NTN Random Access Resource Segmentation for Location Validity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, particularly in non-terrestrial networks (NTNs), face challenges in efficiently managing random access procedures due to variations in user equipment (UE) location information accuracy, which affects timing advance and frequency synchronization, especially in scenarios with poor GNSS signaling.
Innovation Solution
The system configures separate resource sets for random access channel (RACH) operations based on the validity of UE location information, allowing UEs with valid and invalid location information to select appropriate resources for preamble transmission and receive corresponding random access response (RAR) messages with specific formatting to ensure accurate timing advance and synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single set of RACH resources is used for all UEs, then the system is simple to operate, but the reliability of random access deteriorates when UE location information is invalid
Solution Approach 1:
The RACH resources are segmented into two separate sets: a first set for UEs with valid location information and a second set for UEs with invalid location information. This segmentation allows each set to be optimized for its specific use case, improving overall random access reliability while maintaining manageable complexity through structured configuration.
Solution Approach 2:
Different RACH resource configurations are applied locally based on UE-specific conditions. UEs with valid location information use one configuration optimized for timing advance calculation, while UEs with invalid location information use another configuration. This local differentiation ensures each UE uses the most appropriate resources for its situation.
2Measurement precision
If RACH resources are separated based on location information validity, then the timing advance accuracy is improved, but the device complexity increases due to multiple resource sets
Solution Approach 1:
The RACH resources are segmented into two separate sets: a first set for UEs with valid location information and a second set for UEs with invalid location information. This segmentation allows each set to be optimized for its specific use case, improving overall random access reliability while maintaining manageable complexity through structured configuration.
Solution Approach 2:
The system changes key parameters of the RACH resources based on location information validity. The first set uses parameters optimized for UEs that can calculate timing advance from location data, while the second set uses parameters suitable for UEs that cannot. This parameter differentiation directly improves timing advance accuracy for each category.
3Reliability
If the system uses location-based resource selection, then the synchronization performance is improved, but the ease of operation deteriorates due to validity determination requirements
Solution Approach 1:
The UE autonomously determines whether its location information is valid and automatically selects the appropriate RACH resource set based on this determination. This self-service mechanism eliminates the need for network assistance in the selection process, maintaining ease of operation while achieving reliable synchronization through appropriate resource selection.
Data Source
AI summary
Methods and apparatuses of UE for performing random access procedures in NTN. A method of a UE comprises: identifying configuration information including a first and second set of resources for a RACH operation; determining whether current location information of the UE is valid for the RACH operation; selecting the first set of resources based on a determination that the current location information of the UE is valid; selecting the second set of resources based on a determination that the current location information of the UE is invalid; transmitting a RACH preamble on the selected first or second set of resources; and receiving, in response to transmitting the RACH preamble, a RAR MAC PDU. The RAR MAC PDU includes a MAC subPDU comprising a first format of MAC subPDU associated with the first set of resources and a second format of MAC subPDU associated with the second set of resources.