Pathloss-Offset Power Control for Asymmetric Uplink/Downlink Channels
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Solution Overview
Problem
Wireless devices face challenges in determining optimal transmission power for uplink communication after detecting beam failure in asymmetric multi-transmission-reception point operations, particularly when relying on pathloss reference signals from anchor transmission-reception points are unreliable.
Innovation Solution
The wireless device determines a pathloss estimate based on a transmission configuration indicator state associated with an uplink-only device, using a candidate reference signal with or without a pathloss offset, to facilitate beam failure recovery by adjusting transmission power accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wireless device uses pathloss reference signal from the anchor transmission-reception point to determine power for uplink transmission, then the power determination process is simple, but the reliability deteriorates when beam failure is detected
Solution Approach 1:
The patent introduces a pathloss offset as an intermediary parameter that bridges the anchor TRP's pathloss reference signal and the uplink-only device's actual channel conditions. This offset, configured by the network based on TCI state associations, allows the wireless device to accurately estimate pathloss for uplink transmission without directly measuring the uplink channel, thus improving recovery reliability while maintaining estimation simplicity.
Solution Approach 2:
The network performs preliminary configuration by pre-calculating and signaling pathloss offsets to the wireless device before beam failure occurs. These offsets are associated with different TCI states and are prepared in advance, enabling the device to quickly determine appropriate transmission power during beam failure recovery without complex real-time measurements.
2Measurement precision
If the wireless device determines pathloss estimate using candidate reference signal without pathloss offset, then the device complexity is reduced, but the transmission power accuracy deteriorates
Solution Approach 1:
The patent changes the estimation parameter from direct pathloss measurement to pathloss offset application. Instead of measuring the actual uplink channel (which would be complex), the device applies a pre-configured pathloss offset parameter to the anchor TRP's pathloss reference signal. This parameter transformation maintains high estimation accuracy while simplifying the measurement procedure.
3Measurement precision
If the wireless device uses pathloss offset for pathloss estimation, then the transmission power accuracy is improved, but the device complexity increases
Solution Approach 1:
The network autonomously performs the complex task of calculating and configuring pathloss offsets, freeing the wireless device from complex measurements. The device simply applies the pre-provided offsets to determine transmission power, making the operation easy while maintaining high accuracy. The heavy computational burden is shifted to the network side.
Data Source
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AI summary
A wireless device may be configured to communicate with multiple computing devices, such as transmission/reception points. After a beam failure of a cell used for communication between the wireless device and an anchor transmission-reception point, the wireless device may determine a power for transmission to an uplink-only device based on a transmission configuration indicator state of a candidate reference signal and, if indicated, based on a pathloss offset. The determined transmission power may be used to facilitate beam failure recovery via the uplink-only device.