Multi-AP RTWT Timing Frames for TSF Offset Synchronization
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Solution Overview
Problem
In multi-AP communication scenarios, non-AP STAs cannot correctly obtain the start time of a neighboring AP's restricted target wake time service period (RTWT SP), leading to failed channel acquisition and low-latency service communication issues due to misaligned time synchronization function (TSF) timers.
Innovation Solution
Generate and send communication frames containing time information and offsets to enable non-AP STAs to determine the start time of RTWT SPs of neighboring APs, aligning TSF timers and ensuring timely channel acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an AP 1 broadcasts RTWT information of a neighboring AP 2, then the non-AP STA can terminate TXOP before RTWT SP of AP 2 arrives, but the non-AP STA cannot correctly obtain start time of the RTWT SP of the AP 2 due to misaligned TSF timers
Solution Approach 1:
The patent introduces an intermediary information structure (the communication frame with offset field) that mediates between the AP's TSF timer and the non-AP STA's local timer. The offset value acts as a mediator that bridges the time synchronization gap, allowing the non-AP STA to calculate the correct RTWT SP start time by adding the offset to its own timer value, thus resolving the information loss problem
2Area of stationary object
If multiple APs are deployed densely to improve coverage, then network coverage is improved, but inter-cell interference increases and coordination becomes complex
Solution Approach 1:
The patent changes the time parameter representation by introducing an offset value that transforms the absolute TSF timer synchronization problem into a relative time offset problem. This parameter transformation simplifies the coordination complexity by allowing each non-AP STA to independently calculate the correct timing based on its associated AP's timer plus the broadcast offset, eliminating the need for complex multi-AP synchronization protocols
3Ease of operation
If the non-AP STA uses its own TSF timer to determine RTWT SP start time, then the STA can operate independently, but the STA cannot correctly obtain the start time due to timer misalignment
Solution Approach 1:
The patent applies preliminary action by having the AP pre-calculate and broadcast the time offset value before the non-AP STA needs to determine the RTWT SP start time. This preliminary provision of offset information enables the STA to independently and accurately calculate the start time without requiring real-time synchronization or complex coordination during operation
Data Source
Figure 1a~1b
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Figure 2b
AI summary
A communication method and a related apparatus are provided, relate to the field of communication technologies, and may be applied to a wireless local area network system that supports 802.11 series protocols such as a next-generation Wi-Fi protocol of IEEE 802.11ax, like 802.11be, Wi-Fi 7, or EHT, and a next generation of 802.11be, like Wi-Fi 8, UHR, or Wi-Fi AI; and may be further applied to a WPAN system, a sensing system, or the like that supports UWB. A first AP generates and sends a first communication frame, and a first non-AP STA receives and parses the first communication frame. The first communication frame includes first information and second information, the first information indicates first time information corresponding to the first AP, and the second information indicates an offset between the first time information and start time of an RTWT SP of a second AP. According to the method, the start time of the RTWT SP of the second AP can be determined.