Question: For a UE (User Equipment) supporting HSDPA (High-Speed Downlink Packet Access) with capability categories 15-18, what is the primary condition that leads to declaring the probability of event Em (P(Em)) in relation to HS-SCCH (High-Speed Shared Control Channel) detection performance?
Option 1: Successful decoding of data on HS-DSCH (High-Speed Downlink Shared Channel)
Option 2: Receipt of a specific signaling sequence on both HS-SCCH-1 and HS-SCCH-2
Option 3: Signaling on HS-SCCH-1 with observed DTX (Discontinuous Transmission) in the corresponding HS-DPCCH/NACK field
Option 4: Failure to detect any signal on HS-SCCH for a predefined duration
Explanation: The correct answer, Option 3, directly relates to the condition described for declaring the probability of event Em (P(Em)), which is specifically when the UE is signaled on HS-SCCH-1 but observes DTX in the corresponding HS-DPCCH/NACK field. This scenario assesses the detection performance of the HS-SCCH under specific signaling and transmission conditions, reflecting a nuanced understanding of HSDPA operation and signaling protocols in UTRA (UMTS Terrestrial Radio Access) networks.