Constellation Mapping for NOMA Decoding Accuracy
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Solution Overview
Problem
In signal processing using non-orthogonal resources like Superposition Coding (SPC), there is a need for improved decoding accuracy of multiplexed signals at the reception device, as the constellation after multiplexing often lacks gray mapping, leading to increased bit errors and degraded decoding characteristics.
Innovation Solution
A device and method that apply a second constellation corresponding to the symbol position of a first bit string in a first constellation to a second bit string for each transmission signal sequence, ensuring gray mapping is implemented both before and after SPC multiplexing, thereby reducing bit errors and enhancing decoding accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-orthogonal multiple access (NOMA) with superposition coding is used to increase user capacity and spectral efficiency, then the cell communication capability is improved, but the decoding accuracy of multiplexed signals deteriorates due to interference and lack of gray mapping
Solution Approach 1:
The patent applies gray mapping to the second bit string before multiplexing with the first bit string. This preliminary action ensures that even after superposition coding multiplexing, the constellation points maintain gray mapping properties, which limits bit errors to at most 1 bit and prevents degradation of decoding characteristics at the reception device
Solution Approach 2:
The patent applies different constellations to different bit strings based on their power allocation levels. The first bit string uses a first constellation while the second bit string uses a second constellation that is specifically designed to maintain gray mapping properties after multiplexing. This local differentiation in constellation design resolves the contradiction by ensuring appropriate mapping properties for each signal component
2Quantity of substance
If signals are multiplexed on overlapping radio resources using superposition coding, then spectral efficiency is improved, but bit error rate increases due to interference and loss of gray mapping
Solution Approach 1:
The patent performs gray mapping on the second bit string before the multiplexing operation. This preliminary action ensures that the constellation points are arranged such that even after superposition coding combines the first and second bit strings on overlapping resources, the resulting constellation maintains gray mapping properties, thereby limiting bit errors to at most 1 bit
Solution Approach 2:
The patent changes the mapping parameters by applying a second constellation specifically designed for gray mapping to the second bit string. This parameter change in the constellation mapping ensures that the multiplexed signal maintains desirable error properties, resolving the contradiction between high spectral efficiency and low bit error rate
Data Source
AI summary
To provide a device, a method, and a program which are capable of further improving decoding accuracy in a case in which multiplexing/multiple-access using non-orthogonal resources is performed.A device includes: a processing unit configured to apply a second constellation corresponding to a symbol position of a first bit string in a first constellation applied to the first bit string, to a second bit string in regard to a plurality of bit strings to be multiplexed for each of transmission signal sequences to be multiplexed in resource blocks for which at least a part of frequency resources or time resources overlap.