| The subject of interference in communications systems is as old as communications itself. Agamemnon, the King of Mycenes, who captured Troy more than 800 miles away, to get back his niece, the beautiful Eleni, and wanted to notify his wife Clytaemistra about this happy event, used the most sophisticated communication techniques of that time to achieve his purpose. From that time until today, people have been aware of the importance of interference and the effect it can have on communications. Agamemnon used light sources at the peaks of mountains—by the motions of these sources, the information was coded and transmitted from mountain to mountain to arrive at Mycenes the same day.
If we analyze this communication system of Agamemnon, we find that he used three of the most important techniques still used today for interference suppression in communications. The first was the nature and form of the information signal (certain shape of flame), which corresponds to signal modulation techniques of today. The motion of the flames corresponds to modern coding techniques. The use of mountains corresponds to channel estimation techniques, which are used for the exploitation of favorable channel propagation characteristics or the avoidance of unfavorable characteristics through compensation of certain propagation parameters, fading, narrowband, or wideband characteristics.
Over the more than 3,000 years since Agamemnon, the necessary coexistence of information and interfering signals has been accommodated in the design of communication systems. Modern mathematical modeling and simulation techniques as new tools of study greatly facilitated this effort. |