1. Doc: IEEE 15-05-0363-02-004a 27 June 2005 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Qualitative and Quantitative Comparison of Ranging Proposals] Date Submitted: [24 June 2005] Source: [Zafer Sahinoglu, Ismail Guvenc, Mitsubishi Electric Francois Chin, Sam Kwok, Institute for Infocomm Research (Singapore)] Contact: Zafer Sahinoglu Voice:[+1 617 621 7588, E-Mail: zafer@merl.com] Abstract: [This document provides qualitative and quantitative comparison of ranging signal waveforms. Simulation results are reported] 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 15-05-0363-02-004a 27 June 2005 2 Outline Proposed waveforms Proposed receiver architectures Qualitative comparison –Technical differences Simulations Comments

3. Doc: IEEE 15-05-0363-02-004a 27 June 2005 3 8-chip times: 150ns One Bit Always Empty 100ns 8-chip times: 150ns 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) (by MERL)

4. Doc: IEEE 15-05-0363-02-004a 27 June 2005 4 Technical Differences and Commonalities (by MERL) 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 Duration1us0.5us Pulses per symbol1684 Pulses per microsecond16 8 Edge per symbol1614 # of edges per us 1628 Power per pulse PP2P Peak to Side Lobe Ratio (PSLR) - periodic 0 (at the cost of increased noise variance) N/A1/N, N=4 Peak Signal to Interference Ratio6dBN/A3dB Zero Correlation Zone (periodic)Yes (symbol wide)N/AYes Noise Variance (noise only region) 32 Units 2 Units 8 Units Noise Floor Level (DC Offset within 1 us) 1 Unit (16+, 15- in the bipolar correlation template) 2 Units 8 Units

5. Doc: IEEE 15-05-0363-01-004a Saturday, March 12, 2016 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 ** (32 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. Simulations

6. Doc: IEEE 15-05-0363-02-004a 27 June 2005 6 8-chip times: 300ns One Bit Always Empty 200ns 8-chip times: 300ns 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) (by I 2 R) Option-III (Ternary Sequences) ………………………… 12331 45678 30 Pulse Repetition Interval ~ 62.5ns Min Tx CLK = 8/0.3us = 26.6MHz Min Tx CLK ~ 1/62.5 ns = 16MHz Min Tx CLK = 8/0.125us = 64MHz

7. Doc: IEEE 15-05-0363-02-004a 27 June 2005 7 Technical Differences and Commonalities (by I 2 R) 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 Duration2us1us0.5us Pulses per symbol1684 Pulses per microsecond888 Edge per symbol1614 # of edges per us 818 Power per pulse PPP Peak to Side Lobe Ratio (PSLR) - periodic 0 (at the cost of increased noise variance) N/A1/N, N=4 Peak Signal to Interference Ratio6dBN/A3dB Zero Correlation Zone (periodic)Yes (symbol wide)N/AYes Noise Variance (noise only region) in 1us of preamble 16 Units 1 Units 8 Units Noise Floor Level (DC Offset within 1 us) 1 Unit (16+, 15- in the bipolar correlation template) 2 Units 8 Units

8. Doc: IEEE 15-05-0363-01-004a Saturday, March 12, 2016 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. Simulations (I 2 R) Same # pulses per us for all schemes

9. Doc: IEEE 15-05-0363-02-004a 27 June 2005 9 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

10. Doc: IEEE 15-05-0363-02-004a 27 June 2005 10 Simulation Parameters Energy within 2048 is normalized in all schemes Received waveforms are sampled at 4ns Samples averaged over 2000 symbols of 2048ns duration each (~4ms) Search-back step is applied after peak selection

11. Doc: IEEE 15-05-0363-01-004a Saturday, March 12, 2016 Normalized threshold = 0.1 (fixed) Search-back window = 32ns (fixed) Both parameters can be further adjusted and optimized based on the SNR Simulation Results

12. Doc: IEEE 15-05-0363-02-004a 27 June 2005 12 Comments: Option-1 Peak selection is performed after aggregation of the 8 pulses within the burst. However, edge information is weakened due to consecutive pulses and multipath, yielding smoother edges After peak selection using aggregated samples, search- back step is performed on non-aggregated samples, which preserves the edges, but degrades the SNR

