Decoder Noise Power Estimation in OFDM Systems
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Solution Overview
Problem
Conventional systems for determining decoder noise power estimates in wireless transmission systems are ineffective when decoder noise power is not equal or similar to channel noise power, particularly due to negligible channel estimation error, which is common in recent wireless transmission systems.
Innovation Solution
The system computes decoder noise power estimates by receiving a pilot signal through a fading channel, calculating signal power, channel noise power, and channel estimation error, and selecting the estimate with the smallest deviation from measured decoder noise power using multiple channel estimation filters in different domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FIR filtering is used to determine decoder noise power estimate, then the estimation is simple and effective when decoder noise power equals channel noise power, but the estimation becomes inaccurate when channel estimation error is significant
Solution Approach 1:
The patent changes the parameters used in noise power estimation by introducing channel estimation error as an additional factor. Instead of using only channel noise power (as in conventional FIR filtering), the method combines channel noise power with channel estimation error to compute a more accurate decoder noise power estimate, thereby resolving the inaccuracy caused by neglecting estimation error
Solution Approach 2:
The patent introduces channel estimation error as an intermediary element in the estimation process. By computing the channel estimation error separately and incorporating it into the noise power calculation, the method mediates between the simple FIR filtering approach and the complex reality of significant estimation errors, achieving accurate decoding without requiring overly complex processing
2Reliability
If channel estimation error is neglected in the estimation process, then the estimation method remains simple, but the accuracy deteriorates when channel estimation error is not negligible
Solution Approach 1:
The patent implements feedback by computing the channel estimation error based on the received pilot signal and comparing it with the decoded data. This feedback mechanism allows the system to adapt the noise power estimation according to the actual channel conditions, improving decoding reliability while maintaining manageable complexity through iterative refinement
3Measurement precision
If multiple channel estimation filters are used to compute multiple estimates, then the accuracy of decoder noise power estimate improves, but the computational complexity increases
Solution Approach 1:
The patent segments the estimation process by using multiple channel estimation filters (e.g., time-domain filter, frequency-domain filter, and time-frequency-domain filter) to compute multiple separate noise power estimates. Each filter processes the pilot signal independently, allowing parallel computation and improving accuracy through comparison of multiple estimates while managing computational load through selective filtering
Data Source
AI summary
Systems and methods for computing a decoder noise power estimate are provided. A pilot signal transmitted through a fading channel from a wireless transmission source is received. Signal power of the received pilot signal, channel noise power, and channel estimation error are computed. The decoder noise power estimate is determined based on the computed signal power, channel noise power, and channel estimation error.