# An Emergency Alert Broadcast Based on the Convergence of 5G and ATSC 3.0
## 1 Introduction  
Recently, many cities rely on advanced technologies in order to achieve better life qualities. Especially, smart cities offer various automation applications such as autonomous vehicles and smart buildings [1]. The smart cities usually require robust emergency alert systems in order to sustain an acceptable safety level [2]. Therefore, much attention has been paid to advanced telecommunication technologies for rapid and reliable delivery of emergency alerts [3, 4, 5]. Among those technologies, cellular and broadcast networks are considered the most popular dissemination systems for emergency alerts [6, 7, 8]. The cellular networks employ cell broadcast service (CBS) for emergency alert delivery [9]. Since cellular networks can effectively select the base stations whose cells encompass emergency areas, the CBS is suitable for location-based emergency alert services [10]. Furthermore, the CBS is available even when mobile phones are in idle states, since cellular networks support a paging service for incoming calls [11]. Currently, the CBS protocols have been standardized for 2G/3G/4G/5G cellular networks [12]. Therefore, any mobile phone users can receive the CBS messages in emergency cases if the users are located in the cells, which include emergency areas. However, the current CBS protocols just support text-based messages. Moreover, the CBS message allows a limited number of characters such as 360 characters in the case of wireless emergency alerts (WEA) CBS [13]. Therefore, the CBS message just includes limited information. In turn, it is impossible to deliver detail information such as evacuation guidelines. This may often lead to a failure insustaining an acceptable safety level. Moreover, the current CBS protocols may be useless for illiterate persons or foreigners, since the protocols allow only text-based messages [14]. Broadcast networks also offer emergency alert services. Terrestrial digital multimedia broadcast (T-DMB) can deliver emergency alert messages even to mobile users [15; 16; 17; 18]. However, T-DMB just supports text-based messages, which rely on automatic emergency alerting service (AEAS) [19]. Recently, advanced television systems committee (ATSC) 3.0 revealed about 20 standards for ultra-high definition (UHD) TV services and IP-based transmissions [20; 21; 22; 23]. The ATSC 3.0 also specifies a standard for emergency alert broadcast, which is called advanced emergency information (AEA) [24]. One or more AEA messages include multimedia information as well as text data. Therefore, the ATSC 3.0 can deliver more abundant information such as guidelines in various emergency cases. In order to enable an idle-state receiver in the cases of emergency alerts, the ATSC 3.0 transmits wake-up information, which is similar to the paging service of cellular networks. However, most mobile phones including smart phones employ internal antennas. Therefore, the ATSC 3.0 receiver exhibits very poor receiver sensitivity in the internal antenna situation, since the ATSC 3.0 system operates at the carrier frequency of about 600 MHz [25]. This may interfere with reliable usage of the wake-up information especially for mobile-phone users. Some complicated decoding algorithms were suggested for a reliable decoding of the wake-up information at low SNR levels [26; 27]. However, the use of the algorithms may lead to excessive battery consumption. Therefore, the wake-up information is just available for TV receivers with external antennas. On the other hand, the paging service of the cellular networks is available even in the internal antenna case, since the cellular systems operate at much higher carrier frequencies such as 3.5 GHz. For location-based emergency alert services, location information can be embedded into the AEA messages. However, ATSC 3.0 receivers should employ a location-awareness functionality for the location-based services. Even though most smart phones employ GPS modules, the GPS devices do not guarantee high positioning accuracy.