Per-Packet TSCH Macrocell Token Scheduling for LLN Reliability
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Solution Overview
Problem
Deterministic networking in low power and lossy networks (LLNs) faces challenges such as lossy links, low bandwidth, limited resources, and dynamic environmental conditions, which affect packet delivery reliability and timing precision, especially in applications like IoT and industrial automation.
Innovation Solution
The implementation of per-packet, time slotted channel hopping (TSCH) with macrocells and a token-passing mechanism allows for precise scheduling and authorization of packet transmission across multiple hops, ensuring deterministic delivery by dividing the communication schedule into macrocells and using a token to manage transmission rights within these cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If per-packet TSCH scheduling is implemented to achieve deterministic packet delivery, then timing precision and delivery reliability are improved, but device complexity and protocol overhead increase
Solution Approach 1:
The communication schedule is segmented into multiple macrocells, each containing multiple TSCH cells. This segmentation allows the network to divide deterministic delivery guarantees into manageable time blocks, reducing the complexity of managing entire schedules at once while maintaining reliability through structured organization of transmission opportunities
Solution Approach 2:
TSCH schedules are pre-configured and distributed to all nodes before actual data transmission begins. By establishing the complete transmission schedule in advance, nodes can automatically follow predetermined time slots and channels without real-time decision-making complexity, achieving deterministic delivery through pre-planned actions
2Manufacturing precision
If time slotted channel hopping is used to ensure fixed latency, then timing precision is improved, but bandwidth utilization decreases due to rigid time slot allocation
Solution Approach 1:
While maintaining the rigid TSCH time slot structure for deterministic timing, the system dynamically adapts by allowing nodes to claim tokens and transmit during authorized cells based on real-time packet arrival. This dynamic token claiming within the static schedule framework enables better bandwidth utilization without compromising timing precision
Solution Approach 2:
The patent merges the deterministic TSCH time-slotted structure with a token-passing mechanism. The rigid time slots provide timing precision, while the token system allows flexible packet forwarding decisions. By combining these two approaches, the system achieves both fixed latency guarantees and improved bandwidth utilization through efficient resource sharing
3Reliability
If macrocells are introduced to organize TSCH schedules, then packet propagation coordination is improved, but protocol complexity increases
Solution Approach 1:
The patent introduces a hierarchical dimension to TSCH scheduling by organizing time slots into macrocells. This adds a higher-level temporal organization layer above individual TSCH cells, enabling coordinated multi-hop packet propagation across the network while maintaining the underlying TSCH structure. The macrocell concept provides a new dimension for schedule management without fundamentally changing TSCH operation
Data Source
AI summary
In one embodiment, a device in a network receives a time-slotted channel hopping (TSCH) communication schedule. The TSCH communication schedule is divided into a plurality of macrocells, each macrocell comprising a plurality of TSCH cells. The device receives a packet from a routing protocol child node of the device during a particular macrocell of the TSCH communication schedule that is associated with propagation of the packet through the network. In response to receiving the packet, the device claims a token associated with the particular macrocell that authorizes the device to transmit during one or more cells of the macrocell. The device transmits the received packet to a second node in the network during the authorized one or more cells of the particular macrocell.