802.11r PHYs
What is the PHY layer used in IEEE 802.11r?
IEEE 802.11r does not define a new PHY; it uses the PHY layers defined in other 802.11 standards such as 802.11a, 802.11g, 802.11n, or 802.11ac.
Does 802.11r modify the physical layer (PHY) transmissions?
No, 802.11r focuses on fast roaming at the MAC layer and key management but does not change PHY transmission methods.
Can 802.11r be used with OFDM PHY?
Yes, 802.11r is compatible with OFDM PHYs such as those in 802.11a, 802.11n, and 802.11ac.
Does 802.11r support PHY layer enhancements like MIMO?
802.11r works over PHYs that may have MIMO (like 802.11n/ac), but it itself does not add or modify MIMO features.
How does 802.11r impact PHY layer channel switching?
802.11r supports fast roaming, which may require quick channel switching at the PHY layer as clients move between APs on different channels.
Is 802.11r PHY-dependent?
No, 802.11r is designed to be PHY-independent and works on any standard-compliant PHY layer.
Does 802.11r require PHY layer support for fast roaming?
The PHY layer itself does not require changes, but rapid re-association must be supported by the radio hardware for seamless transition.
Can 802.11r be used with DSSS or FHSS PHYs?
While theoretically possible, 802.11r is primarily used with OFDM-based PHYs common in modern Wi-Fi (like 802.11a/n/ac).
What is the typical channel bandwidth with 802.11r?
802.11r supports standard channel bandwidths used by the underlying PHY such as 20 MHz, 40 MHz, and 80 MHz channels.
Does 802.11r affect modulation schemes at PHY?
No, modulation and coding schemes are determined by the PHY and channel conditions, independent of 802.11r.
How does 802.11r support low latency at the PHY layer?
802.11r reduces upper-layer handoff delay but depends on PHY-layer speed and efficiency to deliver low-latency transmissions.
Is there a specific PHY preamble for 802.11r?
No, 802.11r uses the standard PHY preamble of the underlying 802.11 standard in use.
How does 802.11r interact with PHY power control?
802.11r relies on PHY power control mechanisms but does not alter them; power control helps maintain link quality during fast roaming.
What PHY features enhance 802.11r roaming performance?
Features like MIMO, beamforming, and wider channels improve overall throughput and link robustness, complementing fast roaming.
Does 802.11r influence PHY symbol timing?
No, symbol timing is controlled by the PHY standard; 802.11r operates above that layer.
Is PHY layer synchronization affected by 802.11r?
No, synchronization (timing, frequency) is managed at the PHY and MAC layers independently from 802.11r functions.
Can 802.11r improve PHY layer error rates?
Indirectly, by enabling faster roaming and reducing retransmissions due to better signal quality on the new AP.
Are there PHY layer limitations for implementing 802.11r?
Hardware and driver support for rapid channel changes and fast re-association is essential, but no new PHY layer protocols are required.
What PHY bands are typically used with 802.11r?
Both 2.4 GHz and 5 GHz bands are supported, as long as the underlying PHY and APs support 802.11r features.
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