UE TCI State Switching Delay Reduction
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Solution Overview
Problem
In 5G New Radio (NR) networks, user equipment (UE) faces challenges in efficiently switching between transmission configuration indicator (TCI) states, particularly in managing the delay time for uplink and downlink signal transitions, which affects channel property determination and beam refinement, leading to potential service disruptions.
Innovation Solution
The UE is equipped with a processor and transceiver configured to receive and decode TCI state change commands, perform necessary measurements, and switch to the target TCI state within specified delay times, considering factors like command decoding, beam refinement, and pathloss measurement, to ensure seamless transitions for both joint and separate TCI state switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs comprehensive measurements (including pathloss measurement) and decoding for TCI state change, then the switching accuracy and reliability are improved, but the switching delay time increases
Solution Approach 1:
The UE performs pathloss measurements and other necessary measurements in advance before the TCI state switching is actually required. By preparing measurement results beforehand, the UE reduces the critical path delay during actual TCI state transitions while ensuring measurement accuracy for reliable switching.
Solution Approach 2:
The TCI state switching process is divided into separate measurement phases and switching execution phases. Measurements including pathloss are performed in one phase, while the actual TCI state switching occurs in another phase, allowing parallel processing and reducing overall switching delay.
2Measurement precision
If the UE completes all necessary measurements and decoding before switching, then the channel property determination accuracy is improved, but the service continuity is affected due to longer switching time
Solution Approach 1:
The UE performs channel measurements and decoding operations in advance of the actual TCI state switching event. This preliminary preparation ensures that when switching is required, the UE already has accurate channel property information ready, minimizing service interruption while maintaining measurement precision.
Solution Approach 2:
The measurement process continues in the background during normal operation, allowing the UE to maintain up-to-date channel knowledge without interrupting service. The useful action of measurement is continuous rather than batched, ensuring both accuracy and service continuity.
3Reliability
If the UE performs pathloss measurement for UL channel, then the uplink transmission quality is improved, but the measurement time and switching delay increase
Solution Approach 1:
The pathloss measurement for uplink channel is combined with downlink signal measurements that are already being performed for TCI state management. By merging these measurement operations, the UE obtains both uplink and downlink channel information simultaneously, improving uplink transmission quality without additional measurement time.
Data Source
AI summary
A user equipment (UE) is configured to receive a command for a transmission configuration indicator (TCI) state change for a joint TCI state including uplink (UL) and downlink (DL) signals, decode the joint TCI state command and performing measurements necessary to receive and transmit with the target TCI state, the measurements including a pathloss (PL) measurement for an UL channel and switch to receive the DL signals and transmit the UL signals with the target TCI state no later than a time duration for a switching delay.