802.11ah MAC Functions
What is the MAC layer in 802.11ah?
The MAC (Medium Access Control) layer in 802.11ah manages how devices access the wireless medium and controls frame transmission and reception.
What are the primary functions of the 802.11ah MAC layer?
Key functions include frame delimiting, addressing, error detection, medium access control, power saving, and retransmission management.
How does 802.11ah MAC handle medium access?
It uses a modified CSMA/CA mechanism adapted for sub-1 GHz band and low power IoT devices to reduce collisions and conserve energy.
Does 802.11ah MAC support power saving?
Yes, it implements advanced power saving features like Target Wake Time (TWT) to schedule device wake-ups and sleep efficiently.
What role does frame fragmentation play in 802.11ah MAC?
Fragmentation allows large packets to be split into smaller frames to improve reliability over long-range links.
How does 802.11ah MAC ensure reliable delivery?
Through acknowledgments (ACKs), retransmissions, and error detection using CRC to confirm successful frame reception.
What is Target Wake Time (TWT) in 802.11ah MAC?
TWT is a scheduling feature that lets devices negotiate specific times to wake up and communicate, saving battery power.
How does MAC handle addressing in 802.11ah?
The MAC uses standardized address fields to identify source, destination, and intermediate nodes for proper frame delivery.
What is the role of beacon frames in 802.11ah MAC?
Beacon frames synchronize devices, advertise network presence, and deliver information like buffered data and power-saving parameters.
How does MAC manage large numbers of devices in 802.11ah?
It supports hierarchical association and grouping mechanisms to efficiently handle thousands of connected stations.
What error detection method does 802.11ah MAC use?
It uses Cyclic Redundancy Check (CRC) to detect errors in transmitted frames.
How does 802.11ah MAC support QoS (Quality of Service)?
MAC prioritizes traffic by categorizing frames and managing access accordingly, ensuring timely delivery for critical data.
What is the association process in 802.11ah MAC?
Devices authenticate and associate with access points using MAC management frames to join the network.
How are retransmissions handled by 802.11ah MAC?
Lost or corrupted frames are retransmitted based on ACK feedback to maintain reliable communication.
Does 802.11ah MAC support multicast and broadcast?
Yes, it efficiently manages multicast and broadcast transmissions, including buffering and delivery indications.
What is the role of contention window in 802.11ah MAC?
It defines the random backoff period before transmissions to reduce collisions in shared medium access.
How does 802.11ah MAC support security?
The MAC layer works with upper layers to enforce encryption, authentication, and integrity protections.
What are MAC management frames in 802.11ah?
These frames control network functions like association, authentication, synchronization, and disassociation.
How does 802.11ah MAC differ from traditional Wi-Fi MAC?
It is optimized for low power, long range, large device counts, and operates in sub-1 GHz frequencies with specialized scheduling.
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