Frequency-Domain Interpolator for OFDM Channel Estimation
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Solution Overview
Problem
In orthogonal frequency-division multiplexing (OFDM) systems, it is challenging to balance hardware cost and edge performance during frequency-domain interpolation, as increasing the interpolation order reduces inband and outband interference but increases hardware cost and decreases performance, while decreasing the order has the opposite effect, making it difficult to achieve low complexity and effective channel estimation, especially in systems with varying pilot intervals like DVB-T2.
Innovation Solution
A frequency-domain interpolator is introduced, comprising an edge pilot estimation unit, selection units, and a filter unit, which generates edge pilots, selects pilot groups based on a pilot interval ratio and complexity parameter, and calculates coefficient groups to estimate channels, allowing for efficient channel estimation with reduced complexity and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the order of frequency-domain interpolation is increased, then inband interference and outband interference are reduced, but hardware cost is increased and edge performance is decreased
Solution Approach 1:
The patent segments the frequency-domain interpolation process into multiple stages: first performing interpolation on a subset of subcarriers (e.g., every second subcarrier), then performing a second interpolation stage on the results. This segmentation allows the system to achieve high-order interpolation effects while maintaining low hardware complexity by breaking down the complex operation into simpler sequential steps.
Solution Approach 2:
The patent introduces a dynamic selection mechanism where the receiver can adaptively choose different interpolation orders and pilot interval ratios based on channel conditions and system requirements. This allows the system to optimize between interference reduction and hardware cost dynamically, rather than using a fixed high-order interpolation that would always increase hardware complexity.
2Object-affected harmful factors
If the order of frequency-domain interpolation is increased, then inband interference and outband interference are reduced, but edge performance is decreased
Solution Approach 1:
The patent applies different interpolation strategies to different regions of the frequency spectrum. Edge subcarriers (which are more susceptible to interference) receive enhanced interpolation treatment with higher order interpolation, while central subcarriers use lower order interpolation. This local quality approach ensures that edge performance is improved without unnecessarily increasing hardware complexity across the entire system.
Solution Approach 2:
The patent performs preliminary interpolation on a subset of subcarriers before the final interpolation stage. This preliminary action prepares the data by reducing interference in intermediate steps, allowing the final interpolation to achieve better edge performance without requiring the highest possible interpolation order, thus avoiding the hardware cost penalty.
3Quantity of substance
If the pilot interval is increased, then the amount of overhead is reduced, but channel estimation accuracy is decreased
Solution Approach 1:
The patent segments the frequency domain into multiple groups and performs interpolation independently on each group. This segmentation allows the system to use a larger pilot interval (reducing overhead) while maintaining estimation accuracy through the multi-stage interpolation process that compensates for the reduced pilot density in each segment.
Solution Approach 2:
The patent changes the interpolation order parameter dynamically based on the pilot interval. When the pilot interval is increased, the system adjusts the interpolation order and other parameters to maintain optimal channel estimation accuracy. This parameter adaptation allows the system to achieve both reduced overhead and maintained accuracy.
Data Source
AI summary
A frequency-domain interpolator for estimating a plurality of channels corresponding to a plurality of subcarriers comprises an edge pilot estimation unit, for generating a plurality of pilots according to a plurality of input pilots, a pilot interval ratio and a complexity parameter; a first selection unit, for selecting a plurality of pilot groups from the plurality of pilots according to the pilot interval ratio and the complexity parameter; a second selection unit, for generating a plurality of coefficient groups corresponding to the plurality of channels according to a channel profile and a used pilot interval, wherein each of the plurality of coefficient groups corresponds to a set of the plurality of channels; and a filter unit, for generating the plurality of channels according the plurality of pilot groups, the plurality of coefficient groups, and a relation between the plurality of pilot groups and the plurality of coefficient groups.