OFDM Receiver Embedding Emergency Data in Transmission Symbols
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Solution Overview
Problem
Current radio communication systems using Orthogonal Frequency Division Multiplexing (OFDM) face challenges in efficiently transmitting emergency information with low latency and high reliability, especially in multipath propagation conditions, which can lead to increased bit error rates and reduced spectral efficiency.
Innovation Solution
A transmitter and receiver system that embeds emergency information into OFDM symbols using a modulator and emergency information embedder, allowing for rapid transmission and detection of emergency data with low latency, utilizing additional subcarriers at the edge of the spectrum or spreading them across existing subcarriers, and incorporating advanced error correction codes like LDPC and BCH codes for robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of subcarriers is increased to improve spectral efficiency, then spectral efficiency is improved, but robustness deteriorates due to reduced subcarrier bandwidth and increased difficulty of demodulation
Solution Approach 1:
The patent segments the transmission signal into multiple orthogonal subcarriers, where each subcarrier carries a portion of the data. By increasing the number of subcarriers, the total spectral efficiency improves while each individual subcarrier maintains sufficient bandwidth for reliable demodulation through the orthogonal structure that reduces interference between subcarriers.
Solution Approach 2:
The patent transforms the time-domain signal into the frequency domain by introducing multiple frequency dimensions (subcarriers). This dimensional transformation allows data to be parallelly transmitted across multiple frequency channels, achieving high spectral efficiency while the orthogonal frequency division multiplexing structure provides inherent robustness against frequency-selective fading and interference.
2Reliability
If the guard interval is increased to handle multipath propagation, then robustness against multipath is improved, but spectral efficiency deteriorates due to increased overhead
Solution Approach 1:
The patent dynamically adjusts the guard interval duration as a parameter based on the detected multipath propagation conditions. By adapting the guard interval length to match the actual delay spread of the channel, the system achieves sufficient robustness against multipath effects while minimizing the overhead and maximizing spectral efficiency for each transmission condition.
Data Source
AI summary
A transmitter for transmitting payload data and emergency information using data symbols in a single-carrier or multi-carrier broadcast system comprises a modulator configured to modulate one or more transmission symbols with signaling data for use in detecting and recovering the payload data at a receiver and to modulate one or more transmission symbols with the payload data. An emergency information receiver receives emergency information carrying information of an actual emergency. An emergency information embedder embeds emergency information into one or more transmission symbols, wherein the emergency information is embedded within a predetermined time period after its reception by using a resource used for carrying signaling data and/or payload data if no emergency information shall be transmitted. A transmission unit transmits the transmission symbols.