2D Optical Beam Selection with Cartesian Code Segmentation
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Solution Overview
Problem
Achieving high data throughput and wide-angle coverage in optical wireless communication systems while maintaining low power consumption is challenging due to the need for numerous beam codes, which increases computational complexity, especially with low-power processors.
Innovation Solution
Encoding each 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 using Code-Division Multiple Access (CDMA) for beam identification, thereby simplifying the beam selection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If unique codes are used to identify each transmitted beam in a 2D array, then beam identification accuracy is improved, but the number of required codes grows quadratically (N^2) increasing memory usage and transmission power
Solution Approach 1:
The patent segments the unique identification code into two separate components: a row code and a column code. Instead of using one unique N^2 code for each beam position, the system uses two separate N-element code sequences (one for rows, one for columns) whose combination identifies any beam position. This segmentation reduces the total number of codes from N^2 to 2N, directly resolving the contradiction between identification accuracy and code quantity.
2Measurement precision
If cross correlation is performed with every possible CDMA code to select the correct beam, then beam selection accuracy is improved, but computational complexity increases making it difficult to scale with low-power processors
Solution Approach 1:
The patent segments the beam selection process into two independent correlation operations: one for row codes and one for column codes. Instead of performing one complex N^2 correlation, the system performs two simpler N-element correlations separately, then combines the results. This segmentation reduces computational complexity from O(N^2) to O(N), enabling beam selection to scale efficiently with low-power processors while maintaining selection accuracy.
3Adaptability or versatility
If numerous beam codes are transmitted for beam identification, then beam identification capability is improved, but transmission power consumption increases
Solution Approach 1:
The patent segments the code transmission into two separate transmissions: row codes and column codes. Instead of transmitting N^2 unique codes, the system transmits two sets of N codes (totaling 2N codes), reducing the transmission load by a factor of N/2. This segmentation maintains full beam identification capability while proportionally reducing transmission power consumption.
4Area of stationary object
If a 2D array of emitters is used to achieve wide-angle coverage, then coverage area is improved, but the number of emitters and required codes increases quadratically
Solution Approach 1:
The patent applies segmentation to the 2D emitter array by separating the identification system into two independent 1D code sequences (row and column). This allows the system to maintain the 2D array structure for wide coverage while reducing the identification complexity from quadratic to linear scaling. The coverage area benefit of the 2D array is preserved while the code quantity grows only linearly with array dimension rather than with array area.
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, transmission power, and computational complexity, enabling efficient beam selection and data communication with reduced power consumption.
Implementation Method 1
a two-dimensional array of emitters each emitter arranged to emit an optical signal and having an individual coverage area
Implementation Method 2
a receiver configured to receive a feedback from a remote device in the combined coverage area
Data Source
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.