Optical Clock Rate Negotiation for Asymmetric VLC Links
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Solution Overview
Problem
Visible light communication (VLC) systems face inefficiencies due to the varying switching capabilities of different optical sources, which limits their ability to support high data rates, as not all sources can handle the required clock speeds, necessitating support for multiple clock frequencies.
Innovation Solution
A method and apparatus for optical clock rate negotiation in VLC devices, where a first device transmits a frame with its supported clock rate and receives a response from a second device to select a transmission clock rate for subsequent data communication, allowing for asymmetric clock rates and supporting multiple clocks in both the PHY and MAC layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high clock rate is used for data communication, then data transfer efficiency is improved, but compatibility with optical sources having limited switching capabilities deteriorates
Solution Approach 1:
The patent implements dynamic clock rate negotiation between transmitter and receiver devices. The system transitions from static clock rate assignment to dynamic selection, where devices exchange capability information and negotiate the optimal clock rate based on actual conditions. This allows the system to adapt clock rates in real-time, selecting higher rates when both devices support them and lower rates when compatibility is required.
Solution Approach 2:
The patent changes the clock rate parameter based on device capabilities. By introducing clock rate negotiation mechanisms, the system can select from multiple possible clock rate values (e.g., 100s of KHz to 100s of Mbps) depending on which devices are communicating. This parameter adaptation resolves the contradiction by allowing the system to optimize for speed when possible and for compatibility when necessary.
2Adaptability or versatility
If multiple clock frequencies are supported, then compatibility with various optical sources is improved, but system complexity increases
Solution Approach 1:
The patent implements preliminary capability exchange before actual data communication. Devices share their supported clock rate information in advance through negotiation frames, allowing the system to determine the appropriate clock rate before transmitting data. This preliminary action prevents the need for complex runtime detection and adaptation mechanisms, reducing overall system complexity while maintaining multi-clock support.
Solution Approach 2:
The patent uses feedback mechanisms where devices respond to each other's capability declarations. When a transmitter declares supported clock rates, the receiver provides feedback indicating which rates it can accept. This bidirectional feedback simplifies the selection process compared to unidirectional assumption, reducing complexity by making the capability matching explicit and systematic.
3Productivity
If clock rate negotiation is implemented, then data communication efficiency is improved, but communication overhead increases
Solution Approach 1:
The patent implements partial negotiation by exchanging only the necessary clock rate capability information rather than complete device characterization. The negotiation focuses specifically on clock rate compatibility rather than all possible communication parameters. This partial action approach reduces overhead compared to comprehensive capability exchange while still achieving the necessary optimization for efficient data communication.
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
Enables efficient data communication by dynamically adjusting clock rates based on the capabilities of the devices involved, accommodating a wide range of optical sources and improving data transfer efficiency across various VLC applications.
Implementation Method 1
A transmitter including an optical source is configured to transmit VLC signals
Implementation Method 2
A receiver including a photodetector is configured to receive VLC signals
Data Source
AI summary
A method and apparatus conduct an optical clock rate negotiation to support asymmetric clock rates for visible light communication (VLC) in a VLC device. A first frame that includes a receiver clock rate supported by a first VLC device is transmitted at a predetermined clock rate. A response frame that includes a receiver clock rate supported by a second VLC device is received from the second VLC device. A transmission clock rate of the first VLC device is selected based on the response frame from the second VLC device. Subsequent frames for data communication are transmitted to the second VLC device at the selected transmission clock rate of the first device. Alternatively, when conducting optical clock negotiation in the PHY layer, multiple clock rates are supported within a single frame.