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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Enhancement of Ranging & Positioning by Combining TOA & TDOA ] Date Submitted: [21 July , 200 5] Source: [Kwan-Ho Kim(1), Sungsoo Choi(1), Youngjin Park(1), Hui-Myoung Oh(1), Yoan Shin(2),

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Enhancement of Ranging & Positioning by Combining TOA & TDOA] Date Submitted: [21 July, 2005] Source: [Kwan-Ho Kim(1), Sungsoo Choi(1), Youngjin Park(1), Hui-Myoung Oh(1), Yoan Shin(2), Won Cheol Lee(2), and Ho-In Jeon(3)] Company: [(1)Korea Electrotechnology Research Institute(KERI), (2)Soongsil University(SSU), and (3)Kyung-Won University(KWU)] Address: [(1)665-4, Naeson 2-dong, Euiwang-City, Kyunggi-do,Republic of Korea (2) 1-1, Sangdo-5-dong, Dongjak-Gu, Seoul, Republic of Korea (3)San 65, Bok-Jeong-dong, Seongnam, Republic of Korea] Voice:[(1)+82-31-420 6183, (2)+82-2-820-0632, (3)+82-31-753-2533], FAX: [(1)82-31-420 6183, (2)82-2-821-7653, (3)+82-31-753-2532], E-Mail:[(1)sschoi@keri.re.kr, (2)yashin@e.ssu.ac.kr, (3)jeon1394@kornet.net] Re: [] Abstract: [This document proposes proposal for the IEEE 802.15.4 alternate PHY standard.] Purpose: [Final Proposal for the IEEE802.15.4a standard] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  2. Enhancement of Ranging & Positioning by Combining TOA & TDOA KERI-SSU-KWU Republic of Korea K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  3. Contents • Introduction • Signal waveforms • Energy Detection Receiver Architecture • Enhancement Ranging and Positioning based on TOA and TDOA Method • Simulation results K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  4. Introduction • KERI, SSU, and KWU proposed a Ranging and Positioning Scheme based on SORP. • SORP provides a low power, low cost, non-coherent ranging and positioning. • It, however, suffers from the clock drift error due to many number of signal transmission. • Ternary codes with Time Hopping for the provision of SOP supportability has been adopted for our simulation K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  5. Signal waveform using Ternary code • Ranging Preamble can be constructed by repeating ternary code • TOA information is obtained accumulation across PRI • Integrator integrates over the 1.5 ns 60ns 1920ns K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  6. Signal waveform using TH & Ternary code • To mitigate SOP interference, each piconet is assigned a different time hopping sequence. • Ex) Piconet 1 = 1 3 3 1 3 1 1 3 • In addition to ‘0’, the number of 32 ternary code is used. 60ns 1920ns K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  7. Accumulator First Energy Detection Receiver Architecture RER ADC Window Buffers BPF ( )2 LPF/ Integrator offset Accumulator • Energy detector yields an energy signal w.r.t received signal. • Analog LPF operates to provide the DC offset. • DC bias existing on the input to ADC is removed. • RER(Ranging Error Reduction) may reduce the noise suppression and eliminate the uncertainty of the first path arrival. • Fine ranging can be provided by the estimated TOA through comparator with the predetermined threshold. DC level estimator ToA Information Coarse/Fine Timing Detector Sliding Correlator K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  8. Energy Detection Receiver Architecture • Integrator integrates over the 1.5ns • Sliding Correlator 1 : In the initialization process, the transmitted TH code is estimated by using the sliding correlation of TH mask. Alleviates the problem of SOP interference • Sliding Correlator 2 : Estimate the first arrival time by performing the correlation. Sliding Correlator 2 Energy Combining ToA Estimator BPF ( )2 LPF/ Integrator ADC 1D  2D 1D  2D Rearrange Sliding Correlator 1 TH code detection 2D  1D K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  9. Initialization process to find TH code TH mask set 1D  2D Sliding Correlator 2D  1D ADC TH code 획득 Preamble length 1 2 3 M M+1 M+2 M+3 M+K SFD Payload 1 2 N 1 3 3 1 3 1 1 3 1 3 3 1 3 1 1 3 1 3 3 1 3 1 1 3 1D  2D Th Tpri TH mask set N = 4 M = 4 K = 12 2D  1D Acquire corresponding TH code K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  10. TP Th Tpri TOA detection process TH mask Sliding windowing ToA Estimator 1D  2D ADC Sliding Correlator Energy Combining Preamble length 1 2 3 M M+1 M+2 M+3 M+K SFD Payload Channel sounding Acquisition 1 2 N 1 3 3 1 3 1 1 3 1 3 3 1 3 1 1 3 1 3 3 1 3 1 1 3 TH mask Sliding windowing 2symbol 1symbol 1D  2D Energy window idex TOA Estimator Ternary mask K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  11. Process of SORP Scheme with TOA/TDOA [doc. 0615-01] P_FFDs : Independent operation Unknown Universal Reference Time causing T_offset TOA measurement K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  12. RTT12 = T + 2T12 RTT23 = T + 2T23 RTT13 = T12 + 2T + T23 + T13 More