OFDM Receiver Interference Cancellation for Synchronization Stability
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Solution Overview
Problem
Conventional OFDM receivers face instability in reception operations due to narrow-band interference waves, which affect synchronization processes and lead to errors, especially when the amplitude and phase of the interference wave vary over time.
Innovation Solution
An OFDM receiver with an interference wave cancel unit that cancels narrow-band interference components from the input signal, delays the canceled signal by the useful symbol period, and calculates a correlation between the cancel signal and the delayed signal to perform synchronization processing, thereby reducing interference-related errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correlation-based synchronization is used in conventional OFDM receivers, then frequency and symbol synchronization can be achieved, but reception stability deteriorates when narrow-band interference waves are present
Solution Approach 1:
The patent extracts and removes the narrow-band interference wave component from the received OFDM signal before performing correlation-based synchronization. By separating the interference component and subtracting it from the original signal, the synchronization process operates on a cleaned signal free from interference contamination, thus maintaining both accuracy and stability.
Solution Approach 2:
The patent segments the signal processing into distinct stages: interference wave cancellation followed by synchronization processing. This segmentation allows each stage to be optimized independently - the first stage focuses on removing interference while the second stage performs correlation-based synchronization on the purified signal.
2Measurement precision
If narrow-band interference wave component is present in the correlation calculation, then the correlation signal is contaminated, but adding interference cancellation processing increases device complexity
Solution Approach 1:
The patent introduces an interference wave cancel unit as an intermediary component between the signal reception and correlation-based synchronization stages. This mediator processes the received signal to remove interference components before the signal reaches the synchronization unit, ensuring high correlation signal quality while maintaining a clear and organized receiver structure.
3Device complexity
If conventional correlation-based synchronization is used, then the receiver structure remains simple, but synchronization errors occur when interference wave amplitude and phase vary over time
Solution Approach 1:
The patent performs preliminary interference wave cancellation before the correlation-based synchronization operation. By removing the time-varying interference components in advance, the subsequent synchronization process operates on a stable, interference-free signal, ensuring accurate synchronization even when interference characteristics change over time.
Data Source
AI summary
An OFDM receiver receives an OFDM signal. The OFDM signal is composed of a useful symbol period for transmitting a signal relating to data and a guard interval period for transmitting a signal that is the same as part of the signal transmitted in the useful symbol period. An interference wave cancel circuit cancels a narrow-band interference wave component relating to a narrow-band interference wave from the OFDM signal, and outputs the OFDM signal from which the narrow-band interference wave component has been canceled, as a cancel signal. The correlation detection circuit calculates a correlation between a cancel signal output from the interference wave cancel circuit and a cancel signal which has been delayed by the useful symbol period delay circuit by the useful symbol period.