Bidirectional OFDM Modulation Control for Reliable Railway Links
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Solution Overview
Problem
Existing data transmission methods, such as ISDN and OFDM, are inadequate for reliable signal transmission in safety-critical applications like railway technology due to insufficient reliability and the difficulty in obtaining necessary hardware components, and OFDM transmission reliability is insufficient for railway applications.
Innovation Solution
A data transmission method using Time Division Duplex (TDD) with assigned time slots for sending and receiving, dynamic modulation schemes, and control signals to adjust modulation based on transmission quality, ensuring bandwidth reserves for redundancy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OFDM transmission technology is used, then data transmission capability is provided, but transmission reliability is insufficient for railway applications
Solution Approach 1:
The patent implements dynamic adaptation by allowing the modulation scheme to change over time based on transmission quality. The system monitors transmission quality and adjusts modulation schemes dynamically, transforming a static OFDM system into an adaptive one that can respond to changing channel conditions, thereby improving reliability without sacrificing versatility.
Solution Approach 2:
The patent changes the modulation scheme parameter based on transmission quality measurements. By monitoring transmission quality and adjusting the modulation scheme parameter accordingly, the system optimizes the balance between data rate and reliability, ensuring suitable performance for safety-critical railway applications.
2Reliability
If time slots are assigned for bidirectional transmission, then transmission quality stability is improved, but data transmission rate is reduced
Solution Approach 1:
The patent dynamically adjusts the modulation scheme within assigned time slots based on real-time transmission quality feedback. This allows the system to maximize data transmission rate during good channel conditions while maintaining stability during poor conditions, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent uses bandwidth reserves partially - not all available bandwidth is used for data transmission at maximum rate, but a portion is reserved to ensure quality stability. This partial usage of capacity allows the system to maintain stable transmission quality while still achieving high productivity during favorable conditions.
3Reliability
If bandwidth reserves are provided for redundancy, then transmission reliability is ensured, but available bandwidth for data transmission is reduced
Solution Approach 1:
The patent implements partial bandwidth reservation - a portion of the bandwidth is reserved for redundancy and retransmission purposes, while the remaining bandwidth is used for data transmission. This partial reservation ensures reliability for safety-critical applications while maintaining adequate productivity for normal operations.
Solution Approach 2:
The patent prepares bandwidth reserves in advance before transmission interruptions occur. By pre-allocating redundant bandwidth capacity, the system can quickly respond to transmission failures without waiting for resource reallocation, thereby ensuring reliability while minimizing the impact on overall bandwidth utilization.
Data Source
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AI summary
The invention relates to a data transmission method in which signals representing the data (110001, 001001) are transmitted bidirectionally between a first transceiver (TC1) and a second transceiver (TC2). An OFDM method is used to modulate the data signals on several carrier frequencies. For the transmission of signals in both directions, time slots for sending and receiving (ZSS, ZSE) are assigned to the first transceiver (TC1) and the second transceiver (TC2), respectively. Each time slot is assigned a modulation scheme for each carrier frequency used. Control signals, which define at least one modulation scheme to be used, are transmitted with the signals, at least when the modulation scheme for at least one carrier frequency is to be changed.Furthermore, the invention comprises a modem, a railway system, a computer program product and a provisioning device for the computer program product.