SCMA-SC-FDMA Hybrid Access for PAPR Reduction
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Solution Overview
Problem
Current communication systems employing non-orthogonal multiple access schemes, such as SCMA, face challenges in reducing peak to average power ratio (PAPR), which leads to increased distortion and higher implementation costs due to the need for more expensive power amplifiers with larger linear regions.
Innovation Solution
The combination of SCMA with SC-FDMA multiple access techniques is used to reduce PAPR by mapping data bits to sparse codebooks and subcarriers, allowing for efficient power amplification and lower implementation costs through reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-orthogonal multiple access schemes (such as SCMA) are employed to support more connected devices, then device connectivity and spectral efficiency are improved, but peak to average power ratio (PAPR) increases
Solution Approach 1:
The patent combines SCMA with SC-FDMA techniques to create a hybrid multiple access scheme. The SC-FDMA component provides low PAPR characteristics while the SCMA component maintains support for multiple connected devices, thus resolving the contradiction between device connectivity and PAPR reduction
Solution Approach 2:
The patent modifies the signal structure by changing parameters such as mapping data bits to specific subcarriers and using sparse codebooks with controlled sparsity patterns. These parameter changes enable the system to maintain high device connectivity while controlling the PAPR within acceptable limits
2Reliability
If power amplifier linear region is increased to reduce distortion, then communication performance is improved, but implementation cost increases
Solution Approach 1:
The patent applies signal processing techniques before power amplification to pre-distort the signal in a controlled manner. By preliminarily shaping the signal characteristics and reducing PAPR through SC-FDMA integration, the power amplifier can operate in a narrower linear region while still achieving low distortion and maintaining communication performance, thus reducing implementation cost
3Use of energy by moving object
If PAPR is reduced to improve power efficiency, then power amplifier cost is reduced, but device complexity increases
Solution Approach 1:
The patent segments the multiple access functionality into distinct components: SC-FDMA handles the low PAPR requirement through its specific modulation and mapping structure, while SCMA handles the multi-device support through sparse code selection. This segmentation allows each component to be optimized independently, managing overall system complexity while achieving power efficiency
Data Source
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AI summary
A method for transmitting data includes modulating data bits with a constellation to produce modulated data symbols, precoding the modulated data symbols to obtain ns groups of precoded samples, where ns is equal to a number of non-zero terms in a sparse code associated with the transmitting device, mapping the ns groups of precoded samples to groups of subcarriers in accordance with the sparse code associated with the transmitting device, to obtain a plurality of subcarrier-mapped samples, transforming the plurality of subcarrier-mapped samples into encoded data symbols, and transmitting the encoded data symbols.