Double Codebook BCI Reporting for MIMO Overhead Reduction
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Solution Overview
Problem
The existing methods for reporting Best Companion Index (BCI) in multi-user MIMO systems using a double codebook structure face challenges in accurately conveying optimal BCI information, leading to potential performance degradation due to the BCI W2 not being included in the calculated BCI W1 set.
Innovation Solution
The method involves obtaining PMI W1 and PMI W2 sets based on a double codebook, computing a BCI W1 set, and reporting it on a long interval, with the option to shift and confine co-phasing factors based on PMI W2 to ensure the BCI W2 is orthogonal and included in the BCI W1 set, thereby increasing the probability of optimal BCI reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the BCI W2 is not included in the calculated BCI W1 set, then the reporting overhead is reduced, but the performance degrades due to inaccurate BCI reporting
Solution Approach 1:
The patent applies preliminary action by pre-calculating and reporting the BCI W1 set on a long interval before the actual BCI W2 is needed. This advance preparation ensures that when BCI W2 needs to be reported, the foundation (BCI W1 set) is already in place, improving the probability that optimal BCI W2 is included in the pre-reported set without requiring complete re-reporting of all parameters.
Solution Approach 2:
The patent segments the BCI reporting into two distinct components: BCI W1 (reported on long interval) and BCI W2 (reported on short interval). This segmentation allows each component to be optimized independently - BCI W1 provides a stable foundation reported less frequently, while BCI W2 provides fine-grained updates reported more frequently, resolving the contradiction between reporting accuracy and overhead.
2Measurement precision
If the BCI W1 set is reported frequently, then the BCI reporting accuracy is improved, but the signaling overhead increases
Solution Approach 1:
The patent implements periodic action by establishing different reporting intervals for BCI W1 and BCI W2. BCI W1 is reported on a long interval (less frequently), while BCI W2 is reported on a short interval (more frequently). This periodic approach ensures that critical updates are captured timely while avoiding excessive signaling overhead from reporting all parameters at maximum frequency.
Solution Approach 2:
The patent applies dynamics by making the reporting frequency adaptive - different components of the BCI (W1 and W2) are updated at different rates based on their importance and variability. This dynamic reporting strategy allows the system to maintain high measurement precision for time-critical parameters while reducing overhead for more stable parameters.
Data Source
AI summary
A method, mobile terminal, and system for reporting BCI are provided, the method comprises the steps of: obtaining a PMI W1 set and a PMI W2 to be used for a mobile terminal based on a double codebook; computing a BCI W1 set to be used for another mobile terminal based on the PMI W1 set; selecting a BCI W2 from the BCI W1 set based on the PMI W2; and reporting the BCI W1 set and the BCI W2 to a base station,wherein W1 indicates a long-term or wideband component of the PMI and BCI, and W2 indicates a short-term or narrowband component of the PMI and BCI. With the present disclosure, the probability that the optimal BCI W2 is included in the shifted BCI W1 set is increased, and the overhead for feeding-back the BCI is reduced.