Asynchronous NOMA Sub-Streams for Higher Spectral Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-orthogonal multiple access (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 allocated to each user, allowing for increased spectral efficiency without requiring changes to the receiver architecture, and enabling asynchronous transmission among users, thereby allowing partial overlap and improved error performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low FEC code rate is used in NOMA systems, then acceptable performance is provided, but per-user spectral efficiency is limited
Solution Approach 1:
The user's data stream is segmented into multiple sub-streams that are transmitted asynchronously. Each sub-stream can be independently decoded, allowing the system to achieve diversity gain and improve error rate performance without requiring low FEC code rates, thereby resolving the contradiction between reliability and spectral efficiency
Solution Approach 2:
The system transitions from synchronous transmission to asynchronous transmission where sub-streams can start and stop at different times. This dynamic approach allows for flexible resource allocation and eliminates the need for strict timing synchronization, enabling higher spectral efficiency while maintaining acceptable error rates through the diversity of asynchronous sub-streams
2Stability of the object's composition
If synchronous transmission is used, then timing alignment is maintained, but error rate performance is degraded compared to asynchronous systems
Solution Approach 1:
The patent introduces asynchronous transmission where sub-streams dynamically start and stop at different times without requiring timing alignment. This dynamic approach provides diversity gain that improves bit error rate performance by over 1 dB compared to synchronous systems, while the receiver maintains stability through correlation-based detection that does not require precise timing synchronization
Data Source
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.