Frequency Domain Spectral Shaping for Low PAPR Reference Signals
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Solution Overview
Problem
OFDM systems have high peak to average power ratios (PAPR), which can be detrimental to power amplifier efficiency, especially in uplink transmissions where user equipment has limited battery power, and existing methods for applying Frequency Domain Spectrum Shaping (FDSS) to reference signals are not effective in reducing PAPR.
Innovation Solution
The method involves obtaining a base sequence by cyclically repeating sub-group sequences and using a Zadoff-Chu sequence with a length that is a prime number less than half the reference sequence length, and applying frequency domain spectral shaping to both data and reference signals to reduce PAPR, ensuring transparency to the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OFDM systems use conventional reference signals, then channel estimation is accurate, but PAPR remains high which reduces power amplifier efficiency
Solution Approach 1:
The patent changes the fundamental parameter of the reference signal sequence generation by using a new base sequence construction method with cyclic repetition of sub-group sequences, and applies frequency domain spectral shaping with a specific window function to alter the signal's spectral characteristics, thereby reducing PAPR while maintaining channel estimation accuracy
Solution Approach 2:
The base sequence is segmented into sub-group sequences that are cyclically repeated. This segmentation approach allows the reference signal to be constructed from multiple smaller sequence segments, which when combined with frequency domain spectral shaping, reduces the peak power while preserving the necessary correlation properties for accurate channel estimation
2Loss of energy
If FDSS is applied to reference signals using conventional methods, then spectral shaping is achieved, but PAPR reduction is not effective
Solution Approach 1:
The patent modifies the FDSS approach by changing the base sequence construction parameters and applying a specific window function in the frequency domain that is optimized for PAPR reduction, making the spectral shaping process effective for both data and reference signals
Solution Approach 2:
The patent creates a universal FDSS approach that works for both data transmission and reference signal transmission. By designing the base sequence and spectral shaping function to be applicable to both types of signals, the system achieves consistent PAPR reduction across all uplink transmissions
3Productivity
If uplink transmissions use high PAPR signals, then data rate is maintained, but battery power is depleted faster
Solution Approach 1:
The patent changes the signal parameters through new base sequence construction and frequency domain spectral shaping, which reduces the peak power requirements while maintaining the data transmission rate, thereby extending battery life in user equipment
Data Source
AI summary
Aspects of the description provide a method and devices to allow frequency domain spectral shaping (FDSS) to be used on both a reference sequence and data to enable low PAPR. Being able to use FDSS on both the reference sequence and data allows the FDSS to be transparent to the receiver. The method comprises obtaining a first sequence, wherein the first sequence is a base sequence of a set of base sequences, the set of base sequences comprising sub group base sequences, the first sequence obtained by cyclically repeating the sub group sequences at least once; and transmitting, by the device, a reference signal based on the first sequence.