Optical Carrier Splitting for QAM System Reliability
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Solution Overview
Problem
Existing methods for improving QAM system reliability are hindered by high costs and complex implementation, particularly due to the need for multicarrier generation apparatuses and phase modulation with multiple delay units or controllable phase units.
Innovation Solution
A signal transmitting method that splits a single-wavelength optical carrier into multiple subcarriers, performing data modulation and amplitude spread spectrum modulation using low-speed data signals and spreading codes, which reduces the Baud rate and allows for processing with low-speed DACs and electrical devices, thereby improving system reliability without the need for complex multicarrier generation or phase modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher-order QAM modulation is used to increase transmission capacity, then transmission capacity is improved, but anti-noise performance deteriorates
Solution Approach 1:
The patent divides a high-speed data signal into multiple low-speed data streams, each modulating a separate subcarrier. This segmentation allows each DAC to operate at lower speeds with higher ENOB, reducing quantization noise and improving the anti-noise performance of higher-order QAM while maintaining overall transmission capacity through parallel subcarrier transmission.
2Productivity
If a high-speed DAC is used to process high-speed data signals, then transmission capacity is improved, but quantization noise increases
Solution Approach 1:
The patent segments the high-speed data signal into multiple low-speed parallel streams, allowing the use of multiple low-speed DACs with higher ENOB instead of a single high-speed DAC. This reduces quantization noise while maintaining the required data throughput through parallel processing.
Solution Approach 2:
The patent creates multiple copies of the data stream (divided into parallel low-speed streams) that are processed by separate DACs. Each copy is processed at a lower speed with higher precision, and the results are combined to achieve the equivalent of high-speed transmission with reduced quantization noise.
3Reliability
If multicarrier generation apparatus and demultiplexer are used to process data signals, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex multicarrier generation apparatus and demultiplexer from the system. Instead, it uses a simple optical splitter to generate subcarriers and direct parallel processing, thereby maintaining system reliability through low-speed high-precision DACs while dramatically reducing device complexity and cost.
Solution Approach 2:
The patent replaces expensive, complex multicarrier generation equipment with simpler, more cost-effective components such as optical splitters and parallel low-speed DACs. This substitution achieves the same reliability improvement goals at a lower cost and with simpler implementation.
4Reliability
If spectral phase encoder with multiple delay units is used to perform spectrum spreading, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex spectral phase encoder with multiple delay units from the system. Instead, it achieves spectrum spreading and reliability improvement through parallel low-speed DAC processing and amplitude modulation, thereby maintaining the reliability benefits while dramatically reducing device complexity and cost.
Data Source
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AI summary
According to a signal transmitting method, a signal receiving method, and a related device and system, a generated single-wavelength optical carrier may be split into N subcarriers with a same wavelength by using a splitting device, corresponding data modulation and corresponding amplitude spread spectrum modulation are performed on the N subcarriers by using N spreading codes and N low-speed data signals obtained by deserializing a received high-speed data signal, to obtain N spread spectrum modulation signals, and the N spread spectrum modulation signals are combined and output. A multicarrier generation apparatus or the like having a relatively complex structure does not need to be used for optical carrier splitting, and spectrum spreading does not need to be performed in a phase modulation manner in which a plurality of delay units or controllable phase units are required. Therefore, system reliability is improved, and problems such as relatively high costs and a relatively great difficulty in implementation that exist in an existing scheme of improving QAM system reliability are resolved.