CSI Feedback for 3D Beam Downlink Communication
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Solution Overview
Problem
Current radio communication systems face challenges in feeding back channel state information (CSI) suitable for downlink communication using 3D beams, which are essential for advanced LTE systems like LTE-advanced that aim to enhance broadbandization and speed.
Innovation Solution
A radio communication method that involves a radio base station transmitting pre-coded measurement reference signals using different precoding weights between multiple vertical beams, allowing user terminals to generate and feed back CSI, enabling the radio base station to select appropriate precoding weights for downlink communication with user terminals using 3D beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CSI feedback schemes are used for 3D beam downlink communication, then system compatibility is maintained, but CSI feedback accuracy and suitability for 3D beams deteriorates
Solution Approach 1:
The patent segments the CSI feedback process into two distinct parts: horizontal PMI feedback for horizontal beamforming and vertical PMI feedback for vertical beamforming. This segmentation allows each feedback component to be optimized for its specific dimension while maintaining overall system compatibility with conventional feedback mechanisms.
Solution Approach 2:
The patent extends the conventional 2D horizontal beamforming feedback to 3D by introducing vertical beamforming feedback. The vertical PMI provides an additional dimensional component to the CSI feedback, enabling accurate representation of 3D beam characteristics while building upon existing horizontal feedback structures.
2Productivity
If detailed CSI feedback for 3D beams is implemented, then downlink communication performance improves, but feedback overhead increases
Solution Approach 1:
The CSI feedback is segmented into horizontal and vertical components, allowing the system to transmit only the necessary precoding information for each dimension. This reduces the total feedback overhead compared to transmitting complete 3D channel state information, while still enabling effective 3D beamforming through the combined use of horizontal and vertical PMIs.
3Productivity
If precoding weights are optimized for 3D beams, then MIMO transmission efficiency improves, but system complexity increases
Solution Approach 1:
The precoding weight management is segmented into horizontal and vertical components, where horizontal precoding weights and vertical precoding weights are independently selected and combined. This segmentation simplifies the overall complexity by breaking down the 3D precoding problem into two manageable 2D problems, while still achieving optimized MIMO transmission efficiency through their combination.
Data Source
AI summary
The present invention is designed so that it is possible to feed back channel state information (CSI) that is suitable for downlink communication in which 3D beams are used. The radio communication method of the present invention is a radio communication method to allow a radio base station to carry out downlink communication with a user terminal by using a 3D beam that is formed with a horizontal beam having directivity in a horizontal plane and a vertical beam having directivity in a vertical plane, and has the steps in which the radio base station transmits a plurality of measurement reference signals that are pre-coded using different precoding weights between a plurality of vertical beams, and the user terminal transmits channel state information that is generated based on the plurality of measurement reference signals, to the radio base station.