Uplink MIMO Precoding for Low PAPR SC-FDMA Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current MIMO technologies face challenges in effectively applying the Multiple Input Multiple Output (MIMO) scheme to uplink signal transmission, particularly in maintaining low Peak Power to Average Power Ratio (PAPR) and Cubic Metric (CM) properties, which are critical for efficient data transfer in wireless communication systems.
Innovation Solution
The implementation of a method and apparatus for uplink signal transmission using multiple antennas, involving mapping signals to layers, performing Discrete Fourier Transform (DFT) spreading, and precoding with specific matrices to construct Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbols, ensuring uniform transmission power across antennas and layers to maintain optimal PAPR and CM properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MIMO scheme is applied to uplink signal transmission, then data transfer rate and communication performance are improved, but PAPR and CM properties deteriorate
Solution Approach 1:
The patent segments the uplink signal transmission process into distinct functional blocks: DFT spreading module that processes each layer signal separately, layer mapper that distributes signals to antennas, and precoding module that applies specific matrices. This segmentation allows independent optimization of each stage to maintain low PAPR while achieving MIMO data rate improvements.
Solution Approach 2:
The patent changes key parameters including using DFT-spreading to transform time-domain signals to frequency-domain, applying specific precoding matrices (such as DFT-based matrices) that maintain constant envelope properties, and adjusting the mapping between layers and antennas. These parameter changes enable MIMO transmission while preserving low PAPR characteristics.
2Area of stationary object
If multiple antennas are used for uplink transmission, then system coverage and capacity are increased, but transmission power distribution becomes complex
Solution Approach 1:
The patent employs universal precoding matrices that can be applied across multiple antennas and layers with a single unified mathematical operation. The DFT-based precoding matrices provide a consistent framework that handles power distribution uniformly across all antenna elements, simplifying the complexity of multi-antenna power management while extending system coverage.
Solution Approach 2:
The patent uses identical DFT-based precoding matrices replicated across different antenna ports and layers. This copying approach ensures consistent power distribution patterns without requiring complex per-antenna optimization, reducing device complexity while maintaining extended coverage capabilities through multiple antennas.
3Productivity
If precoding is performed with multiple layers, then data transfer rate increases, but maintaining uniform transmission power becomes difficult
Solution Approach 1:
The patent replaces complex mechanical power adjustment mechanisms with mathematical DFT-based precoding operations. The precoding matrices inherently distribute power uniformly across layers and antennas through their mathematical structure, eliminating the need for complex feedback and adjustment mechanisms while maintaining high data transfer rates through multi-layer transmission.
Solution Approach 2:
The patent creates a composite transmission structure by combining DFT spreading, layer mapping, and precoding in a unified signal processing chain. This composite approach integrates multiple functions into a cohesive system that simultaneously achieves high data rates through layer multiplication and uniform power distribution through the mathematical properties of the combined processing stages.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method and apparatus for allowing a UE to transmit uplink signals using a MIMO scheme are disclosed. In order to maintain good Peak power to Average Power Ratio (PAPR) or Cubic Metric (CM) properties when the UE transmits uplink signals using the MIMO scheme, the UE uses a precoding scheme based on a precoding matrix established in a manner that one layer is transmitted to each antenna in specific rank transmission.