802.11ag MAC Functions

What is the role of the MAC layer in IEEE 802.11a/g?

The MAC layer controls access to the wireless medium, coordinating how devices send and receive data to avoid collisions.

How does the MAC layer manage medium access?

It uses the Distributed Coordination Function (DCF), a contention-based protocol with CSMA/CA to avoid collisions.

What is CSMA/CA in 802.11a/g MAC?

Carrier Sense Multiple Access with Collision Avoidance is a mechanism to sense the medium and wait if busy before transmitting.

What is the Point Coordination Function (PCF)?

PCF is an optional centralized MAC function where the access point controls medium access, providing contention-free service.

How does the MAC layer handle acknowledgments?

After a successful frame reception, the receiver sends an ACK frame to confirm delivery, improving reliability.

What are RTS and CTS frames in MAC?

Request to Send (RTS) and Clear to Send (CTS) frames help avoid collisions by reserving the medium before data transmission.

When does the MAC layer use RTS/CTS?

RTS/CTS is used to reduce collisions, especially for large packets or in environments with hidden nodes.

What is the backoff algorithm in 802.11a/g MAC?

After detecting a busy medium or collision, devices wait a random backoff time before retrying transmission to avoid repeated collisions.

How does the MAC layer ensure fair medium access?

By using contention windows and exponential backoff, it prevents any device from monopolizing the medium.

What are interframe spaces (IFS) in MAC?

Fixed wait times between frame transmissions that prioritize different frame types (e.g., SIFS, DIFS) for orderly communication.

What is the Short Interframe Space (SIFS)?

SIFS is the shortest wait time used for high-priority frames like ACKs and CTS, minimizing response delay.

What is the Distributed Interframe Space (DIFS)?

DIFS is a longer wait time used before transmitting new data frames, ensuring higher priority frames get access first.

How does the MAC layer handle frame fragmentation?

Large frames can be split into smaller fragments to improve transmission success in noisy environments.

What is the role of sequence numbers in MAC frames?

They help detect duplicate frames and ensure proper frame ordering.

How does the MAC layer handle retransmissions?

If an ACK is not received, the MAC retransmits the frame after a backoff period, improving reliability.

What is power management in the MAC layer?

Devices can enter sleep mode and use beacon frames and traffic indication maps to save power while maintaining connectivity.

How are association and authentication handled at the MAC layer?

The MAC layer manages the handshake processes allowing devices to join and authenticate with access points.

What is the significance of the MAC address in 802.11a/g?

MAC addresses uniquely identify devices on the wireless network for addressing and communication.

How does the MAC layer support QoS (Quality of Service)?

While basic 802.11a/g does not define QoS, extensions like 802.11e enhance MAC to prioritize traffic types.

What challenges does the MAC layer face in 802.11a/g networks?

Challenges include hidden nodes, interference, collisions, and efficient power management.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

  • setup

  • Reference links