Ranging with MB-OFDM Dave Leeper (Intel)

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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)

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MB-OFDM Ranging

• Eliminating the turnaround latency issue
• Obtaining high accuracy/precision ranging from
  MB-OFDM-based systems

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UWB Ranging via Two-Way Time TransferResults
are Independent of Turnaround-Time Latency
Device A
Device B
Two equations in two unknowns yield
Multiple measurements of tp and to yield finer
precision accuracy, and allow frequency offset
correction.
US Naval Observatory, Telstar Satellite, circa
1962 http//www.boulder.nist.gov/timefreq/time/two
way.htm Unmatched detect-delays in the two
devices may require one-time offset calibration.
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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 gt tp accuracy 1 ns
30 cm / measurement
Simplified Preamble

A
A
A
IA
A
A 127-bit PRBS
Inverted A
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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
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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
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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.