Chaotic modulation and alpha-stable noise parameter modulation methods in spread spectrum communication

With the inspiration from the chaotic communication systems, in which noise likesignals, chaotic signals, have been used as carrier signals due to their broad-bandfrequency spectrum, which have been widely studied in the last twenty years as analternative to the conventional spread spectrum techniques by the discovery of thesynchronization of chaotic dynamical systems. In this thesis, new randomcommunication systems in which noise itself is used as a random carrier instead ofusing chaotic carrier have been introduced.Motivation at the beginning stage of this thesis was to develop more securechaotic communication systems since the security in the existing chaoticcommunication systems could have been easily broken. With this motivation, at thesecond chapter of the thesis, after introducing the main ideas of the existing chaoticcommunication systems, new secure chaotic communication system operating athigh frequencies for wireless communication have been introduced.At the third chapter of the thesis, after introducing the particle filters which wasdeveloped to estimate the states of the nonlinear dynamical systems in non-Gaussianenvironments, by the newly proposed communication schemes, secure recovering ofthe message signal has been aimed by masking the message carrying chaotic signalwith impulsive noise and transmitting it through the Gaussian noise channel andestimating the chaotic signal by using particle filter while achieving synchronizationof the receiver with the transmitter.At the fourth chapter, in the newly proposed random communication schemes,random signals with alpha stable distributions produced in the transmitter part aresent to the receiver through the Gaussian noise channel as random carriers of binarycoded message signal. At the receiver part, random carriers mixed with the Gaussiannoise are estimated by least squares, correntropy and fractional order momentsmethods and hence the binary message signal may be recovered. With these newlyproposed unique secure random communication schemes of which satisfactory biterror performances have been obtained, triggering of further studies in randomcommunication field is expected.