CSI-RS Resource Element Positioning for Backward Compatible Interference Estimation
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Solution Overview
Problem
Current CSI-RS density in LTE systems is insufficient for accurate interference covariance estimation, leading to errors in CQI and rank feedback, which affects transmission scheme selection and results in throughput loss, especially in heterogeneous networks with challenging interference characteristics.
Innovation Solution
Increasing the density of resource elements in a physical resource block (PRB) for CSI-RS while ensuring backwards compatibility with legacy mobile terminals by positioning additional CSI-RS resource elements to be interpreted as muted by older systems, thereby avoiding interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the density of resource elements for CSI-RS is increased to improve channel state information and interference estimation accuracy, then measurement precision improves, but device complexity increases due to additional resource element configuration
Solution Approach 1:
The patent segments the resource element configuration by defining specific patterns (e.g., every 4th or 8th resource element) for CSI-RS within the physical resource block. This segmentation allows increased CSI-RS density for improved measurement precision while maintaining a structured, manageable configuration that does not excessively increase device complexity.
2Reliability
If additional CSI-RS resource elements are added to improve interference covariance estimation, then reliability improves, but loss of information increases due to potential conflicts with legacy terminal interpretations
Solution Approach 1:
The patent applies local quality by making the resource element allocation dependent on the terminal type. Advanced terminals receive enhanced CSI-RS density for improved reliability, while legacy terminals interpret the same resource elements differently (as muted or unused), preserving backward compatibility without information loss for either group.
Solution Approach 2:
The patent resolves the conflict by adding a dimensional distinction between terminal types (legacy vs. advanced). The same physical resource block contains CSI-RS elements that serve different functions for different terminal categories, allowing improved interference estimation for advanced terminals while maintaining compatibility with legacy terminals through differentiated interpretation layers.
3Adaptability or versatility
If resource elements are allocated for enhanced CSI-RS in heterogeneous networks, then adaptability improves, but device complexity increases due to multiple terminal type support requirements
Solution Approach 1:
The patent implements universality by designing the resource element configuration to serve multiple terminal types simultaneously. The same physical resource block structure and CSI-RS patterns are universally applied, but interpreted differently by legacy versus advanced terminals based on their capabilities, enabling heterogeneous network support without requiring separate configurations for each terminal type.
Data Source
AI summary
Methods, apparatus and computer program products define additional resource elements of a physical resource block (PRB) to be allocated for the provision of channel state information reference signals in a manner that does not create issues relating to backwards compatibility for legacy mobile terminals. A method may include receiving a definition of a plurality of resource elements of a PRB to be allocated for provision of channel state information reference signals. At least some of the plurality of resource elements of the PRB that are allocated for the provision of channel state information reference signals correspond in position to resource elements of the PRB that are interpreted by a different type of mobile terminal to be muted. The method also causes channel state information reference signals to be received via the plurality of resource elements of the PRB that are allocated for the provision of channel state information reference signals.