Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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] 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. Outline • Proposed waveforms • Proposed receiver architectures • Qualitative comparison • Technical differences • Simulations • Comments

3. 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 The Other Bit Option-I (Burst PPM) One Bit Always Empty Always Empty Always Empty 8-chip times: 150ns 100ns 100ns 8-chip times: 150ns

4. 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

5. Technical Differences and Commonalities

6. Observation window = 512ns TOA Ambiguity = 256ns Ts3 = 2048ns* Simulations Option 3 (16 pulses per 2us) Option 1 ** (32 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.

7. 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

8. Simulation Results Normalized threshold = 0.1 (fixed) Search-back window = 32ns (fixed) Both parameters can be further adjusted and optimized based on the SNR

9. 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

10. 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

11. 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