Reduced-Size IFFT Channel Estimation for OFDM Systems
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Solution Overview
Problem
Existing OFDM channel estimation methods require large-scale IFFT calculations, leading to inefficiency and increased circuit costs due to non-zero values only at pilot sub-carriers, necessitating a reduction in sampling points without compromising channel estimating efficiency.
Innovation Solution
A channel estimating apparatus and method that perform IFFT with a second number of sampling points on preliminary estimated frequency-domain channel responses, followed by windowing and smoothing to generate time-domain channel impulse responses, and then FFT with the first number of sampling points to produce frequency-domain responses, effectively reducing the scale of IFFT calculations while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large-scale IFFT calculations are performed on preliminary estimated frequency-domain channel responses, then complete channel estimation coverage is achieved, but computational complexity and circuit costs increase
Solution Approach 1:
The patent extracts only the necessary components for channel estimation by performing IFFT with a reduced number of sampling points (second number) instead of processing all frequency-domain responses. This extraction approach maintains the essential channel information while eliminating redundant calculations, directly resolving the contradiction between estimation accuracy and computational complexity
Solution Approach 2:
The patent changes the sampling point parameter of the IFFT operation from the first number (full scale) to the second number (reduced scale). This parameter modification allows the system to achieve adequate channel estimation with fewer computational resources, effectively balancing accuracy requirements with device complexity constraints
2Productivity
If reduced sampling points are used in IFFT, then computational complexity decreases, but channel estimation efficiency may be compromised
Solution Approach 1:
The patent introduces an intermediary approach by using a reduced set of sampling points as a mediator between the full frequency-domain responses and the final channel estimation. This intermediary selection maintains the critical channel information needed for accurate estimation while reducing the computational burden, thus improving productivity without sacrificing measurement precision
Solution Approach 2:
The patent performs preliminary selection of sampling points before executing the full IFFT calculation. By pre-identifying the essential sampling points that contain the most critical channel information, the system can proceed with reduced-scale IFFT operations that maintain estimation accuracy while significantly improving computational efficiency
Data Source
AI summary
A channel estimating technique is applied to an Orthogonal Frequency-Division Multiplexing (OFDM) communication system which receives a plurality of OFDM symbols. In one aspect, a channel estimating method includes performing Inverse Fast Fourier Transform (IFFT) with a second number of sampling points and a phase shift on each of preliminarily estimated frequency-domain channel responses including a first number of response values corresponding to each of the OFDM symbols, so as to obtain a first time-domain channel impulse response corresponding to each of the OFDM symbols, where the first number is lager than the second number. The method also generates a plurality of frequency-domain channel responses corresponding to the OFDM symbols according to the time-domain channel impulse responses.