Bluetooth Indoor Localization System

Transcription

1 Indoor Localzaton System Gunter Fscher 1, Burkhart Detrch 1, and Frank Wnkler 2 1 IHP Innovatons for Hgh Performance Mcroelectroncs Frankfurt (Oder), Germany 2 Humboldt Unversty Berln, Germany IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved

2 Outlne Motvaton Prncples of tme measurement for localzaton System descrpton and components Frst measurement results IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 2

3 Motvaton Indoor localzaton enables locaton-aware servces Gudance n complex facltes usng handheld devces Fndng the locaton of partcular persons and objects Trackng and watchng of actve badges and tags Indoor localzaton system s hard to acheve GPS, DGPS doesn t work wth suffcent relablty Cellular phone systems (GSM) haven t requred accuracy Embeddng n a wdely spread rado system desred Exstng solutons requre changes on moble devce Dedcated hardware for phase measurement, not standard conform System based on RSSI or BER determnaton need calbraton ndoor localzaton system wth ± 1 meter accuracy Allows to localze any devce, no changes on moble Localzaton by tme-of-arrval measurement usng cross correlaton IC IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 3

4 Prncples of Tme Measurement - TOA Measurement of propagaton tme of electromagnetc waves Transmtter (moble) sends sgnal at known tme Measurement of ndvdual tmes of arrval at the base statons Calculaton of three dstances from three propagaton delays + τ 0 + τ τ 2 M IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 4

5 Prncples of Tme Measurement - DTOA Omt knowledge of start tme Introducng addtonal base staton at known poston (one off plane) Stll needs synchronzaton between base statons Calculaton of three dstances from four propagaton delay dfferences + τ 0 + τ τ 2 M + τ 3 3 IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 5

6 Prncples of Tme Measurement - DTDOA Omt base staton synchronzaton: dfferental measurement Master base statons transmts frst sgnal startng counters, moble answers stoppng the counters on the tme measurement statons Calculaton of three dstances from four propagaton delay dfferences Phase 1: + τ offset1 + τ 01 t 0 phase2 + τ M0 1 t phase2 + τ M1 + τ offset3 + τ 03 M 2 + τ offset2 + τ 02 t phase2 + τ M2 3 t phase2 + τ M3 Phase 2: t phase2 = + τ 0M + τ F IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 6

7 Dfferental Tme Dfference of Arrval Phase 1: t 1 = +τ offset + τ 0 Phase 2: t 2 = + τ + τ + τ + τ offset 0 M F M Offset elmnaton: t j = Propagaton tme dfferences: t t 2 t1 = τ M + τ F + τ M τ = t Dstance dfferences: τ M τ t M dj = c ( τ j j = t 0 = τ τ τ + τ j τ M + τ M M j 0 ) 0 τ 0 j M j 0 0 j IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 7

8 Multpath Propagaton Reflecton Lne of Sght Transmtter Recever LoS NLoS up to 100 ns IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 8

9 Reducton of Reflected Sgnals Base statons nstalled n upper corners, usage of drected antennas Good LoS condtons for almost all postons No reflectons from adjacent walls and celng Reflected sgnals from opposte walls mght have much smaller power than the LoS sgnal LoS NLoS M IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 9

10 System Overvew Host Servceprovder AccessPont Management Baseband Processor Rado Baseband Processor Rado Postonng Software Mcrocontroller Master - TMS Correlator & RAM Echo Request Mcrocontroller Correlator & RAM Addtonal TMS Echo Response Moble Devce Baseband Processor Rado Moble Baseband Processor Rado Mcrocontroller Correlator & RAM Mcrocontroller Correlator & RAM Addtonal TMS Addtonal TMS IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 10

11 Cross Correlaton IC Multplcaton of the receved sgnal and a reference 4096 bts multpled n one cycle and summed up Ppelne structure (24 cycles) Recursve VHDL descrpton Sum(2) Sum(3) Bt level 2 Sum(1) Bt level 1 Sum(0) Bt level 0 Input bt vector IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 11

12 Correlaton IC Logc desgn n 0.25µm CMOS Cooperaton wth Humboldt Unversty Berln, Germany Clock rate programmable, code length 4096 bts, 3.5 x 6.7 mm 2 IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 12

13 Demodulated Sgnal Sgnal-to-nose rato typcally between 12 to 18 db Sgnal and nose are low pass fltered Cycle-to cycle jtter n the order of several 10 ns IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 13

14 System Smulatons Requred correlaton code length [bt] Expected range SNR [db] 24 MHz 36 MHz 48 MHz 59 MHz Samplng rate 243 MHz IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 14

15 Evaluaton of the Correlaton Peak Tme resoluton better than samplng rate L1 L2 L3 L4 Tme t 4a t 3a t 2a t 1a t peak t 1b t 2b t 3b t 4b IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 15

16 Measurement Setup Recever Staton Moble Transmtter Recever Staton IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 16

17 Measurement Results forward backward wat Recever Staton Moble Transmtter Recever Staton IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 17

18 Summary localzaton system wth ± 1 meter accuracy presented No changes on moble devce requred Only one data packet necessary for localzaton Dfferental tme dfference of arrval scheme used Base statons don t needed to be synchronzed Dedcated cross correlaton IC fabrcated and tested Made n 0.25µm standard CMOS technology Multplcaton of 4096 bts n parallel and summaton wthn 1 clock cycle (ppelne structure), works fne wth 64 MHz clock rate System mplementaton s a challenge In essence lne-of-sght condtons requred Best soluton s a common ntegraton of the correlaton IC wth a mcrocontroller n cooperaton wth chp manufacturer IHP Im Technologepark Frankfurt (Oder) Germany All rghts reserved 18