OFDM Signal Processing Device Narrow-Band Noise Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing OFDM receivers face increased bit error rate (BER) deterioration when narrow-band noise (NBN) enters the communication band, as current window function preprocessing methods either fail to sufficiently suppress interfering waves or exacerbate the issue depending on the relationship between NBN frequency and subcarrier frequency.
Innovation Solution
A signal processing device that detects the coincidence between NBN frequency and subcarrier frequency, deciding whether to perform a window function process before FFT, thereby optimizing the preprocessing to reduce the influence of interfering waves and maintain BER integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a window function process is performed as preprocessing before FFT to suppress leakage error, then the leakage error is reduced, but the bit error rate deteriorates when narrow-band noise frequency coincides with subcarrier frequency
Solution Approach 1:
The patent applies dynamics by making the window function process conditional rather than fixed. The signal processing device dynamically adjusts whether to apply the window function based on the detected relationship between NBN frequency and subcarrier frequency. When frequencies coincide, the window function is skipped; when they don't coincide, the window function is applied. This dynamic adaptation resolves the contradiction by optimizing performance for different frequency conditions.
Solution Approach 2:
The patent changes the parameter of window function application from a constant setting to a variable condition based on frequency coincidence detection. By detecting whether NBN frequency coincides with subcarrier frequency and adjusting the window function process accordingly, the system optimizes both leakage error suppression and BER performance under different operating conditions.
2Reliability
If no window function process is performed to avoid BER deterioration, then bit error rate is maintained, but leakage error increases
Solution Approach 1:
The system dynamically selects between applying or skipping the window function based on frequency coincidence detection. This dynamic approach allows the system to optimize for BER when frequencies coincide and for leakage error suppression when they don't coincide, resolving the contradiction through adaptive processing.
Solution Approach 2:
The patent changes the processing parameter from a fixed 'no window function' mode to a conditional mode where the window function application is adjusted based on detected frequency relationships. This parameter change enables the system to achieve both low BER and low leakage error under different operating conditions.
3Measurement precision
If existing window function preprocessing is applied uniformly, then leakage error is suppressed, but the system fails to adapt to different NBN frequency conditions
Solution Approach 1:
The patent introduces dynamics by making the window function process adaptive rather than uniform. The system detects the frequency relationship between NBN and subcarriers and adjusts processing accordingly, enabling adaptation to different frequency conditions while maintaining leakage error suppression where beneficial.
Solution Approach 2:
The system changes from a fixed window function parameter setting to a variable setting based on detected frequency conditions. This allows the processing parameters to be optimized for each specific operating condition, achieving both leakage error suppression and adaptability to different NBN scenarios.
Data Source
AI summary
Disclosed is a signal processing device that reduces the influence of an interfering wave to suppress the deterioration of a BER even if narrow-band noise is included in a communication band. In the signal processing device, which is capable of performing an FFT and performing a window function process as preprocessing before the FFT and achieves OFDM demodulation, the window function process is skipped to perform an FFT on a received signal if the frequency of narrow-band noise included in the received signal coincides with the subcarrier frequency of OFDM within a predetermined range. If the frequencies do not coincide with each other, the FFT is performed after the window function process is performed on the received signal. The signal processing device includes an NBN detection/determination section, which determines whether narrow-band noise is included in a subcarrier, and a window function determination section, which determines, in accordance with the degree of coincidence between the frequency of narrow-band noise and the frequency of a subcarrier, whether or not to perform the window function process.