802.11a MAC Functions

What is the MAC layer in 802.11a?

The MAC (Medium Access Control) layer controls how devices access the wireless medium and manages frame delivery in 802.11a.

What are the primary functions of MAC in 802.11a?

Functions include medium access control, frame encapsulation/decapsulation, error checking, and retransmissions.

How does MAC handle medium access in 802.11a?

It uses CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to listen before transmitting and avoid collisions.

What role does MAC play in frame retransmission?

MAC retransmits frames if acknowledgments are not received, ensuring reliable delivery.

How does MAC implement collision avoidance?

By using interframe spaces and random backoff timers before transmitting to reduce chances of collisions.

What is the purpose of ACK frames in MAC?

ACK (Acknowledgment) frames confirm successful reception of data frames, enabling error recovery.

How does MAC layer handle frame fragmentation?

MAC can fragment large frames into smaller ones for better reliability in noisy environments.

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

NAV is a virtual carrier sensing mechanism used by MAC to indicate how long the medium will be busy.

How does MAC manage power saving?

MAC supports power-saving by coordinating sleep and wake times between the access point and stations.

What is the role of RTS/CTS in MAC?

Request to Send (RTS) and Clear to Send (CTS) frames help prevent collisions in hidden node scenarios.

How does MAC prioritize traffic?

Although QoS enhancements came later, basic MAC prioritizes control frames like ACKs and RTS/CTS by using shorter interframe spaces.

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

MAC handles management frames, control frames, and data frames.

How does MAC deal with errors?

MAC uses CRC (Cyclic Redundancy Check) for error detection and requests retransmission on failure.

Is MAC responsible for addressing?

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

How does MAC coordinate with the Physical layer?

MAC provides data frames to the PHY layer for modulation and transmits/receives bits over the air.

What is Distributed Coordination Function (DCF)?

DCF is the fundamental MAC access method in 802.11a using CSMA/CA for channel contention.

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

Yes, PCF is an optional MAC function that allows contention-free access controlled by the access point.

How does MAC support roaming between access points?

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

Where are MAC functions defined for 802.11a?

In the IEEE 802.11-1999 standard and its amendments specific to the 5 GHz band (802.11a).

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