802.11ag MAC Timings ======================= .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What are MAC timing parameters in IEEE 802.11a/g?** MAC timing parameters define intervals and durations used for coordinating frame transmissions and medium access. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the Short Interframe Space (SIFS)?** SIFS is the shortest waiting period between frames, used for high-priority control frames like ACKs and CTS. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the Distributed Interframe Space (DIFS)?** DIFS is the time a device waits after the medium is idle before attempting a new data transmission. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How long is SIFS in 802.11a/g?** In 802.11a and 802.11g, SIFS is typically 16 microseconds. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How long is DIFS in 802.11a/g?** DIFS is calculated as SIFS plus two slot times, typically 34 microseconds in 802.11a/g. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is a slot time?** Slot time is the basic time unit used for backoff intervals and timing calculations in the MAC layer. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the slot time duration in 802.11a/g?** The slot time is 9 microseconds for both 802.11a and 802.11g. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is Extended Interframe Space (EIFS)?** EIFS is a longer waiting period used when a frame with errors is detected, allowing recovery time before retransmission. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How is EIFS calculated?** EIFS = Transmission time of ACK + SIFS + DIFS, typically longer than DIFS to prevent collisions after errors. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the purpose of interframe spaces in MAC timings?** They prioritize access to the medium by spacing transmissions to avoid collisions and allow important control frames timely access. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does the MAC layer use timing for collision avoidance?** Devices defer transmissions by waiting for DIFS and a random backoff period to reduce simultaneous access attempts. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What role does timing play in ACK frame transmission?** The receiver must send an ACK after SIFS to acknowledge successful frame reception promptly. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How is the backoff timer calculated?** The backoff timer is a random number of slot times chosen from the contention window, multiplied by the slot duration. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the minimum contention window size in 802.11a/g?** The minimum contention window (CWmin) is 15 slots, doubling with each retransmission up to a maximum. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the maximum contention window size?** The maximum contention window (CWmax) is 1023 slots in 802.11a/g, used after multiple retries. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How do timing parameters affect throughput?** Shorter interframe spaces and slot times improve throughput but may increase collision risk. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Can MAC timing parameters be adjusted?** Some devices allow limited tuning of parameters like contention windows for performance optimization. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How do timing parameters differ between 802.11a and 802.11b?** 802.11a has shorter slot times (9 µs) compared to 802.11b (20 µs), enabling faster medium access. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Why is timing synchronization important in MAC?** Synchronization ensures all devices use the same timing rules to coordinate access and avoid collisions. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How do access points use timing to coordinate the network?** Access points send beacon frames at regular intervals to synchronize device clocks and timing parameters. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Learnings in this section ` * :ref:`Terminology ` * :ref:`Version Info ` * :ref:`mac_timings Basic Setup on Ubuntu using IPv4 ` * :ref:`Reference links ` .. _mac_timings_step1: .. tab-set:: .. tab-item:: Learnings in this section * In this section, you are going to learn .. _mac_timings_step2: .. tab-set:: .. tab-item:: Terminology * Terminology .. _mac_timings_step3: .. tab-set:: .. tab-item:: Version Info * Version Info .. _mac_timings_step18: .. tab-set:: .. tab-item:: mac_timings Basic Setup on Ubuntu using IPv4 * setup .. _mac_timings_step17: .. tab-set:: .. tab-item:: Reference links * Reference links