1. Consideration of PHY design for 1.08GHz channel
Sept 2012
doc.: IEEE /xxxxr1
September 2013
Consideration of PHY design for 1.08GHz channel
Date:
Presenter:
Changming Zhang
Xiaoming Peng / I2R

2. Author List September 2013 Month Year doc.: IEEE 802.11-13/xxxxr1
Changming Zhang
John Doe, Some Company

3. Sept 2013
Abstract
This document is to propose a PHY design to support low power 1.08GHz PHY
It considers the PHY design with distortion compensation for I/Q imbalance for high order modulation and PA nonlinearity
Xiaoming Peng

4. 1.08GHz modulation and coding schemes Frame structure
September 2013
Roadmap
Background
1.08GHz modulation and coding schemes
Frame structure
IQ imbalance estimation and compensation
PA nonlinearity treatment
Conclusion
Changming Zhang

5. Channelization Consideration for 802.11aj
Month Year
doc.: IEEE /xxxxr1
September 2013
Channelization Consideration for aj
It is necessary to define 1.08GHz PHY
Changming Zhang
John Doe, Some Company

6. 1.08GHz modulation and coding schemes Frame structure
September 2013
Roadmap
Background
1.08GHz modulation and coding schemes
Frame structure
IQ imbalance estimation and compensation
PA nonlinearity treatment
Conclusion
Changming Zhang

7. CMCS Ctrl PHY September 2013 CMCS Index Modulation
Month Year
doc.: IEEE /xxxxr1
September 2013
CMCS
Ctrl PHY
CMCS Index
Modulation
Code Rate (Spreading Factor if not = 1)
Payload Rate，11ad (Mbps)
Payload Rate，1.08GHz (Mbps)
Pi/2-DBPSK
1/2 (32, with pi/2-rotation)
27.5
13.75
Changming Zhang
John Doe, Some Company

8. CMCS OFDM PHY September 2013 CMCS Index Modulation
Month Year
doc.: IEEE /xxxxr1
September 2013
CMCS
OFDM PHY
CMCS Index
Modulation
Code Rate (Spreading Factor if not = 1)
Payload Rate，11ad (Mbps)
Payload Rate，1.08GHz (Mbps) 18
SQPSK
1/2
693
346.5 19
5/8
866.25 20
QPSK
1386 21
1732.5 22
3/4
2079
1039.5 23
16QAM
2772 24
3465 25
4158 26
13/16
4504.5 27
64QAM
5197.5 28
6237
3118.5 29
Changming Zhang
John Doe, Some Company

9. CMCS MR SC PHY September 2013 CMCS Index Modulation
Month Year
doc.: IEEE /xxxxr1
September 2013
CMCS
MR SC PHY
CMCS Index
Modulation
Code Rate (Spreading Factor if not = 1)
Payload Rate，11ad (Mbps)
Payload Rate，1.08GHz (Mbps) 1
pi/2-BPSK
1/2 (2)
385
192.5 2
1/2
770 3
5/8
962.5
481.25 4
3/4
1155
577.5 5
13/16 6
pi/2-QPSK
1540 7
1925 8
2310 9
2502.5
Changming Zhang
John Doe, Some Company

10. CMCS HR SC PHY September 2013 CMCS Index Modulation
Month Year
doc.: IEEE /xxxxr1
September 2013
CMCS
HR SC PHY
CMCS Index
Modulation
Code Rate (Spreading Factor if not = 1)
Payload Rate，11ad (Mbps)
Payload Rate，1.08GHz (Mbps) 10
pi/2-16QAM
1/2
3080
1540 11
5/8
3850
1925 12
3/4
4620
2310 13
13/16 \
2502.5 14
pi/2-64QAM 15
2887.5 16
3465 17
Changming Zhang
John Doe, Some Company

11. CMCS Low power PHY September 2013 CMCS Index Modulation
Month Year
doc.: IEEE /xxxxr1
September 2013
CMCS
Low power PHY
CMCS Index
Modulation
Code Rate (Spreading Factor if not = 1)
Payload Rate，11ad (Mbps)
Payload Rate，1.08GHz (Mbps) 30
pi/2-BPSK
13/28
626
313 31
13/21
834
417 32
52/63
1112
656 33
pi/2-QPSK
1251
625.5 34
1668 35
2224 36
13/14
2503
1251.5
Changming Zhang
John Doe, Some Company

12. 1.08GHz modulation and coding schemes Frame structure
September 2013
Roadmap
Background
1.08GHz modulation and coding schemes
Frame structure
IQ imbalance estimation and compensation
PA nonlinearity treatment
Conclusion
Changming Zhang

