UE CSI/SRS Reporting During DRX With Deterministic Timing
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Solution Overview
Problem
In LTE systems, there is a challenge in efficiently managing channel quality reporting and sounding reference symbols, particularly in scenarios involving carrier aggregation, where existing mechanisms struggle to handle dynamic changes in channel conditions and resource allocation efficiently.
Innovation Solution
The introduction of deterministic UE behavior for CSI/SRS reporting, which includes aperiodic CSI triggers via PDCCH and dynamic SRS transmissions, allows for rapid channel sounding and adaptive resource allocation, enhancing the efficiency of channel quality feedback and uplink resource management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic CSI/SRS reporting is used during DRX, then channel quality feedback is provided, but UE behavior becomes non-deterministic and processing complexity increases
Solution Approach 1:
The patent applies dynamics by making CSI/SRS reporting behavior adaptive to DRX state. The UE dynamically adjusts its reporting behavior based on whether it is in Active Time or Non-Active Time, transitioning between different reporting modes (periodic during Active Time, dropped during Non-Active Time) to optimize both reliability and complexity
Solution Approach 2:
The patent implements self-service through autonomous UE decision-making. The UE independently determines whether to transmit CSI/SRS based on its own DRX state and configured parameters without requiring network intervention, thereby simplifying network-UE coordination while maintaining reliable feedback when needed
2Measurement precision
If aperiodic CSI triggers and dynamic SRS transmissions are introduced, then responsiveness and accuracy of channel quality reporting improve, but device complexity increases
Solution Approach 1:
The patent applies preliminary action through pre-configuration of aperiodic CSI triggers and SRS parameters via RRC signaling before actual transmissions occur. This allows the UE to have complex reporting capabilities ready in advance, which are then activated only when needed, improving accuracy without requiring continuous complex processing
Solution Approach 2:
The patent uses periodic action by combining periodic reporting mechanisms during Active Time with event-triggered aperiodic reporting. This hybrid approach maintains measurement precision through regular updates while reducing overall transmission complexity by limiting aperiodic triggers to specific conditions
3Use of energy by moving object
If DRX is used to reduce power consumption, then energy efficiency improves, but channel quality reporting reliability may deteriorate
Solution Approach 1:
The patent applies periodic action through DRX cycles that alternate between Active Time and Non-Active Time. During Active Time, the UE performs periodic CSI/SRS reporting to maintain reliable channel quality feedback, while during Non-Active Time, reporting is dropped to conserve energy. This periodic pattern ensures reliability when needed while achieving energy savings overall
Data Source
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AI summary
The invention relates to a method for transmitting a periodic channel quality report (CSI) and/or a sounding reference symbol (SRS) from a UE to an eNodeB. To avoid double decoding at the eNodeB in transient phases, a deterministic behavior of the UE is defined by the invention, according to which the eNodeB can unambiguously determine whether the UE will transmit the CSI/SRS or not. According to one embodiment, the UL grants and/or DL assignments received until and including subframe N-4 only are considered; UL grants and/or DL assignments received by the UE after subframe N-4 are discarded for the determination. Additionally, DRX-related timers at subframe N-4 are considered for the determination. In a second embodiment, DRX MAC control elements from the eNodeB, instructing the UE to enter DRX, i.e. become Non-Active, are only considered for the determination if they are received before subframe N-4, i.e. until and including subframe N-(4+k).