Frequency-to-Time Conversion Circuit With Split-Sample Phase Rotation
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Solution Overview
Problem
Current systems face limitations in the update rate of impairment estimation and correction due to the complexity of frequency-to-time domain conversion, which is inefficient and time-consuming, especially when converting error estimates from the frequency domain to the time domain for signal correction.
Innovation Solution
The proposed solution involves a method and circuit for frequency-to-time domain conversion that simplifies the process by generating subsets of samples, applying linear phase rotations, and using shared post-processing to reduce complexity and memory accesses, thereby reducing the number of time domain samples needed for correction, and utilizing a single coefficient fetch per tap pair to enhance processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard frequency-to-time domain conversion process is used, then accurate error correction can be achieved, but the conversion complexity and processing time increase significantly
Solution Approach 1:
The frequency domain samples are divided into two subsets: even-indexed samples and odd-indexed samples. This segmentation allows the conversion process to handle each subset separately with simplified processing, reducing overall complexity while maintaining accuracy. The even samples are processed to generate certain time domain coefficients, while odd samples generate complementary coefficients.
Solution Approach 2:
The patent combines the processing of even and odd frequency domain samples through a unified mathematical framework. By expressing both subsets using the same base equations with different index substitutions, the circuit can share common computational resources and processing paths, reducing hardware complexity while preserving the complete frequency-to-time domain conversion accuracy.
2Reliability
If a standard frequency-to-time domain conversion process is used, then complete error correction can be achieved, but the update rate decreases due to processing time
Solution Approach 1:
By segmenting the frequency domain samples into even and odd subsets, the patent enables parallel or pipelined processing of different coefficient groups. This segmentation reduces the sequential processing burden and allows faster generation of time domain filter coefficients, thereby increasing the update rate while maintaining complete error correction capability.
Solution Approach 2:
The patent transforms the conversion equations by changing the parameter representation - using index substitution (k to k+N/2) to express relationships between even and odd sample processing. This parameter transformation reveals computational redundancies that can be eliminated, speeding up the conversion process and increasing the update rate without sacrificing correction completeness.
3Measurement precision
If complex multipliers are used for frequency-to-time domain conversion, then accurate conversion is achieved, but the circuit complexity and resource requirements increase
Solution Approach 1:
The patent changes the mathematical parameters of the conversion equations by re-indexing and re-grouping terms. This transformation converts operations that would require complex multipliers into operations using only real multipliers, reducing the quantity and complexity of circuit resources needed while preserving conversion accuracy through equivalent mathematical relationships.
Data Source
AI summary
A method for frequency domain to time domain conversion includes receiving a set of frequency-domain samples. Based on the set of frequency-domain samples, a first sample subset comprising a predetermined fraction of the number of samples of the set of frequency-domain samples and a second sample subset comprising the predetermined fraction of the number of samples of the set of frequency-domain samples are generated. A linear phase rotation is applied to the first sample subset and the second sample subset to produce a phase rotated first sample subset and a phase rotated second sample subset. The phase rotated first sample set is post-processed to generate a first set of time-domain samples. The phase rotated second sample set is post-processed to generate a second set of time-domain samples. The first set of time-domain samples and the second set of time-domain samples are reordered to produce an output set of time-domain samples.