CSI Feedback for Multi-User Superposition Transmission
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently transmitting and receiving Channel State Information (CSI) for Multiuser Superposition Transmission (MUST) and Non-Orthogonal Multiple Access (NOMA) techniques, which limits the performance and pairing candidates in multiuser scenarios.
Innovation Solution
A method where user equipment (UE) reports multiple precoding matrix indicators (PMIs) and corresponding channel quality indicators (CQIs) to the base station, including a most preferred and secondary PMI/CQI, allowing for more MUST pairing candidates and improved system performance by considering additional precoding matrix candidates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only a single PMI/CQI is reported by UE, then the feedback signaling is simple, but the number of MUST pairing candidates is limited
Solution Approach 1:
The patent segments the CSI feedback into multiple components: primary PMI/CQI and secondary PMI/CQI. This segmentation allows the UE to provide multiple precoding matrix candidates separately, increasing the number of MUST pairing candidates without overcomplicating the feedback structure. The base station can then select from multiple candidates based on channel conditions.
Solution Approach 2:
The patent adds an additional dimension to the feedback by introducing a secondary PMI/CQI pair alongside the primary one. This dimensional expansion enables the system to consider multiple precoding matrices simultaneously, thereby increasing pairing candidates while maintaining manageable feedback complexity through structured reporting.
2Adaptability or versatility
If multiple PMI/CQI are reported by UE, then the number of MUST pairing candidates increases, but the feedback signaling becomes more complex
Solution Approach 1:
The patent divides the multiple PMI/CQI feedback into distinct segments (primary and secondary pairs), which simplifies the base station's processing by organizing the information in a structured manner. This segmentation approach increases pairing candidates while keeping the feedback mechanism manageable through clear separation of information elements.
Solution Approach 2:
The patent implements partial feedback by reporting only the necessary number of PMI/CQI pairs (primary and secondary) rather than all possible combinations. This partial action approach provides sufficient pairing candidates for MUST operations while avoiding excessive feedback complexity that would arise from reporting every possible precoding matrix.
3Reliability
If multiple precoding matrix candidates are considered, then MUST operation performance improves, but the processing time increases
Solution Approach 1:
The patent applies preliminary action by having the UE pre-calculate and report multiple PMI/CQI pairs in advance, so that when the base station needs to perform MUST operations, the precoding matrix candidates are already prepared. This reduces real-time processing time while maintaining multiple pairing candidates for improved performance.
Solution Approach 2:
The patent uses feedback mechanisms where the UE reports CSI information (PMI/CQI pairs) back to the base station, enabling the base station to select optimal precoding matrices based on actual channel conditions. This feedback loop allows efficient selection from multiple candidates without requiring exhaustive processing of all possibilities.
Data Source
AI summary
A method for transmitting and receiving channel state information (CSI) in a wireless communication system, and an apparatus therefor are disclosed. Specifically, a method for a terminal transmitting CSI in a wireless communication system supporting multi-user superposition transmission (MUST) may comprise the steps of: reporting to a base station a first precoding matrix indicator (PMI) indicating a precoding matrix that is the most preferred by the terminal, and a first channel quality indicator (CQI) that is calculated assuming use of the first PMI; and reporting to the base station a second PMI indicating a precoding matrix that is secondly preferred by the terminal, and a second CQI that is calculated assuming use of the second PMI.