TSCH Network Coordinator Beacon Transmission in Unassigned Slots

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Solution Overview

Problem

Current time-slotted channel hopping (TSCH) network formation processes are inefficient, often requiring multiple hours for nodes to join and synchronize with the network coordinator due to the low probability of receiving beacons transmitted during a small subset of the slot frame.

Innovation Solution

Transmitting beacons during unallocated guaranteed time slots in the TSCH network, which increases the frequency and number of beacons received by adjacent nodes, allowing for faster network formation and synchronization by dynamically adjusting the beacon transmission rate based on the number of connected nodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If beacons are transmitted during a small subset of slot frames (synchronization time slots), then network coordinator can maintain time synchronization, but adjacent TSCH nodes have low probability of receiving beacons and network formation takes multiple hours

Engineering Contradiction:

Improvebeacon reception probabilityVSAvoidnetwork formation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the slot frame structure by introducing a new beacon transmission opportunity in the guaranteed time slot portion, separate from the traditional synchronization time slot beacons. This creates multiple independent beacon transmission channels, increasing the probability that adjacent nodes will receive at least one beacon during their scanning period.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent enables preliminary beacon transmission during guaranteed time slots before the traditional synchronization time slot beacons. By transmitting beacons earlier in the slot frame structure, the network coordinator provides additional opportunities for adjacent nodes to detect and join the network before the standard beacon transmission occurs.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If beacon transmission frequency is increased to reduce network formation time, then adjacent nodes can join faster, but network coordinator consumes more energy and increases channel traffic

Engineering Contradiction:

Improvenetwork formation speedVSAvoidnetwork coordinator energy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic beacon transmission by conditionally transmitting beacons during guaranteed time slots based on whether the slot is assigned to a network node. The transmission behavior adapts to network state, transmitting only when appropriate, thereby increasing formation speed without proportionally increasing energy consumption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent utilizes previously underutilized guaranteed time slots that would otherwise be wasted or used only for data transmission. By repurposing these slots for beacon transmission when nodes are not present, the system increases beacon frequency without requiring additional dedicated beacon resources or proportional energy expenditure.

Inventive Principle:

Principle #34Discarding and recovering

3Adaptability or versatility

If guaranteed time slots are used for beacon transmission, then more beacon opportunities are available, but time slots assigned to joined TSCH nodes may be disrupted

Engineering Contradiction:

Improvebeacon transmission flexibilityVSAvoidtime slot assignment stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by transmitting beacons only in guaranteed time slots that are unassigned to specific network nodes. This selective approach allows beacon transmission flexibility in appropriate locations while preserving the stability and reliability of time slots that are assigned to joined TSCH nodes for their data communication.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses the guaranteed time slot structure as an intermediary mechanism that can serve dual purposes: beacon transmission when nodes are joining or absent, and reliable data transmission when nodes are connected. This intermediary structure resolves the conflict between beacon transmission flexibility and time slot assignment stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10231238B2Forming a time synchronized channel hopping network using guaranteed time slots

Publication Date: 2019.03.12 LANDIS GYR TECH INC

AI summary

A network coordinator in a time-slotted channel hopping (“TSCH”) network can include a processing device and a memory on which instructions are stored for causing the processing device to (i) determine a first guaranteed time slot in a first occurrence of a hopping pattern is unassigned to any TSCH node of a plurality of TSCH nodes in the TSCH network; (ii) transmit a beacon during the first guaranteed time slot in the first occurrence of the hopping pattern; (iii) receive a signal from a TSCH node outside the TSCH network requesting joinder to the TSCH network; (iv) join the TSCH as a joined TSCH node; (v) assign a second guaranteed time slot to the joined TSCH node; (vi) determine the second guaranteed time slot in a second occurrence of the hopping pattern is assigned; and (vii) listen for communication from the joined TSCH node during the second guaranteed time slot.