PUCCH Sequence Design for Low Cross-Correlation and Small PAPR
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Solution Overview
Problem
In LTE systems, the existing 30 root sequences fail to ensure both low cross-correlation and small Peak to Average Power Ratio (PAPR) values for signals transmitted using the Physical Uplink Control Channel (PUCCH), leading to interference issues and reduced coverage.
Innovation Solution
A sequence-based signal processing method is introduced, where sequences {f_n} are determined to meet specific conditions and mapped to subcarriers, ensuring low cross-correlation and small PAPR values, by using sequences from predefined sets or their equivalents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing 30 root sequences are used for PUCCH transmission, then the sequence cross-correlation is optimized, but the PAPR values cannot be ensured to be small
Solution Approach 1:
The patent modifies the parameters of existing root sequences by applying cyclic shifts and phase rotations to generate new sequences with improved PAPR characteristics while maintaining low cross-correlation properties. Specifically, sequences are transformed using operations like x_n = u·e^(2πj·s_n/M) where u is a non-zero complex number, changing the phase parameters to achieve better PAPR performance
Solution Approach 2:
The patent creates composite sequences by combining multiple root sequences with different cyclic shifts and phase rotations. The sequence set includes both original root sequences and their transformed versions, creating a composite structure that achieves both low cross-correlation and small PAPR values simultaneously
2Reliability
If sequences are optimized for small CM values, then the cubic metric is improved, but the PAPR values may not be small
Solution Approach 1:
The patent applies specific parameter transformations to sequences, including phase rotations using complex numbers and cyclic shifts, to decouple the relationship between CM and PAPR optimization. By changing the phase parameters independently, the patent achieves small PAPR values while maintaining acceptable CM values
3Object-affected harmful factors
If low-PAPR sequences are selected from existing sets, then the PAPR values are reduced, but the cross-correlation characteristics deteriorate when time deviation is present
Solution Approach 1:
The patent introduces dynamic cyclic shifts that can be adjusted based on time deviation conditions. The cyclic shift amount is not fixed but can be adapted to compensate for timing errors, maintaining low cross-correlation even when time deviation occurs. This dynamic adjustment preserves both low PAPR and good cross-correlation characteristics
Data Source
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AI summary
This application provides a sequence-based signal processing method and apparatus. A sequence meeting a requirement for sending a signal by using a PUCCH is determined. The sequence is a sequence {fn} including N elements, and fn is an element in the sequence {fn}. The determined sequence {fn} is a sequence that meets a preset condition. Then the N elements in the sequence {fn} are respectively mapped to N subcarriers to generate and send a first signal. With the determined sequence, when the signal is sent by using the PUCCH, a low cross-correlation between sequences can be maintained, and a relatively small PAPR value and a relatively small CM value can be maintained. Therefore, a requirement in a communications application environment in which the signal is sent by using the PUCCH is met.