Sub-Band CQI Fallback for Constrained Uplink CSI Feedback
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently transmitting sub-band channel quality indicators (CQI) due to insufficient uplink resources, leading to incomplete or inaccurate CSI feedback, particularly in scenarios where four-bit CQI values cannot be transmitted.
Innovation Solution
A method and apparatus for wireless communication that allows a UE to determine the sufficiency of uplink resources and selectively transmit either four-bit sub-band CQI values or two-bit differential CQI values based on resource availability, ensuring complete CSI feedback even when four-bit transmission is not possible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four-bit sub-band CQI values are transmitted, then CSI feedback accuracy is improved, but uplink resource consumption increases
Solution Approach 1:
The patent implements dynamic CQI reporting by allowing the UE to adaptively switch between four-bit and two-bit CQI transmission modes based on real-time uplink resource availability. The UE determines whether sufficient uplink resources exist to support four-bit CQI values, and if not, falls back to two-bit differential CQI values, enabling the system to dynamically adjust feedback precision according to resource conditions.
Solution Approach 2:
The patent changes the CQI value parameter representation from fixed four-bit format to a variable format that can be either four-bit absolute CQI or two-bit differential CQI. This parameter flexibility allows the system to optimize between accuracy and resource usage by selecting the appropriate CQI representation based on uplink resource sufficiency.
2Reliability
If uplink resources are allocated for four-bit CQI transmission, then feedback completeness is improved, but resource efficiency deteriorates when resources are insufficient
Solution Approach 1:
The patent prepares for potential resource insufficiency by implementing a fallback mechanism in advance. The UE is configured to attempt four-bit CQI transmission first, but has a pre-planned contingency to switch to two-bit differential CQI if resource checks fail. This beforehand cushioning ensures that feedback can still be transmitted even when resources are insufficient, maintaining reliability while avoiding wasted resource allocation.
3Quantity of substance
If two-bit differential CQI values are used, then uplink resource usage is reduced, but CSI feedback precision deteriorates
Solution Approach 1:
The patent applies partial action by using two-bit differential CQI values only when necessary (when uplink resources are insufficient), rather than always using the reduced-precision format. The system attempts to use the more precise four-bit format first, and only partially resorts to the two-bit format when resource constraints make four-bit transmission infeasible, thus minimizing the loss of precision.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine that a set of uplink resources to be used for transmitting a channel state information (CSI) communication is insufficient to permit one or more four-bit sub-band channel quality indicator (CQI) values to be transmitted in the CSI communication. The UE may determine whether the set of uplink resources is sufficient to permit one or more two-bit sub-band differential CQI values to be transmitted in the CSI communication. The UE may selectively transmit the one or more two-bit sub-band differential CQI values in the CSI communication based at least in part on the determination of whether the set of uplink resources is sufficient to permit the one or more two-bit sub-band differential CQI values to be transmitted in the CSI communication. Numerous other aspects are described.