Full Duplex Mesh Synchronization via Timing Beacons
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Solution Overview
Problem
Existing wireless mesh networks face challenges in frequency and phase synchronization due to variability in wireless link performance, leading to interference among nodes and reduced network throughput, as protocols like IEEE 1588 and SyncE are inadequate for these networks.
Innovation Solution
A method and system for network synchronization in full duplex mesh networks using timing beacons transmitted and retransmitted over a single full duplex radio channel, allowing for simultaneous sending and receiving of synchronization information, and employing self-interference cancellation and orthogonal codes to achieve precise time, frequency, and phase synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS-aided synchronization is deployed to ensure nodes work in unison, then synchronization accuracy is improved, but device complexity and deployment constraints increase
Solution Approach 1:
The patent extracts the timing reference function from GPS-dependent nodes and concentrates it in a dedicated timing master node. The timing master generates and distributes timing beacons to all other nodes (timing slaves) through the wireless mesh network, eliminating the need for each node to have GPS capability while maintaining synchronization accuracy.
Solution Approach 2:
The patent introduces a timing master node as an intermediary that mediates synchronization between all network nodes. This timing master receives timing information (from GPS or other sources) and distributes it to all timing slaves through structured beacon messages, acting as a central coordinator that simplifies the overall system architecture.
2Loss of information
If timing beacons are sent over wireless mesh networks using traditional protocols, then synchronization information is transmitted, but link variability causes synchronization errors and interference
Solution Approach 1:
The patent segments the synchronization protocol into distinct message types with specific functions: timing beacons for time distribution, range requests for distance measurement, and range responses for round-trip time calculation. Each message type contains specific fields (timestamps, identifiers, sequence numbers) that enable robust processing despite wireless variability.
Solution Approach 2:
The patent implements preliminary actions including sequence numbering in beacons, pre-calculated expected response times, and predetermined message exchange patterns. The timing master sends beacons with sequence numbers and the slaves respond with range requests at expected times, allowing the system to anticipate and correct for link variability before it causes synchronization errors.
3Productivity
If full duplex radios are used for simultaneous sending and receiving, then channel utilization is improved, but self-interference increases
Solution Approach 1:
The patent extracts the self-interference problem from the full duplex operation and addresses it through dedicated cancellation mechanisms. The system separates the desired received signal from the self-interference component using antenna isolation, analog cancellation circuits, and digital signal processing to subtract the known self-interference pattern from the received signal.
Solution Approach 2:
The patent implements feedback mechanisms where the transmitting node monitors its own transmitted signal and uses this information to generate and subtract an estimate of the self-interference from the received signal. The system continuously adjusts cancellation parameters based on feedback from the received signal quality, enabling adaptive mitigation of self-interference.
Data Source
AI summary
An approach is disclosed for synchronization of frequency and/or phase in a full duplex network. The method may comprise sending a timing beacon over a single full duplex radio channel from a timing master to a timing slave; receiving the timing beacon over the single full duplex radio channel at the timing slave; sending a retransmitted beacon over the single full duplex radio channel from the timing slave to the timing master; and sending a delta of the timing beacon and the retransmitted beacon from the timing master to the timing slave. The beacon may contain a timestamp. The retransmitted beacon may include a delay calculation. A hybrid analog/digital self-interference cancellation system may be used at the timing master or the timing slave. The method may also include simultaneously sending and receiving the synchronization information over the single full duplex radio channel.