Adaptive Sampling Frequency Control for Multipath Receivers
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Solution Overview
Problem
Existing digital communication receivers face significant performance degradation in strong multipath environments, particularly in terrestrial digital broadcasting systems, due to the inability to effectively manage changing multipath conditions, leading to carrier phase offsets and disruptions in information flow.
Innovation Solution
A method and apparatus for controlling the sampling frequency of a sampling device by estimating the channel impulse response and calculating its characteristics, allowing for precise determination of the sampling frequency to improve symbol timing recovery and reduce intersymbol interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed sampling frequency is used in digital communication receivers, then device complexity is reduced, but receiver performance degrades in strong multipath environments due to inability to adapt to changing channel conditions
Solution Approach 1:
The patent implements dynamic sampling frequency adjustment by estimating channel impulse response characteristics and adapting the sampling frequency accordingly. The system transitions from fixed to variable sampling frequency based on multipath delay spread conditions, allowing the receiver to adapt to changing channel environments while maintaining performance.
Solution Approach 2:
The patent changes the sampling frequency parameter based on estimated channel characteristics. By calculating the multipath delay spread from channel impulse response and adjusting the sampling frequency to satisfy the Nyquist criterion under varying conditions, the system maintains reliable operation without requiring complex structural modifications.
2Measurement precision
If sampling frequency is increased to capture rapid channel changes, then measurement precision of channel conditions improves, but loss of information increases due to intersymbol interference from improper timing
Solution Approach 1:
The patent employs feedback mechanisms where the receiver estimates channel impulse response, calculates multipath delay spread, and uses this information to adjust sampling frequency. This closed-loop approach ensures sampling timing remains synchronized with channel conditions, preventing intersymbol interference while accurately capturing channel variations.
Solution Approach 2:
The patent performs preliminary channel impulse response estimation and multipath delay spread calculation before setting the sampling frequency. By determining appropriate sampling parameters in advance based on channel characteristics, the system avoids information loss from improper timing while maintaining precise channel condition detection.
Data Source
AI summary
A method of controlling sampling frequency of a sampling device (40), where the sampling device (40) generates samples (62) in response to the receipt of a signal (20) resulting from a transmission of a series of symbols through a channel, the method including the steps of estimating (46) a channel impulse response of the channel from the samples, calculating a characteristic of the channel impulse response estimate, and determining (52) the sampling frequency in accordance with the characteristic.