Software-defined radios (SDRs) have been around for more than a decade. The
first complete GLOBAL Positioning System (GPS) implementation was described
by Dennis Akos in 1997. Since then several research groups have presented their
contributions.We therefore find it timely to publish an up-to-date text on the subject
and at the same time include Galileo, the forthcoming European satellitebased
navigation system. Both GPS and Galileo belong to the category of GLOBAL
Navigation Satellite Systems (GNSS).
GSM (GLOBAL System for Mobile communications: originally from Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. Its promoter, the GSM Association, estimates that 80 of the GLOBAL mobile market uses the standard.[1] GSM is used by over 3 billion people across more than 212 countries and territories.[2][3] Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world
