WLAN Mesh Beacon Synchronization via TBTT Offset Segmentation
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Solution Overview
Problem
Current wireless mesh network standards lack a specified methodology for beacon transmission, leading to beacon collisions between mesh access points and do not provide a suitable timing synchronization mechanism, which is essential for maintaining uniform timing and minimizing collisions.
Innovation Solution
A TBTT offset-based beaconing technique is introduced, where mesh points advertise their TBTT offsets to avoid overlapping transmissions, and synchronize their timing with the fastest clock in the network, ensuring non-overlapping beacon intervals and minimizing collisions without requiring modifications to the PHY layer or complex processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distributed beacon transmission is implemented in WLAN mesh networks, then network coverage and robustness are improved, but beacon collisions occur between mesh access points
Solution Approach 1:
The beacon transmission opportunity is segmented by introducing TBTT offsets that divide the beacon period into distinct time slots for different mesh access points. Each MAP is assigned a specific offset value that segments the beacon transmission timeline, preventing simultaneous transmissions and eliminating collisions while maintaining distributed architecture benefits
Solution Approach 2:
The patent implements periodic beacon transmission with synchronized timing using TBTT offsets. All mesh access points transmit beacons periodically at intervals defined by the beacon period, but each MAP uses its assigned offset to stagger transmissions within the period, ensuring periodic coverage without collisions
2Stability of the object's composition
If timing synchronization mechanism is implemented in WLAN mesh networks, then uniform timing is achieved, but device complexity increases
Solution Approach 1:
Each mesh access point autonomously determines its TBTT offset based on information received from neighboring MAPs in their beacon frames. The synchronization mechanism operates in a self-organizing manner where each node independently configures its timing without requiring centralized control or complex coordination protocols, achieving timing uniformity through distributed self-service
Solution Approach 2:
Mesh access points perform preliminary timing configuration by receiving and processing TBTT offset information from neighboring MAPs before initiating their own beacon transmissions. This preliminary action ensures that each MAP is pre-synchronized to the network timing structure, avoiding subsequent timing conflicts and eliminating the need for complex real-time arbitration
3Reliability
If TBTT offset-based beaconing is implemented, then beacon collisions are avoided, but processing requirements increase for mesh points
Solution Approach 1:
Each mesh access point independently calculates and applies its TBTT offset using simple arithmetic operations on received beacon information. The processing requirement is minimized by using straightforward timestamp comparison and offset derivation rather than complex algorithms, achieving collision avoidance through lightweight self-service processing at each node
Data Source
AI summary
A novel and useful synchronization mechanism that functions to provide a uniform time base for mesh points in a WLAN mesh based network. The invention enables timing synchronization to a common reference clock base by advertising the common TSF within beacon transmissions. All MPs in a mesh share a common DTIM interval. The synchronization mechanism enables the mesh points to avoid collisions in the generation and transmission of beacons. The TBTT offsets of the current MP and its neighbors are advertised in beacons so that neighboring MPs that hear the beacons can select non-overlapping TBTT offsets. Each MP receives one or more beacons from its neighbors and compares the timing of its neighbors to that of itself and adopts the highest TSF (i.e. the fastest) in the mesh. Eventually, all MPs in the mesh will adjust their timing to that of the MP with the fastest clock. The reception of beacons by MPs from its neighbors is also advertised. This allows for MPs to verify that the beacons they send are actually heard and are not in collision with beacon transmissions of other MPs.