Question: In a 5G NR (New Radio) network, when using ROHC (Robust Header Compression) for header decompression of PDCP (Packet Data Convergence Protocol) Data PDUs associated with user plane data, what is the sequence of operations performed on received PDCP Data PDUs?
Option 1: Deciphering → ROHC Decompression → SDAP Header Processing
Option 2: ROHC Decompression → Deciphering → SDAP Header Bypassed (for decompression context)
Option 3: SDAP Header Processing → Deciphering → ROHC Decompression
Option 4: Deciphering and ROHC Decompression are performed concurrently, then SDAP Header is processed
Explanation: According to the specified behavior for PDCP entities with user plane data, after receiving PDCP Data PDUs, the first step is to perform deciphering (as explained in clause 5.8), followed by ROHC decompression. The SDAP header is not subject to this ROHC decompression process, indicating it's either processed separately or its handling is determined post-decompression, hence the correct sequence starts with deciphering.