Multi-Criteria Synthesis of Radio Signals to Increase Prospective Communication Systems Noise Immunity

For prospective communication systems (PCS), adaptive to interference action, four-position signals have been synthesized, providing noise immunity at QPSK-signal level when exposed only to AWGN, up to a signal-to-interference ratio of -7 dB, which is 27 dB better than this quality indicator for known modulation types. To realize PCS which is able to change spectral and energy characteristics depending on actual conditions, the 16-positional radio signals with controlled coupling between inphase and quadrature components was synthesized. The obtained signal set allows variations of spectral efficiency from 2.39 to 3.03 bit/s/Hz and crest factor from 1.35 to 1.61. Synthesis of 16-block preamble for Orthogonal Frequency-Division Multiplexing PCS operating in frequency-selective fading is produced. The use of obtained preamble compared to the known preamble leads to the decrease in fractional and integer frequency offset estimation variance by 2.21 dB and 1.56 dB at signal-to-noise ratio in the range from 6 to 12 dB and from -5 to -0 dB, respectively.