Satellite Optical Transceiver With Soft Demodulation and FEC
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Solution Overview
Problem
Traditional satellite wireless communication technologies using radiofrequency (RF) waves face limitations due to spectral band saturation, regulatory constraints, and complex implementation challenges, while optical technologies suffer from atmospheric degradation and signal fading, hindering the deployment of high-speed systems.
Innovation Solution
A satellite communication system employing soft demodulation, error correcting codes, and data interleaving techniques for optical signals, which includes a soft demodulation unit, encoding unit, interleaving unit, and optical carrier modulation to process RF signals, followed by demodulation, deinterleaving, and decoding at the communication station, optimizing data transmission performance and reducing hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical technologies are used for satellite wireless communication, then data transmission speed is improved, but signal reliability deteriorates due to atmospheric turbulence and fading
Solution Approach 1:
The patent applies forward error correction (FEC) coding and interleaving techniques before optical signal transmission to pre-compensate for potential atmospheric turbulence effects. The FEC codes are calculated and applied in advance, and interleaving is performed before transmission to distribute burst errors caused by fading across multiple code words, enabling error correction at the receiver without requiring retransmission.
Solution Approach 2:
The patent implements bidirectional communication with feedback channels that allow the ground station to send channel quality information and control signals back to the satellite. This feedback mechanism enables adaptive modulation and coding adjustments based on real-time atmospheric conditions, improving signal reliability while maintaining high data transmission speeds.
2Reliability
If regenerative satellite architecture is used, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the complex demodulation and decoding functions from the satellite platform, keeping only the essential optical signal transmission capabilities on-board. The complex signal processing operations are relocated to the ground station, which has greater computational resources and power supply capabilities, thereby reducing satellite device complexity while maintaining signal quality through advanced error correction.
3Device complexity
If transparent satellite architecture is used, then device complexity is reduced, but spectral occupation expands due to high sampling frequency requirements
Solution Approach 1:
The patent changes the sampling frequency parameter by using lower sampling rates combined with advanced compression algorithms and efficient modulation schemes. This parameter optimization reduces the spectral occupation of the optical signal while maintaining the transparency architecture's low device complexity, achieving a balance between spectral efficiency and implementation simplicity.
4Reliability
If error correcting codes and interleaving are applied, then signal reliability is improved, but processing time increases
Solution Approach 1:
The patent applies partial error correction by using concatenated coding schemes where only the most critical data portions receive the full error correction treatment. Less critical data uses simplified correction methods, reducing overall processing time while maintaining adequate signal reliability for the most important information streams.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances data transmission performance and reduces hardware complexity, energy consumption, and spectral band expansion, enabling affordable and accessible high-speed data transmission with reduced equipment mass and cost, while compensating for optical channel turbulence.
Implementation Method 1
an optical carrier modulation unit configured to apply, to each interleaved data frame I 2-m, an optical carrier modulation so as to form the optical signal
Data Source
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AI summary
A communication satellite (20) is proposed, configured to transmit an optical signal through an optical transmission channel in response to the reception of at least one modulated and encoded radio frequency signal. The satellite comprises: - a unit (212) for applying soft demodulation to said at least one received radio frequency signal and providing N intermediate demodulated data frames B1-n, each B1-n frame comprising a set of digitized soft values; - a unit (232) for applying an error-correcting code to said B1-n frames and providing N intermediate encoded demodulated data frames B2-n; - a unit (234) for interleaving said N B2-n frames and providing M interleaved I2-m data frames; and - a unit (236) for applying optical carrier modulation to each I2-m frame to form said optical signal.