1. Doc: IEEE 15-05-0383-02-004a 19 July 2005 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, Andy Molisch, Philip Orlik, 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. Doc: IEEE 15-05-0383-02-004a 19 July 2005 2 Outline Signal waveforms Receiver architectures Threshold and search back Simulations Summary Recommendations

3. Doc: IEEE 15-05-0383-02-004a 19 July 2005 3 Objective Study feasibility of non-coherent ranging Evaluate ranging performance of various proposals

4. Doc: IEEE 15-05-0383-02-004a 19 July 2005 4 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

5. Doc: IEEE 15-05-0383-02-004a 19 July 2005 5 4 pulses One Bit Always Empty 4-pulses Option-III (Ternary Sequences) ………………………… 12331 45678 30 Pulse Repetition Interval ~ 62.5ns Option-IV (Pulse PPM) Tp = 4ns Tf = ~125ns PRP ± TH Option-I (Burst PPM) The Other Bit Proposed System Parameters (With Same # Pulses per unit time)

6. Doc: IEEE 15-05-0383-02-004a 19 July 2005 6 Technical Differences and Commonalities Pulse OOK (option-III)Burst PPM (option-I)Pulse OOK (option-IV) Energy Integration period (for ranging) 2~4ns Type of receiver that can receive this Common signaling preamble Coherent, differential & energy detector Coherent, energy detector Symbol Duration2us Pulses per symbol16 Pulses per microsecond888 Edge per symbol164 # of edges per us 828 Power per pulse PPP Peak to Side Lobe Ratio (PSLR) - periodic 0 (at the cost of increased noise variance) N/A1/N Peak Signal to Interference Ratio6dBN/A3dB Zero Correlation Zone (periodic)Yes (symbol wide)N/AYes (fraction of a symbol) Noise Variance (noise only region) in 2us of preamble 32 Units 4 Units 16 Units Noise Floor Level 1 Unit (16+, 15- in the bipolar correlation template) 4 Units 16 Units

7. Doc: IEEE 15-05-0383-02-004a 19 July 2005 7 Energy Detection Receiver Architectures TOA Estimator BPF ( ) 2 LPF / 2-4ns integrator ADC 1D to 2D Conversion Length-3 Vertical Median or Minimum Filtering Removes interference 2D to 1D Conversion with Energy Combining Energy image generation "Path-arrival dates" table 1D to 2D Conversion Assumption path synchronization Matrix Filtering + Assumption/path selection Time base 1-2ns accuracy Time stamping Analog comparator Sliding Correlator Energy combining across symbols interference suppression 1D-2D Conversion 2D-1D Conversion Energy image generation Bipolar template MERL I2RI2R FT R&D

8. Doc: IEEE 15-05-0383-02-004a 19 July 2005 8 LOS Before and After Square-Law A 500MHz pulse (4ns duration) is passed through a channel sampled at 8GHz Received signal energy is collected at 4ns intervals Strong LOS is lost First arriving energy block Strongest energy block First arriving and strongest path Channel realization Energy collection at 4ns

9. Doc: IEEE 15-05-0383-02-004a 19 July 2005 9 Another example Channel realization Energy collection at 4ns With a search back window of 32ns, in this realization the first energy block is missed (the error was 4 energy blocks (2ns +3*4ns = 14ns)

10. Doc: IEEE 15-05-0383-02-004a 19 July 2005 10 Threshold Selection Assume that µ n and σ n 2 mean 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 PFAε

11. Doc: IEEE 15-05-0383-02-004a 19 July 2005 11 Fixed Search Back Fixed search back window length is not very efficient p Strongest energy block x First signal energy z Fixed search back window t threshold y First threshold crossing within 430 (TOA estimate)

12. Doc: IEEE 15-05-0383-02-004a 19 July 2005 12 Adaptive and Iterative Search Back K-iterative search back deals with K consecutive noise only blocks As long as a cluster is detected backward, the search back continues z Strongest energy block x First signal energy p noise dependent threshold y Iterative search back 0123 nn+1n+2n+3 Energy block index

13. Doc: IEEE 15-05-0363-01-004a Wednesday, October 14, 2015 T s 3 = 2048ns* T s 1 = T s 4 = 512ns TOA Ambiguity = 256ns Observation window = 512ns Option 3 (16 pulses per 2us) Option 1 ** (16 pulses per 2us) Option 4 (16 pulses per 2us) * 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. Simulation Settings

14. Doc: IEEE 15-05-0383-02-004a 19 July 2005 14 Results P FA = 0.01, T B = 4ns

15. Doc: IEEE 15-05-0383-02-004a 19 July 2005 15 Results P FA = 0.005, T B = 4ns

16. Doc: IEEE 15-05-0383-02-004a 19 July 2005 16 Results P FA = 0.001, T B = 4ns

17. Doc: IEEE 15-05-0383-02-004a 19 July 2005 17 Results P FA = 0.05, T B = 2ns

18. Doc: IEEE 15-05-0383-02-004a 19 July 2005 18 Results P FA = 0.01, T B = 2ns

19. Doc: IEEE 15-05-0383-02-004a 19 July 2005 19 Results P FA = 0.005, T B = 2ns

20. Doc: IEEE 15-05-0363-01-004a Wednesday, October 14, 2015 Transmitted Time-hopping Sequence ACF of the Transmitted Time-hopping Sequence Zero Correlation Zone Received energy samples (after processed with the time-hopping code) Multipath components Peak Search-back the leading edge Leading Edge Anomaly in Option-4

21. Doc: IEEE 15-05-0383-02-004a 19 July 2005 21 Summary 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 performed the best both in terms of 3ns confidence level and mean absolute error (MAE). –Increasing the sampling rate gained us 2dB 3ns 90% confidence level around 13dB at 2ns sampling interval The MAE is appr. 2ns at 13dB with 2ns sampling interval In order to have SOP support, symbol duration should be prolonged in option-1 –This lowers the achievable bit rate (<1Mbps) Coherent processing is faster with burst PPM

22. Doc: IEEE 15-05-0383-02-004a 19 July 2005 22 Recommendation to the IEEE 802.15.4a TG Lower the bit rate from 1Mbps to 500Kbps –This will provide Non-coherent with option-1 with better SOP support Better non-coherent ranging Adopt option-1 waveform in preamble

23. Doc: IEEE 15-05-0383-02-004a 19 July 2005 23 Backup Slide EBN0 = 22dB, Interference and desired equidistant to the receiver Strong SOP interference is easily suppressed by the way the image is created and by means of length-3 minimum filtering (in ranging) Desired User Energy Multi-user Interference Block Index Symbol Index Minimum Filtering { Length 3 Vertical} Symbol Index Block Index