Question: For a 2.5 kHz subcarrier spacing in E-UTRA, what parameters are used to define the MBSFN reference-signal sequence `r(m)` initialization for the pseudo-random sequence generator?
Option 1: Cell ID and OFDM symbol number within a slot
Option 2: Subframe number within a radio frame and OFDM symbol number within the subframe
Option 3: Slot number within a 10 ms frame and Physical Resource Block (PRB) index
Option 4: Radio frame number and System Frame Number (SFN) modulo 4
Explanation: In E-UTRA for a 2.5 kHz subcarrier spacing, the initialization of the pseudo-random sequence generator for the MBSFN reference-signal sequence `r(m)` relies on the timing within the radio frame structure, utilizing the subframe number within a radio frame and the OFDM symbol number within that subframe, providing temporal diversity and uniqueness for sequence generation across the network.