Multicarrier Signal Receiving Apparatus Channel Estimation
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Solution Overview
Problem
Multicarrier transmission methods using Cyclic Delay Transmit Diversity (CDTD) face channel estimation errors due to increased frequency selectivity, particularly when channel estimation symbols are not arranged for all subcarriers, degrading reception characteristics.
Innovation Solution
A multicarrier-signal receiving apparatus performs Fourier transforms on reception signals, uses a channel estimator to estimate channels based on channel estimation symbols within subcarrier groups with identical phase rotations, and applies channel compensation to data symbols, allowing for precise channel estimation and error suppression by varying phase rotation amounts among subcarrier groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cyclic Delay Transmit Diversity (CDTD) is used to increase frequency selectivity, then reception characteristics are improved, but channel estimation errors occur due to the increased frequency selectivity
Solution Approach 1:
The patent segments the frequency domain into multiple subcarrier groups, where each group is processed independently with its own phase rotation. This segmentation allows channel estimation to be performed separately for each group, reducing the impact of frequency selectivity variations within each group while maintaining the overall frequency diversity benefit of CDTD.
Solution Approach 2:
The patent applies different phase rotation amounts to different subcarrier groups based on local channel conditions. By adapting the phase rotation locally to each subcarrier group's characteristics, the system optimizes channel estimation accuracy for each group while maintaining the global frequency selectivity improvement provided by CDTD.
2Productivity
If channel estimation symbols are arranged sparsely in frequency direction, then resource efficiency is improved, but channel estimation errors increase for subcarriers without estimation symbols
Solution Approach 1:
The patent merges channel estimation information from multiple subcarrier groups by combining the phase rotation results. By merging the estimation results across groups and using the phase rotation relationships between groups, the system achieves accurate channel estimation for all subcarriers even when estimation symbols are sparsely arranged, thereby maintaining resource efficiency.
Solution Approach 2:
The patent performs preliminary phase rotation on channel estimation symbols before transmission, and the receiving apparatus performs corresponding phase compensation during channel estimation. This preliminary action allows the receiver to accurately estimate channel conditions for subcarriers without direct estimation symbols by using the phase-rotated estimation symbols from other subcarriers as reference.
Data Source
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AI summary
A multicarrier-signal receiving apparatus includes: a Fourier-transformer that performs a Fourier transform on reception signals to extract subcarriers; a channel estimator that performs channel estimation on one of the extracted subcarriers using channel estimation symbols included in a subcarrier group to which the one of the extracted subcarriers belongs, the subcarrier group including subcarriers to which an identical phase rotation is added upon transmission; and a channel compensator that performs channel compensation on data symbols included in the one of the extracted subcarriers using a result of the channel estimation performed by the channel estimator on the one of the extracted subcarriers.