CSI Reporting with PMI Quality Metrics for MU-MIMO Scheduling
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Solution Overview
Problem
Existing wireless communication systems face challenges in enhancing Multi-User Multiple Input Multiple Output (MU-MIMO) scheduling performance due to inherent Single User (SU) assumptions in CSI feedback, leading to inappropriate PMI quality and scalability issues with complex codebook designs.
Innovation Solution
A method and device for CSI reporting that includes transmitting CSI report configuration information to UEs, CSI-RS, and receiving PMI quality information (PQI) to enhance MU-MIMO scheduling by accurately determining PMI quality through squared generalized cosine similarity (SGCS) and generalized cosine similarity (GCS) measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If SU assumptions are used in CSI feedback, then implementation is simple, but MU-MIMO scheduling performance deteriorates
Solution Approach 1:
The patent changes the feedback parameter from traditional CQI/PMI/RI to include SGCS (Squared Generalized Cosine Similarity) and GCS (Generalized Cosine Similarity) measurements that explicitly capture MU-MIMO channel quality. This parameter transformation enables the feedback to reflect multi-user interference characteristics while maintaining a manageable feedback structure.
Solution Approach 2:
The patent introduces SGCS and GCS metrics as intermediary measurements that bridge the gap between SU-based CSI feedback and MU-MIMO scheduling requirements. These intermediaries provide the base station with quantitative information about channel similarity and interference levels without requiring complex multi-user channel state knowledge at the UE.
2Productivity
If complex codebook designs are used to improve PMI quality, then scheduling performance improves, but scalability deteriorates
Solution Approach 1:
The patent extracts the essential quality information needed for MU-MIMO scheduling (channel similarity and interference characteristics) from complex codebook designs and represents it through simple SGCS/GCS scalar measurements. This extraction approach captures the critical scheduling information without requiring complex codebook structures, enabling scalability to different antenna configurations and user numbers.
3Quantity of substance
If traditional CSI feedback is used, then feedback overhead is low, but PMI quality is inappropriate for MU-MIMO
Solution Approach 1:
Instead of trying to improve PMI quality within the traditional CQI/PMI/RI feedback framework, the patent inverts the approach by having UEs measure and report channel similarity metrics (SGCS/GCS) directly. This inversion provides the base station with the precise information needed for MU-MIMO precoding selection without the overhead of traditional PMI feedback.
Data Source
AI summary
The disclosure relates to a fifth generation (5G) communication system or a sixth generation (6G) communication system for supporting higher data rates beyond a fourth generation (4G) communication system. A method of a base station in a wireless communication system includes transmitting, to a user equipment (UE), channel state information (CSI) report configuration information including configuration information configuring the UE to report precoding matrix index (PMI) quality information (PQI), transmitting a CSI-reference signal (CSI-RS) to the UE, and receiving, from the UE, a CSI and the PQI determined based on the CSI report configuration information and the CSI-RS.