Question: Which of the following sidelink physical signals in a 5G New Radio (NR) network is primarily used for assisting with phase tracking at the receiver side, to mitigate phase noise and Doppler effects?
Option 1: Phase-Tracking Reference Signals (PT-RS)
Option 2: Channel-State Information Reference Signal (CSI-RS)
Option 3: Demodulation Reference Signals (DM-RS)
Option 4: Sidelink Primary Synchronization Signal (S-PSS)
Explanation: Phase-Tracking Reference Signals (PT-RS) are specifically designed to help the receiver track and compensate for phase variations over time, which can be caused by Doppler shifts or local oscillator phase noise. This is crucial for maintaining coherent demodulation in high-mobility scenarios or at high frequencies where such effects are more pronounced. While DM-RS aids in demodulation and CSI-RS in channel state estimation, and S-PSS in synchronization, PT-RS is uniquely focused on phase tracking.