Visible Light Communication Signal Transmission Spectral Efficiency
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Solution Overview
Problem
Existing visible light communication systems face challenges in improving spectral efficiency without increasing power consumption, while ensuring that baseband signals of OFDM signals remain non-negative real numbers.
Innovation Solution
A signal transmission method that separates an N-point signal into two groups, performs FFT or IFFT, and combines specific signals to form a 3N/2-point signal, which is then sent, allowing the receiver to restore the original N-point signal, thereby enhancing spectral efficiency without increasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct current bias is used to ensure non-negative baseband signal, then spectral efficiency is improved, but power consumption increases
Solution Approach 1:
The patent segments the baseband signal into two independent parts: a non-negative real signal component and an imaginary signal component. By separating these components and processing them independently through FFT/IFFT operations, the system achieves spectral efficiency improvement without requiring direct current bias, thus avoiding the power consumption penalty associated with traditional DCO-OFDM approaches.
Solution Approach 2:
The patent employs asymmetric signal processing by setting specific components to zero (e.g., setting the imaginary part to zero in certain subcarriers) and using asymmetric allocation of signal components across different subcarriers. This asymmetric approach enables the system to achieve non-negative real baseband signals through mathematical construction rather than direct current biasing, resolving the contradiction between spectral efficiency and power consumption.
2Reliability
If existing OFDM modulation is used with non-negative constraint, then baseband signal requirement is met, but spectral efficiency is reduced
Solution Approach 1:
The patent transitions from traditional one-dimensional real-valued OFDM modulation to a two-dimensional complex-valued modulation scheme. By utilizing both real and imaginary components of complex numbers in the baseband signal, the system can satisfy the non-negativity constraint while achieving higher spectral efficiency. The mathematical construction involves creating complex baseband signals where both components contribute to the final optical signal, effectively doubling the spectral utilization compared to traditional real-only OFDM.
Data Source
AI summary
This application provides a signal transmission method and apparatus. The method includes: obtaining, by a transmitter side, a first signal with N points; performing signal separation on the first signal with N points, to obtain two groups of signals (for example, a second signal with N points and a third signal with N points); combining the two groups of signals obtained through separation, to obtain a to-be-sent signal with 3N/2 points; and sending the signal with 3N/2 points to a receiver side, to enable the receiver to restore the first signal with N points from the received signal with 3N/2 points.