4B6B Line Coding for Visible Light Communication Flickering
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Solution Overview
Problem
Visible light wireless communication systems using LED lighting suffer from flickering issues due to uneven ratios of turning-on and turning-off lighting, which affect brightness and user perception, especially when applying existing line coding technologies like 4B5B.
Innovation Solution
The implementation of a 4B6B line coding technology that encodes 4-bit data patterns into 6-bit patterns with an equal number of bits corresponding to 1 and 0, using specific patterns like '111000' and '000111' as idle patterns and '110100' and '001011' as preamble patterns to maintain consistent brightness and reduce flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing line coding technology (4B5B) is applied to visible light wireless communication, then data transmission is enabled, but flickering occurs due to uneven ratios of turning-on and turning-off lighting
Solution Approach 1:
The patent changes the fundamental parameter of line coding from 4B5B to 4B6B, where each 4-bit data is encoded into 6-bit code with equal numbers of 1s and 0s (three of each). This parameter change ensures that the LED turns on and off equally over each coded period, maintaining constant brightness while still enabling data transmission through the balanced pattern.
Solution Approach 2:
The patent introduces asymmetric pattern design where specific 6-bit patterns are assigned for different purposes: data patterns (with equal 1s and 0s), idle patterns (specific reserved patterns like 111000 and 000111), and preamble patterns (specific reserved patterns like 110100 and 001011). This asymmetric assignment resolves the contradiction by ensuring data patterns maintain brightness balance while other patterns serve specialized functions.
2Stability of the object's composition
If 4B5B line coding is used, then continuous generation of 0 or 1 is reduced, but brightness varies between 40% and 80% causing flickering
Solution Approach 1:
The patent changes the code length parameter from 5 bits to 6 bits, enabling equal distribution of 1s and 0s (three each) in every code pattern. This ensures that regardless of which 6-bit pattern is transmitted, the LED will be on for exactly half the period and off for the other half, maintaining constant 50% average brightness while still representing different data values through the specific pattern arrangement.
3Productivity
If on/off keying is used for data transmission, then communication is achieved, but uneven turning-on and turning-off ratios cause visible flickering
Solution Approach 1:
The patent ensures continuous balanced action by designing the 4B6B coding system where every code pattern contains equal numbers of 1s and 0s. This continuity principle ensures that the LED's on/off action is always balanced over each 6-bit period, preventing flickering while maintaining continuous data transmission through the systematic pattern structure.
Solution Approach 2:
The patent introduces periodic balanced patterns where the LED turns on and off in regular, predictable cycles defined by the 6-bit code structure. Each period (6-bit code) contains exactly three 1s and three 0s, creating a periodic on/off action that averages to 50% brightness and eliminates flickering while still encoding data through the specific periodic pattern sequence.
Data Source
AI summary
A visible light wireless communication receiver includes: a source code recognizing unit that receives a source bit stream and recognizes the source bit stream as source codes of a unit of a first number of bits; and a line coding unit that encodes each of the source codes into an encoding code of a unit of a second number of bits, the second number being larger than the first number. In particular, in the encoding code, the number of bits corresponding to 1 is the same as the number of bits corresponding to 0. Therefore, the change in brightness of lighting may be minimized in the visible light wireless communication.