PUSCH DMRS Sequence Design for Frequency Flatness and Low PAPR
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Solution Overview
Problem
In the new radio access technology (NR), the use of π/2 BPSK modulation for uplink DFT-s-OFDM DMRS waveforms results in poor frequency flatness and high peak-to-average power ratio (PAPR) when Gold sequences or computer-generated sequences are employed, leading to out-of-band emission and in-band signal loss, which affects channel estimation performance and uplink coverage.
Innovation Solution
A sequence-based signal processing method is introduced, using a sequence {xn} defined by xn=A·bn·jn, where xn is an element satisfying a preset condition, to maintain good frequency domain flatness and low PAPR, ensuring effective channel estimation and reduced cross-correlation between sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Gold sequence or computer-generated sequence is used for uplink DFT-s-OFDM DMRS waveform with π/2 BPSK modulation, then the sequence can be generated, but frequency flatness becomes poor and PAPR becomes high
Solution Approach 1:
The patent changes the mathematical parameters of the sequence by using a Zadoff-Chu sequence with specific root indices and lengths that are optimized for π/2 BPSK modulation. The sequence is defined with specific properties (constant amplitude, zero auto-correlation) that ensure good frequency flatness when transformed, directly resolving the frequency flatness issue while maintaining generation feasibility
2Reliability
If ZC sequence is used for uplink DFT-s-OFDM DMRS waveform, then frequency flatness is improved, but PAPR becomes higher than transmitted data
Solution Approach 1:
The patent applies local quality by selecting specific root indices and sequence lengths of the Zadoff-Chu sequence that are locally optimized for low PAPR characteristics. The sequence design incorporates specific properties at different positions and parameters to minimize peak power while maintaining the overall frequency flatness required for channel estimation
Solution Approach 2:
The patent introduces dynamic selection of sequence parameters (root index, length) based on the specific transmission conditions and channel characteristics. The system can dynamically adjust the sequence configuration to balance frequency flatness and PAPR requirements for different uplink scenarios
3Ease of manufacture
If ZC sequence is used for uplink DFT-s-OFDM DMRS waveform, then sequence can be generated, but out-of-band emission and in-band signal loss occur
Solution Approach 1:
The patent optimizes the sequence parameters (root index, length, and other characteristics) to minimize spectral leakage and reduce out-of-band emissions. The specific parameter selection ensures that the sequence maintains good autocorrelation properties while reducing the harmful emissions that affect both in-band signal quality and out-of-band spectral purity
Data Source
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.