Wireless AP Sync Frames for Low-Latency Multi-Link Timing

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Solution Overview

Problem

Existing wireless communication systems face challenges in maintaining accurate synchronization between access points and stations, particularly in multi-link devices, leading to potential interference with restricted Target Wake Time Service Periods due to clock drift and TSF offsets, which affect latency-sensitive applications like real-time gaming and augmented/virtual reality.

Innovation Solution

Implementing an enhanced synchronization mode where sync frames are transmitted more frequently than Target Beacon Transmission Times, providing TSF offsets between access points, and indicating synchronization information to stations, ensuring tighter synchronization and preventing interference with scheduled service periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sync frames are transmitted more frequently than TBTTs, then timing synchronization accuracy is improved, but network overhead and device complexity increase

Engineering Contradiction:

Improvetiming synchronization accuracyVSAvoidnetwork overhead

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements an enhanced synchronization mode that dynamically adjusts the transmission frequency of sync frames based on network conditions and application requirements. During this mode, sync frames are transmitted more frequently than regular TBTT intervals to provide tighter synchronization for latency-sensitive applications, while allowing the system to switch between normal and enhanced modes as needed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the transmission parameter of sync frames by sending them at intervals shorter than the standard TBTT period when enhanced synchronization is required. This parameter adjustment provides more frequent timing updates for applications needing sub-TBTT synchronization accuracy without permanently increasing network overhead

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple APs operate on different frequency bands, then network capacity and coverage are improved, but timing synchronization between APs becomes more difficult

Engineering Contradiction:

Improvemulti-band operation capabilityVSAvoidinter-AP timing synchronization

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent introduces sync frames as an intermediary mechanism that carries TSF offset information between APs operating on different frequency bands. These sync frames provide a reference timing signal that allows stations to synchronize across multiple bands without direct inter-AP communication, solving the timing coordination problem in multi-band operations

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent pre-calculates and indicates TSF offset values in sync frames before stations need to perform timing-critical operations. By providing timing reference information in advance through sync frames, stations can adjust their local clocks proactively to maintain synchronization across multiple frequency bands

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If stations wake up more frequently to check for beacon frames, then timing synchronization is improved, but power consumption increases

Engineering Contradiction:

Improvetiming synchronizationVSAvoidstation power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent maintains TWT-based periodic wake schedules for power saving while supplementing with occasional sync frame transmissions. Stations continue to wake up at predetermined TWT intervals for data transmission, and sync frames are sent at strategic moments to update timing information without requiring stations to wake more frequently than their TWT schedule demands

Inventive Principle:

Principle #19Periodic action

4Loss of time

If sync frames are transmitted at higher data rates, then transmission time is reduced, but signal reliability may be compromised

Engineering Contradiction:

Improvesynchronization update timeVSAvoidsignal transmission reliability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent transmits sync frames at enhanced data rates when the wireless channel conditions are favorable, reducing the time required for synchronization updates. The system monitors channel quality and adjusts the data rate parameter dynamically, using higher rates for short sync frames when conditions permit, thereby minimizing transmission time without permanently compromising reliability

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12581434B2Time synchronization over a wireless network for latency-sensitive traffic

Publication Date: 2026.03.17 QUALCOMM INC

AI summary

This disclosure provides systems and methods for synchronizing wireless devices with each other. In some implementations, a device transmits, to at least one wireless station (STA), an indication of an enhanced synchronization mode on a first communication link associated with a first access point (AP) of the device. The device transmits, during the enhanced synchronization mode, a plurality of sync frames on the first communication link more often than Target Beacon Transmission Times (TBTTs) associated with the first communication link, each of the plurality of sync frames indicating a Timing Synchronization Function (TSF) offset between the first AP and a second AP of the device. In some instances, at least one of the plurality of sync frames may be a Fast Initial Link Setup (FILS) Discovery frame carrying a TSF value of the first AP.