802.11an MAC Timings

What are MAC timings in IEEE 802.11an?

MAC timings define parameters like interframe spaces, slot times, and backoff intervals to coordinate wireless transmissions.

Why are precise MAC timings important in 802.11an?

Accurate timings prevent collisions, ensure fair medium access, and improve overall network efficiency.

What is SIFS in 802.11an?

Short Interframe Space (SIFS) is the shortest wait time used between frames like data and acknowledgments.

What is DIFS in 802.11an?

Distributed Interframe Space (DIFS) is the wait time before a station attempts to access the medium when idle.

How does 802.11an use AIFS?

Arbitration Interframe Space (AIFS) allows differentiated wait times for traffic categories to support QoS.

What is the slot time in 802.11an?

Slot time is the basic unit of time for backoff and contention algorithms, typically 9 microseconds in 802.11an.

How does the contention window affect MAC timings?

The contention window determines random backoff periods to avoid collisions during medium access.

What is the purpose of backoff in 802.11an MAC?

Backoff delays transmission attempts after detecting a busy medium, reducing collision probability.

How are retransmission timings defined?

Timers ensure retransmissions occur only after appropriate intervals to avoid congestion.

What timing changes does 802.11an introduce compared to 802.11a?

802.11an adapts timings for wider bandwidth and MIMO operation but keeps slot time typically at 9 µs.

How do MAC timings impact Quality of Service?

Differentiated interframe spaces (AIFS) prioritize traffic, improving QoS support.

What is the relationship between MAC and PHY timings?

MAC timings synchronize with PHY layer symbol durations to optimize frame transmissions.

How is the NAV timer related to MAC timings?

Network Allocation Vector (NAV) sets virtual carrier sensing intervals to avoid collisions during transmissions.

How do timing parameters influence power saving?

Sleep cycles rely on timing coordination for clients to wake and receive buffered data efficiently.

Are MAC timings fixed or adaptive in 802.11an?

Some timings are fixed by the standard; others adapt dynamically based on network conditions.

How do MAC timings help avoid hidden node problems?

Proper interframe spacing and backoff reduce chances of overlapping transmissions from hidden nodes.

What is the impact of incorrect MAC timing settings?

Misconfigured timings lead to increased collisions, retransmissions, and degraded throughput.

How does MAC timing facilitate frame aggregation?

Timing parameters coordinate multiple frame transmissions to improve channel efficiency.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

  • setup

  • Reference links