UL Pathloss Offset for Asymmetric Macro-Micro Coverage
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Solution Overview
Problem
In asymmetric DL-UL communication scenarios where a user equipment receives DL transmissions from a macro base station and sends UL transmissions to a non-co-located micro base station, the pathloss measured from the macro BS/TRP does not accurately reflect the actual pathloss to the micro BS/TRP, necessitating enhancements in UL power control to facilitate accurate pathloss calculation and power headroom reporting.
Innovation Solution
A user equipment (UE) is configured with pathloss offsets for respective TCI states, allowing it to determine pathloss variations and trigger power headroom reports based on these offsets, and adjust transmission power for random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE uses the pathloss measured from the macro BS/TRP for UL power control, then the power control procedure is simple, but the pathloss does not accurately reflect the actual pathloss to the micro UL-only BS/TRP
Solution Approach 1:
The patent introduces a pathloss offset as an intermediary parameter to bridge the gap between the DL pathloss measurement from the macro BS and the actual UL pathloss to the micro BS. The UE applies this offset to the measured DL pathloss to obtain an accurate estimate of the UL pathloss, resolving the contradiction between measurement simplicity and accuracy.
Solution Approach 2:
The patent modifies the pathloss calculation by introducing a configurable offset parameter. The network can adjust this offset parameter to account for the pathloss difference between DL and UL directions, allowing the system to adapt to varying deployment scenarios while maintaining accurate power control.
2Use of energy by moving object
If the micro UL-only BS/TRP reduces or turns off DL transmissions to save energy, then energy consumption is reduced, but the UE cannot accurately determine UL pathloss without DL reference signals
Solution Approach 1:
The network configures the pathloss offset parameter in advance through RRC signaling, before the UE needs to perform UL power control. This preliminary configuration allows the UE to accurately calculate UL pathloss even when the micro BS does not transmit DL reference signals, enabling energy savings at the micro BS while maintaining measurement accuracy at the UE.
Solution Approach 2:
The pathloss offset acts as a mediator that compensates for the absence of DL reference signals from the micro BS. By applying this offset to the DL pathloss measurement from the macro BS, the UE can derive accurate UL pathloss information without requiring active DL transmissions from the energy-saving micro BS.
3Reliability
If the UE triggers PHR based on pathloss variation, then power headroom reporting is timely and accurate, but additional processing and signaling are required
Solution Approach 1:
The patent implements a feedback mechanism where the UE monitors pathloss variation (using the configured offset) and triggers PHR reporting when thresholds are exceeded. This feedback loop ensures that the network receives timely power headroom information when it becomes relevant, improving reliability without requiring continuous reporting and associated complex processing.
Data Source
AI summary
Disclosed are techniques for a UE to use a pathloss offset between the DL pathloss RS from a macro BS/TRP and the actual pathloss for UL transmission to a micro UL-only BS/TRP when reporting power headroom or performing a random access procedure. The UE may receive from a first base station a configuration for one or more pathloss offsets associated with respective one or more TCI states. The UE may determine a pathloss variation toward a second base station between a first pathloss measured at a current time and a second pathloss measured at a previous time based on the one or more pathloss offsets associated with the respective one or more TCI states. The UE may determine that the pathloss variation satisfies a triggering condition for a power headroom report (PHR) for an uplink transmission associated with the TCI states. The UE may trigger a transmission of the PHR.