26
52
106
242
52
52
26
52 52
26 26
26 26
26 26 26 2626
11ax Resource Unit (RU) Distribution
20 MHz
Guard Subcarriers
Null Subcarriers
PHY Preamble
Pilot
Data
RU 26
78.125 kHz
78.125 kHz
RU 52
78.125kHz * 26 = 2.031MHz
78.125kHz * 52 = 4.063MHz
11ax Tone Distribution
Modulation Techniques
Bits per tone
• BPSK 1
• QPSK 2
• 16-QAM 4
• 64-QAM 6
• 256-QAM 8
• 1024-QAM 10
MCS
IndexModulation
Coding
Rate
Relative constellation
error (dB)
0 BPSK 1/2 -5
1 QPSK 1/2 -10
2 QPSK 3/4 -13
3 16-QAM 1/2 -16
4 16-QAM 3/4 -19
5 64-QAM 1/2 -22
6 64-QAM 3/4 -25
7 64-QAM 5/6 -27
8 256-QAM 3/4 -30
9 256-QAM 5/6 -32
10 1024-QAM 3/4 -35
11 1024-QAM 5/6 -35
Moduation RateMin Sensitivity
@ 20 MHz
(dBm)
Min Sensitivity
@ 40 MHz (dBm)
Min Sensitivity
@ 80 MHz (dBm)
Min Sensitivity
@ 160 MHz
(dBm)BPSK 1/2 -82 -79 -76 -73
QPSK 1/2 -79 -76 -73 -70
QPSK 3/4 -77 -74 -71 -68
16-QAM 1/2 -74 -71 -68 -65
16-QAM 3/4 -70 -67 -64 -61
64-QAM 2/3 -66 -63 -60 -57
64-QAM 3/4 -65 -62 -59 -56
64-QAM 5/6 -64 -61 -58 -55
256-QAM 3/4 -59 -65 -53 -50
256-QAM 5/6 -57 -54 -51 -48
1024-QAM 3/4 -54 -51 -48 -45
1024-QAM 5/6 -52 -49 -46 -43
Modulation Techniques
-115
-110
-105
-100
-95
-90
ThermalNoiseFloorvsBandwidth
160MHz @ -92dBm
80MHz @ -95dBm
40MHz @ -98dBm
20MHz @ -101dBm
1MHz @ -114dBm
2MHz @ -111dBm
4MHz @ -108dBm
8MHz @ -105dBm
Thermal Noise
PdBm=10log10(kBTBx1000)
kB=BoltzmannConstant(J/K)
T=temperature(K)
B=bandwidth(Hz)
dBm
} 3dB
BSS Operating Channel Width
BSS Operating
Channel Width
field
HR/DSS, OFDM, ERP, HT, VHT, HE BSS
operating channel width
0 20 MHz or 22 MHz
1 40 MHz
2 80 MHz
3 160 MHz or 80+80 MHz
4-7 Reserved
Take Away
• 11ax Rx radio “listens” to 20MHz (or 40/80/160/80+80 MHz) wide
channel
• Receives ALL tones/subcarriers across BSS channel width
• Processes ALL tones assigned to destination
• NO SNR gain with smaller RUs due to narrower Bandwidth
• Potential for SNR gain by sending individual RUs at higher Tx power
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