Beacon Frame TIM Domain Segmentation for Multicast Indication
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Solution Overview
Problem
In WLAN systems, STAs in power saving mode cannot determine whether buffered broadcast/multicast frames belong to them, leading to unnecessary wake-ups and increased radio channel load when multiple SSIDs or virtual APs are used, as the existing Beacon frame's TIM information domain lacks specific indication of service network or multicast group.
Innovation Solution
The AP sets a broadcast/multicast indication bit associated with the service network or multicast group, allocating an index value for each SSID and multicast group in the Beacon frame, allowing STAs to determine the presence of buffered frames based on this bit and index value, thereby avoiding unnecessary wake-ups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing Beacon frame's TIM information domain is used without service network or multicast group indication, then the structure remains simple, but STAs cannot accurately determine whether buffered frames belong to them, leading to unnecessary wake-ups and increased channel load
Solution Approach 1:
The patent segments the TIM information domain by introducing separate indication bits for different service networks and multicast groups. Each service network and multicast group is assigned a unique identifier and corresponding indication bit, allowing STAs to check only relevant buffered frames for their specific service network or multicast group, thereby improving determination accuracy without requiring complete restructuring of the Beacon frame
Solution Approach 2:
The patent adds a new dimension to the TIM information domain by incorporating service network identifiers and multicast group identifiers as separate fields. This dimensional expansion allows the system to provide fine-grained frame ownership indication while maintaining backward compatibility with existing Beacon frame structures, resolving the contradiction between precision improvement and structure simplicity
2Reliability
If STAs wake up to check for buffered frames without accurate indication, then they can receive any buffered frames, but unnecessary wake-ups increase power consumption and radio channel load
Solution Approach 1:
The patent implements a feedback mechanism where the AP sets specific indication bits in the TIM information domain based on the actual buffered frames for each service network and multicast group. STAs read these indication bits to determine whether to wake up and retrieve frames. This feedback loop ensures that STAs wake up only when relevant frames are buffered, maintaining reliable frame delivery while minimizing unnecessary wake-ups and power consumption
3Adaptability or versatility
If the AP buffers all broadcast and multicast frames for all STAs, then all STAs can receive any buffered frames, but the channel load increases when all STAs wake up simultaneously
Solution Approach 1:
The patent applies local quality by making the frame indication specific to each service network and multicast group rather than applying a universal indication to all frames. Each STA checks only the indication bits relevant to its subscribed service networks and multicast groups, allowing selective frame reception. This approach maintains the versatility of receiving any buffered frame while improving channel efficiency by reducing simultaneous wake-ups
Data Source
AI summary
A method includes: an AP sets a broadcast/multicast indication bit that associates the service network and/or multicast group to the valid state and sends frames that carry the broadcast/multicast indication bit to a STA; the STA determines whether there is broadcast/multicast frame buffered in the AP according to the associated service network and/or multicast group and the received broadcast/multicast indication bit.