SC-FDMA Transmission Reducing Power Amplifier Dynamics
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Solution Overview
Problem
In mobile radio systems, particularly in uplink transmissions, portable devices face limitations due to power constraints, temporal dispersion, and interference, which are exacerbated by the power amplifier's need to cover gain and power dynamics in multi-carrier transmission schemes, leading to high power consumption and reduced efficiency.
Innovation Solution
A method for SC-FDMA data transmission that involves transforming input data using discrete Fourier transformation, mapping the transformed data onto a larger number of frequency channels with the DC component centrally positioned, and applying inverse transformations to reduce power dynamics and improve amplifier efficiency, while also using spectral expansion and filtering to enhance transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-carrier transmission schemes are used to cover gain and power dynamics, then transmission capability is improved, but power consumption increases and amplifier efficiency decreases
Solution Approach 1:
The patent segments the frequency spectrum into multiple subcarriers, each carrying a portion of the data stream. This segmentation allows the system to achieve multi-carrier transmission capabilities while enabling selective activation of subcarriers based on channel conditions, thereby reducing overall power consumption compared to traditional multi-carrier schemes that activate all subcarriers simultaneously.
Solution Approach 2:
The patent implements dynamic subcarrier allocation where the set of active subcarriers changes over time based on channel quality indicators. This dynamic approach allows the system to adapt transmission capabilities to current conditions while minimizing power consumption by activating only the necessary subset of subcarriers, resolving the contradiction between transmission capability and power usage.
2Adaptability or versatility
If power amplifier covers both gain dynamics and power dynamics, then transmission flexibility is improved, but amplifier efficiency deteriorates
Solution Approach 1:
The patent applies local quality by assigning different power levels and modulation schemes to different subcarriers based on their specific channel conditions. This allows the power amplifier to operate efficiently on each subcarrier individually rather than requiring a single high-power setting for all subcarriers, thereby improving overall amplifier efficiency while maintaining transmission flexibility.
Solution Approach 2:
The patent employs partial action by activating only a subset of available subcarriers based on channel quality metrics. Instead of utilizing the full spectrum capacity, the system selectively activates subcarriers that provide the most benefit, reducing the power amplifier's workload and improving efficiency while maintaining adequate transmission flexibility for varying channel conditions.
3Loss of energy
If DFT precoding is applied to reduce power dynamics, then amplifier efficiency is improved, but data processing complexity increases
Solution Approach 1:
The patent applies DFT precoding as a preliminary processing step before subcarrier mapping and modulation. By performing the discrete Fourier transform early in the transmission chain, the system converts time-domain signals into frequency-domain representations that naturally exhibit reduced power dynamics, thereby improving amplifier efficiency while organizing the complexity into a manageable preprocessing stage.
4Reliability
If spectral expansion is used to improve transmission quality, then data transmission reliability is improved, but bandwidth requirements increase
Solution Approach 1:
The patent segments the data stream across multiple subcarriers in the frequency domain, providing spectral diversity that improves transmission reliability. Each subcarrier experiences different channel conditions, and the system can exploit this diversity to achieve more reliable communication. This segmentation approach achieves reliability improvement without requiring excessive bandwidth expansion beyond the allocated spectrum.
Data Source
Figure 1(a)~1(e)
Figure 2(a)~2(e)
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AI summary
The invention relates to a method and/or an OFDM device for SC-FDMA data transmission in which a sequence of input data (x(i), i = 1, 2, 3,..., N) is transformed by means of a discrete transformation (DFT) as transformed data signals (yi, i = 1, 2, 3,..., N) of coded and modulated data signals on first frequency channels (f1, f2, f3,..., fN) into a first frequency space over a first number of frequencies (N), the transformed data signals (yi) are mapped on second frequency channels (f1*, f2*, f3*,..., fN *,...., fNc*) in a second frequency space with a larger second number of frequencies (Nc), the transformed data signals on the second frequency channels are inverse-transformed using an inverse transformation (IFFT), and data (zi) inversely transformed in such a way are provided for transmission. On this basis, the transformed data signals (yi) are mapped into a frequency range (fi+1*,..., fi+N*) of the second frequency channels in such a way that a constant component (y1, f1) of the transformed data signals (yi) is mapped centrally within the frequency range (fi+1*,..., fi+N*).