Question: When a User Equipment (UE) uses Global Navigation Satellite System (GNSS) as the synchronization reference source for V2X sidelink communication, how is the Discontinuous Transmission Frame Number (DFN) primarily derived from the current UTC time obtained from GNSS?
Option 1: DFN is directly derived from the difference between the current UTC time and a fixed reference UTC time, adjusted by an optional offset, using the formula: DFN = FLOOR(0.1*(Tcurrent – Tref – offsetDFN)) mod 1024
Option 2: DFN is calculated based on the UE's location coordinates provided by GNSS, applying a proprietary algorithm to ensure synchronization across different geographical locations.
Option 3: The derivation of DFN from GNSS involves a complex multi-step process including signal strength, satellite constellation, and atmospheric conditions, which are then averaged over a minute window.
Option 4: DFN is not derived from UTC time but rather from the GNSS signal's Doppler shift, which indicates the UE's velocity relative to the satellites.
Explanation: The correct derivation of DFN from GNSS involves a mathematical formula utilizing the current UTC time (Tcurrent), a reference UTC time (Tref), and an optional offset (offsetDFN). This process ensures synchronization for V2X sidelink communication without relying on other factors like location, signal strength, or Doppler shift. Option 1 accurately reflects this process, making it the correct answer.