TABLE OF CONTENTS The first use of electricity as a means of conveying information dates back to the first half of the nineteenth century. In 1837, Samuel Morse invited the telegraph. The first public telegram was sent in 1844. A few decades later in 1876, Alexander Graham Bell was able to convey human voice through electrical signals. This invention was called the telephone.
The use of electromagnetic waves as a means of conveying information between two untethered terminals started over a century ago. In 1887, Heinrich Hertz, using high frequency currents, was able to illustrate the propagation of an electromagnetic wave from a transmitter to a receiver. In 1894, Gugliemo Marconi began his research on wireless communication systems which eventually led to the first patent on wireless communications to be issued to him in 1896.
The first two-way mobile communications systems were used by the police departments during the 30 s and 40 s. Initially, these systems used amplitude modulation. However, by 1940 most of them converted to frequency modulation because of its higher resilience to propagation impairments. During World War II mobile communications was used extensively by the military.
The first public mobile phone system was deployed in the United States just after the war, in 1946, it was called the Mobile Telephone System (MTS). This system was a simplex system, which required the intervention of an operator to place calls. In 1969, an improved mobile system was introduced, known as the Improved Mobile Phone System (IMPS). This...
