Low-PAPR Data and Reference Signal Filtering for 5G Uplink
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Solution Overview
Problem
Existing communication systems face challenges in reducing the peak-to-average power ratio (PAPR) of uplink signals in cellular networks, particularly in DFT-s-OFDM waveforms, which limits coverage and interferes with coherent demodulation due to high PAPR values, especially in 5G networks.
Innovation Solution
Implementing spectrum shaping filters for both data and reference signals, along with specific port mapping and rotation techniques, to align the PAPR of data and DMRS sequences, ensuring identical channel estimation performance across multiple antenna ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM is used for transmission, then data transmission capability is improved, but PAPR increases causing power amplifier nonlinearities and reduced coverage
Solution Approach 1:
The patent extracts the high PAPR component from the OFDM signal by applying a clipping function that removes or attenuates signal peaks above a certain threshold, thereby reducing PAPR while preserving the essential data transmission capability of OFDM
Solution Approach 2:
The patent changes the signal parameters by applying spectral shaping filters that modify the frequency domain characteristics of the OFDM signal, transforming the high PAPR waveform into a low PAPR waveform while maintaining data transmission integrity
2Reliability
If DFT-s-OFDM waveform is used to reduce PAPR, then coverage is improved, but PAPR remains high (around 4 dB) compared to conventional filters
Solution Approach 1:
The patent applies advanced spectral shaping techniques that further modify the signal parameters beyond conventional DFT-s-OFDM, achieving PAPR reduction from 4 dB to 1-2 dB by optimizing the frequency domain signal characteristics
Solution Approach 2:
The patent combines multiple signal processing techniques including DFT-s-OFDM transformation, spectral shaping filters, and selective signal manipulation to create a composite waveform that achieves ultra-low PAPR while maintaining coverage
3Power
If spectrum shaping filtering is applied to reduce PAPR, then PAPR is reduced to 1-2 dB, but receiver performance may be affected and complex filtering operation is required
Solution Approach 1:
The patent applies spectral shaping filtering at the transmitter side before signal transmission, preliminarily reducing PAPR and preventing amplifier nonlinearities, which simplifies the receiver design and maintains receiver performance by avoiding the need for complex compensation algorithms
Solution Approach 2:
The patent introduces carefully designed spectral shaping filters as intermediary elements that transform the signal in a controlled manner, maintaining signal integrity while reducing PAPR, and these filters serve as a bridge between the data signal and the power amplifier
4Power
If different filtering operations are applied to data and reference signals, then PAPR can be optimized, but system complexity increases
Solution Approach 1:
The patent employs a universal spectral shaping filter design that can be applied to both data signals and reference signals with the same filtering operation, eliminating the need for separate filtering operations and reducing system complexity while maintaining PAPR optimization
Data Source
AI summary
Embodiments of the present disclosure relate to systems and methods to generate a signal in a communication network. The method comprises fdtering a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) data signal, and one of a DFT-S-OFDM and orthogonal frequency division multiplexing (OFDM) reference signal (RS) using a data filter and a RS filter respectively, to produce filtered data signal and filtered RS. The RS filter has one to one relationship with the data filter. Thereafter, port mapping the filtered RS to a corresponding port assigned to the transmitter to obtain port mapped filtered RS, wherein the port mapped filtered RS comprises a first subset of non-zero locations comprising of the filtered RS values and a second subset of zero locations comprising of zero values.