SC-FDMA Layer Permutation for Multi-Codeword PAPR Control
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Solution Overview
Problem
The existing SC-FDMA systems face challenges in maintaining a low peak-to-average power ratio (PAPR) and cubic metric (CM) while utilizing multiple antennas for multi-codeword transmission, which affects power consumption and transmission efficiency.
Innovation Solution
The solution involves a data transmission apparatus and method that includes a modulation mapper, layer permutator, transform precoder, and resource element mapper to generate SC-FDMA signals, performing discrete Fourier transform (DFT) on modulation symbols and mapping them to different layers to maintain a single-carrier property and control PAPR/CM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple antennas are used for multi-codeword transmission in SC-FDMA systems, then transmission reliability and capacity are improved, but peak-to-average power ratio (PAPR) and cubic metric (CM) increase
Solution Approach 1:
The patent segments the transmission of multiple codewords across multiple antenna ports by mapping modulation symbols to different layers and performing DFT on layered symbols. This segmentation allows the system to maintain low PAPR/CM characteristics while transmitting multiple codewords simultaneously through spatial diversity, resolving the contradiction between transmission reliability and PAPR control.
Solution Approach 2:
The patent introduces a layer dimension by mapping modulation symbols to multiple layers before performing DFT. This dimensional transformation enables the system to transmit multiple codewords across different spatial layers while maintaining the single-carrier property and low PAPR/CM characteristics, thus improving reliability without sacrificing power efficiency.
2Productivity
If modulation order is increased to improve data rate, then transmission capacity is improved, but PAPR and CM increase
Solution Approach 1:
The patent applies different modulation orders to different layers based on local channel conditions and coding requirements. By assigning higher modulation orders to layers with better channel conditions and lower modulation orders to layers with worse conditions, the system maximizes overall data rate while controlling the maximum PAPR/CM to acceptable levels, resolving the contradiction between productivity and harmful factors.
Data Source
AI summary
An apparatus for data transmission in a multi-antenna system is provided. The apparatus includes: a modulation mapper for modulating codewords into modulation symbols that express a position on a signal constellation; a layer permutator for mapping the modulation symbols to different layers; a transform precoder for generating a discrete Fourier transform (DFT) symbol of a frequency domain by performing DFT on the modulation symbol mapped to the layer; a resource element mapper for mapping the DFT symbol to a physical resource element; and a signal generator for generating a single carrier-frequency division multiple access (SC-FDMA) signal from the DFT symbol mapped to the resource element, wherein a modulation order of the modulation symbols is determined depending on the layer mapped by the layer permutator.