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Positioning in Chinese Digital Television Network Using TDS-OFDM Signals

Positioning in Chinese Digital Television Network Using TDS-OFDM Signals. Linglong Dai, Zhaocheng Wang, Changyong Pan , and Sheng Chen Tsinghua University, Beijing, China University of Southampton, Southampton SO17 1BJ, U.K. 提纲. 研究背景. 1. 2. 基于 TDS-OFDM 信号的时频二维定位算法. 3. 仿真结果. 4. 结论.

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Positioning in Chinese Digital Television Network Using TDS-OFDM Signals

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  1. Positioning in Chinese Digital Television Network Using TDS-OFDM Signals Linglong Dai, Zhaocheng Wang, Changyong Pan, and Sheng Chen Tsinghua University, Beijing, China University of Southampton, Southampton SO17 1BJ, U.K.

  2. 提纲 研究背景 1 2 基于TDS-OFDM信号的时频二维定位算法 3 仿真结果 4 结论

  3. DTV-Based Positioning • Global Positioning System (GPS) [Kaplan05] • Worldwide (Oceans, desert) • Hard to use in indoors, dense urban areas • National securityCompass • Digital Television (DTV)-Based Positioning • Advantages [Spilker05] • Much higher received power : 40 dB (10000 times) • Wider signal bandwidth • Lower Doppler effect DTV-Based Positioning: a promising complementary to GPS

  4. Positioning Using OFDM Positioning Using OFDM Signals Correlation-based timing synchronizationalgorithms[Shalom09] [Mensing07] [Martin09] Low complexity Low Accuracy Super-resolution algorithms(e.g., MUSIC)[Khanzada08] [Li04] High accuracy High complexity Current DTV-Based Positioning Solutions ATSC: Correlationbased on the SYNC signal[Spilker05] ATSC/ASTC-M/H: orthogonal Kasami sequences ssuperimposed on the normal TV signals[Wang06] DVB-T: Correlationbased on the frequency-domainpilots [Kovar08] DVB-H: Artificial delays in single frequency network (SFN)[Thevenon09] Positioning based on Chinese DTV standard (TDS-OFDM signal) Very few ! 4

  5. Contents 1 Background 2 Positioning Using TDS-OFDM Signal 3 Simulation Results 4 Conclusion 5

  6. TDOA-Based Positioning Model in SFN • Single Frequency Network (SFN) • Most DTV systems are deployed in SFN mode • 6 SFN transmitters in Hongkong • Better coverage and higher spectral efficiency • Synchronicity among different transmitters in SFN • Time Difference of Arrival (TDOA) • Remove the common TOA estimation error • Receiver location: intersection of hyperbolic curves • Two fundamental issues • Accurate TOA estimation • Transmitter identification 6

  7. Positioning Using TDS-OFDMSignals (1) • Regarding TPS as Frequency-Domain Pilots • Transmission parameter signaling (TPS) • Inform the coding rate, modulation schemes, etc. • 36 TPS out of the 3780 subcarriers [DTMB06] • Invariant property of TPS regarded asknown pilots • Training information: time-domain onlytime-frequency domains 7

  8. Positioning Using TDS-OFDMSignals (2) • TDM of TPS as Orthogonal Frequency-Domain Pilots • Time-division multiplexing (TDM) of TPS for transmitter identification • Provide the orthogonality in the time domain • No impact on normal TV program 8

  9. Positioning Using TDS-OFDMSignals (3) • Impact of the transmission delay on the received OFDM signal • Integral delay: time shift by samples in the time domain • Fractional delay: phase rotation of in the frequency domain Transmission delay: Fractional delay Integral delay Received signal: 9

  10. Positioning Using TDS-OFDMSignals (3) • Time-Frequency Positioning Algorithm • Integral TOA estimation using time-domain PN sequence • Time-domain correlation to find the correlation peaks • Timing accuracy: • Several meters 10

  11. Positioning Using TDS-OFDMSignals (3) • Fractional TOA estimation using frequency-domain TPS • Firstly: facilitate correlation peaks identification • Secondly: fractional delay estimation 11

  12. Performance Analysis • Ranging Accuracy • Average ranging time • Computational Complexity High accuracy Fast acceptable 12

