802.11ac MAC Functions

What is the MAC layer in 802.11ac?

The MAC (Medium Access Control) layer in 802.11ac manages wireless medium access, frame delivery, and coordination for high throughput Wi-Fi networks.

What are the primary functions of MAC in 802.11ac?

Functions include medium access control using CSMA/CA, frame aggregation, retransmissions, error checking, and QoS support.

How does MAC handle medium access in 802.11ac?

It uses CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) enhanced with frame aggregation and block acknowledgments to optimize throughput.

What role does MAC play in frame retransmission?

MAC retransmits unacknowledged frames and manages block acknowledgments for efficient error recovery.

How does MAC implement collision avoidance?

By employing interframe spacing, random backoff timers, and RTS/CTS mechanisms to minimize collisions in dense networks.

What is the purpose of ACK and Block ACK frames in MAC?

ACK confirms reception of single frames, while Block ACK acknowledges multiple frames aggregated together.

How does MAC layer handle frame aggregation?

MAC supports A-MSDU and A-MPDU aggregation to combine multiple frames, reducing overhead and increasing throughput.

What is the NAV (Network Allocation Vector) in MAC?

NAV is a virtual carrier sensing timer used to indicate when the medium is reserved, helping avoid collisions.

How does MAC manage power saving in 802.11ac?

MAC coordinates power saving modes allowing devices to enter sleep states and wake as needed for efficient energy use.

What is the role of RTS/CTS in MAC?

Request to Send (RTS) and Clear to Send (CTS) frames reduce collisions, especially in hidden node scenarios.

How does MAC prioritize traffic?

Using Enhanced Distributed Channel Access (EDCA), MAC classifies traffic into categories like voice, video, and best effort for QoS.

What types of frames are managed by MAC in 802.11ac?

MAC manages management, control, and data frames to maintain wireless communication integrity.

How does MAC deal with errors?

MAC uses CRC checks to detect frame errors and schedules retransmissions as needed.

Is MAC responsible for addressing?

Yes, MAC handles physical addressing using MAC addresses for source and destination identification.

How does MAC coordinate with the Physical layer?

MAC passes frames to the PHY layer for modulation and handles received data bits for frame reconstruction.

What is Distributed Coordination Function (DCF) in 802.11ac?

DCF is the fundamental MAC access method using CSMA/CA for channel contention.

Does 802.11ac MAC support Point Coordination Function (PCF)?

PCF is optional and less commonly used, providing contention-free periods controlled by the access point.

How does MAC support MU-MIMO in 802.11ac?

MAC schedules and manages simultaneous transmissions to multiple users using MU-MIMO technology.

How does MAC support roaming between access points?

MAC handles authentication, association, and reassociation processes to enable seamless client mobility.

Where are MAC functions defined for 802.11ac?

In the IEEE 802.11ac amendment to the 802.11 standard, which builds on the original 802.11 MAC specifications.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

  • setup

  • Reference links