802.11b MAC Functions
What are MAC functions in IEEE 802.11b?
MAC functions manage frame delimiting, addressing, error detection, and coordination of wireless access.
How does 802.11b MAC handle medium access control?
It uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) to manage access to the shared wireless medium.
What role does frame delimiting play in 802.11b MAC?
It identifies the start and end of each frame, ensuring data is correctly received and processed.
How are addresses managed in 802.11b MAC?
The MAC layer uses multiple address fields to identify source, destination, transmitter, and receiver devices.
What error detection methods are used in 802.11b MAC?
A Cyclic Redundancy Check (CRC) is used for detecting errors in transmitted frames.
How does the MAC layer handle acknowledgments?
It requires ACK frames from the receiver to confirm successful frame reception, enabling retransmissions if needed.
Does 802.11b MAC support frame fragmentation?
Yes, it can fragment large frames into smaller pieces for improved reliability and reduced retransmission overhead.
What is the purpose of retransmission in MAC functions?
Retransmissions ensure data is reliably delivered despite potential wireless errors or collisions.
How does MAC layer handle collisions?
By using CSMA/CA and random backoff timers to avoid and resolve frame collisions on the wireless medium.
What is the function of the NAV (Network Allocation Vector)?
NAV acts as a virtual carrier sensing mechanism to indicate medium occupancy duration, preventing collisions.
How does 802.11b MAC handle power management?
It supports Power Save Mode (PSM) where clients sleep and wake periodically to conserve battery.
What is the role of RTS/CTS in MAC functions?
RTS/CTS handshake helps reduce collisions caused by hidden nodes during transmission.
Does 802.11b MAC support Quality of Service (QoS)?
The original 802.11b standard has limited QoS; later amendments introduced enhanced mechanisms.
How are sequence numbers used in MAC frames?
Sequence numbers help detect duplicate frames and maintain frame order.
How does the MAC layer interact with the physical layer?
MAC prepares frames for transmission and controls timing while the physical layer handles modulation and signal transmission.
What is the duration field in MAC frames used for?
It specifies the time the medium will be reserved for transmission, assisting in collision avoidance.
How does MAC ensure fair access to the medium?
By implementing random backoff timers and contention windows to reduce repeated collisions.
What types of frames are managed by the 802.11b MAC?
Management, control, and data frames are handled to enable network operation and data transfer.
How does the MAC layer support roaming?
Through standardized association and reassociation protocols allowing clients to move between access points.
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