Over the last decades, numerous governments invested a great deal of efforts and funds in designing, launching and operating complex Global Navigation Satellite Systems (GNSS). Since the first experimental Global Positioning Satellite (GPS) satellite was launched in 1978 by the United States of America (USA), many countries decided to join the race and are currently trying to gain independent access to global satellite navigation by launching their own satellite constellation system. Russia was the second country to design such a system, called GLONASS, and recently enhanced its constellation with its latest launch at the end of 2011 [1]. The European Union is also developing its own constellation and currently has two satellites deployed in orbit and they are going through their commissioning phase [2]. The latest to join the race is the Compass system, designed by China, which is currently ahead of the Galileo program, with eleven spacecrafts launched as of April 2012 [3].