Question: In a Terminal Conformance Test for Radio Transmission and Reception (TDD), what triggers the computation of the RLC SDU error rate by the SS (System Simulator)?
Option 1: Receipt of “UE TEST LOOP MODE 3 RLC SDU COUNTER RESPONSE” from the UE, containing the received RLC SDU counter value.
Option 2: Expiration of a predefined test duration timer set on the SS.
Option 3: Completion of a fixed number of transmitted RLC SDU blocks by the SS.
Option 4: Switching to a different radio bearer for data transmission.
Explanation: The correct answer is Option 1 because, according to the procedure, after sending a “UE TEST LOOP MODE 3 RLC SDU COUNTER REQUEST”, the SS waits for the UE's response with a “UE TEST LOOP MODE 3 RLC SDU COUNTER RESPONSE”. This response contains the received RLC SDU counter value, which, when compared with the transmitted RLC SDUs count (maintained by the SS), allows the SS to compute the RLC SDU error rate. This step is crucial for assessing the reliability of data transmission in a TDD setup.