Low Earth Orbit Satellite Communication Networks

Low Earth orbit (LEO) communication networks are the near future of the communication services. What started off as something merely for scientists and students has become an attractive solution for commercial communication. The massive market competition and the huge cost of developing, building and launching conventional satellites, as well as the need of global coverage, have forced the communication industry to look for alternatives and, thanks to the developments in nanotechnology and microtechnology, LEO communication networks are a promising one, since LEO are the closest orbits to the Earth, allowing the setting up of polar orbits and the use of smaller satellites, known as small satellites or SmallSats. The increasing interest in LEO communication systems is the main reason to write this thesis. Previous work has mainly been limited to analyzing and solving the interference of LEO networks with the geostationary ones. However, LEO are not stationary orbits, which means that satellites are not fixed. This fact, together with the small coverage area due to the low altitude, forces us to set up large satellite constellations. The big amount of satellites also causes interference to occur within the system itself, since the number of visible satellites at a point on Earth is often greater than one. The parameter intended to analyze this issue is the signal-to-interference-plus-noise ratio (SINR). This thesis offers an overview of satellite communication, focusing on low orbit communication networks further on. Then, a simulator is developed to analyze the SINR of a polar satellite constellation. The results show a significant decrease of SINR at polar regions. In order to improve SINR value, we decrease the inclination but it does not solve the problem as the low SINR values move to different Earth latitudes. Finally, we simulate the polar constellation using dipoles as ground antennas, obtained a light but promising increase of SINR at the conflict regions