13. Ctrl PHY (The same as 11ad)
Month Year
doc.: IEEE /xxxxr1
September 2013
Frame structure
Ctrl PHY (The same as 11ad)
OFDM PHY
Changming Zhang
John Doe, Some Company

14. MR SC PHY (The same as 11ad)
Month Year
doc.: IEEE /xxxxr1
September 2013
Frame structure
MR SC PHY (The same as 11ad)
HR SC PHY
Changming Zhang
John Doe, Some Company

15. Low power PHY (The same as 11ad)
Month Year
doc.: IEEE /xxxxr1
September 2013
Frame structure
Low power PHY (The same as 11ad)
Changming Zhang
John Doe, Some Company

16. 1.08GHz modulation and coding schemes Frame structure
September 2013
Roadmap
Background
1.08GHz modulation and coding schemes
Frame structure
IQ imbalance estimation and compensation
PA nonlinearity treatment
Conclusion
Changming Zhang

17. SFS-IQ imbalance estimation
Month Year
doc.: IEEE /xxxxr1
September 2013
SFS-IQ imbalance estimation
SFS (Single-Frequency Sequence)
Received baseband signal model:
The phase difference between adjacent symbols is fixed at π/2, but it does not mean SFS is single-frequency signal, it is also constructed by symbols with the same time duration as the preamble and payload.
The transmit MASK mainly depends on the time duration of symbols, so the MASK is maintained after SFS is added.
SFS is in front of the original STF, thus synchronization and channel estimation are not impacted by IQ imbalance .
The length of SFS is 512, but only 128 symbols is enough for IQ imbalance estimation, others are used for initial capture before IQ imbalance estimation.
Changming Zhang
John Doe, Some Company

18. SFS-IQ imbalance estimation
Month Year
doc.: IEEE /xxxxr1
September 2013
SFS-IQ imbalance estimation
By calculating the second-order expectations of every two adjacent: symbols:
Furthermore, let
Then
Thus, we can obtain:
The reason for “≈’’ is due to the neglect of Δθ, which is reasonable as Δθ is quite small.
Changming Zhang
John Doe, Some Company

19. SFS-IQ imbalance compensation
Month Year
doc.: IEEE /xxxxr1
September 2013
SFS-IQ imbalance compensation
With IQ imbalance, the received baseband signal can be expressed as:
Without the presence of IQ imbalance, the baseband signals can be expressed as
IQ compensation can be performed as:
Changming Zhang
John Doe, Some Company

20. Month Year
doc.: IEEE /xxxxr1
September 2013
Explanations
The proposed method for IQ imbalance treatment is almost independent of CFO.
As IQ imbalance is compensated at the front of synchronization, then CFO estimation and compensation is not impacted by IQ imbalance. However, before IQ compensation, CFO estimation and compensation is quite hard.
Consider the complexity, we only address RX frequency-independent IQ imbalance. However, as for frequency-dependent IQ imbalance, the proposed method can also achieve some effects, even though the compensation is not perfect in this case.
Due to the limit of transmit EVM, TX IQ imbalance is not so significant as RX IQ imbalance, so the proposed method that only considers RX IQ imbalance is reasonable.
Changming Zhang
John Doe, Some Company

21. September 2013 L=128, r=0.05，∆r=5； t=0.005，∆t=0.5
Changming Zhang

22. September 2013 L=128, r=0.05，∆r=5； t=0.005，∆t=0.5
Changming Zhang

23. September 2013 L=128, r=0.05，∆r=5； t=0.005，∆t=0.5
Changming Zhang

24. September 2013 L=128, r=0.05，∆r=5； t=0.005，∆t=0.5
Changming Zhang

25. 1.08GHz modulation and coding schemes Frame structure
September 2013
Roadmap
Background
1.08GHz modulation and coding schemes
Frame structure
IQ imbalance estimation and compensation
PA nonlinearity treatment
Conclusion
Changming Zhang

26. Constellation diagram
September 2013
Constellation diagram
Standard constellation
Distorted constellation
PA nonlinearity distorts the constellation. We estimate the distorted constellation (DC) with TBLK in the Header for QAM signals, and demodulate signal according to DC.
Changming Zhang

27. DC estimation analysis
September 2013
DC estimation analysis
Changming Zhang

28. Frame design September 2013
TBLK and payload BLK are with the same modulation;
Every constellation point appears with the same probability in the TBLK.
Changming Zhang

29. DC estimation September 2013
Parameters to be estimated: T distorted amplitudes , T additional phases: (T＝3 for 16QAM)
Likelihood function (LF) for the k-th symbol:
Joint LF:
Let , then
By equaling the above first-order derivatives to zero, we can obtain the estimation results:
Changming Zhang

