Modulation Coding Rate Selection in MU-MIMO Systems
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Solution Overview
Problem
In multi-user MIMO communication systems, mobile devices face challenges in determining the optimal modulation and coding rate due to uncertainty about interferers sharing the same time/frequency resources, making it difficult to match channel quality and adjust transmission parameters effectively.
Innovation Solution
A method where mobile nodes calculate and determine the best modulation and coding rate by selecting a codebook choice, determining possible interferers, and computing antenna weights for both themselves and potential interferers, using these weights to determine an optimal modulation and coding rate before resource assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mobile devices use traditional feedback mechanisms to determine modulation and coding rate, then channel quality information can be obtained, but the accuracy of MCR selection deteriorates due to uncertainty about interferers sharing the same time-frequency resources
Solution Approach 1:
The patent applies preliminary action by having mobile devices calculate and report multiple CQI values corresponding to different potential interferer scenarios before the actual resource assignment occurs. This allows the base station to select the appropriate CQI/MCR combination based on the actual interferers present, thereby resolving the contradiction between measurement accuracy and selection reliability under MU-MIMO conditions.
2Device complexity
If mobile devices calculate MCR without considering potential interferers, then the calculation process is simple, but the communication efficiency deteriorates due to mismatched channel quality and transmission parameters
Solution Approach 1:
The patent applies segmentation by dividing the CQI feedback into multiple segments, each corresponding to a different potential interferer scenario. Instead of calculating a single MCR value, the mobile device calculates multiple CQI values for different interferer combinations, allowing the base station to select the most appropriate one. This segmented approach increases accuracy without requiring the mobile device to perform overly complex real-time calculations.
3Productivity
If multiple users share the same time-frequency resource in MU-MIMO, then system capacity increases, but the difficulty of determining accurate MCR increases due to unknown interferers
Solution Approach 1:
The patent resolves this contradiction by performing preliminary calculations of multiple CQI values before resource assignment. The mobile device pre-calculates channel quality metrics for various potential interferer scenarios, enabling accurate MCR determination even in MU-MIMO environments where multiple users share resources. This approach maintains high system capacity while reducing the actual determination difficulty at the time of resource allocation.
Data Source
AI summary
A method and apparatus for choosing a modulation and coding rate in a MU-MIMO communication system is provided herein. During operation, a node will determine the MCR to feed back to the base even though the mobile does not know which of the possible interferers (if any) will be using the same time/frequency resources as the mobile. This takes place via the mobile node calculating best antenna weights (codebook choice) for each group of subcarriers that can be potentially used by the mobile. Transmit weights v for each interferer are then determined and the weights are utilized to determine a best modulation and coding rate for the mobile.