МЕТОДИКА ВОССТАНОВЛЕНИЯ ИНФОРМАЦИИ КОНЦА OFDM СИМВОЛОВ, СУММИРУЕМЫХ С CAZAC ПОСЛЕДОВАТЕЛЬНОСТЯМИ ПРИ СИНХРОНИЗАЦИИ ПО ЦИКЛИЧЕСКОМУ ПРЕФИКСУ

Abstract

In previous studies, it was proved to increase the synchronization efficiency by the periodic correlation function (CF) of the cyclic prefix (CP) OFDM symbols of LTE technology when using as a CAZAC CP the sequences of the Zadoff-Chu (ZC(2,9)) as part of the "empty" symbols of the central part of the frequency range of the LTE frame transmitted to DownLink (DL) direction. In this study, the symbols of the central part of the frequency range of the LTE frame are not "empty" and the information of the end of the OFDM symbols, on which elements of multiphase sequences are superimposed, is restored on the receiving side. A comparative analysis of the characteristics of cyclic CF sequences of Zadoff-Chu and Frank, used to fill the CP and the end of the characters in the sum with the elements of the binary information sequence, is carried out. The research was carried out in the MATLAB mathematical modeling system on a model of a communication channel close to ideal, with QPSK, 64QAM modulation options for frame information symbols. Analysis of the research results showed that the use of multiphase CAZAC sequences makes it possible to increase the efficiency of synchronization over the CP OFDM symbols of the LTE technology frame both for "empty" symbols and for symbols with the restoration of useful information elements of the end of the OFDM symbol from the sum of binary modulated codes and multiphase sequences. The modulus of the merit factor when filling the CP with the sum of modulated bit data and CAZAC sequences is higher by 0.425dB...1.404dB than when filling the CP with only modulated bit data. When summing sequences, the value of the peak factor of the transmitted symbols increases, but by an insignificant amount – no more than 0.175dB ... 0.418dB, depending on the type of modulation and the choice of the CAZAC sequence.