30. Hard decision demodulation:
September 2013
DC demodulation
Hard decision demodulation:
For every received symbol, the demodulation output is the DC point with the least distance to it.
Soft decision demodulation:
The DC soft demodulation style is similar to the SC soft demodulation, where the SC points should be replaced by the DC points. For example, if we require the LLR output demodulation, it can be depicted as:
Changming Zhang

31. September 2013
11ad’s PA model
OBO=6 dB
Changming Zhang

32. September 2013
11ad’s PA model
OBO=6 dB
Changming Zhang

33. September 2013
11ad’s PA model
OBO=6 dB
Changming Zhang

34. September 2013
11ad’s PA model
OBO=6 dB
Changming Zhang

35. September 2013 Changming Zhang Code Rate EVM (dB) 1/2 -19 5/8 -20 3/4
-21
13/16
-23
Changming Zhang

36. September 2013 Changming Zhang Code Rate EVM (dB) 1/2 -19 5/8 -20 3/4
-21
13/16
-23
Changming Zhang

37. September 2013 Changming Zhang Code Rate EVM(dB) 1/2 -24 5/8 -25 3/4
-26
13/16
-28
Changming Zhang

38. September 2013 Changming Zhang Code Rate EVM(dB) 1/2 -24 5/8 -25 3/4
-26
13/16
-28
Changming Zhang

39. Month Year
doc.: IEEE /xxxxr1
September 2013
Explanations
The preamble, CES and original Header are BPSK signals, and the impact of PA nonlinearity is neglectable.
Distorted constellation estimation is performed after equalization, thus the proposed method is decoupled of ISI.
If the transmit EVM is not controlled well, the impact of PA nonlinearity is serious especially for 64-QAM, and the proposed method can overcome the impact well at receiver.
If the transmit EVM meets the requirements, PA nonlinearity is relatively weak, and impact is weaker, but the proposed method still achieves some performance improvement.
Changming Zhang
John Doe, Some Company

40. September 2013 r=0.05，∆r=5； t=0.005，∆t=0.5 Changming Zhang
Code Rate
EVM(dB)
1/2
-19
5/8
-20
3/4
-21
13/16
-23
Changming Zhang

41. September 2013 r=0.05，∆r=5； t=0.005，∆t=0.5 Changming Zhang
Code Rate
EVM(dB)
1/2
-19
5/8
-20
3/4
-21
13/16
-23
Changming Zhang

42. September 2013 r=0.05，∆r=5； t=0.005，∆t=0.5 Changming Zhang
Code Rate
EVM(dB)
1/2
-24
5/8
-25
3/4
-26
13/16
-28
Changming Zhang

43. September 2013 r=0.05，∆r=5； t=0.005，∆t=0.5 Changming Zhang
Code Rate
EVM(dB)
1/2
-24
5/8
-25
3/4
-26
13/16
-28
Changming Zhang

44. 1.08GHz modulation and coding schemes Frame structure
September 2013
Roadmap
Background
1.08GHz modulation and coding schemes
Frame structure
IQ imbalance estimation and compensation
PA nonlinearity treatment
Conclusion
Changming Zhang

45. Frame structure of 1.08 GHz PHY
September 2013
Conclusion
CMCSs of 1.08 GHz PHY
For Ctrl PHY, OFDM PHY, and Low power PHY, the CMCSs are the same as that of 11ad.
SC PHY is divided into MR SC PHY and HR SC PHY, MR SC PHY corresponds to PSK modulation, and HR SC PHY corresponds to QAM modulation. Here 13/16-16QAM, and 64QAM are new compared with 11ad.
Frame structure of 1.08 GHz PHY
Including Ctrl PHY, OFDM PHY, MR SC PHY, HR SC PHY, and Low power PHY.
The frame structure of Ctrl PHY, MR SC PHY, and Low power PHY are consistent with that of Ctrl PHY, SC PHY, and Low power PHY of IEEE ad, respectively.
Compared with 11ad, SFS is added at the beginning for OFDM PHY, which is used to estimate and compensate IQ imbalance.
Compared with the SC PHY of 11ad, also SFS is added at the beginning for HR SC PHY that used to estimate and compensate IQ imbalance. In addition, TBLK is added before payloads, which is used to estimate distorted constellation to react PA nonlinearity.
The proposed methods that compensate IQ imbalance and PA nonlinearity work well, which can be observed from the performance evaluation.
Changming Zhang

46. September 2013
Thanks！
Changming Zhang