1 / 19

Comparative Evaluation of Ranging Proposals

This document provides a qualitative and quantitative comparison of ranging signal waveforms, with simulation results reported.

dorfman
Download Presentation

Comparative Evaluation of Ranging Proposals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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. 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 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

  4. Technical Differences and Commonalities (by MERL)

  5. 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.

  6. 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 I2R) Option-I (Burst PPM) The Other Bit Min Tx CLK = 8/0.3us = 26.6MHz One Bit Always Empty Always Empty Always Empty 8-chip times: 300ns 200ns 200ns 8-chip times: 300ns Min Tx CLK ~ 1/62.5 ns = 16MHz Min Tx CLK = 8/0.125us = 64MHz

  7. Technical Differences and Commonalities (by I2R)

  8. Observation window = 512ns Same # pulses per us for all schemes TOA Ambiguity = 256ns Ts3 = 2048ns* Simulations (I2R) 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.

  9. 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

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

  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. 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. 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. Table of comparison

  16. Table of comparison

  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. 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. General Summary • At EBN0 = 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 Bulk PPM (Option-1) FT R&D Receiver Architecture MERL Receiver Architecture TH-IR (Option-IV) I2R Receiver Architecture Ternary Sequence (Option-III)

More Related