Network-Assisted PL-RS Maintenance for Fast Inter-Cell UL Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The current specifications for wireless communication systems, particularly in LTE and 5G, lack clear definitions and conditions for managing active uplink transmission configuration indicator (TCI) states, leading to uncertainties in pathloss reference signal (PL-RS) maintenance, which can cause UL transmission delays and scheduling inefficiencies.
Innovation Solution
Implementing a method where the user device receives a set of active TCI states and performs pathloss measurements to obtain power control values before uplink transmissions, allowing for immediate UL transmission by reusing, setting independently, or maintaining a subset of DL TCI states, and indicating PL-RS separately to manage the active UL TCI list effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pathloss measurements are performed for each active uplink TCI state associated with another network node, then uplink transmission power control accuracy is improved, but transmission latency and processing time increase
Solution Approach 1:
The user device performs pathloss measurements and obtains power control values before the actual uplink transmission occurs. By preparing these measurements in advance when TCI states are activated or updated, the device ensures that accurate power control values are ready when needed, eliminating measurement delays during critical transmission moments.
Solution Approach 2:
The patent maintains a buffer of pre-calculated power control values for multiple active uplink TCI states. This cushioning approach ensures that even if measurements need to be performed, the system already has prepared values ready, reducing the time penalty and providing a safety margin for rapid TCI state switching without transmission interruptions.
2Productivity
If the user device maintains pathloss reference signals for all active uplink TCI states, then scheduling efficiency is improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent applies different quality levels of pathloss reference signal maintenance to different uplink TCI states based on their specific needs. Rather than uniformly maintaining all TCI states with equal detail, the system selectively maintains pathloss references for states that are actively used or likely to be activated soon, optimizing the balance between scheduling readiness and processing overhead.
Solution Approach 2:
The system maintains pathloss reference signals for a subset of active uplink TCI states rather than all possible states. This partial action approach focuses resources on the most critical TCI states while still providing sufficient scheduling efficiency for immediate transmissions, avoiding the excessive complexity of maintaining complete pathloss information for every potential state.
3Reliability
If pathloss measurements are performed before uplink transmission, then transmission reliability is improved, but energy consumption increases
Solution Approach 1:
Pathloss measurements are performed in advance during TCI state activation or updates rather than at the moment of transmission. This preliminary action ensures reliable power control values are established before needed, improving transmission reliability while spreading the energy cost over a longer period when the device is already active and processing other tasks.
Solution Approach 2:
The system uses existing downlink reference signals and channel conditions to self-determine uplink pathloss characteristics without requiring additional dedicated measurement transmissions. This self-service approach leverages already-available information to reduce the energy cost of pathloss measurements while maintaining reliable power control for uplink transmissions.
Data Source
AI summary
Techniques to execute UL TCI switching without latency due to pathloss measurements for a list of active TCI states for UL transmission. Pathloss measurement reference signals for UL transmission are maintained to obtain power control value prior to the UL transmission to a network node. In addition, the active TCI list for UL configuration should be aligned between network and the UE by pre-configuration. A UE should prepare the pathloss measurement based on the list of active TCIs. In some implementations, the UE provides feedback to the network as to which UL TCI states it is currently maintaining, either based on network request or when UE is no longer able to maintain the PL-RS for a particular UL TCI state (i.e., the DL signal for the PL-RS is too weak to be detectable). This report could be provided for example via L1 feedback, UL MAC CE or as RRC message.