Multibeam Precoder CSI Feedback Overhead Reduction
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently conveying channel state information (CSI) for multibeam precoders, particularly in reducing overhead and accurately representing non-zero coefficients in CSI feedback, especially for higher-rank Type II codebooks.
Innovation Solution
The implementation of a method that splits CSI feedback into two parts, CSI Part 1 and CSI Part 2, where CSI Part 1 indicates the number of non-zero coefficients, allowing the payload size of CSI Part 2 to be determined based on this indication, thereby reducing overhead and improving the representation of non-zero coefficients across layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multibeam precoder based CSI feedback is used to accurately represent channel state information, then measurement precision is improved, but information overhead increases
Solution Approach 1:
The patent divides the CSI feedback into two distinct parts: CSI Part 1 containing rank indication and number of non-zero coefficients, and CSI Part 2 containing the actual precoder matrix indicators. This segmentation allows the system to efficiently indicate only the necessary information (number of non-zero coefficients) in Part 1, while the actual coefficient data is compactly represented in Part 2, thereby reducing overall overhead while maintaining accuracy.
Solution Approach 2:
The patent introduces a rank restriction parameter that limits the maximum rank value in CSI feedback. By changing this parameter, the system can adapt the payload size of CSI Part 1 dynamically - higher rank restrictions reduce the number of bits needed to indicate non-zero coefficients, thereby reducing overhead while still providing sufficient channel state information for the given channel conditions.
2Adaptability or versatility
If the payload size of CSI Part 2 is made flexible based on non-zero coefficient indication, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by having the wireless device determine and indicate the number of non-zero coefficients in CSI Part 1 before transmitting CSI Part 2. The network node uses this indication to pre-calculate the appropriate payload size for CSI Part 2. This preliminary determination simplifies the overall process by avoiding the need for complex dynamic payload negotiation, as the payload size is predetermined based on the non-zero coefficient count.
Solution Approach 2:
The patent introduces an intermediary mechanism where the indication of non-zero coefficients in CSI Part 1 serves as a mediator that bridges the gap between the fixed structure of CSI Part 1 and the variable content of CSI Part 2. This intermediary indication allows the network node to infer and configure the appropriate payload size for Part 2 without requiring complex real-time calculations or additional signaling overhead.
3Productivity
If rank restriction is applied to reduce payload size, then productivity is improved, but measurement precision may deteriorate
Solution Approach 1:
The patent implements dynamic adaptability by allowing the rank restriction parameter to be configured based on channel conditions and network requirements. The system can dynamically adjust the rank restriction level - applying stricter restrictions when channel conditions are simple or overhead needs to be minimized, and relaxing restrictions when higher precision is needed. This dynamic approach ensures optimal balance between productivity and measurement precision under varying conditions.
Solution Approach 2:
The patent applies local quality by allowing different rank restrictions to be applied to different layers or different CSI reporting configurations. Instead of uniformly restricting all ranks, the system can apply selective rank restrictions based on the importance and characteristics of specific layers or channel conditions, thereby maintaining high measurement precision for critical dimensions while reducing overhead in less critical areas.
Data Source
AI summary
A method (1400) performed by a wireless device (200) for multibeam precoder based channel state information, CSI, feedback reporting is provided, A CSI report comprises a first part, CSI Part 1, and a second part, CSI Part 2. The method (1400) comprises generating (1401) the CSI report, wherein the CSI Part 1 comprises an indication of a number of non-zero coefficients, and a payload size of the indication of the number of non-zero coefficients is dependent on a rank restriction of the wireless device. The method also comprising transmitting (1402) the CSI report to a network node, wherein one or more of a payload of the CSI Part 2 and a payload size of the CSI Part 2 is based on the number of non-zero coefficients indicated in the CSI Part 1.