Question: What is the primary characteristic of a Closed Subscriber Group (CSG) in terms of accessibility within an E-UTRAN and UTRAN?
Option 1: A single cell or a collection of cells open to only a certain group of subscribers, identified by a unique CSG-ID.
Option 2: A set of cells reserved exclusively for emergency services, identifiable by a dynamic ID.
Option 3: A network of cells providing public Wi-Fi hotspots, managed through a variable length identifier.
Option 4: An isolated cell or group of cells used for testing purposes only, without any subscriber identification.
Explanation: This option correctly captures the essence of a Closed Subscriber Group. A CSG limits access to its associated cells to a specific subset of subscribers, with each CSG uniquely identified by a fixed-length identifier (CSG-ID), crucial for managing and restricting network access based on predefined groups.