Simulations on Non-Coherent Ranging - Statistical Analysis of IEEE 802.15.4a Channels

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Simulationson non-coherent ranging] Date Submitted: [19 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 statistical analysis of IEEE 802.15.4a channels’ energy distribution] Purpose: [To provide input for optimization of system design parameters] 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 • Channel energy characteristics • Threshold statistics for CM1 and CM2 • TOA estimation • Mean Absolute Errors

3. Channel Energy Characteristics • Unit energy 1ns raised cosine pulse is passed through CM1 (LOS) and CM2 (NLOS) channels • Received signal energy is collected in 4ns integration intervals • Statistical delay and amplitude characteristics are derived after averaging over 1000 realizations

4. CM1 • PDF of the delay between the first energy block and strongest energy block is exponentially distributed (90% of the time less than 25ns) • Highest energy can reach 0.9, but at a very small probability • It is less than 0.6 at 90% confidence level

5. CM2 • PDF of the delay between the first energy block and strongest energy block is exponentially distributed (90% of the time less than 25ns) • Highest energy can reach 0.45 • It is less than 0.25 at 90% confidence level

6. CM4 • PDF of the delay between the first energy block • 90% of the time less than 22ns • Highest energy can reach 0.6 • It is less than 0.22 (at 90% confidence level)

7. CM8 • PDF of the delay between the first energy block • 90% of the time less than 115ns • Highest energy can reach 0.0009 • It is less than 0.0006 at 90% confidence level

8. Non-Coherent Receiver • Signal processing techniques are applied onto the outputs Z[n] of the ADC to find the first energy arrival 2-4ns Z [n] LPF / integrator BPF ( )2 ADC

9. Optimum Normalized Thresholds • Normalized optimum threshold selection for “first threshold crossing based TOA”

10. Mean Absolute Error • Even at optimum threshold settings, when threshold crossing is applied, the MAE is in the order of nanoseconds • Complex algorithms are needed to identify the first energy block • In the case of SOP interference, it becomes more challenging CM1 CM2 • EBN0: {8, 10, 12, 14, 16, 18, 20, 22, 24, 26}

11. Mean Absolute Error • Single 4ns unit energy pulse in each frame • No IFI • Search back with threshold crossing based TOA tracking • The MAE is lower bounded by 3-4ns • There are very large outliers that increase the MAE • 90% confidence level for 2ns error at 4ns integration would not be achievable even at very high SNRs