# State of the Art of Telecommunication Systems in Isolated and Constrained Areas
## 1 Introduction
As proof, the derailment of the QNS & L train on 6 November 2014, following a landslide that the driver saw too late [8], is an example of an accident that could have been avoided. The train descended a slope to dive into the Moisie River (northeast of Sept-Iles), causing the driver's death. Another example is the event that occurred in 2013 when a company train broke down near Emeril camp in Labrador. On that day, the temperatures were, with the wind factor, around \(-50\)\({}^{\circ}\)C. There was no more heating on the train, and the passengers, including young children, had to regroup for several hours in a wayon to fight the biting cold while waiting for help. Fortunately, Route 500 or Trans-Quebec-Labrador was not far away, which allowed their evacuation. It must be considered that if the failure had occurred upstream in the woods, some passengers probably would not have survived. A telecommunication system would likely have avoided this problem. The start of this railway line is the isolated town of Schefferville, which can only be reached by train or plane. In addition to the previous observations, technological disconnection [9] and lack of energy are not the only causes of the accentuation of the geographic isolation of populations [10]. In fact, isolated territories are unfortunately subject to harsh climatic conditions, especially during the winter season. Winter temperatures can be very low: between \(-40\) and \(-50\)\({}^{\circ}\)C for long periods. Snowfall is also frequent and the depth of snow mixed with ice is significant. The conditions of movement of the population are, in this context, more difficult. The isolation of individuals is, therefore, reinforced. The harsh winter also adds a significant constraint on existing or likely-to-be-developed telecommunications devices. However, this technological challenge of electronic device operation under challenging climates also appears in very hot climate isolated regions. It is the case, for example, in the African deserts. Another difficulty penalizes the establishment of telecommunication systems in isolated territories, thus contributing to the amplification of those populations' isolation. The magnetic field in some regions of the planet and very often in remote areas undergoes partial or total absorption known as white areas [11], making the propagation of the signal very delicate [12]. The article's objective is to make a state of the art of telecommunication systems suitable in isolated regions to highlight an original and effective solution adapted to this type of environment. Before proceeding further, the satellite connection, which has been used in isolated areas for many years at a high cost [13], will not be part of this study. Our contribution in this article is to review telecommunication solutions for isolated areas and present an original solution based on tethered balloons. The paper is structured as follows: Section 2 presents the state of the art of telecommunication systems in an isolated and constrained environment. Section 3 compares communication technologies according to several criteria to emphasize the advantages and disadvantages (benefits and limitations), while Section 4 further describes the chosen solution. Finally, Section 5 concludes the paper with possible future directions of study in this area.