Symmetrical Cable Data Transmission Using Synchronized TDD-OFDM
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Solution Overview
Problem
Existing signal transmission technologies in railway applications, such as ISDN, are outdated and face challenges in ensuring high reliability and symmetry for bidirectional communication, particularly in safety-critical environments.
Innovation Solution
A Time Division Duplex (TDD) method combined with Orthogonal Frequency-Division Multiplexing (OFDM) is employed, where time slots for sending and receiving are synchronized, and each carrier frequency is assigned a modulation scheme, allowing for dynamic adjustment to maintain transmission quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ISDN signal transmission is used, then bidirectional communication is achieved, but reliability and symmetry for safety-critical applications are insufficient
Solution Approach 1:
The patent applies parameter changes by transitioning from ISDN to a modern transmission system based on TDD and OFDM technologies. This involves changing key parameters including the use of synchronized time slots for bidirectional communication, orthogonal frequency division multiplexing for signal modulation, and dynamic modulation schemes that adapt to transmission conditions. These parameter changes enable the system to achieve both high reliability and modern adaptability required for safety-critical railway applications.
2Reliability
If Time Division Duplex with synchronized time slots is used, then symmetrical transmission quality in both directions is achieved, but system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the transmission channel into distinct time slots for uplink and downlink communication. Each time slot is further segmented into multiple orthogonal subcarriers through OFDM. This segmentation approach enables independent optimization of each time slot and subcarrier, allowing synchronized transmission with equal quality in both directions while managing system complexity through modular structure. The segmentation also facilitates dynamic modulation scheme assignment to different carriers based on transmission conditions.
Solution Approach 2:
The patent implements periodic action through the use of periodic synchronization signals and frame structures. Time slots are arranged in periodic frames with regular patterns for uplink and downlink transmission. This periodic structure enables reliable synchronization between transmitter and receiver, ensuring symmetrical transmission quality while providing predictable system behavior that simplifies complexity management through regular, repeating patterns rather than arbitrary timing.
3Productivity
If all available carrier frequencies are used for both directions, then transmission capacity is maximized, but interference and signal quality deterioration occur
Solution Approach 1:
The patent applies preliminary action by performing channel estimation and quality assessment before actual data transmission. The system预先 determines the quality of each carrier frequency and assigns appropriate modulation schemes in advance. This preliminary characterization of the transmission medium allows the system to maximize capacity by using all available carriers while preventing quality deterioration through proactive identification and mitigation of problematic frequencies before they cause transmission errors.
Solution Approach 2:
The patent implements dynamics through dynamic modulation scheme assignment to different carrier frequencies. The system continuously monitors transmission conditions and adjusts the modulation complexity for each carrier based on real-time quality assessments. Carriers with good signal quality can use higher-order modulation for maximum capacity, while carriers experiencing interference or deterioration automatically switch to more robust, lower-order modulation schemes. This dynamic adaptation enables the system to maintain both high transmission capacity and reliable signal quality across all used frequencies.
Data Source
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AI summary
The invention relates to a data transmission method in which data transmission between a first transceiver and a second transceiver is carried out via cable in both directions at a data rate of the same order of magnitude. A time division duplex method is used to transmit the data-representing signals (S) in both directions, in which time slots for transmitting and time slots for receiving the signals (ZSS, ZSE) are each assigned to the first and second transceivers. The assignment of the time slots for the first and second transceivers is synchronized such that one time slot for transmitting and one time slot for receiving (ZSS, ZSE) always run synchronously, and an OFDM method is used for modulating the signals (S). Furthermore, the invention comprises a modem, a railway system, a computer program product, and a delivery device for the computer program product.