Customized Beam Sets for CSI Feedback Overhead Reduction
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Solution Overview
Problem
Current downlink channel state information (CSI) feedback in MIMO systems incurs high signaling overhead, which hampers efficient data rate gains in 5G networks, particularly due to the need to transmit wideband and subband amplitudes and phase combining information for each beam.
Innovation Solution
Customized beam sets are designed for specific environments, allowing user equipment (UE) to select and feedback only the necessary beams and their weights, reducing the number of beams used to represent the downlink channel, thereby minimizing CSI feedback overhead while maintaining channel acquisition performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all beams in the complete beam set are used for CSI feedback, then channel acquisition performance is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts only the necessary subset of beams from the complete beam set that are actually needed to represent the downlink channel in a given environment. The UE identifies and reports only these essential beams with their corresponding indices and combining information, rather than reporting all beams in the complete set, thereby reducing overhead while preserving channel acquisition performance.
Solution Approach 2:
The patent segments the complete beam set into multiple subsets, where each subset contains beams that are relevant for representing the channel in specific environmental conditions. This segmentation allows the system to select and report only the appropriate subset for the current environment, reducing the amount of feedback information required.
2Measurement precision
If a large number of beams are used to represent the downlink channel, then channel representation accuracy is improved, but UE power consumption increases
Solution Approach 1:
The patent extracts only the essential beams needed for accurate channel representation in the given environment, eliminating unnecessary beams from the feedback process. This reduction in the number of beams to be processed and reported directly decreases UE power consumption while maintaining sufficient channel representation accuracy.
3Loss of information
If environment-specific beam sets are designed, then CSI feedback overhead is reduced, but system complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-designing multiple environment-specific beam sets offline, where each beam set is optimized for a particular environmental condition (e.g., indoor, outdoor, urban, rural). During operation, the system simply selects the appropriate pre-designed beam set based on the current environment, avoiding the need for complex real-time beam set generation and reducing online computational complexity.
Data Source
AI summary
Systems and methods are provided that involve the design and use of beam sets for CSI feedback that are customized for to a given environment, for example, a room, a hallway, an outdoor area, an indoor area. This can have the effect of reducing the number of beams within the beam set that are used to represent the downlink channel of a UE in a given environment, with a corresponding reduction in the overhead to feedback CSI. A customized beam set, once determined, is configured on a given UE using signalling. A UE that makes channel measurements on a received reference signal uses the channel measurements to obtain a set of beamforming weights for the customized beam set and sends the weights back to the network as CSI.