LTE Link Adaptation via RSRP Difference Reporting
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Solution Overview
Problem
In LTE systems, existing link adaptation methods require terminals to measure and report additional channel quality indicators (CQI), increasing system overhead and complexity, as they need to determine modulation and coding schemes based on downlink channel quality feedback.
Innovation Solution
A method where terminals calculate differences between the reference signal received power (RSRP) of their home service cell and adjacent cells, reporting the maximum difference to the base station, which then determines the modulation and coding scheme (MCS) and corresponding code rate using a pre-established correspondence relation table, and adjusts transmit power to optimize channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminals measure and report additional CQI for link adaptation, then the reliability of communications and system throughput is improved, but the system overhead and complexity increase
Solution Approach 1:
The patent combines CQI reporting with existing periodic feedback mechanisms (PMI and RI) that terminals already transmit to base stations. By merging these feedback types into a single uplink transmission, the patent achieves reliable channel quality information delivery without requiring separate dedicated CQI reporting channels, thus improving communication reliability while avoiding additional system overhead
Solution Approach 2:
The patent makes the uplink feedback mechanism universal by using a single feedback transmission that carries multiple types of information (CQI, PMI, and RI) simultaneously. This multi-functional approach allows the system to obtain all necessary channel state information through one reporting mechanism, eliminating the need for separate CQI reporting procedures and reducing overall system complexity
2Device complexity
If terminals report CQI feedback in combination with other uplink feedbacks, then the system overhead is reduced, but the feedback complexity increases
Solution Approach 1:
The patent segments the feedback information into distinct components (CQI, PMI, RI) that are organized and transmitted together in a structured format. This segmentation allows the base station to easily parse and process each component separately, reducing the difficulty of detecting and measuring individual feedback parameters while maintaining reduced system overhead through combined transmission
Solution Approach 2:
The patent introduces a standardized feedback message structure that acts as an intermediary between the terminal's multiple feedback parameters and the base station's processing requirements. This intermediate format organizes CQI, PMI, and RI in a unified manner, simplifying the detection and measurement process at the base station while maintaining the benefits of combined feedback transmission
3Measurement precision
If the base station determines MCS based on CQI lookup table, then the link adaptation accuracy is improved, but the processing time and complexity increase
Solution Approach 1:
The patent pre-establishes the correspondence relation table that maps RSRP differences to specific MCS values and code rates. By performing this mapping relationship setup in advance, the base station eliminates the need for real-time CQI measurement and table lookup during active communication, thereby maintaining accurate MCS determination while significantly reducing processing time and computational complexity
4Measurement precision
If terminals perform additional CQI measurement, then the channel quality information accuracy is improved, but the energy consumption and overhead increase
Solution Approach 1:
The patent enables terminals to utilize their existing RSRP measurement capabilities to derive channel quality information without requiring separate CQI measurement functions. By making the terminal self-sufficient with its existing measurement tools, the patent achieves accurate channel quality assessment while avoiding the additional energy consumption associated with dedicated CQI measurement procedures
Data Source
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AI summary
The present invention discloses a link adaptation method, a base station and a terminal in a LTE system, wherein the method comprises: a terminal respectively calculating differences between a measured reference signal received power (RSRP) of a home service cell and the RSRPs of multiple adjacent cells; the terminal reporting the maximum difference in the differences to a base station; and the base station determining a modulation and coding scheme (MCS) for the terminal according to the maximum difference. The present invention does not introduce new overhead of the system, simplifies the flow of the AMC, and therefore improves the frequency spectrum efficiency of the system.