Visible Light Communication Sub-band Allocation for Uniform Transmission
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Solution Overview
Problem
Conventional visible light communication (VLC) techniques face limitations in achieving uniform transmission rates across all regions, with multi-band orthogonal frequency-division multiplexing (OFDM) only increasing rates in overlapping light source regions, and existing optimization methods being costly and inefficient due to limited LED response and output power, as well as the need for costly RGB light sources and wavelength selection filters.
Innovation Solution
A VLC apparatus and method that dynamically allocates sub-bands to visible light sources based on the number of terminals in coverage, using a controller to determine and distribute sub-bands, and modulate transmission data on these sub-bands, allowing for efficient bandwidth allocation and power conservation by putting unused components into sleep mode, thereby enhancing transmission capacity and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-band OFDM is used to modulate different LEDs, then transmission rates are increased in overlapping regions, but transmission rates remain low in non-overlapping regions
Solution Approach 1:
The patent applies local quality by assigning different sub-bands to different LED light sources based on their coverage areas. Each LED modulates data on specific sub-bands appropriate to its coverage region, ensuring that overlapping regions receive data from multiple LEDs on different sub-bands while non-overlapping regions also achieve high transmission rates on their dedicated sub-bands. This resolves the contradiction by making the transmission rate uniform across all regions rather than concentrated only in overlapping areas.
2Productivity
If LED driving circuit and receiving end circuit are optimized, then transmission performance is improved, but the effect is limited due to limited LED response and output power
Solution Approach 1:
The patent segments the frequency spectrum into multiple sub-bands and assigns different sub-bands to different LED light sources. This segmentation allows the system to overcome the limited response and output power of individual LEDs by distributing the transmission load across multiple LEDs operating on different sub-bands. Each LED operates within its capabilities on its assigned sub-band, while the aggregate system achieves high transmission performance through the combined capacity of multiple segmented channels.
3Productivity
If blue filters are added in the receiving end, then transmission rate is improved, but the cost of receiving modules increases drastically
Solution Approach 1:
The patent implements a universal receiving end design that can receive data from multiple LED light sources on different sub-bands without requiring additional optical filters for each LED type. The receiving end uses a single photodetector that captures light from all LEDs, and the distinction between different LED signals is achieved through digital signal processing of the modulated sub-bands. This multi-functional receiving design achieves high transmission rates while avoiding the increased cost associated with multiple optical filters.
4Productivity
If WDM transmission techniques are used, then transmission capacity is increased, but costly RGB light sources and wavelength selection filters are required
Solution Approach 1:
The patent replaces expensive RGB light sources and wavelength selection filters with inexpensive single-color LED light sources that emit in different visible wavelength ranges. Instead of using costly WDM components, the system uses readily available LEDs with naturally different spectral characteristics and distinguishes their signals through digital sub-band processing. This approach achieves increased transmission capacity while dramatically reducing the cost of light sources and eliminating the need for expensive wavelength selection filters.
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 solution enhances transmission capacity, ensures each terminal receives sufficient data, and dynamically allocates resources without additional costs on the receiving end, overcoming the uneven transmission capacity issue of conventional VLC devices while maintaining secure and interference-resistant communication.
Implementation Method 1
A light-emitting diode (LED) can be used to provide the visible light
Implementation Method 2
The controller, the first visible light source or the second visible light source modulate the transmission data on one of the first sub-band and the second sub-band
Data Source
AI summary
A visible light communication apparatus and a method for visible light communication are provided. The method includes calculating a quantity of terminals in coverage of each of a plurality of visible light sources. The visible light sources include a first visible light source and a second visible light source. Determining a quantity of the sub-bands according to the quantity of terminals. The sub-bands include a first sub-band and a second sub-band. Distributing the first sub-band for the first visible light source and the second sub-band for the second visible light source according to the quantity of terminals in coverage of each of the visible light sources, in which the first sub-band and the second sub-band are different from each other. Allocating a bandwidth for each of the terminals according to the distributed sub-bands or a user requirement. Modulating a transmission data on one of the first sub-band and the second sub-band.