Asynchronous Coded Multiple Access NOMA Spectral Efficiency
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Solution Overview
Problem
NOMA systems face limitations in per-user spectral efficiency due to the need for low FEC code rates to maintain acceptable performance, which restricts the efficiency of channel utilization.
Innovation Solution
The implementation of asynchronous coded multiple access (ACMA) systems, where multiple sub-streams are transmitted to each user, allowing for increased spectral efficiency without requiring changes to the receiver, and enabling users to transmit asynchronously without coordination, with each user's sub-streams being encoded and modulated independently and then combined for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low FEC code rate is used to provide acceptable performance in NOMA systems, then reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent segments the transmitted signal into multiple sub-streams, where each sub-stream uses a different FEC code rate. Some sub-streams use low code rates for reliable transmission, while others use high code rates for spectral efficiency. The receiver combines these sub-streams to achieve both reliability and efficiency simultaneously.
Solution Approach 2:
Different parts of the transmitted signal (sub-streams) are assigned different FEC code rates according to their specific requirements. Critical data sub-streams use low code rates for high reliability, while less critical sub-streams use high code rates for better spectral efficiency, optimizing the overall system performance.
2Productivity
If multiple users transmit simultaneously in NOMA systems, then channel utilization is improved, but interference between users increases
Solution Approach 1:
The patent segments the channel resources by assigning different sub-streams with different FEC code rates to different users. This segmentation allows the receiver to separately process and decode each user's signal, reducing inter-user interference while maintaining high channel utilization.
Solution Approach 2:
The patent introduces FEC coding as an intermediary mechanism that protects user signals from interference. By applying error correction coding before transmission, the system can tolerate the presence of interference from other users while maintaining reliable communication.
Data Source
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AI summary
Methods and apparatus for increasing spectral efficiency in non-orthogonal multiple access (NOMA) communication, that implement receiving a signal stream from a user, splitting the signal stream into a plurality of sub-streams, applying a forward error coding (FEC) to each one of the sub-streams, and outputting a corresponding plurality of FEC encoded sub-streams. This can include modulating a corresponding carrier with each of the FEC encoded sub-streams, and combining and transmitting the corresponding plurality of modulated carrier signals. The modulated carrier signals can each carry a respective one of the FEC encoded sub-streams.