Multimode Constellation Transmitter for Spectral Efficiency
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Solution Overview
Problem
Current optical communication systems face challenges in achieving high spectral efficiency due to the narrow pulses and increased bandwidths associated with pulse position modulation (PPM), and existing methods like spatial-coherence modulation and waveguide transverse modes multiplexing do not adequately address these issues.
Innovation Solution
A digital data transmitter that sequentially excites different sets of propagation modes in a physical communication channel, producing distinct spatial energy distributions to transmit data, and a receiver that identifies these modes to decode the information, using either wireless or optical transmitters and receivers with arrays of antennas or optical modulators and detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse position modulation (PPM) is used to achieve high sensitivity at the receiver, then receiver sensitivity is improved, but spectral efficiency deteriorates due to temporally narrow pulses and larger bandwidths
Solution Approach 1:
The invention segments the signal transmission by dividing each symbol period into M time slots, where the signal is transmitted during a single time slot. This segmentation allows the receiver to examine each time slot separately to identify the signal position, achieving high sensitivity through temporal separation while managing bandwidth requirements through structured time division.
Solution Approach 2:
The invention transitions from traditional intensity-based modulation to temporal position-based modulation, adding a time dimension to the signal encoding. By encoding information in the temporal position of pulses within a symbol period rather than in pulse amplitude or frequency, the system achieves high receiver sensitivity through precise temporal detection while maintaining spectral efficiency through structured time slot allocation.
2Quantity of substance
If the number of time slots per symbol interval is increased to improve data capacity, then data-carrying ability is improved, but pulse bandwidth increases causing lower spectral efficiency
Solution Approach 1:
The system segments the frequency spectrum by allocating specific frequency ranges to different propagation modes. Each mode carries a portion of the data stream, and the total data capacity is the sum of capacities across all modes. This segmentation allows increased data capacity through mode division while maintaining spectral efficiency by efficiently utilizing available frequency resources without excessive bandwidth expansion in any single mode.
Solution Approach 2:
The invention adds a spatial dimension to signal transmission by utilizing multiple propagation modes with distinct spatial characteristics. Instead of increasing time slots in a single mode (which would narrow pulses and increase bandwidth), the system distributes data across multiple spatial modes, each with its own temporal characteristics. This dimensional expansion increases data capacity while maintaining spectral efficiency through spatial multiplexing.
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 enables efficient point-to-point digital data transmission by varying propagation modes within each symbol interval, enhancing spectral efficiency and data-carrying capacity while maintaining orthogonality between modes, thus overcoming the limitations of existing methods.
Implementation Method 1
a digital data transmitter capable of sequentially exciting different sets of one or multiple propagation modes in a physical communication channel. Each set of one or multiple modes produces a different spatial distribution of transmitted energy in the physical communication channel.
Implementation Method 2
a digital data receiver connected to receive signals transmitted by the digital data transmitter and configured to identify the sets of one or more propagation modes excited by the digital data transmitter from spatial measurements made by the digital data receiver.
Data Source
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AI summary
An apparatus includes a digital data transmitter capable of sequentially exciting different sets of one or more propagation modes in a physical communication channel. Each set of one or more propagation modes has a different spatial distribution of transmitted energy in the channel. The digital data transmitter is configured to sequentially change the excited set of one or more propagation modes to transmit a different value of data to the communication channel.