802.11aj MAC Functions
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.
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.
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.
How does beamforming work in 802.11aj MAC?
Beamforming is supported using MAC-layer training sequences and feedback exchanges to maintain stable directional links.
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.
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.
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.
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.
What enhancements are made for synchronization?
802.11aj improves beacon timing and time synchronization functions to account for differences in 45 GHz propagation.
Does 802.11aj support spatial reuse?
Yes, MAC-level beam directionality enables better spatial reuse, especially in dense deployments.
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.
How does MAC support fast session transfer?
802.11aj MAC can hand over sessions between 60 GHz and 45 GHz bands without dropping connectivity.
Are power-saving mechanisms defined at the MAC layer?
Yes, sleep and wake cycles are managed through scheduled service periods and doze indications.
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.
How does 802.11aj MAC ensure backward compatibility?
It supports legacy frame formats and scheduling behavior from 802.11ad to interoperate with older devices.
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.
What is the role of Training fields in MAC operation?
These fields help devices align beamforming settings dynamically during association or re-training.
Can MAC functions adapt to interference?
Yes, adaptive scheduling and beam refinement at MAC level help devices mitigate interference.
How is broadcast handled in directional MAC?
Broadcast frames are sent in sector sweep or omnidirectional modes to ensure reception by all nearby nodes.
Is mesh or relay support included in MAC?
No mesh features are directly defined, but PBSS relay extensions may allow forwarding in advanced scenarios.
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