1. 256-QAM TX EVM and RX Sensitivity
Month Year
doc.: IEEE /0xxxr0
January 2011
256-QAM TX EVM and RX Sensitivity
Date:
Authors:
Youhan Kim et al.
Osama Aboul-Magd (Samsung)

2. January 2011
TX EVM
TX EVM requirement ensures that the TX signal quality does not significantly limit the overall link performance
Slope of PER curve consistent between different MCS
No fading, 1x1, 80 MHz, 4096 bytes
To rule out PER impact from other impairments
No phase noise, no PA model
Perfect synchronization, channel estimation
 Impact of TX EVM to PER should be more or less consistent between MCS
If TX EVM is chosen to be X dB more stringent than the overall RX sensitivity requirement for MCS Y, then reasonable to choose TX EVM to be X dB more stringent for MCS Z as well
Youhan Kim et al.

3. January 2011
11n – HT20
Difference between TX EVM requirement and RX sensitivity requirement is mostly consistent across MCS
SNR assuming noise figure + implementation loss = 18 dB
To make SNR = 1 dB for BPSK ½ for consistency w/ next slide B A
RX Sensitivity [dBm]
RX Sensitivity in SNR [dB]
TX EVM [dB]
A+B [dB]
BPSK ½
-82 1 -5 -4
QPSK ½
-79 4
-10 -6
QPSK ¾
-77 6
-13 -7
16-QAM ½
-74 9
-16
16-QAM ¾
-70 13
-19
64-QAM 2/3
-66 17
-22
64-QAM ¾
-65 18
-25
64-QAM 5/6
-64 19
-28 -9
Avg.
-6.3
Youhan Kim et al.

4. TX EVM Requirement for 11ac
January 2011
TX EVM Requirement for 11ac
Previously increased 6 dB for every 4x in QAM order
If increased by 6 dB for 256-QAM as well, then EVM requirement becomes too stringent compared to other MCS A B
MCS
Bits/ Sub-carrier
TX EVM Requirement [dB]
SNR Required to Achieve 10% PER* [dB]
A+B [dB]
BPSK ½
0.5 -5
1.1
-3.9
QPSK ½ 1
-10
4.1
-5.9
QPSK ¾
1.5
-13
6.7
-6.3
16-QAM ½ 2
-16
9.6
-6.4
16-QAM ¾ 3
-19
12.8
-6.2
64-QAM 2/3 4
-22
17.2
-4.8
64-QAM ¾
4.5
-25
18.4
-6.6
64-QAM 5/6 5
-28
19.7
-8.3
256-QAM ¾ 6
-31?
23.9
-7.1
256-QAM 5/6
-34?
25.5
-8.5 6
5.5
Avg.
-6.0 6
5.6 6
5.5 6
5.8
* 1x1, 80 MHz, no analog impairments, perfect channel estimation
Youhan Kim et al.

5. TX EVM Requirement for 11ac
January 2011
TX EVM Requirement for 11ac
Propose -30/-32 dB for 256-QAM 3/4 and 5/6
Difference between TX EVM requirement and RX sensitivity requirement is more consistent with other MCSs A B
MCS
Bits/ Sub-carrier
TX EVM Requirement [dB]
SNR Required to Achieve 10% PER* [dB]
A+B [dB]
BPSK ½
0.5 -5
1.1
-3.9
QPSK ½ 1
-10
4.1
-5.9
QPSK ¾
1.5
-13
6.7
-6.3
16-QAM ½ 2
-16
9.6
-6.4
16-QAM ¾ 3
-19
12.8
-6.2
64-QAM 2/3 4
-22
17.2
-4.8
64-QAM ¾
4.5
-25
18.4
-6.6
64-QAM 5/6 5
-28
19.7
-8.3
256-QAM ¾ 6
-30
23.9
-6.1
256-QAM 5/6
-32
25.5
-6.5
Avg.
-6.0
* 1x1, 80 MHz, no analog impairments, perfect channel estimation
Youhan Kim et al.

6. RX sensitivity in SNR [dB]
January 2011
RX Sensitivity
Simulation setup
TX: No phase noise, no PA model, 4096 bytes
RX: IEEE phase noise included, perfect synchronization/channel estimation
SNR obtained from 80 MHz simulation
HT20, 1x1 (From 11n standard)
VHT 20 MHz, 1x1
RX sensitivity [dBm]
RX sensitivity in SNR [dB]
RX sensitivity* [dBm]
BPSK ½
-82
1.1
-81.9
QPSK ½
-79
4.1
-78.9
QPSK ¾
-77
6.7
-76.3
16-QAM ½
-74
9.6
-73.4
16-QAM ¾
-70
12.8
-70.2
64-QAM 2/3
-66
17.3
-65.7
64-QAM ¾
-65
18.5
-64.5
64-QAM 5/6
-64
19.9
-63.1
256-QAM ¾ -
24.1
-58.9
256-QAM 5/6
25.9
-57.1
* Assuming noise figure + implementation loss = 18 dB
Youhan Kim et al.

7. Proposed RX Sensitivity
January 2011
Proposed RX Sensitivity
MCS
Min. sensitivity – 20 MHz [dBm]
Min. sensitivity – 40 MHz [dBm]
Min. sensitivity – 80 MHz [dBm]
Min. sensitivity – 160 or MHz [dBm]
BPSK ½
-82
-79
-76
-73
QPSK ½
-70
QPSK ¾
-77
-74
-71
-68
16-QAM ½
-65
16-QAM ¾
-67
-64
-61
64-QAM 2/3
-66
-63
-60
-57
64-QAM ¾
-62
-59
-56
64-QAM 5/6
-58
-55
256-QAM ¾
-53
-50
256-QAM 5/6
-54
-51
-48
Youhan Kim et al.

8. January 2011
Pre-Motion 1
Do you support -30 dB and -32 dB as the TX EVM requirements for 256-QAM 3/4 and 5/6, respectively, and to edit the specification framework document (11-09/0992) accordingly?
Youhan Kim et al.

9. January 2011
Pre-Motion 2
Do you support receiver minimum sensitivity for 256-QAM ¾ and 5/6 as shown on slide 7 and to edit the specification framework document (11-09/0992) accordingly?
Youhan Kim et al.