Question: In a NG-RAN, if a UE receives no Real-Time Integrity assistance in a Provide Assistance Data message, how should it interpret the health status of all monitored GNSS satellites and signals for integrity purposes?
Option 1: All satellites and signals are considered "Do Not Use" (DNU=TRUE) by default.
Option 2: The UE should request additional information before determining the health status.
Option 3: All satellites and signals are assumed healthy (DNU=FALSE) unless otherwise indicated.
Option 4: The UE's GNSS receiver will automatically switch to a different constellation.
Explanation: According to the specifications, the absence of Real-Time Integrity assistance in any Provide Assistance Data message implies that all monitored satellites and signals are considered healthy (i.e., DNU=FALSE) for integrity purposes, unless explicitly marked otherwise. This ensures continuity of service when no negative information is provided.