Question: What is the primary purpose of using a Presence Reporting Area Identifier (PRA ID) in a 5G System (5GS), and what type of elements can a Presence Reporting Area (PRA) be composed of?
Option 1: To identify UE capabilities; composed of a list of UE identifiers and Serving and Packet Data Network Gateways (SGW/PGW)
Option 2: For reporting changes in UE presence for policy control or charging decisions; composed solely of Tracking Area (TA) identifiers
Option 3: For reporting changes in UE presence for policy control or charging decisions; composed of a short list of Tracking Areas (TAs) and/or Next Generation Radio Access Network (NG-RAN) nodes and/or cell identifiers within a Public Land Mobile Network (PLMN)
Option 4: To manage Quality of Service (QoS) flows; composed of a combination of Access and Mobility Management Function (AMF) identifiers and Session Management Function (SMF) identifiers
Explanation: The correct answer, Option 3, accurately reflects the primary purpose of PRA IDs as described - for reporting changes in UE presence, which can influence policy control or charging decisions. Additionally, it correctly identifies the composition of a PRA, which can include TAs, NG-RAN nodes, and/or cell identifiers within a PLMN, highlighting the flexibility and granularity of PRAs in managing UE presence across different network elements in a 5GS.