1. Date Submitted: [18 July 2005]
14 April 2019
July 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Qualitative and Quantitative Comparison of UWB Ranging Proposals]
Date Submitted: [18 July 2005]
Source: [Francois Chin, Sam Kwok, Institute for Infocomm Research (Singapore)]
Company: [Institute for Infocomm Research, Singapore]
Address: [21 Heng Mui Keng Terrace, Singapore ]
Voice: [ ] FAX: [ ]
Abstract: [This document provides qualitative and quantitative comparison of ranging signal waveforms with Simulation results]
Purpose: [To help objectively evaluate ranging proposals under consideration]
Notice: This document has been prepared to assist the IEEE P 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 P

2. Proposed receiver architectures Qualitative comparison Simulations
July 2005
Outline
Proposed waveforms
Proposed receiver architectures
Qualitative comparison
Technical differences
Simulations
Comments

3. Proposed System Parameters (With Same # Pulses per unit time)
July 2005
Proposed System Parameters (With Same # Pulses per unit time)
Option-I (Burst PPM)
The Other Bit
One Bit
Always Empty
Always Empty
Always Empty
4-pulses
4 pulses
Option-III (Ternary Sequences)
………………………… 1 2 3 31 4 5 6 7 8 30
Pulse Repetition Interval ~ 62.5ns
Option-IV (Pulse PPM)
Tp = 4ns
Tf = ~125ns
PRP ± TH

4. Simulations (I2R) Observation window = 512ns
Same # pulses per us for all schemes
TOA Ambiguity = 256ns
Ts3 = 2048ns*
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.
Sunday, April 14, 2019

5. Energy Detection Receiver Architectures
July 2005
"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
FT R&D
BPF
( )2
LPF /
2-4ns
integrator
ADC
TOA Estimator
Sliding Correlator
Energy combining across symbols
interference suppression
1D-2D Conversion
2D-1D Conversion
Energy image
generation
Bipolar template
I2R
1D to 2D Conversion
Length-3 Vertical Median or Minimum Filtering
Removes interference
2D to 1D Conversion with Energy Combining
Energy image generation
MERL

6. Energy Map for Sliding Correlator (I2R)
July 2005
Simulation parameters
CM1 channel
energy window size = channel tap separation = ns (16 energy window within PRI of 62.5ns)
16 preamble symbol, each consists 31-chip ternary sequence
Combine / average over symbols (each symbol = 16x31 map)
3 cases
Eb/No = 22 dB, no interference
Eb/No = 15 dB, no interference
Eb/No = 22 dB, SIR = -6dB
CM1 Channel
Leading edge

7. Energy Map with Sliding Correlator (I2R)
Leading edge
July 2005
Eb/No = 22dB, no interference
Energy image
generation
interference suppression
Energy combining across symbols
1D-2D conver-sion
Sliding Correlator
Bipolar Sequence
Symbol Period

8. Energy Map for Sliding Correlator (I2R)
Leading edge
July 2005
Eb/No = 15dB, no interference
Energy image
generation
interference suppression
Energy combining across symbols
1D-2D conver-sion
Sliding Correlator
Bipolar Sequence
Symbol Period

9. Energy Map for Sliding Correlator (I2R)
Leading edge
July 2005
Eb/No = 22dB, SIR = -6dB
Energy image
generation
interference suppression
Energy combining across symbols
1D-2D conver-sion
Sliding Correlator
Bipolar Sequence
Symbol Period

10. Ranging with Option – III
July 2005
Ranging with Option – III
Transmit signaling is pure equally spaced pulses
Method used is sliding correlator, energy detector and coherent detector alike
The sliding correlator output, after symbol combining, has the energy content of the close to channel impulse response, even in the presence of AWGN and SOP interference

11. Technical Differences and Commonalities
July 2005
Technical Differences and Commonalities
Pulse OOK (option-III)
Burst PPM (option-I)
Pulse OOK (option-IV)
Coherent Ternary
Energy Integration period (for ranging)
2~4ns
Type of receiver that can receive this Common signaling preamble
Coherent, differential & energy detector
Coherent, energy detector
Coherent
Symbol Duration
2us
Pulses per symbol 16
Pulses per microsecond 8
Edge per symbol 4
# of edges per us 2
Power per pulse P
Side Lobe to Peak Ratio (periodic)
N/A
1/N
Peak Signal to Interference Ratio
6dB
3dB
Zero Correlation Zone (periodic)
Yes (symbol wide)
Yes (fraction of a symbol)
Noise Variance (noise only region)
32 Units
4 Units
16 Units
Noise Floor Level
1 Unit
0 Units

