802.11h 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 802.11h?** The MAC functions in 802.11h primarily support Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to manage interference and regulatory compliance. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does the MAC layer support Dynamic Frequency Selection (DFS)?** The MAC scans channels for radar signals before transmission and enforces channel switching if radar is detected. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What role does the MAC play in Transmit Power Control (TPC)?** The MAC layer controls the transmit power level of the radio, adjusting it to minimize interference while maintaining communication quality. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC ensure compliance with regulatory requirements?** It implements DFS and TPC algorithms to conform with regional rules for spectrum use, especially in the 5 GHz band. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the Channel Availability Check (CAC) in MAC functions?** CAC is the process where the MAC monitors a channel for radar signals for a set duration before permitting use. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does the MAC layer handle radar detection?** Upon detecting radar pulses, the MAC immediately initiates channel move procedures to vacate the channel. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What are Channel Move Announcements in MAC?** These are notifications sent by the MAC to connected devices to inform them about upcoming channel changes due to radar detection. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC manage Channel Availability Check Time (CACT)?** MAC enforces a mandatory wait time (CACT) on a new channel to ensure no radar presence before usage. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the impact of MAC on channel switching delay?** MAC processes introduce a delay during DFS channel switching to maintain regulatory compliance and network stability. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC coordinate power adjustment with TPC?** The MAC calculates and applies appropriate transmit power based on received signal strength and regulatory limits. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does MAC function in 802.11h affect frame timing?** Yes, certain MAC timings, like defer times and interframe spaces, may be adjusted to accommodate DFS and TPC requirements. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does the MAC handle non-compliant devices in the network?** The MAC may limit communication or reject devices that don’t support DFS and TPC in regulatory domains requiring 802.11h. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the role of MAC in power constraint element?** MAC uses power constraint elements to inform clients of transmit power limitations on specific channels. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC affect beacon transmissions in 802.11h?** MAC inserts DFS and TPC information in beacon frames to inform clients of channel and power management status. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How is MAC involved in radar pulse pattern recognition?** MAC processes radar pulse signatures reported by the PHY layer and triggers DFS actions accordingly. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11h MAC support multiple channel switching?** Yes, MAC can manage sequential channel switches if multiple radar detections occur on different channels. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What MAC management frames are specific to 802.11h?** Frames like Channel Switch Announcement (CSA) and Power Constraint Information Elements are added for regulatory functions. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC handle DFS non-occupancy periods?** After radar detection, MAC enforces a non-occupancy period on the affected channel before it can be reused. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is MAC layer involvement in 802.11h automatic or manual?** MAC functions related to DFS and TPC operate automatically without user intervention. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC contribute to overall Wi-Fi network stability in 802.11h?** By managing channel availability and transmit power dynamically, MAC helps prevent interference and ensures stable connections. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Reference links <802_11h_mac_functions_step17>` .. _802_11h_mac_functions_step17: .. tab-set:: .. tab-item:: Reference links * Reference links