  13. Contents 1 Background 2 Positioning Using TDS-OFDM Signal 3 Simulation Results 4 Conclusion 13

  14. Simulation Results (1) • Main parameters • Central carrier：UHF (770 MHz) • Signal bandwidth： 7.56 MHz • Channel：ITU Indoor A • SARFT 8 • M = 4 • Modulation：QPSK/16QAM • Sampling rate：7.56 MHz*4 • N=3780, K=420 1. Higher accuracy 2. Coincides with the theoretical bound 14

  15. Simulation Results (2) Accuracy in multi-path channels is also high 15

  16. Simulation Results (3) No impact on normal TV program reception 16

  17. Contents 1 Background 2 Positioning Using TDS-OFDM Signal 3 Simulation Results 4 Conclusion 17

  18. Brief Conclusions • The positioning solution using TDS-OFDM signals for Chinese DTV standard in SFN is proposed in this paper; • The TPS embedded in the TDS-OFDM signal is time-division multiplexed as orthogonal frequency-domain pilots; • The proposed time-frequency positioning scheme jointly utilizes the time-domain PN sequence and frequency-domain TPS (pilots) for accurate TOA estimation of each transmitter; • Results obtained have shown that the proposed positioning scheme achieves a higher positioning accuracy compared with the state-of-the-art methods, while imposing a low complexity.

  19. References M. Rabinowitz and J. Spilker, “A new positioning system using television synchronization signals,” IEEE Trans. Broadcast., vol. 51, no. 1, pp. 51-61, Mar. 2005. X. Wang, Y. Wu, and J. Chouinard, “A new position location system using DTV transmitter identification watermark signals,” EURASIP Journal on Applied Signal Processing, vol. 2006, pp. 1–11, 2006. D. Serant, P. Thevenon, M. L. Boucheret, O. Julien, C. Macabiau, S. Corazza, M. Dervin, and L. Ries, “Development and validation of an OFDM/DVB-T sensor for positioning,” in Proc. IEEE/ION Position Location and Navigation Symposium (PLANS’10) (Indian Wells, USA), May 4-6, 2010, pp. 988–1001. Framing Structure, Channel Coding and Modulation for Digital Television Terrestrial Broadcasting System. Chinese National Standard, GB20600-2006, Aug. 2006. C. Mensing, S. Plass, and A. Dammann, “Synchronization algorithms for positioning with OFDM communications signals,” in Proc. 4th Workshop on Positioning, Navigation and Communication (Hannover), March 22, 2007, pp. 205–210. X. Li and K. Pahlavan, “Super-resolution TOA estimation with diversity for indoor geolocation,” IEEE Trans. Wireless Commun., vol. 3, no. 1, pp. 224–234, Jan. 2004. A. Mattsson, “Single frequency networks in DTV,” IEEE Trans. Broadcast., vol. 51, no. 4, pp. 413–422, Dec. 2005. C. yen Ong, J. Song, C. Pan, and Y. Li, “Technology and standards of digital television terrestrial multimedia broadcasting,” IEEE Commun. Mag., vol. 48, no. 5, pp. 119–127, May 2010. J. Wang, Z. Yang, C. Pan, M. Han, and L. Yang, “A combined code acquisition and symbol timing recovery method for TDS-OFDM,” IEEE Trans. Broadcast., vol. 49, no. 3, pp. 304–308, Sep. 2003. L. Dai, Z. Wang, J. Wang, and Z. Yang , “Positioning with OFDM signals for the next-generation GNSS,” IEEE Trans. Consumer Electron., vol. 56, no. 2, pp. 374–379, May 2010. A. Sayed, A. Tarighat and N. Khajehnouri, “Network-based wireless location: challenges faced in developing techniques for accurate wireless location information,” IEEE Signal Processing Magazine, vol. 22, no. 4, pp. 24–40, July 2005. Y. T. Chan and K. C. Ho, “A simple and efficient estimator for hyperbolic location,” IEEE Trans. Signal Processing, vol. 42, no. 8, pp. 1905–1915, Aug. 1994. Guideline for Evaluation of Radio Transmission Technology for IMT-2000. Recommendation ITU-R M.1225, 1997. 19

  20. ありがとう Thank you for your suggestions !

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