# State of the Art of Telecommunication Systems in Isolated and Constrained Areas
## 2 Telecommunication Systems in an Isolated and Constrained Environment
### Telecommunication Towers  
The first telecommunication tower was undoubtedly the Italian [PERSON] device when he succeeded, in 1895, in transmitting a signal over several hundred meters in Bologna. In 1903, [PERSON] developed an electrolytic detector more sensitive than the [PERSON]'s coherer. Receiver sensitivity is a fundamental element when transmitting a signal. It is the minimum power that the receiver must receive to restore the transmitted information. The lower the sensitivity of the receiver, the longer the distance between the transmitter and the receiver. [PERSON], therefore, continued his experiments to gain even more distance. He needed a higher antenna [14]. The height of the emission source is an essential factor in designing a telecommunication system to avoid obstacles during the propagation of the electromagnetic wave and thus avoid the fading problems linked to the wave's reflection. Fortunately, [PERSON] put his Eiffel Tower at his disposal. [PERSON] naturally set up antennas on the latter. We certainly do not realize that the Eiffel Tower was promised to be destroyed after 1900 following the universal exhibition. However, it only owed its survival to being an extraordinary site for receiving transmitters and antennas. Unfortunately, for radio frequency specialists, it is not possible to find an Eiffel tower  
Figure 1: Telecommunication solutions for isolated environment. in every neighborhood. However, metal telecommunication towers (Figure 1) allow the transmitter and the receiver to gain height. The height of the transmitting and receiving antennas avoids problems of reflection of the signal transmitted on the ground (\"ground reflection\") and of fading, meaning the reflection of the signal transmitted on objects (mobile or not). These two effects significantly reduce the range of the telecommunication system. When designing a telecommunication system, engineers try to get as close as possible to a direct path for the wave transmitted to the receiver, a configuration called \"fine of sight\" or line of sight. Intermediate towers are installed between the one carrying the transmitter and the one containing the receiver to increase transmission distance. These towers act as relays by amplifying the signal strength and sometimes by changing the frequency. When these towers are built in an urban environment or close to the city, the electrical network supplies energy to onboard electronic devices. In contrast, in an isolated environment, energy is provided by micro-networks. These micro-networks generally use diesel generators. Hybrid systems were developed in recent years and introduced renewable energies with a preference for photovoltaic panels [15]. These solutions are viable when the sunshine potential of the site of installation allows it. These metal towers or pylons have a height that can vary between 30 m and 150 m. They can, in some cases, be guyed. In urban areas, buildings can serve as telecommunication towers. To correctly dimension a telecommunication system [16], we need to complete a link assessment. This encrypts the strength of the receiver's signal located at a distance that we call from the transmitter. The chain of transmission appears in Figure 2.  
The link budget [17] makes it possible to compute the strength of the signal received by the receiver (PR). We can extract the maximum distance between the transmitter and the receiver, and therefore the telecommunication system's scope, by replacing the strength of the signal received by the receiver (PR) with its sensitivity. A receiver's sensitivity is the minimum power received below which it cannot extract the information with certainty.