Reference Signal Generation for Uplink Channel Estimation
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Solution Overview
Problem
The existing DMRS sequences in LTE and NR systems suffer from high peak-to-average power ratio (PAPR), leading to out-of-band spurious emission and in-band signal loss, which affects channel estimation performance and uplink coverage, and fail to meet current communication application requirements.
Innovation Solution
A signal processing method that generates a reference signal using a sequence modulated by π/2 BPSK, with specific discrete Fourier transform and mapping techniques to improve frequency domain resource allocation, reducing PAPR and enhancing channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the uplink DMRS uses the ZC sequence, then the sequence satisfies CAZAC sequence property, but the PAPR of the DMRS is higher than the PAPR of the uplink transmission signal, resulting in out-of-band spurious emission and in-band signal loss
Solution Approach 1:
The patent changes the sequence type parameter from ZC sequence to Gold sequence or CGS, and adjusts the modulation parameter from traditional BPSK to π/2 BPSK. This parameter change reduces the PAPR of the DMRS to be closer to the uplink transmission signal, thereby reducing out-of-band spurious emission and in-band signal loss while maintaining channel estimation performance
Solution Approach 2:
The patent uses a reference signal with the same sequence type (Gold sequence or CGS) and modulation scheme (π/2 BPSK) as the uplink transmission signal, creating a copy that matches the signal characteristics. This copying approach ensures the DMRS has compatible PAPR with the transmission signal, reducing interference and improving coverage
2Stability of the object's composition
If the uplink DMRS uses the ZC sequence, then the sequence has constant envelope property, but the PAPR is higher causing limited uplink coverage
Solution Approach 1:
The patent changes the sequence parameter from ZC sequence to Gold sequence or CGS, and the modulation parameter from BPSK to π/2 BPSK. This changes the envelope characteristics to match the uplink transmission signal better, reducing in-band signal loss and extending uplink coverage while maintaining stable channel estimation
3Object-generated harmful factors
If the uplink DMRS uses Gold sequence-based sequence or CGS with filter, then frequency flatness is relatively poor, but this is adverse to channel estimation
Solution Approach 1:
The patent changes the sequence type to Gold sequence or CGS with specific parameters and uses π/2 BPSK modulation. This parameter optimization improves frequency flatness while maintaining good autocorrelation properties, thereby enhancing channel estimation performance without the adverse effects of poor frequency flatness
Data Source
AI summary
The present disclosure relates to signal processing methods and apparatus. One example method includes determining a first sequence {x(n)} based on a preset condition and a sequence {s(n)}, generating a reference signal of a first signal by using the first sequence, and sending the reference signal on a first frequency-domain resource. The preset condition is xn=y(n+M)mod K, whereyn=A·ej×π×sn8,M∈{0, 1, 2, . . . , 5}, a length of the first sequence is K=6, n=0, 1, . . . , K−1, A is a non-zero complex number, and j=√{square root over (−1)}. The first signal is a signal modulated by using π/2 binary phase shift keying (BPSK). The first frequency-domain resource comprises K subcarriers each having a subcarrier number of k, k=u+L*n+delta, L is an integer greater than or equal to 2, delta∈{0, 1, . . . , L−1}, u is an integer, and subcarrier numbers of the K subcarriers are numbered in ascending or descending order of frequencies.