USE OF PSEUDO NOISE CODING SEQUENCE CYCLIC SHIFTS FOR TELECOMMUNICATION CHANNEL PERFORMANCE IMPROVEMENT

Abstract

An approach is proposed to design of noise immune and concealed data transfer channel for telecommunication networks. Attention is paid to securing hidden information transmission, as well as its protection from interception by rogue actors. The approach is based on the desired bits spectrum spreading and their additional scrambling by using pseudo noise coding sequences derived from primitive polynomials of eighth and fifteenth orders, which possess good auto and inter correlation properties. It is studied performance of the telecommunication channel that includes frames of 128 bit length, each of which is spectrally spread 256 times with the help of a synthesized pseudo noise coding sequence. The second 32768 chip-long pseudo noise coding sequence is used to mark the frame duration and perform additional information scrambling.

Computer simulation is used to study performance of the designed telecommunication channel. The computer simulation helped to establish that the processing of the additive mixture of the desired signal and interfering ones, which surpass the desired signal two times in terms of power, by the matched filters permits to confidently reveal the information frame structure being transmitted by determining frame beginning pulse and establish the bit values of the desired information. Further improvement of information protection from interception is proposed to achieve by using cyclic shifts of 32768 chip-long pseudo noise coding sequence. Computer simulation helped to find out that ignorance of the cyclic shift leads to inability of information interception by the rogue elements. Research results, obtained in this paper, permit to claim that the designed telecommunication channel, with cyclic shifts according to a secret rule, could be successfully used in practical implementations of noise immune and concealed telecommunication networks.