Optical Camera Communication Modulation for Oversampling Recovery
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Solution Overview
Problem
Optical camera communication (OCC) systems face challenges in signal modulation and demodulation due to environmental factors, leading to performance issues in data transmission and reception, particularly in vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X) communications.
Innovation Solution
The implementation of a method using a processor-controlled LED array for data transmission and a camera-based reception node, which includes orthogonal frequency division multiplexing, oversampling correction, and error correction using artificial intelligence, to improve signal modulation and demodulation performance by adjusting data subframe numbers and sizes based on camera frame rates and pixel densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of data subframes is increased to improve data transmission reliability, then communication reliability is improved, but transmission time increases and productivity decreases
Solution Approach 1:
The patent dynamically adjusts the number of data subframes based on sampling conditions. When oversampling is detected, the system reduces the number of subframes to improve efficiency, while maintaining reliability through selective repetition of essential data. This dynamic adaptation resolves the contradiction by making the system flexible rather than static.
Solution Approach 2:
The system changes the parameter of data subframe quantity based on detected sampling conditions. By monitoring whether oversampling or undersampling occurs, the system adjusts subframe repetition accordingly - using more subframes when needed for reliability and fewer when efficiency is prioritized, thus resolving the trade-off between these two parameters.
2Measurement precision
If the camera frame rate is increased to capture more blinking images for better signal detection, then measurement precision is improved, but energy consumption increases and device complexity increases
Solution Approach 1:
The system uses feedback from the detected blinking pattern to adjust camera operation. By detecting the LED blinking frequency and comparing it with camera frame rate, the system determines optimal sampling conditions and adjusts camera activity accordingly, achieving good signal detection without continuous high-rate operation, thus reducing energy consumption while maintaining precision.
Solution Approach 2:
The camera frame rate is dynamically adjusted based on the detected blinking signal characteristics. Rather than operating at maximum frame rate continuously, the system adapts the camera's sampling rate to match the actual communication needs, reducing energy consumption while maintaining sufficient measurement precision for reliable signal detection.
3Reliability
If data subframes are repeated multiple times to prevent data loss during oversampling, then reliability is improved, but transmission time increases
Solution Approach 1:
Instead of repeating all data subframes uniformly, the system applies partial repetition only where necessary based on detected sampling conditions. When oversampling is detected, essential data subframes are repeated with appropriate sequence numbers to ensure recovery, but not all subframes are duplicated, thus reducing unnecessary transmission time while maintaining reliability.
Solution Approach 2:
The data transmission is segmented into multiple subframes with individual sequence numbers, allowing selective repetition and reconstruction. This segmentation enables the system to handle oversampling by identifying and repeating only the necessary segments rather than transmitting entire data blocks multiple times, optimizing the balance between reliability and transmission time.
4Productivity
If the LED blinking rate is increased to transmit more data faster, then productivity is improved, but signal detection difficulty increases and measurement precision decreases
Solution Approach 1:
The LED transmission uses periodic blinking patterns with defined on/off cycles, creating regular, detectable signal periods. This periodic structure allows the receiving camera to synchronize and detect blinks accurately even at higher rates, maintaining measurement precision while achieving higher productivity through increased blinking frequency and faster data transmission.
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
This approach enhances OCC signal decoding performance, prevents data loss during undersampling or oversampling, and improves error correction, enabling effective communication under various environmental conditions, including non-ideal indoor and outdoor scenarios.
Implementation Method 1
a light emitting diode (LED) array including a plurality of LEDs blinking according to an instruction executed by the processor
Implementation Method 2
a camera configured to photograph blinking images of an LED array
Data Source
AI summary
A method of modulating an optical camera communication (OCC) signal by an OCC transmission node in an OCC system includes acquiring a binary data signal, grouping the binary data signal for every k bits to convert the binary data signal into a global phase shift signal having an integer value from 0 to M−1 (=2k−1), generating a data signal group by mapping the global phase shift signal to first to Mth mapping sequences in the form of an n*M/2-bit sequence based on a preset symbol group mapping table, generating a pulse wave signal by modulating the data signal group, and blinking each of a plurality of light sources included in the OCC transmission node according to the pulse wave signal. Accordingly, performance of the communication system may be improved.