Asynchronous Time Slot Scheduling in Wireless Mesh Networks
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Solution Overview
Problem
In conventional wireless mesh networks, child nodes synchronize their time slots with parent nodes, leading to synchronized listen events, which disrupt communication and force child nodes to repeat the discovery process, wasting limited battery power.
Innovation Solution
The child node receives time sync beacons from the parent node, computes and reports a delta and offset between their time slot numbers and start times, allowing the parent node to schedule transmissions accordingly, enabling the child node to remain paired without synchronizing time slot schedules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If child nodes synchronize their time slots with parent nodes, then listen events occur at the same time, but communication is lost and battery power is wasted
Solution Approach 1:
The patent applies asymmetry by deliberately desynchronizing time slots between parent and child nodes. Instead of symmetric synchronization where both nodes operate on the same time schedule, the system uses asymmetric time slot allocation where child nodes offset their listen events from parent node transmissions, preventing simultaneous occurrence and enabling reliable communication while conserving battery power
2Ease of operation
If child nodes synchronize listen events with parent node, then time slot coordination is simplified, but communication capability is lost
Solution Approach 1:
The patent inverts the conventional approach by having child nodes deliberately avoid synchronizing their listen events with parent node transmissions. Instead of aligning time slots to simplify coordination, the system offsets them to prevent collision, then uses alternative coordination mechanisms to maintain communication capability
3Reliability
If child nodes repeat the discovery process to pair with different parent node, then communication is restored, but battery power is consumed
Solution Approach 1:
The patent applies preliminary action by establishing proper time slot offset configuration during the initial pairing process. This prevents communication loss before it occurs, eliminating the need for child nodes to repeat the discovery process and consume additional battery power to restore communication
Data Source
AI summary
A wireless mesh network includes a child node coupled to a parent node. The parent node transmits time sync beacons that indicate a time slot number and a start time for a current time slot. The child node receives the time sync beacons and determines a delta between the current time slot number of the child node and the current time slot number of the parent node. The child node also computes an offset between a start time of the current slot of the child node and the start time of the current slot of the parent node. The child node reports the delta and the offset to the parent node. Based on the delta and the offset, the parent node determines when, and on what channel, the child node is predicted to be receiving transmissions, and then schedules transmissions to the child node accordingly.