Pre-DFT PT-RS Design for Low-PAPR DFT-S-OFDM
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Solution Overview
Problem
Existing wireless communication technologies face challenges in accurately tracking phase noise and frequency drifts due to oscillator imperfections and Doppler shift, particularly at high carrier frequencies, which degrade detection performance and require efficient compensation methods.
Innovation Solution
A flexible and UE-specifically configurable phase tracking reference signal (PT-RS) design for DFT-s-OFDM waveforms, utilizing pre-DFT insertion to preserve the single-carrier property, reduce peak-to-average power ratio, and enable efficient multiplexing, with configurable burst periodicity and length based on UE-specific parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase tracking reference signals are inserted after DFT (post-DFT insertion), then phase tracking capability is improved, but peak-to-average power ratio increases and single-carrier property is lost
Solution Approach 1:
The patent applies pre-DFT insertion by placing phase tracking reference signals before the DFT operation in the transmit signal processing chain. This preliminary placement allows the reference signals to be transformed along with the data through DFT and IFFT, maintaining the single-carrier property and low PAPR while still enabling phase tracking at the receiver through correlation operations on the transformed signals.
Solution Approach 2:
The patent uses the DFT-s-OFDM transformation itself as an intermediary mechanism. By inserting reference signals before DFT and using the transformed version after IFFT for correlation, the system leverages the transformation process to maintain signal properties while still providing phase tracking capability. The intermediary transformation preserves the single-carrier characteristics while enabling the reference signals to function for phase estimation.
2Stability of the object's composition
If phase tracking reference signals are inserted before DFT (pre-DFT insertion), then single-carrier property and low PAPR are maintained, but phase tracking accuracy may be reduced
Solution Approach 1:
The patent employs feedback through correlation operations at the receiver. The received signal is correlated with locally generated reference signals that have undergone the same DFT and IFFT transformations. This feedback mechanism allows accurate phase estimation by comparing the transformed reference signals with the received transformed signals, compensating for the potential accuracy loss from pre-DFT insertion.
Solution Approach 2:
The patent replaces direct post-DFT phase measurement with an indirect correlation-based measurement approach. Instead of measuring phase directly after DFT, the system uses correlation between transformed reference signals and received signals to estimate phase, substituting a more complex signal processing mechanism that preserves the single-carrier property while achieving accurate phase tracking.
3Measurement precision
If more phase tracking reference signals are transmitted, then phase tracking accuracy is improved, but signal overhead increases
Solution Approach 1:
The patent applies partial action by inserting phase tracking reference signals at specific partial positions within the data blocks rather than continuously. The reference signals are placed at strategically selected positions before DFT, and their transformed versions are used for correlation-based phase estimation. This partial placement provides sufficient phase tracking accuracy while minimizing the overhead compared to continuous reference signal transmission.
Data Source
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AI summary
Systems, methods, apparatuses, and computer program products relating to phase tracking reference signal (PT-RS) design, for example, for discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM), are provided. One method may include forming, by a network node, a phase tracking reference signal (PT-RS) sample sequence using outer-most constellation points corresponding to scheduled modulation order of data channel, and scrambling the phase tracking reference signal (PT-RS) sample sequence with a user equipment-specific sequence.