WLAN Access Point Beacon Scheduling for Station Power Management
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Solution Overview
Problem
Existing implementations of the IEEE 802.11 downlink scheme do not efficiently coordinate the wake/sleep states of wireless stations to minimize power consumption and optimize downlink data packet delivery in WLANs with multiple stations, leading to inefficient use of available downlink time.
Innovation Solution
The method involves sending a beacon frame with a traffic indication map (TIM) to manage a downlink data transmission interval, which includes a polling period and a data delivery period, allowing only stations with buffered data to send polling frames and restricting wireless channel access, thereby optimizing channel usage and reducing power consumption by determining precise wakeup times for data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stations wake up frequently to check for downlink data packets, then data delivery reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic wake/sleep cycles for stations, where stations wake up at scheduled intervals to receive data packets and then return to sleep mode. This periodic action allows stations to balance between checking for data (reliability) and conserving energy (power consumption) by not remaining continuously awake.
Solution Approach 2:
The access point performs preliminary scheduling of downlink data packets and determines optimal wake times for stations before the actual data transmission. This preliminary action allows stations to wake up only when necessary, improving power efficiency while ensuring data is delivered during their active periods.
2Speed
If all stations remain awake to receive downlink packets, then data transmission speed is improved, but overall network efficiency deteriorates
Solution Approach 1:
The patent applies different wake/sleep schedules to different stations based on their individual data needs and traffic patterns. Instead of a uniform approach, each station's wake time is optimized locally, allowing the network to achieve both fast transmission for active stations and high overall efficiency through reduced idle listening.
Solution Approach 2:
The system dynamically adjusts station wake times based on real-time network conditions, buffered data amounts, and traffic priorities. This dynamic scheduling allows the network to adapt transmission speeds and station activity levels, optimizing both individual data transmission speed and overall network efficiency.
3Loss of information
If the AP sends beacon frames frequently, then channel utilization information is updated more often, but channel overhead increases
Solution Approach 1:
The patent optimizes beacon frame transmission parameters, such as the interval between beacons and the content included in each beacon, based on current network conditions and station requirements. By changing these parameters dynamically, the system maintains up-to-date channel information while minimizing the energy overhead associated with frequent beacon transmissions.
Data Source
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AI summary
In a wireless local access network (WLAN), an access point (AP) broadcasts a beacon frame to a plurality of stations. The AP receives an indication frame from a station of the plurality of stations. The indication frame indicates that the station is available to receive a data packet for the station buffered at the AP. The AP indicates to the station a wakeup time for the station to wake up, and sends the data packet to the station at or after the wakeup time.