OFDM Receiver Interference Power Estimation
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Solution Overview
Problem
Conventional noise power calculation methods in OFDM receivers depend on the frame structure, making them unreliable for symbols without specific signals like CP signals, leading to inaccurate reliability information and degraded LDPC decoding performance.
Innovation Solution
A receiver that calculates interference power based on the number of samples exceeding a threshold during the OFDM symbol period, allowing for stable interference power estimation without relying on specific signal types, and uses this power to generate reliable demodulation data even in symbols without CP signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional noise power calculation methods using frame structure (TMCC/AC signals) are used, then noise power can be estimated for symbols with specific signals, but noise power cannot be estimated for symbols without specific signals (e.g., symbols without CP signals)
Solution Approach 1:
The patent extracts the interference detection function from the frame-structure-dependent noise power calculation method. By detecting interference waves in individual samples and counting exceeding samples, the method separates interference detection from the requirement of specific frame structures (TMCC/AC signals), enabling noise power estimation for any symbol type regardless of frame structure.
Solution Approach 2:
The received signal itself serves as the basis for interference detection without requiring external reference signals. By using the received signal samples directly and comparing them against a threshold, the method eliminates the need for separate pilot signals or frame structure elements, allowing self-sufficient noise power estimation in all symbol types.
2Reliability
If frame structure-dependent noise power calculation is used, then LDPC decoding performance can be improved for symbols with valid noise power, but decoding performance degrades for symbols without valid noise power estimation
Solution Approach 1:
The patent implements feedback by using the counted number of interference-exceeding samples to determine noise power, which then feeds into reliability information generation for LDPC decoding. This feedback mechanism ensures that symbols with high interference counts receive appropriate reliability weighting, improving decoding performance by preventing erroneous decisions based on unreliable noise power estimates.
Solution Approach 2:
The patent changes the parameter used for noise power calculation from frame-structure-dependent signals to the count of samples exceeding a threshold. This parameter transformation enables continuous noise power estimation across all symbol types, maintaining reliability information accuracy and preventing degradation in LDPC decoding performance.
3Stability of the object's composition
If average noise power in symbol direction is used, then impulse interference effect can be reduced, but accurate noise power estimation for individual symbols is lost
Solution Approach 1:
The patent segments the noise power estimation process into symbol-level measurement by counting interfering samples in each symbol. This segmentation allows individual symbol noise power to be determined without averaging across symbols, maintaining both symbol-level precision and overall reception stability through subsequent processing that considers the distributed noise power measurements.
Data Source
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AI summary
A receiver (10) includes a demodulator that demodulates a modulation wave modulated according to orthogonal frequency division multiplexing (OFDM). The demodulator (11) includes an interference wave detector (102) that detects that received modulation wave includes interference wave when received power of each sample of the received modulation wave exceeds a threshold, and upon the detection, executes replacement processing of replacing a received signal exceeding the threshold with a predetermined value, a first interference wave power estimation unit (104) configured to estimate interference wave power included in an OFDM symbol included in the received modulation wave on the basis of the number of samples that have been subjected to the replacement processing, and a demodulated data generator (12) that demodulates the received modulation wave by executing demodulation processing of demodulating the received modulation wave that has been subjected to the replacement processing on the basis of the interference wave power.