Question: What triggers the RLC receiver to initiate an RLC status report in addition to polling by the RLC, within the E-UTRAN's RLC sublayer ARQ mechanism?
Option 1: Detection of a missing RLC PDU or RLC PDU segment
Option 2: Receipt of a complete set of RLC PDUs
Option 3: Expiration of a predetermined timer without receiving new RLC PDUs
Option 4: Instruction from the E-UTRAN's control plane to reset the ARQ process
Explanation: In the context of E-UTRAN's RLC sublayer, the Automatic Repeat Request (ARQ) mechanism ensures reliable data transfer. One of its features is the ability to request status reports. While polling is one method used by the RLC to obtain these reports, the receiver also has the capability to autonomously trigger a status report when it identifies gaps in the sequence of received data, specifically upon detecting a missing RLC PDU or segment. This proactive approach helps in promptly addressing transmission errors and maintaining data integrity.