Channel Equalization Using Zero-Padded Time Domain Signal Search
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Solution Overview
Problem
Current radio receivers face challenges in accurately estimating the channel response for Digital Radio Mondiale (DRM) signals, particularly in handling multipath delay spreads that exceed half the length of the transformed time domain signal, which affects the interpolation of channel response information.
Innovation Solution
A method and apparatus that transform a frequency domain signal into a time domain signal, search for the location of minimum energy, and pad the signal with zeroes at that location before transforming it back into a frequency domain signal to estimate the channel response, allowing for accurate channel equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional channel response estimation methods are used, then the process is simple, but the estimation accuracy deteriorates when multipath delay spreads exceed half the length of the transformed time domain signal
Solution Approach 1:
The patent applies preliminary action by zero-padding the time-domain signal before performing the inverse Fourier transform. This preparatory step extends the signal length to accommodate multipath delay spreads that would otherwise cause estimation errors, allowing accurate channel response estimation even in challenging propagation conditions.
Solution Approach 2:
The patent transforms the problem from the frequency domain to the time domain through Fourier transformation, performs zero-padding in the time domain (adding a temporal dimension), and then transforms back to the frequency domain. This dimensional transition allows the system to handle extended delay spreads that cannot be accommodated in the original signal length.
2Reliability
If the signal length is increased to handle larger multipath delay spreads, then the robustness improves, but the processing time and computational load increase
Solution Approach 1:
The zero-padding operation is performed as a preliminary step before the inverse Fourier transform, efficiently extending the signal to accommodate multipath delays. This approach achieves robustness against varying delay spreads without requiring significantly increased processing time, as the padding operation itself is computationally inexpensive.
Data Source
AI summary
A method of estimating a channel response of a channel is provided that includes transforming a frequency domain signal received via the channel into a time domain signal and searching the time domain signal for a location of minimum energy. The method also includes padding the time domain signal with zeroes at the location of minimum energy and transforming the padded time domain signal to a second frequency domain signal. The second frequency domain signal is used as an estimated channel response for the channel.