802.11ac Packet Formats

What is the basic structure of an 802.11ac packet?

An 802.11ac packet consists of a MAC header, Frame Body (payload), and Frame Check Sequence (FCS).

What types of frames are used in 802.11ac?

Management frames, control frames, and data frames make up the types of packets used.

How does the MAC header in 802.11ac differ from previous standards?

It includes additional fields to support features like MU-MIMO, beamforming, and frame aggregation.

What is the purpose of the PHY preamble in 802.11ac packets?

The PHY preamble allows synchronization, channel estimation, and informs the receiver about modulation and coding schemes.

What new fields are introduced in 802.11ac packet formats?

Fields supporting Very High Throughput (VHT), such as VHT-SIG-A and VHT-SIG-B, are included for signaling enhanced capabilities.

How does frame aggregation work in 802.11ac packets?

Multiple data frames can be aggregated into a single transmission to improve efficiency, using A-MPDU and A-MSDU formats.

What role does the Frame Check Sequence (FCS) play?

FCS is used for error detection, ensuring the integrity of received packets.

Are there legacy fields in 802.11ac packet formats?

Yes, legacy fields are preserved for backward compatibility with older 802.11 devices.

How does 802.11ac handle QoS in packet formats?

QoS is supported via the QoS Control field in the MAC header, facilitating traffic prioritization.

What is the VHT-SIG field?

The VHT-SIG (Very High Throughput Signal) field carries transmission parameters specific to 802.11ac.

Does 802.11ac use extended sequence control?

Yes, extended sequence control fields help manage packet ordering and retransmissions in high throughput scenarios.

How is MU-MIMO reflected in packet formats?

Special signaling in the packet header coordinates simultaneous transmissions to multiple clients.

Are encryption details part of the packet format?

Encryption headers and trailers are added when security protocols like WPA2/WPA3 are used.

What is the maximum packet size supported in 802.11ac?

With frame aggregation, packets can be aggregated up to several megabytes, greatly increasing throughput.

How does 802.11ac ensure compatibility with older packet formats?

It uses legacy preamble and headers at the beginning of packets so older devices can detect and defer transmissions.

How are control frames formatted in 802.11ac?

Control frames remain similar to earlier standards but may include additional flags to support new features.

Where can I find detailed 802.11ac packet format specifications?

In the IEEE 802.11ac amendment to the 802.11 standard and related Wi-Fi Alliance documentation.

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