Distributed Scheduling for Multi-Hop Wireless Networks
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Solution Overview
Problem
Current scheduling mechanisms in multi-hop wireless networks, particularly in 6TiSCH, face challenges in scalability and conflict avoidance, especially in networks with high node density, where centralized scheduling becomes inefficient and decentralized techniques are more attractive but require improved mechanisms to ensure reliable and low-latency communication.
Innovation Solution
A distributed scheduling method where each node listens for signals to create a local record of scheduled transmissions, determines a preliminary schedule, and sends it to its parent node for confirmation to avoid conflicts, allowing for parallel transmissions and efficient resource utilization through optimal overprovisioning and adaptive scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized scheduling is used, then conflict avoidance is improved, but scalability deteriorates in high node density networks
Solution Approach 1:
The centralized scheduling function is segmented and distributed to individual nodes. Each node independently determines its own transmission schedule based on local records of scheduled transmissions, eliminating the need for a central scheduler and enabling the network to scale to high node densities while maintaining conflict avoidance through decentralized decision-making
Solution Approach 2:
A schedule record message acts as an intermediary mechanism, allowing nodes to share scheduling information without requiring centralized coordination. Nodes exchange schedule record messages containing their scheduled transmissions, enabling conflict-free decentralized scheduling by providing the necessary information for other nodes to make scheduling decisions
2Productivity
If decentralized scheduling is used, then scalability is improved, but conflict avoidance deteriorates
Solution Approach 1:
Nodes perform preliminary scheduling actions by determining their transmission schedules in advance based on recorded scheduled transmissions from other nodes. This preliminary action allows nodes to proactively avoid conflicts rather than reacting to them, maintaining reliability in decentralized networks
Solution Approach 2:
The schedule record message exchange implements a feedback mechanism where nodes communicate their scheduled transmissions to others. This feedback allows nodes to adjust their scheduling decisions based on information about other nodes' schedules, ensuring conflict avoidance through iterative information exchange and coordination
3Reliability
If more timeslots are allocated, then reliability is improved, but resource utilization deteriorates
Solution Approach 1:
The transmission schedule is made dynamic and adaptive rather than static. Nodes can adjust their scheduled transmissions based on changing network conditions, traffic demands, and topology changes. This dynamic approach allows the system to allocate timeslots efficiently, providing redundancy when needed for reliability while maximizing resource utilization by avoiding unnecessary allocations
Data Source
AI summary
Arrangements described herein provide a distributed means of scheduling communications directed towards a sink node from other nodes in a multi-hop wireless network. By listening for other messages assigning schedules to other nodes, each node is able to create its own local record of scheduled transmissions in its area. This allows each node to determine a preliminary schedule. Having said this, the parent node of the node will have additional information regarding the scheduled local transmissions. Accordingly, the node sends the preliminary schedule to its parent node for confirmation that it provides no collisions/conflicts with other scheduled transmissions. As the parent node is involved in the scheduling of each child node, it is better able to determine whether the child nodes are proposing schedules that may conflict with each other.