# Call Model and Test-Verification Methods for PS-LTE Core Equipment
###### Abstract  
Existing technologies in disaster and safety communication networks (DSCNs) face problems such as narrow bandwidth, low transmission rate, and difficulty in securing channels. Conversely, public safety long-term evolution (PS-LTE) technology provides high-speed, low-latency, quick-setup, and high-security data access for multimedia-based mission-critical services. To perform tests on each unit of core equipment with PS-LTE technology, a new call model such as push-to-talk, which is a service representing PS-LTE, is required. Moreover, objective and consistent metrics and methods are required for administering tests on the unique functions of DSCNs newly constructed with PS-LTE technology. This paper proposes a call model for the core facilities of DSCNs established in Korea, and it also suggests test and verification methods for all the areas of PS-LTE, including mission-critical push-to-talk, evolved multimedia broadcast and multicast service, and coverage and quality assessment for wireless services. DSCN; PS-LTE; MCPTT; performance test; eMBMS +
Footnote †: journal: _Electronics_  
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in March 2015. For Release 13, the main designs for Stage 2 architecture and the detailed designs for Stage 3 protocol were completed in 2015, and Release 13 was confirmed in March 2016 [1, 2, 3, 4]. The standardization of disaster and safety communication began in 3 GPP Release 12, and research on MCPTT services and the mode of operation for standalone base stations were completed in Release 13 [5]. In other words, applying Release 13 for the construction of DSCNs is recommended as it includes completed core standardization for disaster and safety communication. The Federal Communications Commission (FCC) of the US selected LTE as the technology to be used for DSCNs in 2011 and allocated the D-Block of the 700 MHz band. PS-LTE-based DSCNs are planned to be established by 2021 in a form wherein commercial and private networks run in parallel [6, 7]. Canada and Chile have completed the frequency allocation of PS-LTE, and the EU has started joint research on the transition to PS-LTE. DSCNs refer to a communication infrastructure that establishes a field command and situation propagation system and facilitates their joint utilization. Such a system can respond actively and cohesively in crisis situations, and it is used for public safety during peacetime and for relief efforts in disaster situations. As climate change is accelerating the frequency of natural and large-scale disasters, building an advanced system to effectively respond to these disasters is necessary [8, 9, 10, 11]. Korea began the construction of DSCNs in 2019, with expected completion by the first half of 2021. DSCNs are dedicated communication networks for eight disaster response agencies, including police, military, and fire departments, which enable an integrated response to disasters and are used for disaster management tasks during peacetime. The established network draws primarily from private networks and utilizes a part of commercial networks. Its frequency band (band 28) uses 20 MHz, with 718-728 MHz for uplink and 773-783 MHz for downlink. For securing the call rights of DSCNs, of particular interest are the core national infrastructure, roads, and densely-populated areas, which represent areas where disaster response agencies, including police and fire departments, are mainly active. Because expected damage in case of a disaster is severe in these areas, private networks should be utilized to ensure reliable communications at all times. Because PS-LTE is established for public purposes, most of it is being led by the state, and checking whether it satisfies performance requirements before and after its establishment is necessary.