Channel Quality Feedback Using Differential Sub-Channel WQI
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Solution Overview
Problem
In high-bandwidth optical communication scenarios with significant frequency selective fading, existing methods for feeding back channel quality information face challenges in ensuring precision while minimizing feedback overheads, as the variations in sub-channel quality indicators (WQIs) are large and require extensive bit usage.
Innovation Solution
A method where a terminal device sends a first data packet with originally measured channel quality information for N sub-channels, followed by a second data packet containing differences in channel quality information measured in a later time unit, reducing the overall bit count by encoding and indicating the differences, thus ensuring precision without normalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal device feeds back the actually measured WQI to the network device, then the precision of the fed-back WQI is ensured, but the overheads in the feedback process are high
Solution Approach 1:
The patent extracts only the essential information needed for channel quality feedback by using differential encoding. Instead of transmitting the complete WQI values, it transmits only the difference between current and historical WQI values, thereby reducing feedback overhead while maintaining measurement precision.
Solution Approach 2:
The patent changes the parameter representation from absolute WQI values to differential values (changes in WQI). This parameter transformation reduces the number of bits required for feedback while preserving the precision of channel quality information through selective differential encoding.
2Ease of operation
If the WQI fed back by the terminal device to the network device is normalized from 0x00 to 0xff, then the feedback process is simplified, but it is difficult to ensure precision of the fed-back WQI in scenarios with high bandwidth and significant channel frequency selective fading
Solution Approach 1:
The patent introduces dynamic adaptive encoding where the encoding method switches between differential encoding and absolute value encoding based on channel conditions. This dynamic approach maintains precision in high-bandwidth scenarios while preserving operational simplicity through adaptive selection of encoding strategies.
Solution Approach 2:
The patent performs preliminary encoding decisions by comparing the magnitude of WQI changes against thresholds before transmission. This preliminary action determines whether differential or absolute encoding should be used, ensuring precision is maintained while keeping the feedback process manageable through pre-planned encoding strategies.
3Loss of information
If the terminal device feeds back WQIs of all eight sub-channels with 8 bits each, then complete channel quality information is provided, but the feedback overhead becomes excessively high
Solution Approach 1:
The patent segments the feedback information by sub-channel and applies selective differential encoding to each sub-channel's WQI. This segmentation allows the system to maintain complete channel quality information across all sub-channels while reducing overall feedback overhead through targeted encoding of only the necessary differential values.
Data Source
AI summary
This application provides a method for feeding back channel quality information and an apparatus, to reduce feedback overheads of the channel quality information. The method includes: A terminal device sends first indication information and M pieces of first channel quality information that correspond to N sub-channels and that are measured in a first time unit to a network device; and the terminal device sends second indication information and L pieces of third channel quality information that correspond to the N sub-channels and that are measured in a second time unit to the network device, where third channel quality information of a first sub-channel in the N sub-channels indicates a difference between second channel quality information of the first sub-channel and first channel quality information of the first sub-channel.