Reduced CSI-RS Density for FD-MIMO Overhead Management
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Solution Overview
Problem
Current FD-MIMO systems face challenges in reducing CSI-RS density, leading to increased overhead and impact on system performance due to the need for additional CSI-RS resources or ports for beamforming, which affects cell-edge and cell-center performance.
Innovation Solution
The implementation of reduced density CSI-RS techniques, including separate and joint coding of PRB decimation and PRB offset, antenna port renumbering, and collision handling, to minimize overhead and maintain system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If reduced density CSI-RS is implemented, then overhead is reduced, but measurement precision deteriorates due to fewer reference signal resources
Solution Approach 1:
The patent transitions from two-dimensional CSI-RS patterns (frequency and time) to three-dimensional patterns by incorporating the code division multiplexing dimension. This allows the system to maintain comprehensive channel measurement capabilities across frequency, time, and code domains while using reduced overall density, thereby reducing overhead without sacrificing measurement precision.
Solution Approach 2:
The patent makes CSI-RS resources universal by enabling the same physical resources to serve multiple antenna ports through code division multiplexing. Different antenna ports share the same time-frequency resources but are distinguished by different code sequences, allowing reduced density configurations to maintain support for multiple ports and functions.
2Productivity
If reduced density CSI-RS is used, then system performance improves, but device complexity increases due to advanced coding and collision handling
Solution Approach 1:
The patent segments the complexity management into distinct layers: standardized higher-layer parameters for configuration, standardized physical-layer procedures for measurement and reporting, and standardized collision handling rules. This segmentation allows complex functionality to be achieved through coordinated standardization across different protocol layers rather than requiring complex device implementation.
Solution Approach 2:
The patent introduces new configurable parameters for reduced density CSI-RS patterns, including density factors, PRB offset configurations, and code division multiplexing parameters. These parameter changes enable flexible control over CSI-RS density and distribution, allowing the system to optimize performance while managing complexity through standardized parameter configuration.
3Loss of energy
If reduced density CSI-RS is implemented, then overhead is reduced, but adaptability worsens due to limited CSI-RS resource configurations
Solution Approach 1:
The patent introduces dynamic configurability for reduced density CSI-RS through higher-layer parameters that can be adjusted based on channel conditions, traffic requirements, and deployment scenarios. The system can dynamically select different density factors, PRB offset patterns, and code division multiplexing configurations, maintaining adaptability while operating at reduced density to minimize overhead.
Solution Approach 2:
The patent adds code division multiplexing as an additional dimension to CSI-RS configuration, enabling the system to differentiate between multiple antenna ports and transmission configurations within the same time-frequency resources. This extra dimension restores adaptability by providing multiple distinguishable signal paths even when overall resource density is reduced.
Data Source
AI summary
Techniques discussed herein can facilitate reduced density CSI (Channel State Information)-RS (Reference Signals). One example embodiment can be employed at a UE (User Equipment) and can comprise processing circuitry configured to receive and process a configuration message that comprises one or more configuration parameters for one or more CSI (Channel State Information)-RS (Reference Signal) APs (Antenna Ports) of a configurable density CSI-RS. The configuration parameters indicate a density of CSI-RS resource per Physical Resource Block (PRB) per CSI-RS AP and a PRB offset. The processing circuitry is further configured to determine a set of REs (Resource Elements) for the one or more CSI-RS APs of the configurable density CSI-RS based on the one or more configuration parameters and perform measurements on the configurable density CSI-RS from the set of REs to determine one or more CSI parameters. The one or more configuration parameters are provided per CSI-RS resource configuration.