CSI-RS Overhead Reduction via Frequency Shifted Decimation
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Solution Overview
Problem
In Class B FD-MIMO systems, the CSI-RS signaling overhead is excessive due to the need for high resolution feedback, which can offset performance gains from increased CSI resolution, especially in scenarios with a large number of beams.
Innovation Solution
The proposed solution reduces CSI-RS overhead by decimating CSI-RS REs, allowing them to be transmitted every N PRBs, and applying frequency shifts to provide frequency diversity, thereby reducing the density of CSI-RS signals and enabling more efficient use of resources without compromising CSI resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high resolution CSI feedback is implemented in Class B FD-MIMO systems, then system performance is improved, but CSI-RS signaling overhead increases excessively
Solution Approach 1:
The patent segments the CSI-RS transmission by dividing the frequency spectrum into multiple bands and assigning different subset configurations to different frequency ranges. This allows selective application of density reduction in specific frequency regions where channel conditions permit, thereby reducing overall overhead while maintaining necessary resolution in critical bands.
Solution Approach 2:
The patent changes the density parameter of CSI-RS transmission by introducing subset configurations that selectively activate or deactivate specific CSI-RS resources based on frequency band, channel conditions, and beam characteristics. This dynamic parameter adjustment reduces signaling overhead while adapting to maintain adequate CSI resolution where needed.
2Productivity
If CSI-RS density is reduced to minimize overhead, then resource efficiency is improved, but CSI resolution may be compromised
Solution Approach 1:
The patent applies local quality by configuring different CSI-RS subset densities for different frequency bands and spatial regions. In frequency regions with favorable channel conditions or lower mobility, sparser CSI-RS configurations are used. In regions requiring higher precision or experiencing challenging conditions, denser configurations are maintained, thus preserving measurement precision where critical while improving overall resource efficiency.
Solution Approach 2:
The patent implements partial action by transmitting CSI-RS only in a subset of available frequency resources rather than uniformly across all resources. The subset configuration selectively activates necessary CSI-RS transmissions based on predicted channel conditions, allowing the system to use just enough CSI-RS resources to maintain adequate resolution without excessive overhead.
Data Source
AI summary
Techniques for measuring CSI (Channel State Information) based on beamformed CSI-RS having reduced overhead are discussed. One example embodiment configured to be employed in a UE (User Equipment) comprises a memory; and one or more processors configured to: process higher layer signaling indicating one or more CSI-RS resources associated with a plurality of REs (Resource Elements) comprising a RE for each CSI-RS resource for each of one or more CSI-RS APs (Antenna Ports) in each of a plurality of continuous PRBs (physical resource blocks); process additional higher layer signaling comprising one or more CSI-RS parameters that indicate a subset of the plurality of REs associated with a beamformed CSI-RS transmission; decode one or more CSI-RSs from the indicated subset; and measure one or more CSI parameters based on the decoded one or more CSI-RSs.