Adaptive CQI Reporting Format Selection for Wireless Systems
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Solution Overview
Problem
Current multi-rank channel quality indicator (CQI) reporting in wireless communication systems faces challenges with under-reporting or over-reporting errors due to the bounded differential reporting format, which can limit channel capacity and throughput.
Innovation Solution
A method that adjusts extreme CQI values to ensure accurate reporting within the bounded differential format, comparing performance metrics for multi-rank and single-rank CQI sets to select the optimal reporting format, and dynamically altering CQI values to reduce errors and improve throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If bounded differential reporting format is used for multi-rank CQI reporting, then the number of bits required for reporting is reduced, but under-reporting or over-reporting errors occur
Solution Approach 1:
The patent applies dynamics by making the CQI reporting format adaptive rather than fixed. The system dynamically selects between absolute reporting and bounded differential reporting based on channel conditions and CQI value characteristics. When differential reporting would cause excessive error (large CQI differences), the system switches to absolute reporting, thereby resolving the contradiction between bit efficiency and reporting accuracy.
Solution Approach 2:
The patent changes the reporting parameter format based on conditions. It introduces a reporting mode indicator that switches between absolute CQI reporting and bounded differential CQI reporting. This parameter change allows the system to optimize between bit usage and accuracy by selecting the appropriate reporting format for given channel conditions.
2Productivity
If extreme CQI values are reported using bounded differential format, then bit usage is efficient, but reporting errors increase
Solution Approach 1:
The patent applies preliminary action by checking whether extreme CQI values fall within the bounded differential range before committing to differential reporting. The system evaluates the CQI difference between layers in advance and determines the appropriate reporting format beforehand, preventing excessive error from occurring in the first place.
Solution Approach 2:
The patent implements feedback through the reporting mode indicator that provides information about the selected reporting format. The base station uses this feedback to correctly interpret the CQI values, and the system can adapt future reporting based on the performance and channel conditions observed from previous reports.
3Reliability
If bounded differential reporting is used, then channel capacity utilization is limited due to errors, but changing to absolute reporting increases bit requirements
Solution Approach 1:
The system dynamically adapts the reporting format to channel conditions, switching between absolute and bounded differential reporting based on the actual CQI values and their differences. This dynamic approach ensures reliable channel capacity utilization by selecting the format that minimizes error for given conditions while maintaining reporting precision.
Data Source
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AI summary
A communication device is arranged to operate in a cellular communication system and report Channel State Information, CSI, including a channel quality by a Channel Quality Indicator, CQI, which reports a CQI set. The communication device comprises a receiver arranged to receive antenna-specific reference signals, a channel estimator arranged to evaluate channel conditions from the reference signals to determine values of a CQI set, a reporting processor arranged to determine whether a bounded differential reporting format prevents values of the CQI set to be accurately reported, and to determine a CQI set such that the bounded differential reporting format allows the values of the CQI set to be reported to reduce under-reporting or over-reporting errors that arise from the use of the bounded differential reporting format, and to form a CSI report including the values of the CQI set using the bounded differential reporting format, and a transmitter arranged to send the CSI report. A method and computer program for implementing the method are also disclosed.