STA Power Save Mode Frame Transmission via Poll Duration
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Solution Overview
Problem
The existing wireless LAN systems face inefficiencies in power save mode operations, particularly in frame transmission and reception, as stations frequently switch between awake and doze states, leading to suboptimal power management and reduced throughput.
Innovation Solution
A method and apparatus for a station (STA) operating in a wireless local area network that includes transmitting a poll frame with a duration field to request buffered frames, receiving acknowledgement frames, and entering a doze state after receiving acknowledgement, allowing for efficient data transmission and reception during polled service periods, and enabling the STA to control service periods based on AP's transmission state, thereby optimizing power consumption and channel usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the station frequently switches between awake and doze states to save power, then power consumption is reduced, but throughput and efficiency deteriorate
Solution Approach 1:
The access point performs preliminary actions by buffering multiple frames before the station wakes up, and transmits them all during a single service period. This eliminates the need for the station to frequently wake up, maintaining low power consumption while improving throughput by delivering multiple frames in one go.
Solution Approach 2:
The service period mechanism ensures continuous useful action by maintaining the channel open for the station to receive multiple frames without interruption. The duration field in the poll frame and corresponding NAV settings ensure the transmission continues uninterrupted, maximizing throughput during the awake period while minimizing wake-up frequency.
2Device complexity
If the access point transmits only one frame in response to the station's request, then the protocol simplicity is maintained, but traffic processing efficiency deteriorates
Solution Approach 1:
The access point performs preliminary action by pre-buffering multiple frames before the station requests them. When the station sends a poll frame, the AP already has multiple frames ready to transmit, eliminating the need for multiple request-response cycles and improving traffic processing efficiency without complicating the protocol.
Solution Approach 2:
Multiple frame transmissions are merged into a single service period. Instead of transmitting one frame at a time through separate protocol exchanges, the AP combines multiple frame transmissions into one continuous operation, improving efficiency while maintaining protocol simplicity through the use of the duration field and NAV mechanism.
3Reliability
If the station remains in awake state to receive frames, then data reception completeness is improved, but power consumption increases
Solution Approach 1:
The station dynamically adjusts its operational state based on the service period mechanism. During the service period indicated by the duration field, the station remains awake to ensure complete data reception. After the service period ends (when NAV reaches zero), the station transitions to doze state to save power. This dynamic state management ensures reliable reception when needed while minimizing power consumption.
Solution Approach 2:
The power save operation uses periodic action through defined service periods. The station wakes up for specific service periods to receive frames, then returns to doze state. This periodic wake-up pattern ensures complete data reception during active periods while significantly reducing power consumption compared to continuous awake operation.
4Loss of time
If the station wakes up more frequently to check for buffered data, then data reception timeliness is improved, but power save efficiency deteriorates
Solution Approach 1:
The access point performs preliminary action by buffering multiple frames in advance before the station wakes up. When the station wakes for a service period, all buffered frames are already ready for transmission. This eliminates the need for the station to wake up frequently to check for data, improving power save efficiency while maintaining timely data reception through the single service period mechanism.
Data Source
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Figure 3(a)~3(c)
AI summary
The present invention relates to methods of transmitting and receiving a frame, which are performed by a station operating in a power save mode in a wireless LAN system. The method includes: transmitting a poll frame requesting the transmission of a buffered frame to an access point AP, wherein the poll frame includes a sustain time field that indicates a service section; and receiving at least one buffered frame from the AP within the sustain time in response to the poll frame. A method is provided for transmitting and receiving a frame executed by a station (STA) operating in a power sub mode in a wireless LAN system. The method includes transmitting a first poll frame requesting the transmission of a buffered frame to an access point AP, receiving an acknowledgement ACK frame in response to the first poll frame, and receiving at least one buffered frame from the AP.