Question: In E-UTRAN, when initiating a Cell Traffic Trace, what is the role of the O&M and how does the eNB communicate with the MME?
Option 1: The O&M defines all conditions for Cell Traffic Trace; upon fulfillment, the eNB allocates a Trace Recording Session Reference, sending it with the Trace Reference to the MME via the S1 interface.
Option 2: The O&M triggers the trace start; the eNB then sends trace configuration over the X2 interface to neighboring eNBs and to the MME on the S1 interface for handover preparation.
Option 3: The eNB autonomously decides when to start a Cell Traffic Trace, informing the O&M and MME (via S1 interface) after the trace has begun, without any predefined conditions.
Option 4: Cell Traffic Trace is initiated by the MME, which sends trace activation messages over the S1 interface to the eNB and simultaneously over the X2 interface for direct peer-to-peer coordination.
Explanation: This option correctly reflects the process. The Operations & Maintenance (O&M) system defines conditions for initiating a Cell Traffic Trace in E-UTRAN. Once met, the eNB allocates a unique Trace Recording Session Reference and communicates this, along with the Trace Reference, to the MME using the CELL TRAFFIC TRACE message over the S1 interface.