13. Doc: IEEE 15-05-0363-02-004a 27 June 2005 13 Comments: Option-3 Excellent autocorrelation properties enables efficient search back step at high SNR The autocorrelation properties comes in the expense of increased noise variance due to using bipolar sequences of length twice the number of pulses May choose false edges at the search back step in the presence of noise

14. Doc: IEEE 15-05-0363-02-004a 27 June 2005 14 Comments: Option-4 Has autocorrelation side lobes Zero-correlation zone sequences can be effectively used to enable efficient search back Noise variance is smaller compared to option 3

15. Doc: IEEE 15-05-0363-02-004a 27 June 2005 15 Table of comparison Pulse OOK (option-III)Burst PPM (option-I)Pulse OOK (option-IV) SignalingSpaced out pulse seqClustered pulse seqTH pulse seq Energy Integration period (for ranging) 2~4ns Energy Integration period (for data comm.) 2ns ~ PRI (30ns)Half Symbol period2ns ~ 4ns Common signaling for preamble No Time hoppingTime Hopping Type of receiver that can receive this Common signaling preamble Coherent, differential & energy detector Coherent, energy detector Not suitable for differential detection Available #pulses for noise averaging for leading edge detection Each pulse contributes to noise averaging There is only one leading edge for each burst of pulses in each symbol Each pulse contributes to noise averaging Additional complexity for Coherent receiver to receive preamble with common signaling No (conventional despreading with equally space chips) Yes (2 layer sync, TH then code de- spreading) Yes (looks like much longer spreading code with sparsely distributed pulses)

16. Doc: IEEE 15-05-0363-02-004a 27 June 2005 16 Table of comparison Pulse OOK (option-III)Burst PPM (option-I)Pulse OOK (option-IV) Inter-pulse interference during ranging operation Less due to high PRI (e.g. ~60ns @ ~16MHz PRF) More due to small inter pulse interval (but, this could be an issue for the coherent detector, which will look into the pulses….) Random due to pulse hopping Clock rate (Ranging)High in receiver Low in transmitter (e.g. 16MHz) High in receiver Low in transmitter (e.g. 26.6MHz) High in receiver High in transmitter (e.g. 64MHz) Power saving transmission within symbol period Not possiblePossibleNot possible Transmit power (Ranging) High in receiver Low in transmitter High in receiver Low in transmitter High in receiver High in transmitter

17. Doc: IEEE 15-05-0363-02-004a 27 June 2005 17 Implication of Ranging preamble on Common Signaling The choice of ranging preamble (RP) for energy detector will eventually determine the common signaling scheme, that is to be received by coherent, differential and energy detectors, as –the chosen ranging preamble (RP) will be the synchronisation preamble for energy detector; –As such, (RP) will be the preamble for common signaling preamble, as common signaling preamble is to be understood by energy detector too –It is important to design a (RP) for energy detector, that can be understood by coherent and differential detector receivers with minimal additional cost / complexity

18. Doc: IEEE 15-05-0363-02-004a 27 June 2005 18 Summary of comparisons Preamble options understood by coherent, differential and energy detector as common signaling? –Option-IV not feasible for differential detector Available pulses for leading edge detection averaging given preamble length –Option-I suffers because it has only one leading edge per burst of pulses within one symbol Additional complexity for coherent receiver due to common signaling –Additional layer of Time hopping for option-I and option-IV Power consumption for ranging preambles –High for option-IV due to higher transmit clock rate

19. Doc: IEEE 15-05-0363-02-004a 27 June 2005 19 General Summary At E B N 0 = 17dB or higher, 88% confidence level is achieved for 3ns or less ranging error (4ms preamble) Confidence level can be further increased by adaptive selection of the threshold and search back window size FT R&D Receiver Architecture MERL Receiver Architecture I 2 R Receiver Architecture Bulk PPM (Option-1) Ternary Sequence (Option-III) TH-IR (Option-IV)