12. Anomaly in Option-4 (Due to short Zero Corr Zone)
Transmitted
Time-hopping
Sequence
ACF of the
Transmitted
Time-hopping
Sequence
Zero Correlation Zone
Multipath
components
Peak
Leading
Edge
Received energy
samples (after
processed with the
time-hopping code)
Search-back the
leading edge
Sunday, April 14, 2019

13. Simulation Parameters
July 2005
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

14. Assume that µn and σn2 mean and the variance of the noise respectively
July 2005
Threshold Selection
Assume that µn and σn2 mean and the variance of the noise respectively
Probability that a noise only sample greater than a threshold ε is
Probability of threshold crossing within K consecutive noise only samples
The corresponding threshold is
PFA ε

15. Simulation Assumptions
July 2005
Simulation Assumptions
Acquisition of the Multipath Peak is assumed
No timing drift
Static channels
Pulse-PPM is not simulated as the timing hopping codes is not available

16. Simulation Results (Pulse-OOK)
July 2005
Simulation Results (Pulse-OOK)

17. Simulation Results (Pulse-OOK)
July 2005
Simulation Results (Pulse-OOK)

18. Simulation Results (Burst-PPM)
July 2005
Simulation Results (Burst-PPM)

19. Simulation Results (Burst-PPM)
July 2005
Simulation Results (Burst-PPM)

20. At high Es/No, MAE increases with FA
July 2005
Simulation Summary
At high Es/No, MAE increases with FA
the ranging performance is FA-limited
At low Es/No, MAE decreases with FA
High FA leads to lower threshold; it is easier for the low signal strength leading edge to cross the threshold, thus better detection probability
Based on 4ns energy window
3ns 90% confidence level around 11dB for Burst-PPM
3ns 90% confidence level around 10dB for Pulse-OOK
Possible reason
within 2us, Pulse-OOK has 16 signal accumulation, and 32 noise enhancement, per path SNR gain in averaging = 162/32 = 8
within 2us, Burst-PPM has 4 signal accumulation, and 4 noise enhancement, per path SNR gain in averaging = 42/4 = 4
Option-3 performed the best both in terms of 3ns confidence level and mean absolute error (MAE)

21. Other comparisons July 2005 Pulse OOK (option-III)
Burst PPM (option-I)
Pulse PPM (option-IV)
Signaling
Spaced out pulse seq
Clustered pulse seq
TH pulse seq
Energy Integration period (for ranging)
2~4ns
Energy Integration period (for data comm.)
2ns ~ PRI (30ns)
Half Symbol period
2ns ~ 4ns
Common signaling for preamble
No Time hopping
Time 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
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)

22. Other comparisons July 2005 Pulse OOK (option-III)
Burst PPM (option-I)
Pulse PPM (option-IV)
Inter-pulse interference during ranging operation
Less due to high PRI
(e.g. ~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)
(e.g. 26.6MHz)
High in transmitter
(e.g. 64MHz)
Power saving transmission within symbol period
Not possible
Possible
Transmit power (Ranging)

23. Implication of Ranging preamble on Common Signaling
July 2005
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

24. Summary of comparisons
July 2005
Summary of comparisons
Autocorrelation sidelobes
Option-IV does have sidelobes, Zero Corr zone duration?
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
Typically, coherent receiver can perform ranging with code despreading alone
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
SOP performance
lower SOP suppression for option-I due to fewer hops per unit time

25. July 2005
Recommendation
Adopt Ternary based pulse-OOK waveform (option-3) for preamble signaling
Justifications
Ranging preamble for energy detector will be in common signaling; coherent receiver will have to detect the same preamble. It does not unnecessarily burden the coherent receiver with two layer despreading (TH + code despreading)
Zero auto-corr zone through the whole preamble symbol
Lower power consumption due to low transmit clock rate
Probably best SOP performance, especially in dense multipath environment