802.11bn MAC Functions ========================= .. 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 the MAC functions in IEEE 802.11bn?** In 802.11bn, MAC functions include frame delimiting, reliable transmission, access coordination, acknowledgments, error detection, and novel enhancements like multi‑AP coordination for ultra‑high reliability. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11bn handle access to the channel (medium access)?** It uses enhanced coordination via features like Coordinated Spatial Reuse (Co‑SR) and updated CSMA/CA rules to optimize when and how stations transmit. .. panels:: :container: container pb‑4 :column: col-lg-12 p-2 :card: shadow **Does 802.11bn support frame aggregation at the MAC layer?** Yes — like preceding standards, 802.11bn supports aggregation (A‑MPDU, etc.) to reduce overhead and improve throughput. .. panels:: :container: container pb‑4 :column: col-lg-12 p-2 :card: shadow **What acknowledgment mechanisms are used in 802.11bn?** It supports standard ACKs and block acknowledgments; it may also include mechanisms that acknowledge multiple subframes or MPDUs in improved ways. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How are MAC addresses used in 802.11bn?** MAC addressing works similarly to previous Wi‑Fi standards: each station has source/destination addresses in frames; also new addressing or identifiers may be used for multi‑AP or multi‑link coordination. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How does 802.11bn ensure reliable delivery of frames?** Through retransmissions, acknowledgments, block ACKs, sequence numbering, and error detection (CRC etc.). .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **Is there support for MAC level QoS in 802.11bn?** Yes — priority access (e.g. via EDCA), scheduling, and capability negotiation ensure delay‑sensitive traffic is served appropriately. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How does 802.11bn handle legacy device compatibility at the MAC layer?** Sony mode fallbacks, or compatibility modes, are expected, so legacy 802.11 devices can still be accommodated, often with protection mechanisms in mixed environments. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **What about MAC frame control and addressing fields?** The 802.11bn frames expand existing fields to include extra indicators for new features (multi‑AP, multi‑link, new MCS, etc.), but keep backward‑compatible formatting. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **Does 802.11bn define enhanced scheduling at MAC layer?** Yes — features like coordinated transmission among multiple APs, improved spatial reuse, and more sophisticated scheduling are part of the MAC enhancements. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How are retransmissions managed in 802.11bn under high interference?** Retries are coordinated via MAC‑level sequence numbers; enhanced features (e.g. multi‑AP or beamforming) help reduce the need for retransmission. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **What new physical‑MAC interaction does 802.11bn offer?** There are new PHY features (like new MCS, distributed RUs, etc.) that require MAC to adapt (e.g. for resource allocation, modulation schemes, and management of spatial streams). .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How does 802.11bn MAC improve latency?** Through better scheduling, new modes that reduce queueing delay, multi‑AP coordinated transmissions, and reducing MPDU loss during BSS transitions. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **What is MAC protocol data unit (MPDU) loss, and how is it reduced in 802.11bn?** MPDU loss refers to data frames dropped or corrupted; 802.11bn aims to reduce loss by about 25% in BSS transitions and normal operation, via stronger error correction, spatial reuse, etc. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **Is there support for multi‑AP coordination in MAC Functions?** Yes — multi‑AP coordination (MAPC), Coordinated Spatial Reuse, Coordinated Beamforming etc. are part of the MAC/PHY joint behaviour. .. panels:: :container: container pb‑4 :column: col-lg-12 p-2 :card: shadow **How are error‑detection and integrity handled at the MAC layer?** MAC frames use CRC/FCS; also frame sequence control and retransmission count help maintain integrity. .. panels:: :container: container pb‑4 :column: col-lg-12 p-2 :card: shadow **Are there MAC‑level power saving features in 802.11bn?** Yes — power savings for APs and STAs are considered; for example mechanisms to reduce transmissions under low traffic and more efficient resource units. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **Does 802.11bn use new Modulation and Coding Schemes (MCS) at MAC level?** Yes — 802.11bn introduces additional MCS values and finer modulation choices to improve adaptation to channel conditions. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How does the MAC manage resource allocation with distributed Resource Units (dRU)?** The MAC coordinates which Resource Units are assigned (including distributed RUs) for uplink/downlink communications, balancing power, range, and interference. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **What is unequal modulation in 802.11bn’s MAC layer?** Unequal modulation allows different spatial streams in a beamformed PPDU to have different modulation orders, improving throughput and robustness. .. panels:: :container: container pb‑4 :column: col-lg‑12 p-2 :card: shadow **How are MAC retries and backoff adapted in 802.11bn?** Backoff and retry behavior accounts for interference, spatial reuse, and may have adjusted timers or windows to suit reliability‑focused environments. .. panels:: :container: container pb‑4 :column: col-lg‑12 p‑2 :card: shadow **What is the expected timeline or status of MAC functions implementation for 802.11bn?** As of available sources, 802.11bn is in development (Ultra High Reliability mode), with full specification expected around 2028. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Reference links ` .. _mac_functions_step17: .. tab-set:: .. tab-item:: Reference links * Reference links