## 2 Overview of IoT Applications Used for AIS and Fire Detection
The AIS, as shown in Figure 2, is composed of a transmitter, two receivers (TDMA VHF), a computer, a Digital Selective Calling (DSC) system, a satellite positioning system (GPS, GLONASS, and BEIDU), and a Display Control Unit (DCU) (control screen), and is interfaced with the vessel's instruments (gyroscopic or satellite compass, heading change speed indicator (optional), and log). Figure 2: AIS architecture. AIS uses the two VHF frequency ranges from 161,975 MHz to 162,025 MHz, which have been reserved worldwide for this application. AIS employs the Gaussian Minimum Shift Keying (GMSK) modulation type with the rate of 9600 bauds. GMSK is a type of digital modulation that effectively encodes data by altering the carrier frequency in a way that reduces interference and spectrum spreading. It shapes the modulated signal using a Gaussian-shaped filter, which improves bandwidth efficiency and lessens fading and noise sensitivity. This modulation method enables AIS to broadcast data over a given frequency range while preserving precise and dependable connection between ships and shore stations. The packets containing 168 or 440 bits are preceded by a 24-bit preamble, making it possible to synchronize the receiver [16]. To structure and transmit data between ships and shore stations in the AIS, High-Level Data Link Control (HDLC) frames are utilized. These frames offer flow control, error detection, and synchronization for dependable communication. In order to maximize data transmission efficiency and signal integrity, AIS also uses Non-Return to Zero Inverted (NRZI) encoding, in which transitions or their lack indicate binary data. The accurate and effective interchange of information throughout the AIS network is made possible by HDLC frames and NRZI encoding working together. These HDLC-based frames also include a Cyclic Redundancy Check (CRC) code. AIS sound footprint is close to background noise, and the frames are only 30 ms long. The idea of satellite reception of AIS signals is at present being studied by a variety of projects financed by the European Space Agency and the European Commission as well as private initiative projects. The European Space Agency's SAT-AIS initiative, for example, sought to develop and demonstrate the capacity of receiving AIS signals from spaceborne receivers [17]. NASA's Traffic Awareness for General Aviation-Data Information Service (TAMDAR-DIS) project also included AIS reception to improve general aviation situational awareness [18]. Furthermore, collaborative activities in Canada, such as the Space-based AIS Experiment, which involved the Canadian Space Agency and industry partners, focused on showing the feasibility and usefulness of receiving AIS signals from space [19]. The RUBIN 7 and 8-AIS missions from LuxSpace/OHB, the COMDEV NTS nanosatellite mission, and the US military satellite TacSat-2 have all been conducted testing the capability of AIS from space [20]. These programs, together with research and development accomplishments by academic institutions and government agencies, jointly contribute to the advancement of AIS signal reception technology and vessel monitoring capabilities around the world. The operational nanosatellites-based AIS missions have been used as presented in Table 1.