1. Post equalizer SNR estimation
May 2015
doc.: IEEE /0496r1
March 2018
Post equalizer SNR estimation
Date: 2018-March-5
Authors:
Name
Company
Address
Phone
Alecsander Eitan
Qualcomm
Assaf Kasher
Michael Grigat
Deutsche Telekom
Alecsander Eitan (Qualcomm)
Edward Au (Marvell Semiconductor)

2. March 2018
Introduction
TDD operation requires to have a “Link Maintenance” feature, which includes various parameters regarding the quality of the received signal at the receiver side.
Some of these parameters are Post Equalizer SNR and LDPC statistics.
This presentation presents the expected behavior of Hard-Decision EVM as a candidate for Post Equalizer SNR estimation and the correlation to LDPC statistics.
Alecsander Eitan (Qualcomm)

3. What is Hard-Decision EVM ?
March 2018
What is Hard-Decision EVM ?
Estimation of the Post Equalizer SNR is very simple given that the transmitted symbols are known.
Hard-Decision EVM is one of the most simplest methods to estimate the Post Equalizer SNR. The estimation can be done as part of the de-mapping process.
Post Equalizer SNR based on re-encoded symbols are more accurate (if the LDPC was successfully decoded) but is more complex and expensive.
Post Equalizer SNR and Hard-Decision EVM are supporting a very wide range of SNR values.
Hard-Decision EVM requires some correction function to reduce the bias.
Alecsander Eitan (Qualcomm)

4. Post Equalizer SNR - True and HD based
March 2018
Post Equalizer SNR - True and HD based
Alecsander Eitan (Qualcomm)

5. Simulation DMG SC MCS: 10,11,12,12.1 (16QAM)
March 2018
Simulation
DMG SC
MCS: 10,11,12,12.1 (16QAM)
Per each SNR: 100 frames, 20 FDE blocks
Fixed point with analog impairments
AWGN channel
Vertical bars present 5 and 95 percentiles
HD based Post Equalizer SNR correction function not included
Alecsander Eitan (Qualcomm)

6. Post Equalizer SNR - True and HD based
March 2018
Post Equalizer SNR - True and HD based
Alecsander Eitan (Qualcomm)

7. Post Equalizer SNR - True and HD based
March 2018
Post Equalizer SNR - True and HD based
Alecsander Eitan (Qualcomm)

8. Post Equalizer SNR - True and HD based
March 2018
Post Equalizer SNR - True and HD based
Alecsander Eitan (Qualcomm)

9. Post Equalizer SNR - True and HD based
March 2018
Post Equalizer SNR - True and HD based
QPSK
Alecsander Eitan (Qualcomm)

10. Post Equalizer SNR - True and HD based
March 2018
Post Equalizer SNR - True and HD based
QPSK
Alecsander Eitan (Qualcomm)

11. Post Equalizer SNR and LDPC average iterations
March 2018
Post Equalizer SNR and LDPC average iterations
Alecsander Eitan (Qualcomm)

12. Post Equalizer SNR and LDPC average iterations
March 2018
Post Equalizer SNR and LDPC average iterations
Alecsander Eitan (Qualcomm)

13. March 2018
Conclusion
The HD based Post Equalizer EVM is a good approximation method for the Post Equalizer EVM.
Low variability
Wide dynamic range
Saturation effect at low SNR – to be compensated by correction function
Saturation effect at high SNR caused by quantization
Compensation per modulation is required
Alecsander Eitan (Qualcomm)