CSI Feedback Restriction via Unused Control Channel Bits
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Solution Overview
Problem
In closed-loop MIMO wireless systems using codebook based precoding, the evaluation of all possible precoding matrices for CSI reporting is computationally intensive, leading to increased power consumption, memory usage, and processing resources at the UE, and often results in the network node having to perform additional processing to identify appropriate CSI for scheduling.
Innovation Solution
Transmitting a feedback restriction indicator using unused bit resources in control channels to limit the parameters evaluated by the UE for CSI reporting, dynamically configuring the restrictions based on criteria such as signal quality, battery life, and traffic load, thereby reducing the subset of CSI parameters to be evaluated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE evaluates all possible precoding matrices for CSI reporting in closed-loop MIMO systems, then the system can achieve optimal precoding selection and maximum spectral efficiency, but the computational complexity, power consumption, and processing resources at the UE increase significantly
Solution Approach 1:
The patent segments the codebook into multiple subsets, each associated with different feedback restriction indicators. Instead of evaluating all precoding matrices, the UE only evaluates matrices within the restricted subset indicated by the feedback restriction indicator transmitted by the network node. This segmentation reduces the search space from the entire codebook to a manageable subset while maintaining optimal precoding selection within that subset.
Solution Approach 2:
The patent applies partial action by having the UE evaluate only a portion of the available precoding matrices rather than all of them. The feedback restriction indicator specifies a subset of the codebook that the UE should evaluate, representing partial evaluation that is sufficient for achieving good system performance without the excessive computational burden of complete evaluation.
2Measurement precision
If the UE evaluates all possible precoding matrices for CSI reporting, then the most accurate CSI can be obtained for scheduling decisions, but the power consumption and battery life at the UE deteriorate
Solution Approach 1:
The codebook is segmented into multiple subsets with different levels of precision or applicability. The feedback restriction indicator directs the UE to evaluate only the relevant subset, reducing computational effort and power consumption while maintaining sufficient CSI accuracy for the current channel conditions and network requirements.
Solution Approach 2:
The feedback restriction indicator dynamically adjusts the evaluation subset based on current system conditions such as channel quality, network load, and UE capability. This dynamic adaptation allows the system to balance between CSI accuracy and power consumption, selecting appropriate evaluation subsets that match current operational requirements rather than always performing exhaustive evaluation.
3Adaptability or versatility
If the network node receives full CSI reports from all UEs, then comprehensive scheduling decisions can be made, but the network node must perform additional processing to identify appropriate CSI for scheduling
Solution Approach 1:
The patent extracts and transmits only the necessary feedback restriction information from the full set of possible feedback parameters. By taking out only the essential subset indication and transmitting it via feedback restriction indicators, the network node reduces the amount of CSI data that needs to be processed and stored, while still maintaining the ability to make flexible scheduling decisions based on the received subset-restricted CSI reports.
4Productivity
If unused bit resources in control channels are utilized for feedback restriction indicators, then the system can dynamically configure CSI reporting restrictions without additional signaling overhead, but the control channel structure must be modified
Solution Approach 1:
The patent makes unused bit resources in the control channel multi-functional by utilizing them for transmitting feedback restriction indicators. These bits, which would otherwise be reserved or unused, are repurposed to carry additional information about codebook subset restrictions. This multi-functionality allows the system to enhance CSI reporting control capabilities without requiring additional dedicated signaling resources or increasing overall signaling overhead.
Data Source
AI summary
Systems and methods are disclosed for utilizing unused bit resources to convey restrictions on parameters evaluated for a feedback report in a Multiple-Input Multiple-Output (MIMO) wireless communication system. In one embodiment, a method of operation of a transmitting node in a wireless network includes transmitting a feedback restriction indicator to a receiving node, where the feedback restriction indicator is an unused bit resource in one or more instances of a control channel that is indicative of one or more desired restrictions on parameters to be evaluated by the receiving node for a feedback report to be provided from the receiving node. The method of operation of the transmitting node further includes receiving the feedback report from the receiving node, where the feedback report is limited according to the feedback restriction indicator.