ses 12 and 13. The basic technology components, like QoS prioritization and emergency calls, are available already in Releases 8-11. Public safety users need to have the priority over other users in the congested area. Such functionalities include access control with access class barring, admission control with preemption, and prioritization in resource allocation. Proximity services (D2D) are included in Release 12 and enhanced D2D in Release 13. Also, group communications is included in Release 12 and mission-critical push-to-talk in Release 13 as well as standalone base station. The main 3GPP features for public safety are summarized in Figure 16.23. Some of the features are implemented in the mobile networks and some of the features in the application servers and devices. LTE Release 8-11 LTE Release 12-15 5G Release 16+ Mobile radio + core Voice over LTE Group calls 5G features for ultra- Emergency calls Device-to-device reliable low latency Quality of Service Standalone BTS communications Applications Mission-critical TETRA voice, video, data interworking Completed 2009-13 Completed 2014-18 Figure 16.23 Public safety features in 3GPP. 16.3 LTE-Advanced Pro Technologies Option 1 Option 2 Option 3 Option 4 Option 5 Services Services Services Services Services Radio Radio Radio Radio Radio ((II)) ((II)) ((II)) ((i)) ((p)) ((p)) Shared Shared Shared Dedicated Dedicated spectrum spectrum spectrum spectrum spectrum = Public safety operator = Mobile network operator Figure 16.24 Functionality split options for public safety implementation with mobile network operator. LTE public safety service can be organized in a number of different ways, and the responsibilities and functionalities can be divided between the public safety operator and the mobile network operator. The main five options are shown in Figure 16.24. The target in most options is to take advantage of the existing mobile network coverage and capacity. Options 1-3 use shared spectrum with the mobile operator, while options 4-5 have a dedicated spectrum