Question: What is a characteristic of the frequency hopping between symbol groups for NB-IoT random access preamble with a 1.25 kHz subcarrier spacing?
Option 1: The symbol groups always hop by a fixed number of twelve sub-carriers in frequency.
Option 2: The symbol groups hop by one, three, or eighteen sub-carriers in frequency.
Option 3: Repetitions of symbol groups only hop by a single sub-carrier in frequency for cell size optimization.
Option 4: Frequency hopping is not utilized between symbol groups with this subcarrier spacing.
Explanation: In NB-IoT random access preamble using a 1.25 kHz subcarrier spacing, frequency hopping between symbol groups is characterized by hops of one, three, or eighteen sub-carriers. This variability in hopping intervals supports adaptability for different deployment scenarios, including various cell sizes and interference conditions, enhancing the robustness of the random access procedure in diverse network environments.