PreDFT-GI-DFT-s-FDM Waveform for Millimeter-Wave PAPR Reduction
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Solution Overview
Problem
Current wireless communication systems, particularly those using new radio (NR) technologies, face challenges in improving spectral efficiency and power amplification due to high peak-to-average-power ratio (PAPR) in single-carrier waveforms, which limits the transmit power level and affects phase tracking in millimeter-wave communications.
Innovation Solution
The implementation of PreDFT-GI-DFT-s-FDM single-carrier waveform, where data samples are concatenated with a known sequence and transformed using discrete Fourier transform (DFT) and inverse DFT, allowing for efficient power amplification and phase tracking by using the guard interval as both a cyclic prefix and phase tracking reference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single-carrier waveform is used in millimeter-wave NR systems, then spectral efficiency can be improved, but the peak-to-average-power ratio (PAPR) becomes high which limits transmit power level
Solution Approach 1:
The patent segments the single-carrier waveform into two distinct parts: data samples and a known sequence (guard interval). This segmentation allows the known sequence to serve as a reference for power amplification while the data samples carry information, thereby reducing the overall PAPR and enabling higher transmit power levels without compromising spectral efficiency
Solution Approach 2:
The known sequence acts as an intermediary element between the data samples and the power amplification process. By inserting this known sequence as a guard interval, the system creates a reference signal that facilitates power tracking and reduces PAPR, allowing the power amplifier to operate more efficiently at higher power levels
2Productivity
If single-carrier waveform is used in millimeter-wave NR systems, then spectral efficiency can be improved, but phase tracking becomes difficult due to high PAPR
Solution Approach 1:
The known sequence serves as an intermediary reference signal that enables phase tracking. By placing this known sequence adjacent to the data samples, the receiver can use it as a reference to track phase variations caused by high PAPR, thereby maintaining reliable phase tracking despite the challenges posed by single-carrier waveforms
Solution Approach 2:
The patent introduces a distinct known sequence with recognizable characteristics (analogous to a color change) that stands out from the data samples. This known sequence provides a clear reference point for phase tracking, allowing the receiver to distinguish and track phase variations even in the presence of high PAPR effects
3Reliability
If guard interval is used as cyclic prefix, then inter-symbol interference can be reduced, but the sequence length increases which may affect timing synchronization
Solution Approach 1:
The known sequence serves multiple functions simultaneously: it acts as a guard interval to prevent inter-symbol interference, provides a reference for phase tracking, and enables timing synchronization. This multi-functionality allows the system to achieve reliable ISI protection without proportionally increasing the overall sequence length, as the same elements serve multiple purposes
Data Source
AI summary
Certain aspects of the present disclosure relate to communication systems, and more particularly, to single-carrier waveform generation for transmission. An exemplary method generally includes concatenating a first sequence of data samples with samples of a known sequence to generate a first series of samples, performing a discrete Fourier transform (DFT) on the first series of samples to generate a first series of frequency-domain samples, mapping the first series of frequency-domain samples and first zero values to first tones of a system bandwidth, performing an inverse discrete Fourier transform (IDFT) on the mapped first series of frequency-domain samples and the mapped first zero values to generate first time-domain samples of a first orthogonal frequency domain multiplexing (OFDM) symbol, and transmitting the first OFDM symbol as a single-carrier waveform in a first period.