CSI-RS Tracking Reference Signaling for UE Idle Mode Power Saving
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Solution Overview
Problem
User equipment (UE) in wireless communications systems face challenges in receiving dynamic transmit power updates for channel state information reference signals (CSI-RS) when operating in idle or inactive modes, which impacts power consumption and network efficiency.
Innovation Solution
UE receives control messages indicating whether to use CSI-RSs as tracking reference signals (TRSs) for automatic gain control and time/frequency tracking in idle or inactive modes, with optional power offset configurations, allowing dynamic power adjustments based on CSI-RS resource occasions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If UE operates in idle or inactive modes to save power, then power consumption is reduced, but the UE cannot receive dynamic transmit power updates for CSI-RS
Solution Approach 1:
The network configures the UE with CSI-RS resource occasions and power offset values before the UE transitions to idle or inactive mode. This preliminary configuration includes providing multiple power offset values corresponding to different power saving modes, enabling the UE to autonomously determine and apply the appropriate power level without needing to receive updates while in the low-power state.
Solution Approach 2:
The UE is empowered to autonomously select and apply the appropriate power offset value from the configured set based on its current power saving mode. This self-service mechanism allows the UE to independently manage its receive power without network intervention, eliminating the need for continuous network communication while in idle or inactive modes.
2Reliability
If UE uses CSI-RS for tracking in idle/inactive modes, then tracking performance is improved, but network overhead increases
Solution Approach 1:
The network performs preliminary configuration of multiple CSI-RS resource occasions with different power offset values before the UE enters idle or inactive mode. This advance preparation includes providing power offset configurations that correspond to different power saving modes, enabling the UE to maintain reliable tracking without requiring ongoing network signaling.
Solution Approach 2:
The invention introduces power offset values as configurable parameters that adjust the transmit power of CSI-RS resources based on the UE's power saving mode. By changing the power parameter dynamically through configuration rather than continuous signaling, the network achieves adaptive tracking performance while minimizing overhead.
3Adaptability or versatility
If multiple CSI-RS resource occasions are configured with different power offsets, then power management flexibility is improved, but device complexity increases
Solution Approach 1:
The network provides all necessary power offset configurations in advance through RRC signaling or system information before the UE transitions to idle or inactive mode. This preliminary action includes configuring multiple power offset values corresponding to different power saving modes, eliminating the need for complex real-time decision-making or additional signaling while the UE is in low-power state.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive, while in a connected mode, a control message indicating whether the UE is to use channel state information (CSI) reference signals (CSI-RSs) as tracking reference signals (TRSs) when the UE operates in an idle more or an inactive mode. The UE may transition to the idle more or the inactive mode and may perform, while in the idle more or the inactive mode, automatic gain control (AGC), time/frequency tracking, or both, using the CSI-RSs as the TRSs based on the control message indicating that the UE is to use the CSI-RSs as the TRSs. In some examples, the UE may perform the AGC, time/frequency tracking, or both, based on one or more CSI-RS resource occasions associated with the CSI-RSs.