OFDM Optical Signal Pilot Loading via Subcarrier Superimposition
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Solution Overview
Problem
In optical communication systems, the prior art limits the number of subcarriers that can be loaded with pilot signals, as not all subcarriers are utilized for baseband signals, restricting the implementation environment and pilot signal loading capacity.
Innovation Solution
A method that determines a subcarrier for loading a pilot signal and updates its content based on pilot signal information, using techniques like Hilbert transform or superimposition of periodic signals to enable loading on all subcarriers, thereby increasing the number of subcarriers and pilot signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If subcarriers not loaded with baseband signals are used for loading pilot signals, then pilot signal loading is enabled, but the quantity of remaining subcarriers is limited which restricts the quantity of pilot signals that can be loaded
Solution Approach 1:
The patent enables all subcarriers to serve dual functions - both data transmission and pilot signal loading. By allowing subcarriers loaded with baseband signals to also carry pilot signals through superimposition, the system achieves multi-functionality where each subcarrier contributes to both data communication and channel estimation, thereby increasing the quantity of loadable pilot signals without restricting implementation environments
Solution Approach 2:
The patent merges the baseband signal and pilot signal onto the same subcarrier through superimposition technique. Instead of allocating separate subcarriers for pilot signals, the invention combines both signal types on all subcarriers, maximizing the utilization of available frequency resources and enabling the quantity of pilot signals to match the total number of subcarriers
2Quantity of substance
If all subcarriers are used for loading baseband signals, then data transmission capacity is maximized, but no subcarriers remain for loading pilot signals
Solution Approach 1:
The patent combines baseband signals and pilot signals on the same subcarriers through superimposition, allowing all subcarriers to carry both types of signals simultaneously. This merging approach ensures that data transmission capacity is maximized while channel estimation capability is maintained, as pilot signals are embedded within the data-carrying subcarriers
Solution Approach 2:
The patent changes the parameter of subcarrier utilization from exclusive (either data or pilot) to inclusive (both data and pilot). By modifying how subcarriers are allocated and utilized, the system achieves both high data transmission capacity and reliable channel estimation, as the superimposed pilot signals on all subcarriers provide sufficient information for accurate channel characterization
Data Source
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AI summary
A method, an apparatus, and a device for modulating an orthogonal frequency division multiplexing optical signal are provided and relate to the field of optical communications technologies. The method includes: performing bit-to-symbol mapping and serial-to-parallel conversion on a baseband signal to obtain at least two sub symbol sequences of the baseband signal; determining, from all subcarriers of an OFDM signal, a subcarrier used for loading a pilot signal; updating, according to information of the pilot signal, content corresponding to the subcarrier used for loading the pilot signal; and performing inverse discrete Fourier transform, parallel-to-serial conversion, digital-to-analog conversion, and electrical amplification processing on content currently corresponding to all the subcarriers of the OFDM signal, and modulating a light wave by using processed data and a bias electrical signal, to form an OFDM optical signal loaded with the pilot signal. According to the method, pilot signals may be loaded on all subcarriers of an OFDM optical signal, a quantity of subcarriers loaded with pilot signals is increased, and further, a quantity of pilot signals loaded on the OFDM optical signal is increased.