List of PPDUs Supported in 802.11be
What is a PPDU in IEEE 802.11be?
A PPDU (Physical Protocol Data Unit) is the complete transmission unit at the physical layer that includes the preamble and data payload.
What types of PPDUs are defined in 802.11be?
802.11be defines EHT PPDUs, which include EHT-SU, EHT-MU, EHT-TB, and EHT-Trigger-Based variants, tailored for various transmission modes.
What is an EHT PPDU?
An EHT (Extremely High Throughput) PPDU is the new format used in 802.11be, supporting high data rates and advanced features like 4096-QAM.
What is included in a PPDU preamble in 802.11be?
The preamble includes legacy, HE (if backward compatibility is needed), and EHT-specific fields for synchronization, channel estimation, and signaling.
What modulation types are supported in 802.11be PPDUs?
802.11be supports modulation types up to 4096-QAM, which allows 12 bits per symbol and improves spectral efficiency.
How does the PPDU format enable backward compatibility?
Legacy and HE preamble fields in the PPDU ensure that older Wi-Fi devices can detect the transmission and defer appropriately.
What is the role of EHT-SIG fields in the PPDU?
EHT-SIG fields carry critical signaling information like MCS, RU allocation, and user-specific parameters used in decoding the data.
What is the EHT-STF in the PPDU preamble?
The EHT-STF (Short Training Field) is used for signal detection, AGC convergence, and initial synchronization of the receiver.
What is the EHT-LTF used for in the PPDU?
The EHT-LTF (Long Training Field) provides channel estimation for accurate demodulation of the data portion in MU and SU PPDUs.
What is the typical structure of a PPDU in 802.11be?
Preamble → Header (L-SIG, RL-SIG, HE-SIG, EHT-SIG) → Data → Optional fields depending on the transmission type.
How are different users supported in a multi-user PPDU?
The EHT-MU PPDU contains user-specific segments with independent MCS, spatial stream allocation, and resource units (RUs).
Does the PPDU support Multi-Link Operation (MLO)?
Yes, each link in an MLO session can transmit its own PPDU, potentially simultaneously, improving aggregate throughput.
How are guard intervals handled in 802.11be PPDUs?
802.11be supports shorter guard intervals (as low as 0.8 µs) to improve efficiency, especially in high-density or short-range deployments.
Can PPDU formats vary by frequency band?
Yes, PPDU format and field length may vary between 2.4 GHz, 5 GHz, and 6 GHz bands, depending on bandwidth and modulation.
How is channel sounding supported in 802.11be PPDUs?
EHT PPDUs include LTFs for channel sounding, supporting enhanced beamforming and MU-MIMO operations.
What is the maximum size of a PPDU in 802.11be?
The maximum PPDU duration is typically limited to 5.484 ms for a single transmission, but actual size depends on channel and MCS.
Is there any change in CRC or FCS handling in PPDUs?
No major changes—PPDUs still include frame check sequences (FCS) for error detection at the MAC/PHY boundary.
How are broadcast/multicast PPDUs transmitted?
They use the EHT-Broadcast PPDU format, typically with lower MCS and broader compatibility across devices.
How do PPDUs interact with the MAC layer?
The MAC layer constructs MPDUs which are passed to the PHY layer and encapsulated into PPDUs for transmission over the air.
Where can I find official PPDU format details for 802.11be?
In the IEEE 802.11be (EHT) standard draft/specification documents, especially sections related to PHY layer operations.
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