Pathloss Measurement on Unlicensed Spectrum via COT Segmentation
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Solution Overview
Problem
Pathloss measurement accuracy degrades in beam-based 5G/NR systems operating on unlicensed spectra due to restrictions on CSI-RS transmissions and the absence of CSI-RS during channel occupancy times, affecting transmit power control.
Innovation Solution
A method and apparatus for validating the practicability of pathloss measurement configurations, allowing measurement based on configured reference signals when practicable or switching to alternative signals on the same quasi-co-location chain when not, ensuring continuous pathloss measurement and transmit power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LBT-based channel access mechanism is used for periodic reference signals, then channel access compliance is improved, but transmission reliability and measurement accuracy deteriorate due to uncertainty and potential signal absence
Solution Approach 1:
The gNB performs LBT and acquires channel occupancy time (COT) in advance before transmitting periodic reference signals. The COT is configured to cover multiple reference signal occasions, ensuring that the signals can be transmitted without performing LBT at each occasion. This preliminary action eliminates the uncertainty of per-signal LBT while maintaining compliance with channel access requirements.
Solution Approach 2:
The patent implements periodic reference signal transmissions within a configured COT structure. Instead of performing LBT for each individual signal transmission, the system uses periodic signaling within the pre-acquired COT, transforming the access mechanism from event-driven LBT to structured periodic transmission with initial LBT.
2Adaptability or versatility
If LBT is performed for each periodic reference signal transmission, then channel access rules are followed, but pathloss measurement accuracy deteriorates due to signal absence and transmission uncertainty
Solution Approach 1:
The gNB performs LBT and acquires channel occupancy time (COT) in advance before transmitting periodic reference signals. The COT is configured to cover multiple reference signal occasions, ensuring that the signals can be transmitted without performing LBT at each occasion. This preliminary action eliminates the uncertainty of per-signal LBT while maintaining compliance with channel access requirements.
Solution Approach 2:
By establishing a continuous COT that spans multiple reference signal occasions, the patent ensures uninterrupted transmission of periodic reference signals. This continuous transmission mode eliminates gaps caused by repeated LBT attempts, ensuring that the UE can continuously measure pathloss without interruption, thereby improving measurement accuracy and reliability.
3Object-affected harmful factors
If CSI-RS is restricted during channel occupancy times, then interference management is improved, but pathloss measurement capability deteriorates due to absence of measurement reference signals
Solution Approach 1:
The patent segments the COT into distinct functional regions: an initial LBT access phase followed by a reference signal transmission phase. During the reference signal phase, CSI-RS transmissions are explicitly allowed and configured, while other transmissions may be restricted. This segmentation enables selective interference management that protects pathloss measurement signals while maintaining overall interference control.
Solution Approach 2:
The patent applies different transmission rules to different parts of the COT. Specifically, within the COT, CSI-RS resources configured for pathloss measurement are granted transmission permission while other signals may be restricted. This local quality approach allows the system to maintain strict interference control overall while creating protected zones for critical measurement signals.
Data Source
AI summary
There are provided measures for enabling/realizing pathloss measurement on an unlicensed spectrum, i.e. arrangement of an appropriate pathloss reference signal for operation on an unlicensed spectrum. Such measures exemplarily comprise that a communication node or element in a communication system, which is configured for beam-based operation on an unlicensed band, obtains a pathloss measurement configuration, including a reference signal for pathloss measurement, validates practicability of pathloss measurement based on the configured reference signal, and controls pathloss measurement, wherein pathloss is measured based on the configured reference signal in a case where the configured reference signal is practicable, or pathloss measurement is skipped or pathloss is measured based on another reference signal being on the same quasi-co-location chain as the configured reference signal in a case where the configured reference signal is not practicable.