802.11aj 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 MAC functions in 802.11aj?** MAC functions in 802.11aj manage directional medium access, beamforming, scheduling, and support for 45 GHz/60 GHz operations tailored for China and global markets. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What makes MAC in 802.11aj different from 802.11ad?** 802.11aj adds dual-band (45 and 60 GHz) support, enhanced compatibility mechanisms, and optimized synchronization for regional requirements. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the role of the PCP in 802.11aj?** The PCP coordinates beaconing, channel access, and scheduling in PBSS environments, similar to 802.11ad but adapted for dual-band use. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does beamforming work in 802.11aj MAC?** Beamforming is supported using MAC-layer training sequences and feedback exchanges to maintain stable directional links. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11aj still use CSMA/CA?** Yes, CSMA/CA is used during Contention-Based Access Periods (CBAPs), while Service Periods (SPs) allow for scheduled access. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What types of MAC frames are used in 802.11aj?** 802.11aj reuses control, management, and data frames from 802.11ad, with enhancements for band indication and compatibility. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11aj manage dual-band switching at the MAC level?** It uses enhanced beaconing and control signaling to support fast transitions between 45 GHz and 60 GHz channels. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is there QoS support in 802.11aj MAC?** Yes, service prioritization is achieved through traffic categories and scheduled service periods, just like in 802.11ad. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What enhancements are made for synchronization?** 802.11aj improves beacon timing and time synchronization functions to account for differences in 45 GHz propagation. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does 802.11aj support spatial reuse?** Yes, MAC-level beam directionality enables better spatial reuse, especially in dense deployments. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is PBSS in 802.11aj MAC?** A Personal Basic Service Set (PBSS) is an ad-hoc network formed without infrastructure, coordinated by a PCP. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does MAC support fast session transfer?** 802.11aj MAC can hand over sessions between 60 GHz and 45 GHz bands without dropping connectivity. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Are power-saving mechanisms defined at the MAC layer?** Yes, sleep and wake cycles are managed through scheduled service periods and doze indications. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What new IEs (Information Elements) are used in MAC frames?** MAC frames include IEs to indicate band support, capabilities, and synchronization parameters for dual-band operation. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How does 802.11aj MAC ensure backward compatibility?** It supports legacy frame formats and scheduling behavior from 802.11ad to interoperate with older devices. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Does the MAC layer assist in channel bonding?** While bonding is primarily a PHY function, MAC coordinates use of bonded channels and frame aggregation over them. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **What is the role of Training fields in MAC operation?** These fields help devices align beamforming settings dynamically during association or re-training. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Can MAC functions adapt to interference?** Yes, adaptive scheduling and beam refinement at MAC level help devices mitigate interference. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **How is broadcast handled in directional MAC?** Broadcast frames are sent in sector sweep or omnidirectional modes to ensure reception by all nearby nodes. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow **Is mesh or relay support included in MAC?** No mesh features are directly defined, but PBSS relay extensions may allow forwarding in advanced scenarios. .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Reference links ` .. _mac_functions_aj_step17: .. tab-set:: .. tab-item:: Reference links * Reference links