Industrial Controller Packet Delay Tracking Without Timestamp Overhead
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Solution Overview
Problem
Industrial applications face challenges in maintaining low bounded latency and reliability in wireless communication networks, leading to unexpected delays that affect the precision of industrial devices, and existing methods like timestamping introduce overhead.
Innovation Solution
A method for transmitting data packets to industrial controllers that includes determining and appending delay times to the packet headers at primary and secondary network nodes, allowing the controller to generate commands considering these delays without adding timestamp overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If timestamp is added to track delay during transmission, then delay tracking capability is improved, but overhead on wireless link increases
Solution Approach 1:
The patent extracts the delay tracking function from the data packet payload (timestamp) and implements it through a separate mechanism using packet counters and timing information maintained by network nodes. This separates the measurement function from the data transmission, improving measurement capability without increasing packet overhead.
Solution Approach 2:
The patent introduces an intermediary mechanism where network nodes (primary and secondary) maintain packet counters and timing information to track delay. Instead of embedding timestamps in every packet, the system uses intermediate tracking at network nodes to determine delay based on packet sequence numbers and transmission timing.
2Reliability
If low modulation and coding scheme is used to ensure reliability, then reliability is improved, but spectral efficiency decreases
Solution Approach 1:
The patent applies partial redundancy by using packet counters and selective acknowledgment mechanisms rather than full redundancy through low MCS. The system transmits packet index information and uses selective retransmission based on acknowledgment status, achieving reliable delivery with higher spectral efficiency than conservative low MCS approaches.
Solution Approach 2:
The patent implements feedback mechanisms where the industrial controller sends acknowledgments for received packets, and network nodes use this feedback to determine retransmission needs. This feedback-driven approach enables reliable communication with adaptive retransmission, achieving reliability without permanently using low-efficiency modulation schemes.
3Manufacturing precision
If delay compensation is implemented, then performance precision is improved, but system complexity increases
Solution Approach 1:
The patent implements preliminary action by having network nodes pre-calculate delay values based on packet counters and timing information before packets reach the industrial controller. The controller receives pre-computed delay compensation values, enabling precise performance control without implementing complex real-time delay calculation and compensation mechanisms.
Data Source
AI summary
Embodiments of the present disclosure provide a method for transmitting a data packet intended for an industrial controller. The method is performed by a primary network node in the wireless communication network. The method includes receiving a data packet from at least one industrial device. The method includes determining a delay time associated with the received data packet. The delay time is indicative of a delay of the received data packet occurred during transmission of the received data packet to the primary network node. The method further includes forming a data packet intended for the industrial controller. The method further includes transmitting the data packet intended for an industrial controller, to one or more secondary network nodes in the wireless communication network. The forming of the data packet intended for the industrial controller includes forming the data packet from the received data packet and the determined delay time.