802.11ax MAC Timings
What are MAC timing parameters in IEEE 802.11ax?
They define precise timing intervals for frame exchanges, medium access, and retransmissions to coordinate wireless communication.
What is SIFS in 802.11ax?
Short Interframe Space (SIFS) is the shortest waiting time between frame transmissions, used for ACKs and CTS frames.
What is AIFS and how is it used?
Arbitration Interframe Space (AIFS) varies by traffic priority and controls medium access delays in contention-based transmissions.
How does 802.11ax handle backoff timing?
Stations choose random backoff intervals within contention windows to avoid collisions and ensure fair medium access.
What is the purpose of Slot Time in MAC timings?
Slot Time is the basic unit of time used for counting backoff periods and sensing the channel.
How does MAC timing coordinate MU transmissions in 802.11ax?
Trigger frames are scheduled with specific timing to allow multiple users to transmit simultaneously without collisions.
What timing changes does 802.11ax introduce over 802.11ac?
Reduced SIFS, optimized AIFS, and flexible timing parameters to support OFDMA and spatial reuse.
What is the role of the Extended Interframe Space (EIFS)?
EIFS is a longer wait used after detecting erroneous frames to avoid interference during retransmission.
How does the MAC layer use timing for power saving?
It uses Target Wake Time (TWT) scheduling to coordinate sleep and wake intervals efficiently.
What is the impact of timing on throughput?
Proper timing minimizes collisions and idle periods, maximizing channel utilization and throughput.
How is timing handled during retransmissions?
The MAC uses backoff timers and waits defined by AIFS and SIFS before retrying failed transmissions.
What timing controls are in place for QoS in 802.11ax?
Different AIFS and contention window sizes are assigned to traffic categories to prioritize delay-sensitive data.
How does spatial reuse affect MAC timings?
Spatial reuse mechanisms adjust Clear Channel Assessment (CCA) thresholds and timing to allow simultaneous transmissions.
What is the significance of Multi-User SIFS (MU-SIFS)?
MU-SIFS is a shortened SIFS interval used to separate multi-user transmissions efficiently.
Are timing parameters configurable in 802.11ax?
Yes, certain timing values like AIFS and contention windows can be adjusted for traffic management.
How does the MAC coordinate uplink and downlink timing?
The AP schedules transmissions using trigger frames and ensures timing synchronization among clients.
What is the MAC’s role in beacon timing?
Beacons are transmitted at regular intervals to synchronize stations and convey network information.
How does MAC timing affect latency?
Reduced interframe spaces and optimized backoff decrease transmission delays, improving latency-sensitive applications.
What timing challenges arise in dense network environments?
Increased contention requires fine-tuned timing parameters to reduce collisions and maintain performance.
How is timing critical for efficient OFDMA operation?
Precise timing ensures resource units are allocated and transmissions are synchronized to avoid overlap and interference.
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