Non-coherent Ranging with A-priori Noise Variance Knowledge

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Non-coherent ranging results with a-priori knowledge of noise variance] Date Submitted: [24 June 2005] Source: [Ismail Guvenc, Zafer Sahinoglu, Mitsubishi Electric] Contact:Zafer Sahinoglu Voice:[+1 617 621 7588, E-Mail: zafer@merl.com] Abstract: [This document provides performance results of non-coherent ranging receivers, under the assumption that noise variance is accurately estimated and available a-priori] Purpose: [To help objectively evaluate ranging proposals under consideration] 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. Option-III (Ternary Sequences) Pulse Repetition Interval ~ 62.5ns 4 5 6 7 8 1 2 3 30 31 ………………………… Option-IV (Pulse PPM) Tp = 4ns PRP ± TH Tf = ~125ns Proposed System Parameters (With Same # Pulses per unit time) (by MERL) Option-I (Burst PPM) The Other Bit One Bit Always Empty Always Empty Always Empty 8-chip times: 150ns 100ns 100ns 8-chip times: 150ns

3. Filtering + Assumption/path selection Time base 1-2ns accuracy Energy image generation Removes interference Assumption path synchronization Matrix Analog comparator Time stamping "Path-arrival dates" table 1D to 2D Conversion Length-3 Vertical Median or Minimum Filtering 2D to 1D Conversion with Energy Combining 1D to 2D Conversion BPF ( )2 LPF / 2-4ns integrator interference suppression Energy image generation Energy combining across symbols 1D-2D Conversion Sliding Correlator 2D-1D Conversion ADC Bipolar template Energy Detection Receiver Architectures FT R&D TOA Estimator I2R MERL

4. Observation window = 512ns TOA Ambiguity = 256ns Ts3 = 2048ns* Simulations Option 3 (16 pulses per 2us) Option 1 ** (16 pulses per 2us) Option 4 (16 pulses per 2us) Ts1 = Ts4 = 512ns * Since option-3 uses 31 chip sequences, 1984ns symbol duration is used for option-3 to have multiples of 4ns sampling duration. However, total energy used within 4ms duration are identical for all cases. ** A training sequence of all 1’s are used. Random training sequence will introduce self interference that will degrade the performance.

5. Threshold Selection • Assume that µn and σn2mean and the variance of the noise respectively • Probability that a noise only sample greater than a threshold ε is • Probability of threshold crossing within K consecutive noise only samples • The corresponding threshold is PFA ε

6. Results • PFA = 0.1, TB = 4ns

7. Results • PFA = 0.05, TB = 4ns

8. Results • PFA = 0.01, TB = 4ns

9. Results • PFA = 0.005, TB = 4ns

10. Results • PFA = 0.001, TB = 4ns

11. Results • PFA = 0.1, TB = 2ns

12. Results • PFA = 0.05, TB = 2ns

13. Results • PFA = 0.01, TB = 2ns

14. Results • PFA = 0.005, TB = 2ns

15. Conclusion • A-priori knowledge of noise variance improved ranging performance • Threshold is set according to the noise variance and probability of missing a block, not according to the percentage of the highest signal energy block • This made option-4 suffered. • Option-1 (after processing gain) performed the best both in terms of 3ns confidence level and mean absolute error (MAE). • 3ns confidence level can be 90% around 15dB, at 4ns sampling interval, and around 13dB at 2ns sampling interval • MAE is around 2ns at 15dB at 4ns sampling interval, and at 13dB at 2ns sampling interval