Adaptive CQI Subband Grouping for Channel Information Reduction
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Solution Overview
Problem
In mobile communication systems, the existing methods for generating channel quality indicators (CQI) are inefficient due to the large size of control information required, especially in MIMO systems and multi-carrier systems like OFDM, where abrupt channel variations and multiple subcarriers lead to increased channel information size.
Innovation Solution
A method that groups subcarriers into channel quality indicator subbands, with each subband's size dependent on the system bandwidth, allowing for selective reporting of CQI values, reducing the overall size of channel information transmitted by using compression schemes like DCT and selective reporting based on channel quality, and predicting future frequency band allocation for optimal resource management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel information is carried by each subcarrier in a multi-carrier system, then channel information accuracy is improved, but the size of channel information is abruptly raised
Solution Approach 1:
The patent segments the frequency band into multiple subbands, with each subband containing multiple subcarriers. Instead of carrying channel information for each individual subcarrier, the system carries channel information at the subband level. This segmentation approach maintains sufficient channel information accuracy for link adaptation while dramatically reducing the total size of channel information that needs to be transmitted and processed.
2Measurement precision
If multiple CQIs are reported in a MIMO system, then channel status accuracy is improved, but the size of control information is proportionally increased
Solution Approach 1:
The patent merges the channel information from multiple subcarriers within each subband into a single representative CQI value. By combining the channel characteristics of multiple subcarriers into one subband-level CQI, the system maintains accurate channel status information needed for MIMO operations while reducing the number of separate CQI reports required, thus decreasing control information size.
3Productivity
If the system bandwidth exceeds the coherence bandwidth, then system capacity is improved, but abrupt channel variation appears within the system bandwidth
Solution Approach 1:
The patent applies local quality by making the channel information representation adaptive to local channel conditions within different subbands. Each subband can have its own CQI value that reflects the local channel characteristics, allowing the system to handle abrupt channel variations within the overall bandwidth while maintaining high system capacity. This local adaptation enables accurate link adaptation even when the total bandwidth exceeds the coherence bandwidth.
Data Source
AI summary
A method for generating a channel quality indicator (CQI) in a mobile communication system is presented. The method includes grouping a number of subcarriers to form at least one channel quality indicator subband for generating a channel quality indicator, and generating a channel quality indicator in each channel quality indicator subband, wherein a size of each channel quality indicator subband is dependent on a system bandwidth value and is an integer multiple of a downlink frequency resource unit size, wherein the downlink frequency resource unit size is prescribed according to the system bandwidth value.