Algorithms to form and process signals for multilevel defense of transmitted data based on the principles of cognitive and software-defined radio

Two approaches of data communication system development were considered which provide multilevel defense of transmitted data with dynamic change in structure of radio signal. In accordance with the first approach, the application of a special algorithm for initial estimation of symbol time offset based on the analysis of the preamble in a receiver is justified. It is shown that this algorithm provides a 2.5 dB reduction in the variance of time offset estimate in multipath channel. In addition, the possibility to use phase and timing discriminator of OQPSK-signal to receive spectral efficient radio signals generated in a universal shaper was shown. According to the second approach, an algorithm for shaping multi-position radio signals based on multi-criteria synthesis of signal set was proposed. It is shown that this algorithm allows to significantly increase system immune to narrow-band interferences as well as to improve energy efficiency of data communication system.