PHY LayerL2-L3

RU Tone Plans (802.11ax)

PHY Wi-Fi 6 (11ax)

802.11ax HE Resource Unit (RU) Definitions - IEEE 802.11ax D8.0 §27.3.2 | All RU sizes, tone counts, channel widths8 rows#

RU Size	Total Tones	Data Tones	Pilot Tones	Null/Guard	Approx BW	Max RUs per 20MHz	Max simultaneous STAs (all 26-t RUs)	Engineering Notes
26-tone RU	26	24	2	0	2 MHz	9	9 per 20 MHz	Smallest RU. Minimum allocation for one STA. IoT/sensor ideal. 24 data tones → MCS 0-11 supported but low throughput (max ~4 Mbps at MCS 11).
52-tone RU	52	48	4	0	4 MHz	4	4 per 20 MHz	Mid-size. 4 non-overlapping per 20 MHz channel. Doubles data tones vs 26-tone.
106-tone RU	106	102	4	0	8 MHz	2	2 per 20 MHz	Note: a 20 MHz channel has 2×106-tone RUs + 1×26-tone center RU = 106+26+106+guard tones = 234 data tones total.
242-tone RU	242	234	8	0	20 MHz	1	1 (full 20 MHz SU)	Full 20 MHz channel as single RU. Standard SU-OFDM case. 234 data tones (vs 52 in legacy HT 802.11n = 4.5× more data tones).
484-tone RU	484	468	16	0	40 MHz	1	1 (full 40 MHz)	Full 40 MHz SU allocation. 468 data tones.
996-tone RU	996	980	16	0	80 MHz	1	1 (full 80 MHz)	Full 80 MHz SU. 980 data tones.
2×996-tone RU	1992	1960	32	0	160 MHz	1	1 (full 160 MHz)	Full 160 MHz SU. Two 80 MHz channels bonded. 1960 data tones.
4×996-tone RU (802.11be only)	3984	3920	64	0	320 MHz	1	1 (full 320 MHz)	New in 802.11be. 4×80 MHz bonded. Requires no DFS interference across all sub-bands. 3920 data tones.

RU Combinations per Channel Width - IEEE 802.11ax §27.3.2 | All valid RU packing options14 rows#

Channel Width	Valid RU Combination	Total Data Tones Used	Remaining Tones	Num Schedulable STAs	Overhead %	Notes	-	-
20 MHz	9× 26-tone	9×24=216	18 guard/pilot	9	-	Maximum STA count per 20 MHz. Each gets 24 data tones. Total = 216 data tones out of 234 possible.
20 MHz	4× 52-tone	4×48=192	42	4	-
20 MHz	2× 106-tone + 1× 26-tone	204+24=228	6	3	-	Most common mixed packing. Central 26-tone for small device, two 106-tone for larger devices.
20 MHz	1× 242-tone (SU)	234	0	1	-	Full channel SU. No OFDMA.
40 MHz	18× 26-tone	432	-	18	-	Maximum STAs in 40 MHz.
40 MHz	2× 242-tone	468	-	2	-	Two full 20 MHz SU slices.
40 MHz	1× 484-tone (SU)	468	-	1	-	Full 40 MHz SU.
80 MHz	37× 26-tone	888	-	37	-	Maximum STAs in 80 MHz. IEEE 802.11ax spec maximum MU user count in single PPDU.
80 MHz	4× 242-tone	936	-	4	-	Four 20 MHz slices.
80 MHz	1× 996-tone (SU)	980	-	1	-	Full 80 MHz SU.
160 MHz	74× 26-tone	1776	-	74	-	Theoretical maximum - requires perfect scheduling. Unusual in practice.
160 MHz	1× 2×996-tone (SU)	1960	-	1	-	Full 160 MHz SU.
320 MHz (be)	148× 26-tone	3552	-	148	-	802.11be maximum. Multiple APs would need coordination for this density.
320 MHz (be)	1× 4×996-tone (SU)	3920	-	1	-	Full 320 MHz SU (802.11be only).

HE OFDM Subcarrier Count Comparison - 802.11ax vs Prior Generations at 20 MHz4 rows#

Standard	Total Subcarriers	Data Subcarriers	Pilot Subcarriers	Null/Guard	Subcarrier Spacing	Symbol Duration	Data Subcarrier Gain vs 802.11n	Notes
802.11a/g (OFDM)	64	48	4	12 (DC+guard)	312.5 kHz	4.0 µs (0.8µs GI)	-	Original OFDM. 64-pt FFT.
802.11n/ac (HT/VHT)	64	52	4	8 (DC+guard)	312.5 kHz	4.0 µs (0.8µs GI)	52/48 = +8% vs 802.11a	Added 4 more data subcarriers vs 802.11a by reducing guard.
802.11ax (HE)	256	234	8	14 (DC+guard)	78.125 kHz	16.0 µs (0.8µs GI)	234/52 = +4.5×	4× more subcarriers due to 4× narrower spacing. 4× longer symbol = better multipath. Massive data capacity increase.
802.11be (EHT)	256	234	8	14	78.125 kHz	16.0 µs (0.8µs GI)	Same as ax (20 MHz)	EHT uses same 20 MHz subcarrier plan as HE. Gain is from 320 MHz bandwidth.