List of PPDUs Supported in 802.11ax
What is a PPDU in IEEE 802.11ax?
PPDU stands for Physical Protocol Data Unit; it is the physical layer frame used to transmit data over the wireless medium.
How does the 802.11ax PPDU differ from earlier standards?
802.11ax introduces new PPDU formats to support OFDMA, MU-MIMO, and longer OFDM symbols for improved efficiency.
What are the main components of an 802.11ax PPDU?
Typical components include a Legacy Preamble, High Efficiency (HE) Preamble, SIGNAL fields, Data payload, and a CRC.
What is the role of the HE-SIG-A field in 802.11ax PPDU?
HE-SIG-A conveys information about resource allocation and transmission parameters for OFDMA and MU-MIMO.
What modulation schemes are used in 802.11ax PPDUs?
802.11ax supports up to 1024-QAM modulation for higher data rates.
How does OFDMA affect the PPDU structure?
OFDMA divides the frequency spectrum into Resource Units (RUs), with signaling fields indicating RU allocations in the PPDU.
What is the purpose of the Legacy Preamble in 802.11ax PPDU?
It ensures backward compatibility with legacy devices by providing recognizable signals.
What are the different PPDU types in 802.11ax?
They include HE SU PPDU, HE MU PPDU, HE Trigger-based PPDU, and HE Extended Range PPDU.
How does 802.11ax PPDU handle multi-user transmissions?
By using HE MU and Trigger-based PPDUs with resource allocation info in signaling fields.
What is the HE-LTF field in 802.11ax PPDU?
HE-LTF (High Efficiency Long Training Field) is used for channel estimation and synchronization.
Does 802.11ax support longer OFDM symbol durations?
Yes, symbol duration can be extended to improve range and robustness.
How does 802.11ax PPDU improve spectral efficiency?
Through OFDMA, MU-MIMO, higher modulation, and flexible resource allocation within the PPDU.
What is the difference between HE-SIG-A and HE-SIG-B fields?
HE-SIG-A provides common signaling for all users; HE-SIG-B carries user-specific information in MU transmissions.
How does PPDU format support both uplink and downlink transmissions?
Different PPDU formats and trigger-based transmissions coordinate uplink and downlink multi-user access.
Are there any changes in PPDU preamble lengths in 802.11ax?
Yes, HE PPDU preambles are longer to accommodate additional signaling fields.
How is error detection handled in 802.11ax PPDU?
Error detection uses CRC fields within the PPDU to ensure data integrity.
Can the PPDU format adapt to different channel widths?
Yes, 802.11ax supports 20, 40, 80, and 160 MHz channels, with PPDU adapting accordingly.
Where can I learn more about 802.11ax PPDU specifications?
The IEEE 802.11ax standard documents and related technical papers provide detailed PPDU format descriptions.
Topics in this section,
In this section, you are going to learn
Terminology
Version Info
setup
Reference links