Time-Slotted Barrage Relay Network Synchronization
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Solution Overview
Problem
Ad hoc wireless networks, such as sensor networks deployed in tunnels or caves, lack a common time reference due to the absence of external sources like GPS, necessitating synchronization methods independent of external time references.
Innovation Solution
A time-slotted barrage relay network (BRN) achieves synchronization through a two-phase process: coarse synchronization via message flooding and fine synchronization using time-of-arrival (TOA) information exchanged between nodes, with nodes adjusting their local clocks to align with a pre-assigned network time reference node or autonomously generating a new reference if none exists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receivers are used to provide network-wide time reference, then time synchronization accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the time reference function from external GPS receivers and implements it through internal node coordination. Each node uses its local clock and TOA measurements to compute synchronization without requiring external hardware, thereby eliminating GPS dependency while maintaining synchronization capability.
Solution Approach 2:
The system enables nodes to self-synchronize using their own local clocks and received TOA information. The synchronization protocol allows each node to independently calculate its time offset based on messages from neighbors, eliminating the need for centralized GPS control and reducing overall system complexity.
2Speed
If coarse synchronization via message flooding is used, then synchronization speed is improved, but measurement precision deteriorates
Solution Approach 1:
The patent segments the synchronization process into two distinct phases: coarse synchronization using rapid message flooding to establish initial time alignment across the network, and fine synchronization using TOA information exchange between neighboring nodes to refine accuracy. This segmentation allows each phase to optimize for its specific goal without compromising the other.
Solution Approach 2:
The coarse synchronization phase uses excessive broadcasting of synchronization messages to rapidly establish initial time alignment across the entire network, prioritizing speed over precision. Subsequently, the fine synchronization phase applies partial TOA measurements from neighboring nodes to achieve the required precision, avoiding the need for all nodes to perform expensive precise measurements simultaneously.
3Measurement precision
If fine synchronization via TOA information exchange is used, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The synchronization process is segmented into coarse and fine phases, where the coarse phase quickly establishes initial timing across the network using message flooding, and the fine phase subsequently refines precision using localized TOA exchanges. This segmentation confines the time-consuming precise measurements to a secondary phase after rapid initial alignment is achieved.
Solution Approach 2:
The system performs preliminary coarse synchronization before fine synchronization by first rapidly distributing time reference information across the network through message flooding. This preliminary action establishes a baseline time alignment that reduces the amount of additional adjustment needed during the fine synchronization phase, thereby minimizing total synchronization time while achieving required precision.
Data Source
AI summary
Systems and methods are presented for establishing network-wide time synchronization in a time-slotted barrage relay network. In the first phase, nodes obtain coarse, slot-level time synchronization by estimating the time-of-arrival (TOA) of a message that rapidly floods the network via the barrage relay mechanism. In the second phase, fine time synchronization is achieved via a messaging protocol that exchanges TOA information between neighboring nodes.