NTN to TN Mobility Configuration for UE Power Reduction
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Solution Overview
Problem
In the coexistence of non-terrestrial networks (NTN) and terrestrial networks (TN), user equipment (UE) faces challenges in reducing power consumption during cell search and measurements, particularly when NTN cells overlap with multiple TN cells, and handling reference timing due to propagation delays and differing timing alignments.
Innovation Solution
A method for user equipment to receive a cell search and measurement configuration from a non-terrestrial network, including information on carrier frequencies and tracking areas, allowing it to initiate and perform cell searches and measurements efficiently by applying the configuration, using the timing of the first detected TN cell to adjust offset values for subsequent measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE performs blind cell search and measurements on all carrier frequencies without SMTC configuration, then UE can detect cells on any frequency, but UE power consumption increases significantly
Solution Approach 1:
The network performs preliminary actions by configuring SMTC parameters (periodicity, offset, duration) and providing a list of candidate carrier frequencies to the UE before the UE performs cell search. This allows the UE to limit its measurements to specific time windows and frequencies, significantly reducing power consumption while maintaining reliable cell detection capability.
2Device complexity
If UE uses NTN cell timing as reference for TN cell measurements, then timing configuration can be simplified, but measurement accuracy decreases due to propagation delays
Solution Approach 1:
The patent introduces an intermediary reference timing mechanism where the UE uses the timing of a detected TN cell as a reference for measuring other TN cells, rather than directly using NTN cell timing. This intermediary approach maintains measurement accuracy by using a timing reference that is synchronized with the TN network, while still allowing the network to provide SMTC configuration parameters to manage complexity.
3Loss of information
If UE performs measurements on all overlapping TN cells in NTN coverage area, then complete mobility information is obtained, but measurement time and processing complexity increase
Solution Approach 1:
The patent segments the measurement process by dividing the coverage area into NTN tracking areas and providing the UE with a configured list of candidate carrier frequencies specific to each tracking area. This segmentation allows the UE to perform measurements only on relevant frequencies in its current location, obtaining complete mobility information for its area while significantly reducing overall measurement time and processing complexity.
Data Source
AI summary
The disclosure is directed to a method used by a user equipment for implementing non-terrestrial network (NTN) to terrestrial network (TN) communication and a user equipment using the same method. In one of the exemplary embodiments, the disclosure is directed to a method used by a user equipment for implementing NTN to TN communication. The method would include not limited to: receiving a cell search and measurement configuration from a non-terrestrial network (NTN), the cell search and measurement configuration comprises information of at least one carrier frequency and at least one NTN tracking area (TA) associated with the carrier frequency; initiating a cell search and measurement procedure; and performing the cell search and measurement procedure by applying the cell search and measurement configuration.