Dynamic Traffic Indication Map for WLAN Power Save
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Solution Overview
Problem
In wireless local area networks (WLAN) systems, stations (STAs) in power save mode face challenges in efficiently managing power consumption and radio medium occupation due to the lack of an effective method for reporting buffered traffic, leading to unnecessary power consumption and reduced throughput.
Innovation Solution
A method and apparatus for determining the type of receiving STA indicator based on the number of associated STAs with buffered traffic, generating a traffic indication map (TIM) element, and optimizing its size by using bit sequence or bitmap types, which is transmitted within beacon frames to manage power save mode operations, allowing STAs to efficiently transition between awake and doze states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the AP uses a fixed-size bitmap TIM element to indicate buffered traffic for all STAs, then the TIM element structure is simple and easy to parse, but the TIM element size becomes large when many STAs are associated, causing unnecessary medium occupation and power consumption
Solution Approach 1:
The patent segments the TIM element into multiple parts: a first TIM element indicating whether buffered traffic exists, and a second TIM element containing detailed STA identification information only when needed. This segmentation allows STAs to quickly check for buffered traffic without parsing the entire TIM structure, reducing power consumption while maintaining parsing simplicity.
Solution Approach 2:
The patent implements a dynamic TIM element structure where the size and content of the TIM element adapt based on the number of associated STAs and whether buffered traffic exists. When no buffered traffic exists or few STAs are associated, a compact format is used; when many STAs are associated and buffered traffic exists, expanded format with detailed STA information is used, optimizing both power consumption and parsing efficiency.
2Loss of information
If the TIM element includes detailed information for all associated STAs, then the information completeness is high, but the TIM element size increases, causing longer transmission time and medium occupation
Solution Approach 1:
The patent extracts only the essential buffered traffic indication information into the first TIM element, separating it from detailed STA identification information. This extraction allows the TIM element to convey the critical message of whether buffered traffic exists without including all detailed STA information, thereby reducing transmission time and medium occupation while maintaining information completeness for power save operation.
Solution Approach 2:
The patent uses partial action by including only the necessary portion of STA information in the TIM element - specifically, whether buffered traffic exists and basic STA identification. Detailed STA information is omitted or provided on-demand, reducing TIM element size and transmission time while providing sufficient information for STAs to make power save decisions.
3Speed
If the AP transmits the TIM element frequently to ensure STAs can quickly check for buffered traffic, then the responsiveness is high, but the power consumption and medium occupation increase
Solution Approach 1:
The patent implements periodic transmission of the TIM element within beacon frames at standardized intervals defined by the WLAN protocol. This periodic action provides a balanced approach where STAs can wake up at regular intervals to check for buffered traffic, maintaining responsiveness while avoiding excessive transmission frequency that would increase power consumption and medium occupation.
Solution Approach 2:
The patent changes the TIM element parameters (size, content, format) dynamically based on the network state, including the number of associated STAs and the presence of buffered traffic. By adapting the TIM element parameters to current conditions, the system maintains high responsiveness when needed while reducing transmission overhead during normal operation, thereby optimizing the balance between detection speed and power consumption.
Data Source
AI summary
A method for a power save mode operation in a wireless local area network (WLAN) system is provided. The method comprising determining a type of a receiving station (STA) indicator on the basis of the number of STAs which are associated with the AP and which intend to transmit buffered traffic; generating a traffic indicator map (TIM) element including information which indicates the receiving STA indicator and the type of the receiving STA indicator, transmitting the TIM element, receiving a poll frame for requesting data frame transmission from one STA among the STAs and transmitting the data frame to the STA.