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Ranging with MB-OFDM Dave Leeper (Intel)

Ranging with MB-OFDM Dave Leeper (Intel). List of participants Anuj Batra (TI) Vern Brethour (Alereon) Bob Huang (Sony) Ebrahim Sabrimania (Univ of Minn) Shin Sato (Sony) Gadi Shor (Wisair) Ahmed Tewfik (Univ of Minn). MB-OFDM Ranging. Eliminating the turnaround latency issue

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Ranging with MB-OFDM Dave Leeper (Intel)

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  1. Ranging with MB-OFDMDave Leeper (Intel) List of participants Anuj Batra (TI) Vern Brethour (Alereon) Bob Huang (Sony) Ebrahim Sabrimania (Univ of Minn) Shin Sato (Sony) Gadi Shor (Wisair) Ahmed Tewfik (Univ of Minn) Multi-band OFDM Alliance

  2. MB-OFDM Ranging • Eliminating the turnaround latency issue • Obtaining high accuracy/precision ranging from MB-OFDM-based systems Multi-band OFDM Alliance

  3. Unknown propagation delay Unknown clock offset Message 1 Message 2 UWB Ranging via Two-Way Time Transfer*Results are Independent of “Turnaround-Time Latency” Device A Device B Two equations in two unknowns yield: Multiple measurements of tpand to yield finer precision & accuracy, and allow frequency offset correction. * US Naval Observatory, Telstar Satellite, circa 1962 http://www.boulder.nist.gov/timefreq/time/twoway.htm Unmatched detect-delays in the two devices may require one-time offset calibration. Multi-band OFDM Alliance

  4. Time T “Strobes” Generation Simulation Multipath: Typical CM1 Channel; Noise: AWGN, 0 dB SNR Time Quantized To: 1 / (528 MHz) = 1.9 ns steps Max Quantizing Error ~ 1 ns => tp accuracy ~ 1 ns ~ 30 cm / measurement Simplified Preamble … A A A IA A A = 127-bit PRBS Inverted A Multi-band OFDM Alliance

  5. Precision “Vernier” for Ranging(Byproduct of Sample Timing Clock Adjustment) Sampler FIR Baseband Signal FIR Matched to Preamble Sequence Sampling Clock Phase Adjust Vernier Readout Step Size = 250 ps or Less Multi-band OFDM Alliance

  6. Time T “Strobes” Generation Simulation Multipath: CM3 Channel #20; Noise: AWGN, 0 dB SNR Some Channels will Require Carefully Set Thresholds Simplified Preamble … A A A IA A A = 127-bit PRBS Inverted A Multi-band OFDM Alliance

  7. MB-OFDM Ranging Summary • TWTT removes the issue of “turnaround latency”. • MB-OFDM preamble alone enables ranging accurate to ~1 foot (30 cm) per measurement. Addition of sampling-clock phase-correction vernier yields precision better than 10 cm. • Techniques to yield even finer resolution per measurement are under study at Sony, U.Minn. • Multiple measurements over multiple 528 MHz sub-bands will enable preamble-ranging accuracy & precisions to 10 cm or better. • Conclusion: MB-OFDM is fully capable of high accuracy/precision ranging. Multi-band OFDM Alliance

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