Question: In UMTS networks, what happens when the source RNC expects but does not receive a RANAP RELOCATION COMMAND or RELOCATION PREPARATION FAILURE message for 'Failed relocation preparations with UE involved for PS domain'?
Option 1: The event is ignored and not counted in any failure cause.
Option 2: It is added to a 'No Reply' measurement cause, which is specific to this scenario.
Option 3: The source RNC re-sends the RELOCATION REQUIRED message.
Option 4: The failure is attributed to a generic 'Unknown Cause' category.
Explanation: If expected RANAP messages are not received by the source RNC in response to a RELOCATION REQUIRED message for UE involved relocation in the PS domain, this scenario is counted under a 'No Reply' measurement cause, used for tracking failures due to lack of response.