LTE Data Processing Using Preset Function to Reduce Out-of-Band Leakage
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Solution Overview
Problem
Current LTE systems are prone to out-of-band leakage due to sensitivity to frequency and time offsets, leading to reduced demodulation performance, and new technologies like FBMC and GFDM are not fully compatible with LTE, MIMO, and channel estimation.
Innovation Solution
A data processing method and apparatus that applies a preset function, the product of a time-domain and frequency-domain root raised cosine functions, for inverse and fast Fourier transforms, incorporating filter bank processing to minimize interference and inhibit out-of-band leakage while maintaining compatibility with LTE systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CP-OFDM technology is used in LTE system, then channel estimation accuracy is improved and multipath delay is eliminated, but out-of-band leakage increases and spectrum efficiency decreases
Solution Approach 1:
The patent changes the time-domain waveform parameters by applying a window function (product of raised cosine functions) to the CP-OFDM signal. This modifies the signal's spectral characteristics to reduce out-of-band leakage while preserving the cyclic prefix structure that enables accurate channel estimation.
Solution Approach 2:
The patent creates a composite signal structure by combining CP-OFDM with a window function (product of raised cosine functions in time domain). This composite approach integrates the advantages of both techniques: the robust channel estimation of CP-OFDM and the spectral confinement of windowed signals.
2Object-generated harmful factors
If guard interval is used in frequency domain to reduce out-of-band leakage, then spectrum efficiency decreases
Solution Approach 1:
The patent extracts and removes the harmful out-of-band leakage components by applying a window function that tapers the signal edges. This eliminates the need for additional guard intervals while maintaining spectral efficiency, as the windowing directly suppresses leakage without consuming extra bandwidth resources.
3Object-generated harmful factors
If FBMC or GFDM technology is used to inhibit out-of-band leakage, then compatibility with LTE, MIMO, and channel estimation deteriorates
Solution Approach 1:
The patent creates a universal solution that works across multiple LTE functions (channel estimation, MIMO, various modulation schemes) by applying a general window function framework. This single approach provides spectral confinement benefits while maintaining compatibility with all LTE features, unlike FBMC or GFDM which require system-level redesign.
Solution Approach 2:
The window function acts as an intermediary between the CP-OFDM signal and the spectral requirements. It mediates the conflict by shaping the signal spectrum to reduce leakage while preserving the underlying CP-OFDM structure that enables LTE compatibility, MIMO operation, and channel estimation.
4Adaptability or versatility
If F-OFDM or UFMC technology is used to achieve LTE compatibility, then out-of-band leakage is not inhibited well and demodulation performance decreases
Solution Approach 1:
The patent applies parameter changes to the time-domain signal by introducing a window function with specific mathematical properties (product of raised cosine functions). This parameter modification directly addresses the spectral leakage issue while maintaining the signal structure needed for LTE compatibility and acceptable demodulation performance.
Data Source
AI summary
Provided is a data processing method and apparatus. The method includes: performing an inverse fast Fourier transform (IFFT) on frequency-domain data of L consecutive symbols to obtain time-domain data of the L consecutive symbols, wherein the frequency-domain data of the L consecutive symbols have a subcarrier spacing of fsc, and L≥2; and modulating the time-domain data of the L consecutive symbols with a preset function, where the modulated time-domain data of the L consecutive symbols have a symbol interval of 1/f1, and f1<fsc; where a length of a value interval of an independent variable of the preset function is N/f1, and N is a real number greater than or equal to 1.