DFT-s-OFDM Signal Transmission with Phase Offset for PAPR Reduction
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Solution Overview
Problem
In current new radio (NR) communication systems, the transmission of uplink signals in a discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-s-OFDM) waveform results in poor transmission performance and low efficiency due to the inability to fully utilize the degree of freedom of a multiple-input multiple-output (MIMO) channel during single-layer transmission.
Innovation Solution
A signal transmission method where the transmitting end maps modulation symbols to multiple layers, performs discrete Fourier transform (DFT) on some layers and DFT with phase offset on others, and then applies specific processing to obtain a DFT-s-OFDM signal, thereby reducing peak to average power ratio (PAPR) and improving transmission performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-layer transmission is used in DFT-s-OFDM waveform, then implementation complexity is reduced, but transmission performance and efficiency are low
Solution Approach 1:
The patent segments the transmission layers into two groups: first layers that undergo DFT processing and second layers that undergo DFT with additional phase offset. This segmentation allows the system to maintain multi-layer transmission capability while managing complexity through structured processing differentiation.
Solution Approach 2:
Different processing operations are applied to different layers based on their specific characteristics. The first layers receive DFT processing while the second layers receive DFT plus phase offset, creating local quality differences that optimize transmission performance for each layer's specific role in the MIMO channel.
2Productivity
If multi-layer transmission is used in OFDM waveform, then transmission efficiency is improved, but peak to average power ratio (PAPR) increases
Solution Approach 1:
The patent introduces phase offset as an additional parameter to the DFT processing for second layers. This parameter change allows the system to maintain multi-layer transmission efficiency while controlling the peak to average power ratio through the additional phase modulation degree of freedom.
3Power
If phase offset is applied to all layers, then PAPR is reduced, but transmission performance cannot be fully optimized
Solution Approach 1:
The patent applies phase offset selectively only to second layers rather than all layers. This local quality differentiation allows PAPR reduction where needed while preserving the ability to optimize transmission performance in first layers through standard DFT processing, achieving a balance between power control and transmission efficiency.
Data Source
AI summary
A signal transmission method and an apparatus are provided, to resolve a problem, in a conventional technology, that transmission performance is poor when a signal is transmitted in a DFT-s-OFDM waveform. A transmitting end maps a plurality of modulation symbols to a plurality of layers, performs discrete Fourier transform (DFT) on a modulation symbol at a part of the layers to obtain a first symbol, and performs discrete Fourier transform DFT and phase offset on a modulation symbol at a remaining part of the layers to obtain a second symbol. Phase offset is performed on a symbol at a part of layers, so that a PAPR can be reduced.