Question: In NB-IoT, for single-tone NPUSCH with UL-SCH demodulation and 15 kHz subcarrier spacing, where in the slot are uplink demodulation reference signals transmitted?
Option 1: In the 3rd block of the slot
Option 2: In the 4th block of the slot
Option 3: Across the entire slot for increased robustness
Option 4: Only in the last block of the slot
Explanation: According to NB-IoT specifications, uplink demodulation reference signals for single-tone NPUSCH with UL-SCH demodulation and 15 kHz subcarrier spacing are transmitted in the 4th block of the slot. This placement is crucial for efficient demodulation at the receiver end, highlighting the importance of standardized signal positioning in wireless communication protocols.