Question: What is a key architectural requirement for Mission Critical (MC) service architecture in terms of its integration with existing network infrastructure?
Option 1: Mandatory deployment of a dedicated, isolated network for MC services
Option 2: Implementation of all group management functions on the User Equipment (UE)
Option 3: Functional decomposition into distinct logical functions to enable reuse and integration with existing PLMN architecture
Option 4: Exclusive use of the application plane for all MC service provisioning, without a signalling control plane split
Explanation: This is correct because one of the general architectural requirements for MC services is to develop economies of scale by allowing Public Land Mobile Network (PLMN) operators to reuse the MC service architecture for non-public safety customers with similar functionality. This necessitates breaking down the MC service architecture into distinct logical functions, making it easier to integrate with existing network architectures and facilitating shared components across different types of services.