802.11w Physical Rates
Does IEEE 802.11w define new physical rates?
No, 802.11w does not define new physical rates; it builds on the PHY layer of existing standards like 802.11a/g/n.
What is the focus of 802.11w regarding physical rates?
802.11w focuses on enhancing the security of management frames, not on modifying the PHY layer or data rates.
Which PHY layers support 802.11w features?
OFDM (802.11a/g), HT (802.11n), and later PHYs (like VHT and HE) can support 802.11w management frame protection.
Are the physical rates affected when management frames are protected?
No, physical rates remain the same; the management frame content is encrypted and authenticated without impacting modulation or coding.
What data rates are typically used for management frames in 802.11w?
Management frames are often sent at lower mandatory rates (e.g., 6 Mbps in 802.11a/g) to maximize compatibility and reliability.
Does 802.11w allow rate adaptation for protected management frames?
Yes, rate adaptation mechanisms still apply, but devices often use conservative rates for critical management frames.
Can high data rates be used for protected management frames?
Technically yes, but it’s not common practice since higher rates are more susceptible to interference and errors.
Does frame protection increase the size of management frames?
Yes, the addition of cryptographic protection slightly increases frame size, but not enough to affect rate selection significantly.
Is 802.11w compatible with 802.11n or newer PHY standards?
Yes, 802.11w features can be used alongside higher data rate standards like 802.11n, 802.11ac, and 802.11ax.
Are there any PHY rate limitations when using 802.11w?
No specific limitations; devices use the PHY rates supported by their hardware and negotiated capabilities.
Does 802.11w impact MCS (Modulation and Coding Scheme) selection?
No, MCS selection is handled by the base 802.11 standard and is independent of 802.11w security enhancements.
Can 802.11w be used in 2.4 GHz and 5 GHz bands?
Yes, since it is PHY-agnostic and works with both 802.11a/g/n/ac implementations.
Do higher physical rates reduce the effectiveness of 802.11w?
No, but higher rates may be less reliable for management frames in noisy environments, which could affect delivery of protected frames.
Is there any PHY overhead due to 802.11w encryption?
No additional PHY layer overhead is introduced; encryption-related overhead is confined to the MAC layer.
How are low data rates beneficial for 802.11w management frames?
Lower rates ensure broader coverage and more reliable delivery, especially for critical management operations.
Is channel bonding affected by 802.11w?
No, 802.11w does not affect channel bonding or other PHY-layer enhancements.
Are protected management frames rate-negotiated?
No, the data rate for management frames is usually selected based on mandatory rates and link conditions, not negotiated like data frames.
Do protected frames use the same preamble and PPDU formats?
Yes, the PHY layer frame structure, including the preamble and PPDU format, remains unchanged.
Does 802.11w protection impact transmission speed?
The added security may cause slight processing delays, but it does not directly affect the physical data rate used over the air.
What’s the best practice for selecting rates with 802.11w enabled?
Use lower mandatory rates for management frames to ensure delivery, and apply dynamic rate selection for data traffic.
Topics in this section,
Modulation |
BW |
Tsc |
FSP=BW/Tsc |
Tdata=1/FSP |
GI=Tdata/4 |
Symbol=Tdata+GI |
1/Symbol |
Bits/Symbol |
Code rate |
Usable sc |
Rate |
|---|---|---|---|---|---|---|---|---|---|---|---|
BPSK |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
1 |
1/2 |
48 |
1.5 |
BPSK |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
1 |
3/4 |
48 |
2.25 |
QPSK |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
2 |
1/2 |
48 |
3 |
QPSK |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
2 |
3/4 |
48 |
4.5 |
16-QAM |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
4 |
1/2 |
48 |
6 |
16-QAM |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
4 |
3/4 |
48 |
9 |
64-QAM |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
6 |
2/3 |
48 |
12 |
64-QAM |
5 |
64 |
78.125 |
12.8 |
3.2 |
16 |
0.0625 |
6 |
3/4 |
48 |
13.5 |
BPSK |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
1 |
1/2 |
48 |
3 |
BPSK |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
1 |
3/4 |
48 |
4.5 |
QPSK |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
2 |
1/2 |
48 |
6 |
QPSK |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
2 |
3/4 |
48 |
9 |
16-QAM |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
4 |
1/2 |
48 |
12 |
16-QAM |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
4 |
3/4 |
48 |
18 |
64-QAM |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
6 |
2/3 |
48 |
24 |
64-QAM |
10 |
64 |
156.25 |
6.4 |
1.6 |
8 |
0.125 |
6 |
3/4 |
48 |
27 |
BPSK |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
1 |
1/2 |
48 |
6 |
BPSK |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
1 |
3/4 |
48 |
9 |
QPSK |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
2 |
1/2 |
48 |
12 |
QPSK |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
2 |
3/4 |
48 |
18 |
16-QAM |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
4 |
1/2 |
48 |
24 |
16-QAM |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
4 |
3/4 |
48 |
36 |
64-QAM |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
6 |
2/3 |
48 |
48 |
64-QAM |
20 |
64 |
312.5 |
3.2 |
0.8 |
4 |
0.25 |
6 |
3/4 |
48 |
54 |
Reference links