Dimmable Visible Light Communication Using Punctured Turbo Codes
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Solution Overview
Problem
Existing visible light communication (VLC) systems face limitations in error correction schemes, particularly for dimmable applications, as they often rely on constant weight codes that restrict dimming rates and require dedicated encoding/decoding methods, making them impractical for arbitrary dimming requirements and high code rates.
Innovation Solution
A dimmable VLC system employing turbo codes combined with puncturing and scrambling techniques, allowing for adaptive dimming control through on-off keying, where the Hamming weight of codewords matches desired dimming rates, and using iterative decoding algorithms to maintain performance even with puncturing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant weight codes are used for error correction in dimmable VLC, then error correction capability is improved, but dimming rate flexibility deteriorates
Solution Approach 1:
The encoded message is divided into two segments: non-punctured bits that maintain error correction capability and punctured bits that enable dimming control. This segmentation allows the system to achieve both reliable error correction and flexible dimming rates by selectively processing different portions of the codeword.
Solution Approach 2:
The system dynamically changes the parameter of code rate by applying puncturing to the encoded message. By varying the puncturing rate, the system can adapt to different dimming requirements while maintaining the underlying error correction structure, thus achieving both reliability and flexibility.
2Reliability
If dedicated encoding/decoding methods are designed for different dimming rates, then error correction performance is improved, but system complexity increases
Solution Approach 1:
A single turbo code encoder and decoder are designed to handle all dimming rates universally. The encoder applies puncturing based on the desired dimming rate, while the decoder uses iterative decoding that automatically adapts to the puncturing pattern. This universal approach eliminates the need for multiple dedicated encoding/decoding methods while maintaining error correction performance across all dimming rates.
Solution Approach 2:
The iterative decoding process incorporates feedback mechanisms where the decoder repeatedly refines its estimate of the transmitted message by exchanging information between component decoders. This feedback loop enables the single decoding method to effectively handle the variable code rates resulting from different puncturing patterns, achieving high performance without increasing system complexity.
3Productivity
If code rate is increased for higher data transmission, then productivity is improved, but error correction capability deteriorates
Solution Approach 1:
The system dynamically adjusts the effective code rate by applying puncturing to the turbo-coded message. The base turbo code provides strong error correction at lower code rates, and by selectively puncturing bits according to the desired dimming rate, the system can increase the effective code rate for higher data transmission while the iterative decoder maintains error correction capability through its adaptive decoding process.
Data Source
AI summary
An apparatus and method using error correcting for visible light communication are provided. The error correction includes generating an encoded message from an original message by using a predetermined coding method, puncturing the encoded message based on a determined dimming value or rate, and/or puncturing rate, generating a scrambled message by scrambling the punctured message, and providing the scrambled message to a visible light source.