Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Ranging Signal Waveforms: Non-coherent Ranging Proposals (Overview) Date Submitted: [13 June, 2005] Source: [Zafer Sahinoglu] Company [Mitsubishi Electric.] Address [201 Broadway, Cambridge, MA 02139] Voice617 621-7588], FAX: [617 621-7549], E-Mail: [zafer@merl.com] Re: [802.15.4a.] Abstract: [Overview of ranging receiver architectures for non-coherent reception] Purpose: [To promote discussion in 802.15.4a.] 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.

Outline Signal Waveforms Receiver Architecture Comparison of Proposals Issues in Non-coherent ranging Suggestions

There are 4 waveforms under consideration Signal Waveforms There are 4 waveforms under consideration Bulk PPM IR-TR (Impulse Radio Transmitted Reference) MTOK sequences TH-IR (Time Hopping Impulse Radio)

Option-I One Bit The Other Bit Always Empty Always Empty Always Empty 100ns 8-chip times: 150ns 100ns 8-chip times: 150ns The Other Bit Always Empty Always Empty Always Empty 8-chip times: 150ns 100ns Enough long not to cause IFI : 100ns 8-chip times: 150ns

Option-II Ts = 500ns « 11 » 2-PPM + TR base M = 2 « 01 » « 11 » 2-PPM + TR base M = 2 One bit/symbol « 01 » « 10 » « 00 » (coherent decoding possible)

Ternary Signaling for Synchronization & Ranging Option-III To compare fairly, with option-I, which has 8 pulses in 500ns, the PRI for option-III is 62.5ns Ternary Signaling for Synchronization & Ranging Pulse Repetition Interval ~ 62.5ns -Common signaling (Mode 1) for ALL Detectors -Receiver-specific signaling (Mode 2) for ED 1 2 3 4 5 6 7 8 30 31 ………………………… Non-inverted pulses are blue, Inverted pulses are green. Synchronisation / Ranging preamble = Binary Base Sequence repeated For K times… …………… …………… ................. Symbol Interval =1937.5ns Symbol Interval =1937.5ns Tuesday, November 27, 2018

Option-IV Illustration: Use of an 8-ary Time Hopping code of length 4 Use of such a TH code combined with the band plan may allow to handle the SOP issue Code order and length are scalable to meet different requirements Tp = 4ns, Tc = 20 ns, Tf = 160 ns, Tsymbol = 640 ns PRP ± TH Tp Tc Tf

Recommended Architecture for Ranging with Non-Coherent Rx (MERL) (No FFT routine is needed, being different from doc#0269) Energy image generation Removes interference 2-4ns Length-3 Vertical Median or Minimum Filtering 1D to 2D Conversion LPF / integrator BPF ( )2 ADC 2D to 1D Conversion with Energy Combining TOA Estimator

Recommended Architecture for Ranging with Non-Coherent Rx (I2R) TOA Estimator Energy image generation & interference suppression 2D-1D conver-sion interference suppression 2-4ns Energy combining across symbols 1D-2D conversion Sliding Correlator LPF / integrator BPF ( )2 ADC Bipolar Template

Recommended Architecture for Ranging with Non-Coherent Rx (FT R&D) Time base 1-2ns accurate 4ns Time-stamping LPF / integrator Analog Comparator "Path-arrival dates" table BPF ( )2 1D to 2D Conversion Filtering + Assumption/path selection Assumption path synchronization Matrix TOA measure

Signal energy collection architecture is the same Commonalities Signal energy collection architecture is the same Sampling resolution is the same (e.g., 2ns-4ns) 1D to 2D conversion for interference removal seems to be adopted in all the architectures BPF LNA ADC Signal RF Part Analog comparator Energy image generation 1D to 2D Conversion Interference removal 2D to 1D Conversion TOA Estimator

Ranging Architecture Comparison MERL architecture works with all signal waveforms Its performance would be Very high in Option-4 (FT) High in Option-1 (MERL, TDC) Moderate in Option-3 (I2R) I2R and MERL receiver architectures have good support for scalability in TDOA applications (unsure about FT) Receive from TDOA stations simultaneously, without changing the RF front Decode TOA from each station at the post filtering Energy Matrix Generator-I Post Filtering 2D-1D conversion TOA Est. Post Filtering Energy Matrix Generator-M 2D-1D conversion TOA Est.

Feature Comparison Pulse OOK (option-III) Burst PPM (option-I) TH-IR Signaling Spaced out pulse seq Clustered pulse seq Time Hopping Impulse Radio Energy Integration period (for ranging) 2~4ns 2ns-4ns Performance @1Mbps without SOP TBD Performance @1Mbps with SOP Good in com. Mode Questionable in ranging (Sufficient processing gain to handle) good in ranging mode (Not much processing gain to handle the comm. mode) Good in ranging and comm. Pulse amplitudes may be a drawback Common signaling for preamble No Time hopping Time Hopping Additional complexity for Coherent receiver to receive preamble with common signaling No Yes (2 layer sync, TH then code de-spreading) TH Inter-pulse interference during ranging operation Less due to long PRI (30ns @ 33MHz PRF or ~60ns @ ~16MHz PRF) More due to small inter pulse interval Sampling rate in ranging Low in transmitter High in receiver Low in receiver High in transmitter

Issues in Non-coherent ranging Square-law operation is non-linear Relative improvement in SNR by statistical multiplexing is higher, when pulse amplitudes are higher Option-1 requires longer preamble than option-4 to achieve the same SNR level Error floor can be lowered for the same SNR level, by having narrower integration intervals - Preamble length For a given sampling resolution Mean absolute ranging error Higher sampling resolution + EbN0 25dB

Suggestions Test the ranging performance of the three proposals at a sufficiently high SNR without SOP To see the best achievable ranging accuracy with 90% confidence level To derive the required preamble length Test the ranging performance of the three proposals at the 90% level SNR from step-1 with SOP (SIR=0dB, 10dB) Quantify the degradation in ranging accuracy and confidence level