Question: What are the two types of uplink reference signals supported in E-UTRA?
Option 1: Demodulation reference signal, associated with transmission of PDCCH or PBCH
Option 2: Demodulation reference signal, associated with transmission of PUSCH or (S)PUCCH and Sounding reference signal, not associated with transmission of PUSCH or (S)PUCCH
Option 3: Sounding reference signal, associated with transmission of PDCCH or PBCH and Demodulation reference signal, not associated with transmission of PUSCH or (S)PUCCH
Option 4: Demodulation reference signal, associated with transmission of PDSCH or PMCH
Explanation: In E-UTRA, two types of uplink reference signals are supported. The demodulation reference signal is used for the transmission of PUSCH (Physical Uplink Shared Channel) or (S)PUCCH (Short/ Scheduling Physical Uplink Control Channel), while the sounding reference signal is not associated with these transmissions. This distinction highlights their roles in facilitating channel estimation and feedback for uplink data transmission and control signaling, respectively.