Question: In a TDD (Time Division Duplex) UMTS (Universal Mobile Telecommunications System) network, what does the probability of event Em (P(Em)) specifically measure regarding HS-SCCH (High-Speed Shared Control Channel) detection performance?
Option 1: The likelihood of successful HSDPA (High-Speed Downlink Packet Access) data transmission when signaled via HS-SCCH.
Option 2: The probability that a UE (User Equipment) observes DTX (Discontinuous Transmission) in the HS-SICH ACK/NACK field despite being signaled on HS-SCCH, indicating failed decoding of HSDPA data signaling.
Option 3: The rate at which the SS (Serving Station) correctly indicates HSDPA data transmission to UEs via HS-SCCH without errors.
Option 4: The overall throughput of HSDPA data when transmitted over HS-SCCH in a TDD environment.
Explanation: This probability reflects instances where the UE fails to correctly decode the signaling for HSDPA data sent over the HS-SCCH, leading to the observation of DTX in the corresponding ACK/NACK field. This is a critical aspect of evaluating the detection performance of HS-SCCH in TDD UEs supporting HSDPA.