1. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Edge Detection in dense multipath and heavy interference] Date Submitted: [15 May 2005] Source: [Zafer Sahinoglu, Mitsubishi Electric] Contact: Zafer Sahinoglu Voice:[+1 617 621 7588, E-Mail: zafer@merl.com] Abstract: [This document provides a technical recommendation on how the first arriving signal energy can be detected in dense multipath and heavy SOP interference] Purpose: [To point out basic requirements for a signal waveform to deal with multipath and SOP interference in edge detection] 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.

2. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a2 Zafer Sahinoglu, May 11, 2005 Mitsubishi Electric Research Labs

3. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a3 Signal Parameters Signal Energy Conditioner Channel Characteristics Signal Energy Collector Signal TOA Estimate Signal Energy Edge Detector Generic Architecture for Ranging Received signal energy is collected Energy vector is processed to suppress noise artifacts and enhance signal containing parts Edge detection is performed channel

4. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a4 Outline Ranging signal waveforms SOP Interference –Deficiencies of coherent energy combining A look into signal energy conditioning techniques Edge detection for ranging

5. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a5 M chip times One Bit The Other Bit TH- freedom Always Empty M chip times Always Empty TH freedom Always Empty Signal Waveforms Always Empty Enough long not to cause IFI optional

6. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a6 SOP Interference Desired user signal Interference Without time-hopping, edge information may not be recovered under SOP interference Received energy Deviation from the true the TOA

7. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a7 Implicit TH code: {1,3,3,1} – bits: {1,0,0,1} Implicit TH code: {1,1,3,3} - bits: {1,1,0,0} Example Acquisition Waveform Piconet-I Piconet-II Using the two specified bit waveforms (TH freedom = 0) Bit interval

8. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a8 SOP Interference (2) Strong SOP interference even with a different transmission pattern can be deleterious to coherent energy combining –Example simulation: CM2 (desired and interferer with different channel realizations) Energy Window Size = 4ns E B N 0 = 22dB (both desired and interferer) receiver desired transmitter interferer True TOA

9. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a9 How to Filter Out SOP Interference? Signal processing of energy samples before coherent combining –Correlation properties of the samples –Frequency domain analysis (FFT) –Statistical multiplexing

10. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a10 (1) (2) (M)(1) (2) (M) (1)(2) (N) E(N, TH(N))E(N, TH(N)+1)…E(N, TH(N)+M) ………… E(2, TH(2))E(2, TH(2)+1)…E(2, TH(2)+M) E(1, TH(1))E(1, TH(1)+1)…E(1, TH(1)+M) (1) (2) (M) E(1,1)E(1,2) E(1,M) E(2,1)E(2,2) E(2,M) E(N,1)E(N,2) E(N,M) Frame interval Generating an Energy Image

11. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a11 Desired user code-2 {2,1,2,1} Interference code {1,3,1,2} Pulse compression Narrower energy windows or Energy matrix Thicker vertical edges frame interval Energy Image Illustrations

12. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a12 Interference when received according to time hopping sequence TH2 (CM2-49) Desired user when received according to its own time hoping sequence TH1 (CM2-43) “Desired user (TH1) + Interferer (TH1)” when received according to the time hoping sequence TH1 (CM2-43 for desired user and CM2-49 for interferer) Frame index Energy window index “Desired user (TH1)+ Interferer (TH2)” when received according to the time hoping sequence TH1(CM2-43 for desired user and CM2-49 for interferer) Frame index Energy window index Frame index

13. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a13 FFT Analysis of Energy Image Desired user energy forms vertical lines in multipath channels Interference forms a pattern that repeats itself along a vertical line –(Left) – energy window size: 4ns, TH code length: 4

14. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a14 Energy Image Superposition Simulation settings (single pulse): –CM2 (Residential NLOS) and no SOP interference –E B N 0 = 18dB, T F =200ns, W E = 4ns –Transmission duration 60µs (for 10 images) –Vertical edge detection with a “Prewitt” method (see Matlab image toolbox) –RAM: 1.5KB N 1 Energy window index Frame index N=1 1 30 1 50Energy window index Frame index N = 10 30 1 1 50 When pulse compression with M chips, edges will be only thicker and MN images needed

15. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a15 Recommended Edge Analysis Architecture Energy VectorEnergy Matrix Generator Vertical Edge Detector FFT Analysis TOA estimate

16. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a16 Summary and Conclusion Coherent energy combining may not be sufficient to accurately detect leading edges Energy images provide more insight into whereabouts of leading edge even under dense multipath and SOP interference Signals should be transmitted with a distinguishable pattern for the energy detectors –This can be achieved by Coarse block time-hopping Pulse compression with very low PRF

17. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a17

18. April 25th 2005Doc: IEEE 15-05-0269-004a Zafer Sahinoglu, Mitsubishi Electric SlideTG4a18