Pathloss Reference Signal Activation for Beam Switching
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Solution Overview
Problem
In wireless communication networks, user equipment (UE) faces challenges in rapidly switching to optimal beams due to outdated reference signal measurements, leading to potential delays and reduced data throughput, especially when channel conditions change rapidly.
Innovation Solution
The implementation of quasi-co-located (QCL) reference signals allows the UE to measure and report received power of downlink pathloss reference signals, enabling faster beam switching by considering the characteristics shared with other reference signals, thereby improving uplink power control and reducing switching delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE measures RSRP of pathloss reference signals periodically, then the pathloss estimation is maintained, but the measurements become outdated when channel conditions change rapidly
Solution Approach 1:
The UE performs RSRP measurements of pathloss reference signals in advance and maintains these measurements for a configured duration or until a more recent measurement is available. This preliminary action allows the UE to have ready-to-use pathloss estimates without waiting for periodic updates, thereby reducing beam switching delay while maintaining acceptable measurement accuracy.
2Speed
If the UE updates pathloss measurements frequently, then the beam switching is faster, but the measurement overhead and processing complexity increase
Solution Approach 1:
The system dynamically adjusts the beam switching process by determining whether a target pathloss reference signal is 'known' based on timing relationships between reference signal reception, RSRP measurement transmission, and activation command reception. This dynamic approach allows the UE to switch beams rapidly when conditions permit (reducing complexity) while still maintaining accurate measurements when needed (improving speed without unnecessary complexity).
Solution Approach 2:
The patent changes the parameter of measurement recency by introducing a timing-based determination of whether a pathloss reference signal is 'known'. Instead of always performing frequent measurements, the system changes the measurement parameter state based on whether the timing conditions are met, allowing fast switching when the target signal is known and more careful measurement when it is not.
3Reliability
If the UE waits for latest RSRP measurements before switching beams, then the pathloss estimation is accurate, but the beam switching delay increases
Solution Approach 1:
The UE performs RSRP measurements of pathloss reference signals in advance and maintains these measurements for a configured duration or until a more recent measurement is available. This preliminary action allows the UE to have ready-to-use pathloss estimates without waiting for periodic updates, thereby reducing beam switching delay while maintaining acceptable measurement accuracy.
Solution Approach 2:
The system uses a 'known' target pathloss reference signal as a copy or substitute for the actual target signal when direct measurement is not available. By determining timing relationships and using previously measured RSRP values as proxies, the UE can reliably estimate pathloss for beam switching without waiting for fresh measurements, thus maintaining reliability while reducing delay.
Data Source
AI summary
Methods and systems to activate beams for beam switching based on measurements of a downlink reference signal that is QCL Type-D with a downlink pathloss reference signal are disclosed. A UE may measure and report to a base station the RSRP of the reference signal that is QCL Type-D with a target downlink pathloss reference signal. Based on the reported RSRP measurements, the base station may activate the target pathloss reference signal to command the UE to update the pathloss measurements of the target pathloss reference signal for uplink power control of a beam corresponding to the target pathloss reference signal. The UE may determine whether the target pathloss reference signal is considered known for uplink power control based on the timing relationship among the reception of the reference signal from the base station, the transmission of the RSRP measurement of the reference signal, and reception of the activation command.