TSCH Coordinator Handover Using Beacon-Based Root Re-Election
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Solution Overview
Problem
In time-slotted channel hopping (TSCH) networks, the loss of connectivity or power to a coordinator disrupts synchronization, necessitating reconnection and resynchronization of multiple nodes, which is inefficient and disruptive.
Innovation Solution
A synchronization tree is maintained using a root coordinator and enhanced beacons that allow coordinators to detect loss of connectivity, elect a new root coordinator, and maintain network synchronization by transmitting beacons across channels and timeslots, enabling efficient reconnection and resynchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single root coordinator is used to maintain synchronization in TSCH networks, then network synchronization is maintained, but the network is vulnerable to disruption when the root coordinator is lost
Solution Approach 1:
The patent implements preliminary action by having coordinator nodes pre-identify potential new root coordinators before the actual root coordinator is lost. Enhanced beacons are transmitted in advance containing synchronization information and candidate coordinator identifiers, so that when the root coordinator fails, nodes can immediately switch to a pre-identified candidate without disruption to the synchronization tree.
Solution Approach 2:
The patent uses enhanced beacons as an intermediary mechanism to facilitate the transition from the original root coordinator to a new root coordinator. These beacons carry synchronization information and candidate coordinator identifiers, acting as a mediator that enables smooth handover and maintains network continuity during the coordinator transition.
2Reliability
If coordinator loss requires full reconnection and resynchronization of all nodes, then network integrity is restored, but network operation is disrupted and efficiency is reduced
Solution Approach 1:
The patent segments the network into hierarchical levels with the root coordinator at the top and multiple coordinator nodes at lower levels. When the root coordinator is lost, only the immediate child coordinators need to re elect a new root, while other parts of the network continue operating with their existing coordinators. This segmentation limits the scope of disruption and maintains overall network productivity.
Solution Approach 2:
The patent implements preliminary action by pre-distributing synchronization information and candidate coordinator identifiers through enhanced beacons before the root coordinator is lost. This allows coordinator nodes to have ready-to-use synchronization data, enabling them to quickly re establish connections without requiring full network-wide resynchronization, thus maintaining high operational efficiency.
3Reliability
If enhanced beacons are transmitted across multiple channels and timeslots, then coordinator loss detection and new root election is enabled, but communication overhead increases
Solution Approach 1:
The patent makes enhanced beacons multi-functional by embedding multiple types of information within a single beacon transmission. These beacons simultaneously convey synchronization information, candidate coordinator identifiers, and network status data. This universality reduces the total number of separate transmissions needed, thereby limiting the increase in communication overhead while maintaining robust coordinator loss detection capability.
Data Source
AI summary
A synchronized wireless network includes a root coordinator and any number of other coordinators that are synchronized with the root coordinator, e.g., according to a communication schedule established by the root coordinator and transmitted to the other coordinators in one or more beacons. The other coordinators coordinate operations of individual area networks by establishing communication schedules for the respective area networks, and transmitting beacons including such other schedules to any number of nodes of such networks. Upon detecting a loss of connectivity with the root coordinator, coordinators or nodes of area networks monitor channels and timeslots for beacons transmitted by other coordinators of the synchronized wireless network, and elect one of their own to serve as a root coordinator, or select one of the other coordinators for synchronization, based on contents of such beacons.