DRX Control Mechanism for CSI/SRS Transmission Synchronization
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Solution Overview
Problem
In LTE mobile communication systems, the existing DRX control mechanisms face challenges in accurately managing CSI/SRS transmission and reception, leading to mismatches between mobile stations and base stations, which affect estimation accuracy and cause interference, especially when Active Time is suddenly changed or extended.
Innovation Solution
A mobile station determines whether to transmit quality information based on its state after a predetermined time, and adjusts its transmission accordingly, even if a scheduling request is made before that time, while the base station controls its expectations to match the mobile station's state, avoiding mismatches in CSI/SRS operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the mobile station discontinuously receives PDCCH to reduce battery consumption, then energy efficiency is improved, but transmission timing synchronization between mobile station and base station deteriorates
Solution Approach 1:
The base station performs preliminary determination of whether to receive CSI/SRS before the actual transmission timing, and communicates this expectation to the mobile station in advance. This allows the mobile station to prepare and transmit at the correct timing even while in DRX inactive state, maintaining synchronization without continuous monitoring.
Solution Approach 2:
The base station provides feedback to the mobile station about its expected CSI/SRS reception status. The mobile station uses this feedback to adjust its transmission behavior, ensuring that transmissions occur only when the base station is prepared to receive, thereby maintaining synchronization under DRX operation.
2Ease of operation
If the mobile station determines CSI/SRS transmission based on current state, then transmission control simplicity is improved, but estimation accuracy at base station deteriorates
Solution Approach 1:
The base station provides feedback to the mobile station about whether it expects to receive CSI/SRS. The mobile station uses this feedback to determine transmission timing, ensuring that CSI/SRS is transmitted only when the base station is in a state to accurately estimate channel quality, thereby resolving the contradiction between simple control and accurate estimation.
3Measurement precision
If the mobile station transmits CSI/SRS continuously, then channel quality estimation accuracy is improved, but energy consumption increases
Solution Approach 1:
The system uses the base station's own reception state and scheduling decisions to control the mobile station's CSI/SRS transmission. The mobile station transmits CSI/SRS only when the base station indicates it expects reception, eliminating unnecessary transmissions and reducing energy consumption while maintaining estimation accuracy when needed.
Solution Approach 2:
The base station provides feedback to the mobile station about its CSI/SRS reception expectations, enabling the mobile station to transmit only when channel quality estimation is actually needed at the base station, thus balancing energy consumption with estimation accuracy under DRX operation.
4Measurement precision
If the base station expects CSI/SRS transmission, then channel quality monitoring is improved, but process load increases when mismatches occur
Solution Approach 1:
The base station performs preliminary determination of whether it expects to receive CSI/SRS before the actual transmission timing, and communicates this expectation to the mobile station in advance. This preliminary action prevents mismatches where the base station would otherwise need to handle unexpected transmissions or missing expected transmissions, reducing process load while maintaining monitoring capability.
Data Source
AI summary
A mobile station that communicates with a base station, including: means that determines whether to transmit, to the base station, quality information indicating radio quality when a predetermined time elapses based on a state, of the mobile station, which is an active state or not in discontinuous reception control; and means that, even when it is determined not to transmit the quality information based on the determination, transmits the quality information when the predetermined time elapses in a case where a scheduling request is transmitted to the base station before the predetermined time elapses.