Shestopal Y. Methods of improving of energy efficiency and secrecy of digital radio relay transmission systems

Actual scientific and technical problem is solved in the thesis, which consists in a new complex approach to provide the minimum transmitter power sufficient to obtain a given probability of signal reception error and improved secrecy of information. Researches of influence of modulation types of a signal are carried out on power of radio relay station transmitter. It is shown that the best results are achieved when using a QPSK modulation type. With the given bandwidth, it is proposed to use AM signal with an increased level of signals and their number by automatically setting the maximum amplifier output voltage. A method is proposed to determine the signal / noise ratio and a level of signal error, enabling to develop a system of automatic power control of radio relay station transmitter for simplex and duplex types using transmitted signal error via a feedback channel. Developing a telecommunication system (TCS), it is efficient to use a broadband signal with a wide base, which provides increased noise immunity for interference, improved electromagnetic compatibility of systems and secrecy of information transmission. Broadband noise-like signal is generated using a number of known modulating pseudo-random sequences (PRS) by direct spread spectrum approach, but such systems cannot be considered protected from unauthorized access. A significant increase of the secrecy of information transmission provides the use of a noise-like signal using PRS based on chaos. Studies have shown that the use of PRS with six secret keys based on PRS with 2 chaotic signals should be considered an effective one. Such systems are significantly protected from unauthorized encoding, in contrast to TCS with known PRS (m-sequences, Gold’s PRS, Kasami’s PRS, etc.). Creating a system with a broadband noise-like signal with 2 antenna channels are used code division of signals in the receiver and optimal signal processing by using Rake type receivers. The possibility of creating a feedback channel in the system to adjust transmitter power of simplex and duplex radio relay system is emphasized.