Reference Signal Repetition for Channel Estimation Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, the non-orthogonality of subcarriers with different OFDM symbol lengths leads to significant degradation of channel estimation accuracy, especially when spatial filtering is applied, as it causes interference and affects the efficiency of channel estimation.
Innovation Solution
The proposed solution involves a base station and terminal apparatus configuration where the number of repetitions of a reference signal is adjusted based on downlink control information, allowing the terminal apparatus to map and transmit data and reference signals in a way that maintains orthogonality, even with different OFDM symbol lengths, thereby enhancing channel estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If signals with different OFDM symbol lengths are multiplexed in the frequency domain, then frequency utilization efficiency is improved through FDM, but orthogonality between subcarriers is lost causing interference and degradation of channel estimation accuracy
Solution Approach 1:
The patent segments the frequency spectrum into distinct resource blocks allocated to different terminal apparatuses with different OFDM symbol lengths. By dividing the frequency resources and assigning them to specific terminals, the system maintains orthogonality within each segment while allowing different symbol lengths, thus resolving the contradiction between frequency utilization and channel estimation accuracy.
Solution Approach 2:
The patent applies local quality by configuring resource blocks with specific subcarrier spacing and OFDM symbol length characteristics tailored to individual terminal apparatuses. Each terminal receives localized frequency resources optimized for its specific requirements, allowing different OFDM configurations coexist without mutual interference, thereby maintaining both high frequency utilization and accurate channel estimation.
2Productivity
If MU-MIMO is applied to allow multiple terminal apparatuses to share identical time/frequency resources, then frequency utilization efficiency is improved, but channel estimation accuracy deteriorates due to non-orthogonal pilots from different OFDM symbol lengths
Solution Approach 1:
The patent segments frequency resources into dedicated resource blocks for each terminal apparatus participating in MU-MIMO. By allocating specific frequency segments to each terminal, the system enables multiple terminals to share time/frequency resources while maintaining orthogonal pilot signals, thus achieving both improved frequency utilization and preserved channel estimation accuracy.
Solution Approach 2:
The patent changes key parameters including subcarrier spacing and OFDM symbol length for different terminal apparatuses within the MU-MIMO framework. By adjusting these parameters and allocating them to specific resource blocks, the system maintains pilot orthogonality while enabling efficient resource sharing, resolving the contradiction between MU-MIMO performance and channel estimation accuracy.
Data Source
AI summary
A terminal apparatus using large FFT points transmits a reference signal such that short OFDM symbols are repeated.