S38 3310 Tietoverkkotekniikan diplomityseminaari 09 05 2006 Title

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 • • 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 4

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 5

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. 4 GHz ISM band ps S S S M M/S sb piconet 2 S ps piconet 1 Scatternet with two piconets Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 6

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 L 2 CAP HOST CONTROLLER INTERFACE data CONTROLLER LINK MANAGER BASEBAND LINK CONTROLLER RADIO Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 7

Bluetooth essentials – packet structure • Basic rate 1 Mb/s • Enhanced Data Rate 2 Mb/s or 3 Mb/s • in EDR packets modulation is changed during the burst from 2 FSK to PSK (backwards compatible) • EDR mostly affects radio layer LSB MSB ACCESS CODE 68/72 b HEADER PAYLOAD 54 b 0 -2745 b General basic rate packet format MSB LSB ACCESS CODE 72 b HEADER GUARD SYNC 54 b 5 µs 11 µs 2 FSK PAYLOAD 16 -8200 b PSK General enhanced data rate packet format Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 8

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 9

Bluetooth RF measurements – TX tests • TX tests either power measurement as function of frequency or frequency as function of time 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 20 d. B 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 2 FSK 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 Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 10

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 11

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 12

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 1 x 12 GSM Signaling BT tester IQ Relay box ATT Multiplexer 1 x 4 CW Spectr An Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 13

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 & 3 G signaling tester for coexistence testing • Altogether ~ 200 k€ • Calibration of the transmission paths from 30 MHz to 13 GHz with 1 MHz steps Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 14

Software implementation - UI Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 15

Software implementation – data storage • System creates ~50 Mb/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 16

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 17

¿Questions? DANKE! Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 18

World’s leading EMS provider to communications technology customers Elcoteq Presentation / Jussi Savolainen Tuesday, May 09, 2006 19