CSI Report Lifetime Control in Radio Networks
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Solution Overview
Problem
In radio communications networks, especially in LTE, there is a challenge in ensuring the reliability of Channel State Information (CSI) estimates due to outdated measurements and frequent changes in transmission conditions, such as beam directions, which can lead to corrupted CSI reports and increased RRC reconfiguration needs, affecting scheduling decisions and device mobility.
Innovation Solution
The network node controls the lifetime of CSI measurements by transmitting messages to wireless devices to discard existing estimates or use CSI estimates corresponding to a determined period, ensuring that CSI reports are not corrupted by previous measurements and reducing the need for RRC reconfigurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wireless device continuously transmits CSI reports based on existing measurements, then the reporting frequency is maintained, but the CSI estimates become outdated and corrupted due to changes in transmission conditions
Solution Approach 1:
The network node proactively transmits a message to the wireless device before the CSI estimates become corrupted, instructing the device to discard existing CSI estimates. This preliminary action prevents the degradation of CSI accuracy while maintaining continuous reporting frequency.
2Adaptability or versatility
If the network node frequently sends RRC reconfiguration messages to update transmission conditions, then the transmission parameters are kept current, but the signaling overhead and device complexity increase
Solution Approach 1:
The patent extracts the CSI estimate discarding function from the comprehensive RRC reconfiguration procedure. By using a separate, simplified message type specifically for discarding CSI estimates, the system reduces the signaling overhead and processing complexity associated with full RRC reconfigurations while maintaining the ability to update transmission conditions when necessary.
3Use of energy by moving object
If the wireless device maintains CSI estimates for extended periods, then the measurement overhead is reduced, but the CSI reports become unreliable due to channel variations
Solution Approach 1:
The network node monitors the validity of CSI estimates based on channel condition changes and provides feedback to the wireless device by transmitting a message when CSI estimates should be discarded. This feedback mechanism ensures that the wireless device maintains CSI estimates for optimal periods without excessive overhead, while preventing the use of corrupted estimates.
Data Source
AI summary
A method performed by a wireless device (121, 122) for determining Channel State Information, CSI, estimates to be transmitted in a CSI report for the wireless device (121, 122) to a network node (110) in a radio communications network (100) is provided. The wireless device (121, 122) receives a message comprising an indication to use CSI estimates corresponding to a determined period of time. In response to said message, the wireless device (121, 122) determines CSI estimates to be used in the CSI report to the network node (110) according to the received indication. A wireless device (121, 122) is also described.A network node (110) and method therein for controlling CSI estimates transmitted by one or more wireless devices (121, 122) in CSI reports to the network node (110) in a radio communications network (100) are also provided.