Details of SORP for Obtaining TDOAs • Distances among the positioning FFDs are calculated from RTT measurements and known time interval T • Using observed RTT measurements and calculated distances, TOAs/TDOAs are updated T12 = (RTT12 – T)/2 T23 = (RTT23 – T)/2 T13 = (RTT13 – T12 – T23 – 2T) RTT34 = T34 + T + T34 TOA34 = (RTT34 - T)/2 RTT24 = T23 + T + T34 + T + T24 TOA24 = (RTT24 - T23 - TOA34 - 2T) TOA14 = (RTT14 - T12 - T23 - TOA34 - 3T) RTT14 = T12 + T + T23 + T + T34 + T + T14 TDOA12 = TOA14 – TOA24 TDOA23 = TOA24 – TOA34 K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  13. Ranging Error due to Clock Drift tp : propagation delay TAT TBR reply time(T) Device A Device B • Assumptions : • tp : 30 ns, reply time(T) : 1 ms • Device A : +10PPM, Device B : -10PPM • tp = ((TAR – TAT) - (TBR – TBT))/2 = ((1e-3+60e-9)(1+10e-6) – (1e-3)(1-10e-6))/2 = (1.000060e-3 – 1e-3 + 1.000060e-8 + 1e-8)/2 = 40ns to : clock drift TAR TBT Longer Reply time cause more effect due to clock drift Timing error of 10ns causes Ranging Error of 3m. K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  14. TOA, TDOA Ranging Method(1) • The ranging error due to Clock drift can be avoided by using SDS-TWR(IEEE-15-05-334) and difference of long term(TT) • Ranging can be obtained by TOA and TDOA • Robust to GDOP problem • Ranging performance can be enhanced by using threshold of energy level. TDOA Ranging(only) TDOA & TOA Ranging K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  15. TOA, TDOA Ranging Method TT T RTTT_A TAG TT’ • TOAT_A = ((RTTT_A – T) + (RTTA_T – T’))/4 • TOAT_B = (TOAT_A + T’ + TA_B) – mA_B’’ where, ’’ = (TT’’/TT) mA_B • TOAT_C = (TOAT_A + T’ + TA_C) – mB_C’’’ where, ’’’ = (TT’’’/TT) mB_C Reference B RTTA_T Master : TX T’ Beacon A TOAT_A TT’’ Reference C mA_B : RX TAG Beacon B TA_B Master TOAT_B TT’’’ Reference A mB_C Beacon C TA_C TOAT_C • TDOAA_B = TOAT_B – TOAT_A • TDOAA_C = TOAT_C – TOAT_A K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  16. Mode 1 Proposed Mode Mode 2 Comparison between proposed ranging types Reference B Reference B Reference B sync sync sync Reference C Reference C Reference C TAG TAG TAG Master Master Master Reference A Reference A Reference A K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  17. Parameter conditions(1) K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  18. Simulation results(1) - Channel Model : Residential LOS environment(CM1) - Eb/No : 9dB BPF ( )2 LPF/ Integrator ADC 1D  2D Sliding correlator I2R Ranging method Sliding correlator Accumulator 1D  2D Coarse TOA Fine TOA Proposed Ranging method K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  19. Simulation results(2) - Channel Model : Residential LOS Environment (CM8) - Eb/No : 9dB • The detection of leading edge depends on the threshold of ADC. BPF ( )2 LPF/ Integrator ADC Sliding correlator Leading edge K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  20. Parameter Conditions (2) 4bytes Preamble SFD Payload 1 2 3 4 5 6 16 ts 1 2 4 thpri 1 2 3 4 5 6 8 tpri 1 2 4 th K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  21. Simulation results(1) Initialization for detecting TH code TH code set TH code detection • Clock speed : 500MHz • Channel model : CM1 • Analog integration size : 1.5ns • 8-ary TH code : Barker code used • Eb/No = 9dB 2D  1D Sliding Correlator 1 1D  2D BPF ( )2 LPF/ Integrator ADC Simulation Conditions K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  22. Simulation results(2) • Process to detect leading edge using Ternary code mask TH code mask Sliding Correlator 2 Energy Combining ToA Estimator BPF ( )2 LPF/ Integrator ADC 1D  2D Leading edge K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  23. Conclusion (1/2) • Suggested an enhanced Ranging and Positioning Mechanism based on Energy Detection receiver. • Option I • Signal waveform : Same as I2R’s proposal • Ternary code has been used to estimate the arrival time • Could find an accurate arrival time by using noise reduction method and accumulations. • Option II • Signal waveform : Combination of Timing Hopping andTernary Code • Robust to SOP interference. • TH code has been used to estimate the rough receiving time. • Accurate timing has been obtained by using Ternary and its correlations. K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  24. Conclusion (2/2) • It does not guarantee a good result when the PRI is not large enough. • Combination of TOA with TDOA provided better ranging and positioning performance. • Could provide better performance for the bad GDOP case. • The performance of ranging can be enhanced to a great extent when a proper selection of threshold level can made. K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

  25. Acknowledgment • This work has been supported partly by HNRC of IITA and TTA. K. Kim, S. Choi, Y. Park, H. Oh, Y. Shin, W. Lee, and H. Jeon

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