UE PLMN Selection for Non-Terrestrial Networks
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Solution Overview
Problem
Wireless devices face challenges in accessing non-terrestrial cellular networks due to service rejections, unknown locations, country restrictions, and mismatched network associations, leading to connectivity issues and regulatory compliance challenges.
Innovation Solution
A method for user equipment (UE) to perform public land mobile network (PLMN) selection by initiating a first NAS procedure with a non-terrestrial network (NTN), handling service rejections, and subsequently searching for and registering with a terrestrial network to provide location information, thereby enabling access to the NTN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE attempts to access a non-terrestrial network (NTN) directly, then connectivity to NTN is achieved, but service rejection occurs due to unknown location or country restrictions
Solution Approach 1:
The UE performs a preliminary registration with a terrestrial network before attempting NTN access. This preliminary action establishes location information and network context that prevents subsequent service rejection when accessing NTN, thereby improving access success rate without compromising connectivity reliability.
2Loss of information
If a UE performs location determination procedures before NTN access, then location information is available for network selection, but access time and procedure complexity increase
Solution Approach 1:
The patent combines the location determination procedure with the initial network registration procedure. The UE determines its location and provides this information during the same registration procedure used to establish network access, rather than performing separate location determination steps. This merging eliminates redundant procedures and reduces overall access time while ensuring location information is available for proper NTN selection.
3Reliability
If a UE searches for terrestrial networks before accessing NTN, then location information can be provided to avoid service rejection, but network access delay increases
Solution Approach 1:
The patent implements a dynamic network access strategy where the UE adaptively selects between direct NTN access and terrestrial network-based access based on real-time conditions. The UE monitors NTN service availability and attempts direct access when possible, switching to terrestrial network routing only when NTN access is rejected or unavailable. This dynamic approach maximizes access speed while maintaining reliability by using terrestrial networks as a fallback rather than a mandatory preliminary step.
Data Source
AI summary
Systems, devices and methods for a user equipment (UE) to perform public land mobile network (PLMN) selection with a non-terrestrial network (NTN). A UE performs a non-access stratum (NAS) procedure with a public land mobile network (PLMN) of an NTN. The UE receives a NAS message from the PLMN, and the NAS message indicates that the UE is not allowed to access a core network of the NTN. The NAS message may indicate that the UE is not allowed to access the core network of the NTN because a location of the UE is unknown to the NTN, that access to the NTN is not allowed in a country in which the UE is located, or that a location of the UE is not within a country associated with the NTN. The UE modifies its PLMN search procedure responsive to receiving the NAS message.