# An Emergency Alert Broadcast Based on the Convergence of 5G and ATSC 3.0
## 1 Introduction
Therefore, some mobile users may fail in receiving the AEA messages due to the positioning error even in the cases that the users exist in emergency areas. Note that cellular networks inherently offer location-based emergency alert services, since the networks can easily select the appropriate base stations, which encompass emergency areas. In order to improve the emergency alert broadcast service in mobile environments, we propose a novel emergency alert broadcast approach, which is based on the convergence of the 5G cellular network and the ATSC 3.0 network. Note that the 5G and the ATSC 3.0 are the latest protocols in cellular and broadcast networks, respectively. For the approach, we present a convergence architecture, which is suitable for the emergency alert broadcast. The convergence architecture employs themon-3 GPP networking function (N3 IWF) [28], which is an element of the 5G service based architecture (SBA) [29]. The N3 IWF is standardized for interworking betweennon-3 GPP network such as ATSC 3.0 network and 5G core network [28]. We also present a modified AEA table, which associates the AEA message with the corresponding CBS message. Based on the association, an alerting authority can reliably deliver an emergency message on the convergence network for emergency alert service. We also propose a novel scenario for the emergency alert service on the convergence network. Especially, the scenario specifies the role of the N3 IWF for the broadcast of CBS and AEA messages on the convergence network. The scenario also specifies the relations among the CBS paging, the CBS message broadcast, and the AEA message broadcast. This allows a simultaneous transmission of CBS message and AEA message on the convergence network. Since the presented method effectively exploits the convergence, the scheme takes the advantages of the 5G and the ATSC 3.0 networks: multimedia information from the ATSC 3.0 network, and paging service and location-based service from the 5G cellular network. Furthermore, the proposed method can lower delivery latency, since users can receive the CBS message and the AEA message from the 5G and the ATSC 3.0 networks, respectively. Some general architectures for combination of 5G and ATSC 3.0 networks have been suggested in [30] and [31]. However, the architectures [30; 31] never reveal a specific framework for emergency alert broadcasts. Moreover, the architectures [30; 31] never include a specific procedure for simultaneous delivery of 5G CBS message and AEA message. Therefore, the main contributions of this paper are as follows:  
* We extended the general architectures into a 5G and ATSC 3.0 convergence network for emergency alert broadcast. The general architectures never reflect the interfaces among alerting authority, 5G CBS message generation, and AEA message application for the simultaneous delivery. We incorporated the interfaces into the convergence network. Furthermore, we added the functionality of CBS paging [8] to the convergence network, which enables mobile phones to receive AEA message as well as CBS message. Since the convergence network exhibits a unique architecture for emergency alert broadcast, the extension into the convergence network is a main contribution. * We also proposed a novel framework for more reliable emergency alert broadcasts. The presented framework is utilized for a synchronization between CBS paging and AEA message in the 5G and ATSC 3.0 convergence network. The framework controls the delivery of AEA message, which guarantees that the AEA message is transmitted after the CBS paging is asserted. Since the framework exhibits a novel structure for the synchronization, the proposed framework is another contribution in this paper. * In addition, we presented a novel procedure for simultaneous delivery of 5G CBS message and AEA message. Especially, the proposed procedure specifies the operations of the presented framework. The procedure guarantees that idle-state mobile phones can receive AEA message as well as CBS message using the CBS paging.