MU-MIMO Terminal Feedback Weight Selection for Interference Reduction
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Solution Overview
Problem
In MU-MIMO, selecting suitable transmission weights for spatial multiplexing is challenging due to unpredictable interference, and existing feedback methods like Implicit Feedback lack flexibility in pairing, making it difficult to minimize interference between users.
Innovation Solution
A terminal apparatus with an estimation unit and a feedback controller that selects and feeds back multiple transmission weights to the base station based on channel estimation, allowing for flexible pairing and interference reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only one transmission weight is fed back from the mobile station (Implicit Feedback method), then the feedback system is simple, but the degree of freedom of pairing is limited and flexible pairing that suppresses interference cannot be achieved
Solution Approach 1:
The feedback information is segmented into two parts: a first feedback result indicating a transmission weight most suitable for the channel, and a second feedback result indicating another transmission weight. This segmentation allows the base station to have multiple transmission weight options for pairing decisions, enhancing pairing flexibility while maintaining manageable feedback complexity.
Solution Approach 2:
The patent adds an additional dimension to the feedback by introducing a second transmission weight indication beyond the single transmission weight in traditional Implicit Feedback. This dimensional expansion provides the base station with more degrees of freedom in pairing selection, enabling flexible pairing that can suppress interference between spatially multiplexed users.
2Adaptability or versatility
If multiple transmission weights are fed back from the mobile station, then pairing flexibility is improved, but the amount of feedback information and processing complexity increase
Solution Approach 1:
The patent applies local quality by providing different types of transmission weight information for different purposes: the first feedback result (most suitable transmission weight) optimizes individual user performance, while the second feedback result (another transmission weight) enables pairing flexibility. This differentiated approach provides exactly the right amount of information for each pairing decision scenario without excessive complexity.
Solution Approach 2:
The patent changes the parameter of feedback information from a single transmission weight index to multiple transmission weight indications. This parameter change enables the base station to select optimal pairing combinations while the mobile station only needs to evaluate and report transmission weights based on channel conditions, keeping processing complexity manageable through structured parameter reporting.
3Ease of operation
If transmission weights are selected without considering channel estimation, then the selection process is simple, but the accuracy of transmission weight selection for minimizing interference is reduced
Solution Approach 1:
The patent applies preliminary action by having the mobile station perform channel estimation using reference signals from the base station before selecting transmission weights. This preliminary channel characterization enables accurate identification of the most suitable transmission weight and alternative transmission weights, ensuring precise pairing decisions while keeping the selection process systematic and manageable.
Solution Approach 2:
The patent uses feedback mechanisms where the mobile station reports channel information and transmission weight preferences back to the base station. This feedback loop enables the base station to make informed pairing decisions based on actual channel conditions, achieving high accuracy in transmission weight selection while maintaining operational simplicity through automated feedback-based decision making.
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 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. When the selection unit selects two transmission weights or more, the feedback controller feeds back the selected two transmission weights or more to the base station.