Research on the Properties of Complex Signal Ensembles Obtained by Frequency Segments Permutation
Keywords:cognitive telecommunication systems, multiple access interference, cross-correlation function, complex signal, maximum emissions of side lobes of the cross-correlation function
For cognitive telecommunication systems, the problem of reducing the level of multiple access interference (intrasystem interference), which occur during the simultaneous operation of different subscribers of one system in a common frequency band, is relevant. To this end, the formation methods of large ensembles of complex signals obtained by permutation of the frequency segments of the output sequences with a low level of interaction in the time domain, have been developed . The cross-correlation level of the received signals shows the degree of signal interaction in the time domain and, thus, makes it possible to assess the level of multiple access problems in the cognitive telecommunication system. An important task is to determine the maximum emission level of the cross-correlation functions of the resulting complex signal ensembles depending on the filtering bands and, accordingly, their impact on the volume of the ensembles. Also, the dependence of multiple access interference level on the number and duration of pulses in the output sequences, which are used to form complex signal ensembles based on the frequency segments permutations, was interesting. The solution of these problems will make it possible to simplify the procedure for determining the width of the filter bands for the formation of complex signal ensembles by permutation of frequency segments.