Sequence-Based Signal Processing for PUSCH
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Solution Overview
Problem
In the LTE and NR communication systems, the use of π/2 BPSK modulation for DFT-s-OFDM DMRS waveforms results in poor frequency flatness and high PAPR, leading to out-of-band emission, in-band signal loss, and limited channel estimation performance due to the use of Gold sequences or CGS, while ZC sequences cause higher PAPR and affect uplink coverage.
Innovation Solution
A sequence-based signal processing method that utilizes specific sequences with preset conditions to maintain good frequency domain flatness and low PAPR, employing complex number operations to generate sequences that satisfy these criteria, such as x_n = A·b_n·j^n, where b_n = u·(1-2·s_n) and u is a non-zero complex number, ensuring low cross-correlation and PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Gold sequence or CGS is used for uplink DFT-s-OFDM DMRS waveform with π/2 BPSK modulation and filtering, then the sequence can be generated, but frequency flatness becomes poor which does not facilitate channel estimation
Solution Approach 1:
The patent changes the fundamental parameter of the sequence type from Gold sequence/CGS to a specifically designed sequence with controlled autocorrelation and cross-correlation properties. The sequence is defined by x_n = A·b_n·j^n where b_n = u·(1-2·s_n), transforming the sequence structure to achieve both good frequency flatness and low PAPR characteristics suitable for π/2 BPSK DFT-s-OFDM modulation
2Reliability
If ZC sequence is used for uplink DFT-s-OFDM DMRS waveform, then the sequence provides good autocorrelation properties, but PAPR becomes higher than PAPR of transmitted data causing out-of-band emission and in-band signal loss
Solution Approach 1:
The patent modifies the sequence construction by introducing a specific phase rotation pattern (j^n) and binary sequence mapping (1-2·s_n) that transforms the ZC sequence structure. This parameter change reduces the PAPR to be comparable to data transmission while maintaining the essential autocorrelation properties needed for channel estimation
Solution Approach 2:
The patent creates a composite sequence structure combining multiple mathematical transformations: the base sequence s_n, the binary mapping (1-2·s_n), the phase rotation (j^n), and the scaling factor (u). This composite construction achieves the desired balance between autocorrelation properties and PAPR reduction
3Reliability
If ZC sequence is used for uplink DFT-s-OFDM DMRS waveform, then the sequence can be generated with good autocorrelation, but uplink coverage is limited due to high PAPR
Solution Approach 1:
By changing the sequence parameters through the transformation x_n = A·b_n·j^n with b_n = u·(1-2·s_n), the patent reduces PAPR to levels comparable to data transmission. This parameter modification enables the reference signal to adapt to uplink coverage requirements while preserving the autocorrelation properties essential for reliable channel estimation across different coverage scenarios
Data Source
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AI summary
This application provides a sequence-based signal processing method and apparatus. A sequence used for sending a signal on a PUSCH is determined. The sequence is a sequence {xn} including N elements, xn is an element in the sequence {xn}, and the determined sequence {xn} is a sequence satisfying a preset condition. Then, a first signal is generated and sent. By using the determined sequence, when a signal is sent on the PUSCH, relatively good sequence frequency domain flatness can be maintained, and a relatively low PAPR value and a relatively low cross-correlation between sequences can be maintained, thereby satisfying a communications application environment in which a signal is sent on the PUSCH, especially an NR system scenario or an NR similar scenario.