1. Signal Waveform Comparisons
Z. Sahinoglu, I. Guvenc, P. Orlik
Digital Communications and Networking Group
Wednesday, June 05, 2019

2. 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
Saturday, May 28, 2005

3. Coherent receivers exploit chip sequence patterns
Features of Option-I
Coherent receivers exploit chip sequence patterns
Non-coherent receivers see in which half the energy arrives
In ranging preamble, each piconet is assigned a different sequence of bits
Symbol rate is
1Msps (after rate ½ code)
Saturday, May 28, 2005

4. Example SOP preambles in Ranging with Option-I
Piconet-I bit sequence: {1,0,0,1,1}
Piconet-II bit sequence: {1,1,0,0,0}
Saturday, May 28, 2005

5. Ranging Performance of Option-I
Very resilient to SOP interference due to proper selection of preamble bit sequences
For non-coherent radios,
inter-pulse-interference due to multipath does not need to be resolved
Statistical multiplexing is needed to increase SNR due to spreading bit energy over many pulses
Preliminary results
A train of 8-pulses
EbN0 = 22dB, SIR = 0dB (randomly generated 30 symbols in the preambles of desired and interference)
CM1
Integration interval: 4ns
Ranging error: 3ns (72%)
Better accuracy if narrower energy windows
Saturday, May 28, 2005

6. Modulation with Option-I
Additional time hopping of blocks is needed to support 2-SOP
Ex: Another 160ns interval in each half of the frame
When same bit waveforms are used, symbol rate needs to be halved
It is still an option to use different waveforms in communication to increase symbol rates
Saturday, May 28, 2005

7. 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)
Saturday, May 28, 2005

8. Pulses (or doublets) are spread over the entire 500ns symbol duration
Option-II Features
Pulses (or doublets) are spread over the entire 500ns symbol duration
Non-coherent decoding and ranging with this waveform has not been simulated yet
Has potentially better SOP isolation than Option-I in communication mode
Saturday, May 28, 2005

9. Option-III
Criteria/Target – balance max post-despreading SNR and low auto-correlation side lobes
Ternary Seq [ ]
After Square Law
& Integration in PRI
Unipolar M-Seq [ ]
In AWGN
Soft output
Noncoherent detection of OOK
Sliding
Correlator
LPF /
integrator
BPF
( )2
ADC
Sample Rate 1/Tc
{1,-1} Binary Sequence
Bipolar M-Seq [ ]
Saturday, May 28, 2005

10. Zero autocorrelation side lobe sequences
Option-III Features
Zero autocorrelation side lobe sequences
Under SOP interference, correlator peak is 3dB degraded in non-coherent reception due to suboptimal correlation
This makes identification of weak multipath components difficult
After the square-law device, the integrator integrates over the PRI (~30ns)
In option-I, integration interval is 2ns or 4ns.
Longer integration interval collects more noise in
Longer integration interval collects more interference energy in
Saturday, May 28, 2005

11. Recommended Architecture for Ranging with Non-Coherent Rx
(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
I will get into the details of the colored blocks in the next round !!! ZS
TOA Estimator
Saturday, May 28, 2005

12. Effect of Number of Pulses on Performance for Non-Coherent Modulation and Ranging: An Example
Case 1: Single Pulse Per Symbol
N = 1
s = 0
s = 1 μ1
MN0
MN0+2NsEb
σ12
MN02
MN0+4N0NsEb
PDF
s = 0
s = 1
Transmitting one pulse with large energy
Energy
Energy of this pulse is NsEb μ1
Saturday, May 28, 2005

13. Effect of Number of Pulses on Performance for Non-Coherent Modulation and Ranging: An Example
Case 2: Multiple Pulses Per Symbol
N = Ns
s = 0
s = 1 μ2
NsMN0
Ns(MN02+2Eb)
σ22
NsMN02
Ns(MN02+4N0Eb)
Transmitting many pulses with less energies
PDF
s = 0
s = 1
Energy
Energy of each pulse is Eb, and there are Ns number of pulses μ2
Saturday, May 28, 2005

14. The energy per symbol can be collected in a single
Effect of Number of Pulses on Performance for Non-Coherent Modulation and Ranging
The energy per symbol can be collected in a single
pulse (N=1), or in Ns pulses
The means and variances statistics of the square-law
device outputs can be observed in the absence and
presence of signal
The Euclidean distance between the means for s=0,
and s=1 are the same for both cases (2NsEb)
However, the variance term when using larger number
of pulses increases
Saturday, May 28, 2005

15. Current Status
MERL is simulating Option-III according to the recommended block diagram, and will share the observations soon
Preliminary Option-I results are shared on slide 5
There are still unincorporated optimization techniques to improve edge detection performance
Adaptive threshold selection
Search back window selection etc
Saturday, May 28, 2005