Power Management Subfield for WLAN Traffic Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing IEEE 802.11 standard for WLAN systems creates significant transmission overhead and congestion due to the need for PS-Poll frames and concentrated frame delivery around beacons, especially in interactive voice-over-WLAN applications, which reduces channel capacity and increases collisions.
Innovation Solution
A power management method that uses a designated sub-field in the MAC header to manage power states, allowing wireless stations to transition between awake and doze states based on data availability and a periodicity timer, and introduces an interactive traffic power management mode that decouples frame delivery from beacons, reducing overhead and spreading traffic load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PS-Poll frames are used to manage power states in 802.11 WLAN, then power saving is achieved, but transmission overhead increases significantly
Solution Approach 1:
The patent extracts the power management function from the beacon-based delivery mechanism by introducing a separate power management subfield in the MAC header. This allows power state indication to be decoupled from the TIM/PS-Poll exchange, eliminating the need for dedicated PS-Poll frames while maintaining power saving functionality.
Solution Approach 2:
The patent combines power management indication with the existing MAC header structure by utilizing the power management subfield. This merges the power state notification function into the regular frame structure, eliminating separate PS-Poll frames and reducing overall transmission overhead.
2Device complexity
If frame delivery is concentrated around beacons, then power management is simplified, but channel congestion and collisions increase
Solution Approach 1:
The patent segments the frame delivery process by introducing a deliver opportunity field that can be set independently of beacon timing. This allows frames to be delivered at multiple distributed opportunities rather than being concentrated around beacons, reducing channel congestion while maintaining manageable power management through the subfield approach.
Solution Approach 2:
The patent introduces dynamic deliver opportunities that can be flexibly scheduled based on traffic conditions rather than being fixed to beacon intervals. The deliver opportunity field allows the system to adaptively create delivery windows at optimal times, spreading traffic load dynamically to avoid congestion while maintaining power efficiency.
3Reliability
If STAs wake up for every beacon to check TIM, then buffered frame delivery is ensured, but power consumption increases
Solution Approach 1:
The patent enables STAs to check the power management subfield in received frames before waking up for full beacon processing. This preliminary check allows STAs to determine if there is buffered data for them without fully activating, enabling them to remain in low-power state when no data is available and thus reducing power consumption while maintaining reliable delivery.
Solution Approach 2:
The patent implements a feedback mechanism where the AP sets the power management subfield to indicate buffered data availability. STAs can monitor this subfield and adjust their wake-up behavior accordingly, creating a feedback loop that optimizes power consumption based on actual data availability while ensuring reliable frame delivery when needed.
Data Source
AI summary
A power management method, in which creation of deliver opportunities for a wireless station (STA) of a WLAN system is managed using a designated sub-field of the frame control field in a MAC header. In one embodiment, the STA is adapted (i) to use the power management sub-field to communicate its power state to the access point (AP) and (ii) to run a periodicity timer, which starts when the STA has transitioned to the doze state. The STA transitions to the awake state either when it has a data frame available for transmission to the AP or when the periodicity timer runs out. In another embodiment, the AP and STA create deliver opportunities by entering a new mode of operation referred to as interactive traffic power management (ITPM) mode, during which the power management sub-field is ignored and the more data sub-field is used to communicate the power state and manage transitions of the STA between the awake and doze states. Embodiments of the invention improve WLAN system performance when the traffic load is such that data frames become available for transmission both at the STA and AP at relatively regular intervals, which is typically the case for interactive voice-over-WLAN applications.