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

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Recommended Ranging Signal Waveforms] Date Submitted: [25 April 2005] Source: [Zafer Sahinoglu, Mitsubishi Electric] Contact: Zafer Sahinoglu Voice:[+1 617 621 7588, E-Mail: zafer@merl.com] Abstract: [Presents signal waveform options to achieve precision ranging with both coherent and non-coherent receivers] Purpose: [To discuss which signal waveform would be the most feasible in terms of performance and implementation trade-offs] 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. Suggested Ranging Signal Waveforms Zafer Sahinoglu April 25, 2005 Mitsubishi Electric Research labs Cambridge, MA USA

3. Features • A train of pulses in each frame (PRP) • Enables small pulse amplitudes • Increases coherent-ranging performance • Coarse time-hopping at resolutions of the reference frequency • Provides • additional piconet isolation to coherent receivers • piconet isolation to non-coherent receivers • Increases energy edge detection performance of non-coherent receivers

4. Ranging Signaling Option-A 320 ns Multipath tolerance (e.g., 220 ns) T1 (time-hopping margin) (e.g., 100ns) Multipath tolerance M-chip times T1-TH1 M-chip times TH1 (e.g. 60ns) symbol with 0-ns time hopping symbol with TH1 nanosecond time hopping • A train of pulses in a frame is coarsely time-hopped • TH1 may correspond to the integer multiples of the 1/ (reference frequency) • 66MHz => ~ {15, 30, 45, 60,75,90} nanoseconds • Maximum allowable time-hopping interval would be T1.

5. Frame index Frame index Energy window index Energy window index 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) Frame index Frame index Energy window 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) “Desired user (TH1) + Interferer (TH1) ” when received according to the time hoping sequence TH1 (CM2-43 for desired user and CM2-49 for interferer)

6. Ranging Signaling Option-B (by Vern) One Bit Optionally Empty Always Empty Always Empty 32 32 32 Next potential active time 32 chip times The Other Bit Optionally Empty Always Empty Always Empty 32 32 32 Only 160 ns of channel multipath tolerance in this case. Next potential active time 32 chip times We transmit one or the other of these patterns to carry data.

7. Option-C (Particular Case of Option-B) One Bit Always Empty Always Empty Always Empty M chip times The Other Bit Always Empty Always Empty Always Empty Enough long not to cause IFI M chip times Optionally empty slots in Option-B must be converted to “always empty”

8. Option-C implies time-hopping with a less degree of freedom TH code: {1,3,3,1,1} TH code: {1,1,3,3,3}

9. Option-D (Modified Option-C) One Bit TH-freedom Always Empty Always Empty Always Empty M chip times The Other Bit TH freedom Always Empty Always Empty Always Empty Enough long not cause IFI M chip times Optionally empty slots in Option-B must be converted to “always empty”

10. Summary • Train of pulses placed in frames in a time-hopping manner increases ranging performance of both coherent and non-coherent receivers • Only time-hopping at coarse levels is needed • Options: • Option-A seems to be the most complex • Option C is a particular case of Option-B • Option-D would outperform Option-C in non-coherent under an interfering piconet • Numerical values are for illustrative purposes only