Reference Signal Phase Rotation for PAPR Reduction
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Solution Overview
Problem
Existing methods for ensuring orthogonality of reference signals in wireless communication systems, such as those used in LTE and future 5G systems, face challenges in reducing peak-to-average power ratio (PAPR) and raw cubic metric (RCM) while maintaining signal integrity, particularly in uplink multi-user multiple-input multiple-output (MU-MIMO) scenarios.
Innovation Solution
The method involves splitting reference signals into multiple symbol sequences, multiplying them by coefficients with a magnitude of 1 to perform phase rotation, and mapping these sequences onto time-frequency resources using various mapping techniques, including consecutive, interleaved, and equally spaced methods, to reduce PAPR and RCM while ensuring orthogonality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference signals are transmitted using conventional methods (time division, frequency division, or code division), then orthogonality of reference signals is ensured, but peak-to-average power ratio (PAPR) and raw cubic metric (RCM) remain high
Solution Approach 1:
The reference signal is divided into multiple blocks in the time domain, where each block contains multiple symbol sequences. This segmentation allows independent phase rotation processing for each block, reducing the overall PAPR and RCM while maintaining orthogonality through block-level separation
Solution Approach 2:
Phase rotation coefficients are applied to different symbol sequences within blocks, changing the phase parameter of the reference signal. This parameter modification reduces peak power variations and cubic metric values while preserving the orthogonality property through carefully selected rotation angles
2Object-generated harmful factors
If reference signals are split into multiple blocks to reduce PAPR/RCM, then PAPR and RCM are reduced, but orthogonality of reference signals may be compromised
Solution Approach 1:
The reference signal structure is segmented into multiple blocks with clear time-domain separation. Each block undergoes independent phase rotation, and the segmentation ensures that orthogonality is maintained at the block level while allowing PAPR/RCM reduction within each segment
Solution Approach 2:
Phase rotation coefficients are pre-calculated and applied to each symbol sequence before transmission. This preliminary phase adjustment ensures that orthogonality is preserved while the PAPR and RCM are reduced through optimized phase distribution across blocks
Data Source
AI summary
Embodiments of the present invention disclose a reference signal transmission method. A transmitting apparatus multiplies M first symbol sequences by M coefficients respectively to obtain M second symbol sequences, where M is a positive integer greater than 1, the symbol sequence includes L symbols, L is a positive integer greater than 1, and the M coefficients each have a magnitude of 1. The transmitting apparatus maps the M second symbol sequences onto a first time-frequency resource to obtain a frequency domain signal. The transmitting apparatus performs an IFFT operation on the frequency domain signal to obtain a time domain signal. And the transmitting apparatus sends the time domain signal.