTs measured simultaneously
• Capable of measuring any Bluetooth device which implements at
minimum the controller
RF Shield
Climate
chamber
Multiplexer
1x12
Multiplexer
1x12
GSM
GSM
Signaling
BT
tester
IQ
Relay box
ATT
Multiplexer
1x4
Multiplexer
1x4
Multiplexer
1x4
CW
Spectr
An
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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System setup - equipment
Device
Description
BT tester
Bluetooth signaling tester capable of performing EDR measurements
RF shield
Attenuates interfering RF signals
Temperature chamber
Used in extreme temperature conditions (typ. -20ºC and +55 ºC)
Relay box
Used to filter unwanted frequencies e.g. in out-of-band spurious measurement
IQ
Signal generator capable of producing Bluetooth modulated interfering signals
CW
Signal generator capable of producing continuous wave signals
Spectr an
Spectrum analyzer capable of gating
GSM signaling
GSM & 3G signaling tester for coexistence testing
• Altogether ~ 200 k€
• Calibration of the transmission paths from 30MHz to 13GHz with
1MHz steps
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Software implementation - UI
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Software implementation – data storage
• System creates ~50Mb/day of data  text files or excel sheets
are not an option
• Writer (test system/test engineer) and reader (customer
project/RF designer) are separated
• Graphs and reports must be easily extractable from database
• Short response time for new graphs and reports
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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Conclusions and further work
• This type of system is never finished as interface to a new DUT
must be built every time and data storage is updated
• Error handling updates
• Calibration
• Measurement equipment SW updates
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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¿Questions?
DANKE!
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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World’s leading EMS provider
to communications technology
customers
Elcoteq Presentation / Jussi Savolainen
Tuesday, May 09, 2006
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