Multi-Carrier Waveform Selection for Spectral Leakage Suppression
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Solution Overview
Problem
Current multi-carrier systems, such as LTE, face challenges with high spectral leakage and interference due to frequency and time offset sensitivity, leading to reduced spectral efficiency and compatibility issues with OFDM technology, particularly in suppressing out-of-band leakage and maintaining demodulation performance.
Innovation Solution
A data modulation and demodulation method for a multi-carrier system that selects and uses flexible waveform functions based on specific parameters to perform polyphase filtering, allowing for improved suppression of out-of-band leakage and enhanced compatibility with LTE systems, using waveform functions like rectangular, raised cosine, and root raised cosine functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CP-OFDM technology is used to solve multipath delay, then channel estimation accuracy is improved, but spectral leakage and interference between sub-bands increase
Solution Approach 1:
The patent applies parameter changes by modifying the waveform function parameters (such as filter length, transition band width, and roll-off factor) to optimize the balance between spectral leakage suppression and channel estimation accuracy. By adjusting these parameters, the system can adapt to different channel conditions and requirements.
Solution Approach 2:
The patent employs composite materials by combining multiple filtering techniques (e.g., root raised cosine filtering, polyphase filtering) with OFDM modulation to create a hybrid waveform structure that achieves both multipath delay resolution and spectral leakage suppression simultaneously.
2Object-generated harmful factors
If guard intervals are adopted in frequency domain, then spectral leakage is suppressed, but spectral efficiency decreases
Solution Approach 1:
The patent extracts and removes the need for traditional guard intervals by implementing frequency domain filtering that inherently suppresses spectral leakage at the boundaries between sub-bands, thereby eliminating the overhead associated with guard intervals and improving spectral efficiency.
Solution Approach 2:
The patent changes the filtering parameters (filter length, cutoff frequency, transition band) to achieve effective spectral leakage suppression with minimal impact on useful signal bandwidth, thus maintaining high spectral efficiency while suppressing harmful spectral leakage.
3Productivity
If new multi-carrier schemes (FBMC, GFDM) are used to suppress out-of-band leakage, then spectral efficiency is improved, but compatibility with LTE and demodulation performance deteriorate
Solution Approach 1:
The patent achieves universality by designing a filtering-based multi-carrier system that can operate in both LTE-compatible mode and enhanced spectral efficiency mode. The system can adaptively select different waveform functions and filtering parameters to maintain compatibility with existing LTE infrastructure while optionally improving spectral efficiency when conditions permit.
Solution Approach 2:
The patent applies dynamics by making the waveform function selection and filtering parameters adaptive rather than fixed. The system can dynamically adjust between different modulation schemes and filtering configurations based on channel conditions, synchronization accuracy, and compatibility requirements, thereby resolving the trade-off between spectral efficiency and LTE compatibility.
4Adaptability or versatility
If F-OFDM and UFMC are used to maintain LTE compatibility, then adaptability is improved, but out-of-band leakage suppression performance deteriorates
Solution Approach 1:
The patent combines multiple filtering techniques (polyphase filtering, root raised cosine filtering) with F-OFDM/UFDM structures to create an enhanced composite waveform that maintains LTE compatibility while significantly improving out-of-band leakage suppression compared to standard F-OFDM or UFMC implementations.
Solution Approach 2:
The patent optimizes the filtering parameters (filter length, transition band width, roll-off factor) to achieve better out-of-band leakage suppression while maintaining compatibility with LTE systems. By carefully tuning these parameters, the system can reduce spectral leakage without compromising the fundamental LTE compatibility requirements.
Data Source
AI summary
Disclosed in the embodiments of the present application are a data modulating and demodulating method, a data transmission method and node for multi-carrier system. The data modulating method including: selecting, by a transmitting node, corresponding waveform functions based on values of a first parameter, wherein the first parameter includes K values corresponding to K different waveform functions, respectively, and K is an integer greater than 1; and performing, by the transmitting node, using the selected waveform functions, modulation on time domain data sequences processed by Inverse Fast Fourier Transform (IFFT) to obtain a modulated data sequence. The first parameter may be configured by a base station for a UE. Also provided by the embodiments of the present application are a corresponding demodulation method and data transmission method and node.