Semi-persistent CSI Reporting with Uplink CCA
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Solution Overview
Problem
In wireless communication systems, especially in unlicensed spectrum access, the failure of uplink clear channel assessment (CCA) can lead to undefined behavior in wireless devices (WDs), resulting in incomplete or failed semi-persistent channel state information (CSI) reporting. This can cause network nodes to continue transmitting CSI measurement resources unnecessarily, wasting downlink network resources.
Innovation Solution
The proposed solution specifies the behavior of wireless devices (WDs) when they cannot transmit Hybrid Automatic Repeat Request Acknowledgements (HARQ-ACK) due to uplink CCA failures. WDs are instructed to refrain from CSI measurement and reporting during activation commands if CCA fails, and to continue CSI measurement but refrain from reporting during deactivation commands until CCA succeeds within a specified time interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless devices perform uplink clear channel assessment before transmitting HARQ-ACK, then channel access reliability is improved, but transmission delay increases when CCA fails
Solution Approach 1:
The wireless device performs clear channel assessment (CCA) in advance before transmitting the HARQ-ACK signal. This preliminary action ensures that the channel is clear before transmission, improving reliability. The device checks the channel occupancy and determines whether to proceed with transmission, thereby avoiding collisions and ensuring reliable channel access.
2Reliability
If network nodes continue transmitting CSI measurement resources when CCA fails, then measurement coverage is maintained, but network resource waste increases
Solution Approach 1:
The wireless device provides feedback to the network node when it fails to transmit the HARQ-ACK signal due to CCA failure. This feedback mechanism allows the network node to understand that the uplink transmission failed and to adjust its behavior accordingly. The network node can then stop transmitting CSI measurement resources, avoiding waste of downlink network resources while maintaining measurement coverage when successful.
3Productivity
If wireless devices refrain from CSI reporting when CCA fails, then network resource efficiency is improved, but CSI availability for scheduling may be reduced
Solution Approach 1:
The wireless device partially performs the CSI reporting function by refraining from transmission only when CCA fails, while continuing to perform it when CCA succeeds. This partial action approach optimizes resource efficiency by avoiding unnecessary transmissions when the channel is busy, while still maintaining CSI availability when the channel is clear. The device balances between resource efficiency and information availability based on channel conditions.
Data Source
AI summary
A method, system and apparatus for semi-persistent channel state information (CSI) reporting procedures with uplink (UL) clear channel assessment (CCA) are disclosed. According to one aspect, a method includes receiving a signal indicating activation or deactivation of semi-persistent channel state information (CSI) reporting and responsive to receiving the signal, attempt to transmit a Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK), the attempt being subject to success or failure of a clear channel assessment (CCA). When the CCA fails and when the signal indicates activation, the method includes refraining from CSI measurement and reporting unless CCA subsequently succeeds before expiry of a time interval. When the CCA fails and when the signal indicates deactivation, the method includes continuing CSI measurement but refraining from CSI reporting unless CCA subsequently succeeds before expiry of a time interval.