Beam-Formed CSI-RS Two-Plane Sounding for 5G Overhead Reduction
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Solution Overview
Problem
In massive MIMO and 3D MIMO communications systems, the transmission of numerous channel state information reference signals (CSI-RS) by base stations consumes significant network resources, leading to performance overhead due to the need for exhaustive sounding of all beam directions, which is particularly excessive in millimeter wave systems.
Innovation Solution
The method involves beam-formed CSI-RS transmission using different planes, such as azimuth and elevation, where the transmission point initially sounds in one plane, receives feedback, and then adapts sounding in the second plane based on the feedback, reducing the need to exhaustively sound all directions and minimizing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the eNB transmits a large number of CSI-RS signals to facilitate channel information between each transmit antenna and each receiver antenna, then channel measurement accuracy is improved, but network resource consumption increases significantly
Solution Approach 1:
The patent segments the exhaustive CSI-RS transmission process into two phases: a first plane sounding phase that covers all directions, and a second plane refinement phase that focuses only on selected directions. This segmentation reduces the total number of CSI-RS transmissions required while maintaining measurement accuracy through targeted refinement.
Solution Approach 2:
Instead of performing exhaustive sounding in all directions equally, the patent applies partial action by first conducting comprehensive sounding, then performing refinement only in the selected preferred directions. This partial refinement approach reduces overall resource consumption while maintaining necessary measurement precision.
2Loss of information
If the eNB performs exhaustive sounding of all beam directions, then complete channel state information is obtained, but communications overhead increases
Solution Approach 1:
The patent performs preliminary exhaustive sounding in the first plane to identify preferred directions before conducting the second plane refinement. This preliminary action ensures that complete channel information is initially obtained, then selectively refined, reducing subsequent overhead while maintaining information completeness.
Solution Approach 2:
The patent transitions from two-dimensional exhaustive sounding to a hierarchical approach using different planes: first plane for comprehensive coverage and second plane for directional refinement. This dimensional approach reduces overhead by focusing refinement resources on specific angular dimensions rather than exhaustively covering all combinations.
3Reliability
If the eNB transmits CSI-RS for every transmit antenna, then channel information between each antenna and receiver is facilitated, but system performance deteriorates due to resource overhead
Solution Approach 1:
The patent applies local quality by performing detailed refinement sounding only in the selected preferred directions rather than uniformly across all directions. This localized refinement maintains channel information accuracy for the most important directions while reducing overall resource consumption that would otherwise degrade system performance.
Data Source
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AI summary
A method for operating a reception point includes receiving a plurality of first directional reference signals spanning a first plane, selecting at least one first directional reference signal from the plurality of received first directional reference signals that meets a first selection criterion, sending a first feedback indicating the selected at least one first directional reference signal, receiving a plurality of second directional reference signals spanning a second plane oriented in accordance with the selected at least one first directional reference signal, selecting at least one second directional reference signal from the plurality of received second directional reference signals that meet a second selection criterion, and sending a second feedback indicating the selected at least one second directional reference signals.