Power Saving Mechanisms in IEEE 802.11ag protocol
What is the purpose of power saving mechanisms in 802.11a/g?
To reduce energy consumption of wireless devices, especially battery-powered clients, while maintaining connectivity.
How does the Power Save Mode (PSM) work in 802.11a/g?
Clients enter sleep mode periodically, waking up to receive buffered data from the access point.
What role does the Traffic Indication Map (TIM) play in power saving?
TIM is a bitmap in beacon frames indicating which clients have buffered data waiting at the AP.
How do clients know when to wake up in power save mode?
They periodically listen to beacon frames containing the TIM and check if the AP has data for them.
What is the Delivery Traffic Indication Message (DTIM)?
DTIM is a special beacon that indicates multicast/broadcast frames buffered at the AP, prompting clients to wake.
How does the Listen Interval affect power saving?
It defines how often a client wakes to receive beacon frames; longer intervals save more power but increase latency.
What is the role of the PS-Poll frame?
PS-Poll allows a sleeping client to request buffered unicast frames from the AP.
How does the AP handle buffered frames for sleeping clients?
It stores frames and indicates their presence in TIM until the client wakes and requests delivery.
What is Automatic Power Save Delivery (APSD)?
APSD is an enhanced power saving feature allowing scheduled data delivery, reducing latency and power consumption.
Is APSD supported in 802.11a/g?
APSD was introduced in 802.11e but can be implemented alongside 802.11a/g devices for QoS power saving.
How does the Beacon Interval affect power saving?
Longer beacon intervals reduce wake-up frequency, saving power but increasing data delivery delay.
What is the significance of the Power Management bit in frame headers?
It signals if a client is entering or leaving power save mode to the AP.
How does power saving affect network latency?
Power saving introduces latency because clients may be asleep when data arrives, causing delays.
Can power saving cause packet loss?
If not properly synchronized, clients might miss frames buffered during sleep, but the protocol minimizes this risk.
How do clients balance power saving and performance?
By adjusting listen intervals and wake-up patterns based on application needs and traffic.
What challenges exist in power saving for 802.11a/g?
Maintaining synchronization, managing buffered frames, and handling multicast/broadcast efficiently.
How does multicast affect power saving?
Multicast frames are delivered only at DTIM intervals, so clients may remain awake longer to receive them.
Do access points have special roles in power saving?
Yes, APs buffer frames and manage TIMs to support clients’ power saving operations.
Can firmware updates improve power saving?
Yes, updates can optimize algorithms, timing, and handling of power saving features.
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