2D Beam Selection With Cartesian Coding for Optical Wireless Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical wireless communication systems face challenges in achieving high data throughput and wide-angle coverage while maintaining low power consumption, particularly due to the computational complexity of beam selection procedures using a large number of unique codes, which is exacerbated by the use of low-power processors.
Innovation Solution
The system encodes each light beam with a pair of codes representing its coordinates in a Cartesian coordinate system, reducing the number of required codes from N^2 to 2N, and uses Code-Division Multiple Access (CDMA) for beacon signals to simplify beam identification, allowing efficient beam selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of unique codes are used to identify each beam in a two-dimensional array, then beam identification accuracy is improved, but computational complexity and memory requirements increase quadratically
Solution Approach 1:
The patent segments the beam identification system into two independent components: row codes and column codes. Instead of using N² unique codes for N×N beams, the system uses N row codes and N column codes, where each beam is identified by the combination of its row and column codes. This segmentation reduces the total number of codes from quadratic to linear growth, directly resolving the contradiction between identification accuracy and computational complexity.
Solution Approach 2:
The patent introduces a two-dimensional coding structure where beams are identified not by single unique codes but by pairs of codes representing coordinates in a row-column matrix. This dimensional transformation allows the system to maintain precise beam identification while reducing the code space from N² to 2N codes, effectively converting a quadratic problem into a linear one.
2Productivity
If transmission power is increased to achieve high data throughput and long range, then communication performance is improved, but eye-safety requirements are violated
Solution Approach 1:
The patent divides the coverage area into multiple small-angle beams arranged in a two-dimensional array, where only one beam is actively transmitting data at a time while others transmit low-power beacon signals. This segmentation allows the system to achieve wide coverage without requiring any single beam to transmit at high power, thus maintaining eye-safety while providing high data throughput through selective beam activation.
Solution Approach 2:
The patent implements a system where multiple beams are available but only one is fully activated for data transmission at any given moment. The other beams transmit reduced-power beacon signals for identification and selection purposes. This partial activation strategy ensures that no single beam exceeds eye-safety power limits while still providing high throughput capacity when the optimal beam is selected.
3Area of stationary object
If multiple small angle beams are used to achieve wide-angle coverage, then coverage area is improved, but the number of required unique codes increases quadratically
Solution Approach 1:
The patent segments the code assignment system into row-based and column-based code sets. For an N×N beam array providing wide coverage, instead of assigning N² unique codes to each beam, the system assigns N row codes and N column codes, where each beam is identified by the combination of its row and column indices. This reduces the total code quantity from quadratic to linear growth, directly resolving the contradiction between coverage area and code quantity.
Solution Approach 2:
The patent transforms the code identification system from a one-dimensional unique code assignment to a two-dimensional row-column coordinate system. Each beam's position in the coverage area is represented by a pair of codes (row code, column code) rather than a single unique code, reducing the total number of codes required from N² to 2N while maintaining the ability to uniquely identify all N×N beams.
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 reduces memory usage and transmission power, simplifies computation, and enhances the scalability of beam selection, especially in systems with limited CPU and memory capabilities.
Implementation Method 1
a two-dimensional array of emitters, each emitter arranged to emit an optical signal
Implementation Method 2
a receiver configured to receive a feedback from a remote device
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An optical wireless communication device (100) comprising: a two-dimensional array of emitters (110) each emitter arranged to emit an optical signal and having an individual coverage area; wherein the two-dimensional array of emitters (110) is arranged to create a combined coverage area larger than the individual coverage area, with each individual coverage area evenly distributed within the combined coverage area; a receiver (120) configured to receive a feedback from a remote device in the combined coverage area; and a controller (101) configured to assign an address to each emitter out of the two-dimensional array of emitters, each address comprising a pair of codes representing coordinates on an X-axis and a Y-axis, respectively, according to a Cartesian coordinate system, to uniquely identify each emitter in the Cartesian coordinate system; wherein each emitter out of the two-dimensional array of emitters (110) is configured to send a beacon signal comprising its address for assisting the remote device to provide the feedback, with the plurality of emitters configured to send beacon signals according a Code-Division Multiple Access; and the controller (101) is configured to select an emitter out of the two-dimensional array of emitters (110) for establishing an optical wireless data link with the remote device according to the feedback received from the remote device.