Power Efficient PS-Poll Mechanism for WLAN Battery Life
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Solution Overview
Problem
Current power save mechanisms in IEEE 802.11 wireless network devices, such as the Distributed Coordination Function (DCF) power saving mechanism (PSM), often lead to unnecessary power consumption due to inefficient handling of buffered data transmission and sleep states in low power stations.
Innovation Solution
Implementing a power efficient PS-Poll method where the access point (AP) indicates in the ACK frame whether it will delay buffered data transmission, allowing low power stations to enter a doze state after sending a PS-Poll, and supporting TXOP power save operations to reduce active time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the station remains in sleep state to save power, then power consumption is reduced, but the station cannot receive buffered data from the AP
Solution Approach 1:
The station periodically wakes up at designated times (after SIFS following ACK transmission) to check for buffered data from the AP, then returns to sleep state. This periodic wake-sleep cycle allows the station to maintain data reception capability while minimizing power consumption by being active only when necessary.
2Reliability
If the station stays awake to receive buffered data immediately after PS-Poll, then data reception is ensured, but power consumption increases
Solution Approach 1:
The station transmits the PS-Poll frame in advance to request buffered data from the AP. The AP then prepares the data and transmits it after a standardized SIFS interval, allowing the station to enter sleep state immediately after sending PS-Poll without missing the data transmission.
Solution Approach 2:
The station follows a periodic pattern of waking up to send PS-Poll, receiving ACK and buffered data, then returning to sleep state. This structured periodic operation ensures data reception while minimizing active time and power consumption.
3Use of energy by moving object
If the AP delays buffered data transmission after ACK, then the station can enter doze state earlier to save power, but data transmission is postponed
Solution Approach 1:
The AP transmits buffered data at periodic intervals (after SIFS following ACK) rather than immediately, allowing the station to enter doze state earlier. This periodic transmission approach balances power savings with acceptable data delivery timing.
Data Source
AI summary
A IEEE 802.11 Wireless Local Area Network (WLAN) system of an access point (AP) and one or more stations (STAs) reduces power consumption and increases battery life of power efficient low power STAs by decreasing the amount of time that a power efficient low power STA remains in an awake state. After indicating power efficient low power operation during association with an AP supporting such operation, the power efficient low power STA may enter the doze state from the time that the power efficient low power STA sends a PS-Poll until the power efficient low power STA receives the buffered DATA frame from the AP. While implementing the power efficient PS-Poll method, the AP can send the buffered DATA frame to the STA SIFS after the AP sends an ACK to the received PS-Poll from the STA.