Channel State Information Feedback Reduction via UE Grouping
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Solution Overview
Problem
Current mobile communication systems face challenges in efficiently transmitting and receiving channel state information, particularly in massive MIMO environments, due to high feedback overhead, which affects system performance and resource management.
Innovation Solution
A method is introduced where a base station transmits CSI-RS to user equipment (UEs) for calculating channel state information, and UEs report angular information based on CSI-RS, with configuration information determining operation modes. This method groups UEs into representative and sub-UEs, allowing only representative UEs to transmit channel state information, reducing feedback overhead by utilizing angular reciprocity and channel sparsity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If all user equipments transmit channel state information independently, then channel state information can be obtained from all UEs, but feedback overhead increases significantly
Solution Approach 1:
The patent merges the channel state information reporting of multiple UEs by grouping them into representative UE and sub-UE structures. The representative UE reports channel state information that is then shared with sub-UEs, combining multiple individual reports into a single consolidated report. This reduces feedback overhead while maintaining information completeness for all grouped UEs.
Solution Approach 2:
The patent segments UEs into representative UEs and sub-UEs based on angular information and spatial characteristics. This segmentation allows the system to treat different UEs differently in the feedback process, where representative UEs provide full channel state information while sub-UEs receive shared information, thereby reducing overall feedback overhead without losing essential channel state data.
2Measurement precision
If channel state information is transmitted for all user equipments, then accurate channel estimation is achieved, but computational complexity increases
Solution Approach 1:
The patent combines channel estimation computations by having the representative UE perform the computationally intensive channel state information calculation once, and then share the results with sub-UEs. This merging approach maintains accurate channel estimation for all UEs in the group while significantly reducing the total computational complexity compared to each UE independently calculating and reporting channel state information.
3Loss of energy
If angular information is used for UE grouping, then feedback overhead is reduced, but system complexity increases
Solution Approach 1:
The patent changes the parameter used for UE identification and grouping from individual channel state information to angular information parameters (such as angle of arrival, angle of departure, or beam direction). This parameter change enables UEs to be grouped based on their spatial characteristics, allowing the representative UE to represent multiple sub-UEs and significantly reducing feedback overhead despite the added complexity of angular information processing.
Data Source
AI summary
A method for a base station to receive channel state information in a wireless communication system is disclosed. The method includes transmitting, to a plurality of user equipments (UEs), CSI-RS for calculating the channel state information; receiving, from the plurality of UEs, angular information related to a channel state between the base station and the plurality of UEs based on the CSI-RS; transmitting, to the plurality of UEs, configuration information for calculating the channel state based on the angular information, the configuration information including information determining an operation mode of the plurality of UEs; and receiving, from the plurality of UEs, the channel state information calculated based on the operation mode.