MU-MIMO Terminal Feedback Weight Selection
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Solution Overview
Problem
In MU-MIMO, the challenge lies in selecting multiple users for spatial multiplexing, as interference between down-link transmissions is unpredictable and difficult to manage with existing feedback methods like Implicit Feedback, which lacks flexibility in pairing due to limited feedback options.
Innovation Solution
A terminal apparatus with an estimation unit to determine channel conditions using reference signals, a selection unit to choose optimal transmission weights, and a feedback controller to dynamically feed back these weights to the base station, allowing for flexible pairing and interference minimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Implicit Feedback method is used in SU-MIMO, then feedback complexity is reduced, but pairing flexibility is insufficient for MU-MIMO
Solution Approach 1:
The patent applies dynamics by transitioning from a static feedback approach (single transmission weight index in SU-MIMO) to a dynamic feedback mechanism where multiple transmission weight indices are fed back based on channel conditions. The terminal device determines a plurality of transmission weight indices corresponding to different spatial multiplexing scenarios, enabling the system to adapt flexibly to varying channel states and user pairing requirements in MU-MIMO.
Solution Approach 2:
The patent segments the feedback information into multiple transmission weight indices instead of providing a single index. Each index corresponds to a specific transmission weight suitable for different spatial multiplexing configurations. This segmentation allows the base station to select appropriate transmission weights for different user pairs, achieving flexible pairing while maintaining manageable feedback complexity through structured information organization.
2Loss of information
If single transmission weight is fed back, then feedback overhead is reduced, but interference suppression capability is insufficient
Solution Approach 1:
The patent applies preliminary action by having the terminal device pre-calculate and feed back multiple transmission weight indices that correspond to different spatial multiplexing scenarios before actual data transmission. The base station uses these pre-prepared indices to quickly determine appropriate transmission weights for different user pairs, enabling proactive interference suppression without increasing real-time feedback overhead significantly.
Solution Approach 2:
The patent enhances the feedback mechanism by introducing multiple transmission weight indices instead of a single index. This enriched feedback provides the base station with more options to select transmission weights that minimize interference between spatially multiplexed users. The feedback structure is designed to provide comprehensive information while controlling overhead through efficient indexing and selection strategies.
3Productivity
If multiple users are spatially multiplexed, then communication throughput is improved, but interference between transmissions increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting transmission weight parameters based on channel conditions and user pairing requirements. The terminal device determines multiple transmission weight indices corresponding to different spatial multiplexing configurations, and the base station selects appropriate weights to maximize throughput while minimizing interference. This parameter optimization enables the system to achieve high throughput in MU-MIMO while controlling interference through adaptive weight selection.
Data Source
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AI summary
Provided is a terminal apparatus including an estimation unit that estimates a channel to a base station by using a reference signal transmitted from the base station, a selection unit that selects a transmission weight desirable for second down-link transmission from the base station to another terminal apparatus spatially multiplexed with first down-link transmission on the channel from a plurality of transmission weight candidates in accordance with an estimation result by the estimation unit, and a feedback controller that controls feedback of the transmission weight selected by the selection unit to the base station.