Receiver Channel Equalization for Time-Varying Doppler Effects
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Solution Overview
Problem
Receivers face challenges in effectively removing channel effects, such as Doppler effects, from communications signals, especially in time-varying channels, which affect signal quality and accuracy in transmission and reception systems.
Innovation Solution
The method involves generating time-varying channel response estimates in the frequency domain to remove channel effects, using techniques like least-mean-squared algorithms and Fast Fourier Transforms, and iteratively refining these estimates to achieve accurate channel equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-invariant channel equalization is used, then the equalization process is simple and computationally efficient, but it cannot effectively remove channel effects in time-varying channels
Solution Approach 1:
The patent applies dynamics by transitioning from static time-invariant channel equalization to dynamic time-varying channel equalization. The system models the channel impulse response as time-varying and updates the equalization parameters adaptively over time to track channel changes, thereby maintaining equalization effectiveness in time-varying environments while managing computational complexity through efficient algorithms.
Solution Approach 2:
The patent changes the parameter representation from fixed time-invariant channel responses to time-varying channel responses that adapt to changing channel conditions. By modeling the channel impulse response as a function of both time and delay, and updating these parameters dynamically, the system achieves effective equalization in time-varying channels while controlling complexity through structured parameter updates.
2Measurement precision
If iterative refinement of channel response estimates is performed, then measurement precision of channel effects improves, but processing time increases
Solution Approach 1:
The patent implements feedback by using the estimated channel impulse response to generate equalized signals, then using these equalized signals to refine the channel response estimates through least-mean-squared techniques. This iterative feedback process continues until convergence or a maximum number of iterations is reached, improving measurement precision while managing processing time through efficient convergence properties.
Solution Approach 2:
The patent performs preliminary channel response estimation using available pilot signals before full equalization processing. This preliminary action provides an initial channel response estimate that can be refined iteratively, reducing the total processing time by avoiding starting from scratch while still achieving high measurement precision through subsequent refinement steps.
Data Source
AI summary
Systems and techniques relating to channel equalization in received communications signals are described. In one aspect, a communications signal of a channel is obtained and channel effects are removed from the communications signal by generating one or more time-varying channel response estimates.