PRP Wireless Transmission with Packet Redundancy
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Solution Overview
Problem
Existing safety-critical data transmission systems, particularly in process engineering and mobile work equipment, face challenges in ensuring reliable wireless data transfer between networks due to potential disruptions in redundant transmission links, which can lead to inadmissible data transmission failures.
Innovation Solution
The method involves transmitting data packets multiple times over the same transmission path, supported by PRP, with a feedback mechanism to prevent re-sending of error-free packets, and using error correction values to enhance redundancy, allowing for the acceptance of packet losses while ensuring data integrity through forward error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transmitted wirelessly using PRP over two transmission links, then redundancy is provided and security is improved, but data transmission may still be disrupted in an unacceptable manner from a security-critical perspective
Solution Approach 1:
The data stream is segmented into individual data packets, each transmitted independently multiple times. This allows selective acknowledgment and retransmission of only failed packets rather than entire data streams, improving reliability while reducing unnecessary retransmissions that could cause further disruptions.
Solution Approach 2:
Error detection codes are preliminarily attached to each data packet before transmission. This preliminary error detection capability allows the receiving end to immediately identify corrupted packets and request selective retransmission, preventing propagation of erroneous data and reducing the need for extensive retransmission protocols.
2Reliability
If data packets are transmitted multiple times over the same transmission path, then redundancy is significantly increased, but transmission time and data throughput are reduced
Solution Approach 1:
A feedback mechanism using selective acknowledgment packets is implemented where the receiving end sends acknowledgments only for successfully received data packets. This allows the transmitting end to identify which packets need retransmission, optimizing the balance between redundancy and throughput by avoiding retransmission of already successfully delivered packets.
Solution Approach 2:
The transmission system dynamically adjusts the number of retransmission attempts based on packet priority and system conditions. Critical safety-related packets receive multiple retransmission attempts, while less critical data uses fewer attempts, optimizing overall data throughput while maintaining necessary redundancy for safety-critical communications.
3Reliability
If error correction values are assigned to each data packet, then forward error correction is enabled and data integrity is enhanced, but device complexity and processing overhead increase
Solution Approach 1:
Different error correction schemes are applied to different data packets based on their priority and criticality. Safety-critical packets receive robust forward error correction with higher redundancy, while non-critical packets use simpler error detection. This localized quality approach enhances data integrity for critical communications without unnecessarily increasing complexity for all traffic.
Solution Approach 2:
The system applies error correction selectively rather than universally. Forward error correction is applied only to the minimum necessary packets to achieve the required safety integrity level, rather than adding error correction overhead to every single packet. This partial application reduces processing complexity while maintaining sufficient data integrity for safety-critical operations.
Data Source
Figure 1
AI summary
The invention relates to a method for operating a transmission system (1) that comprises a first network (2) and at least one additional network (3), in which data are exchanged between said at least two networks (2, 3) by means of data of the first network (2) being fed to duplication means (4), these fed data being wirelessly transmitted to separator means (5) via at least two transmission paths (6, 7) using PRP, and being forwarded from said separator means (5) to the connected additional network (3), the invention being characterised in that the data are transmitted in the form of data packets and in that each data packet is transmitted multiple times via the same transmission path (6, 7).