Wireless System Using Spread Spectrum Signals under the Conditions of Possible Jamming by Retransmitted Interference

Presently, it is very important to design wireless systems that are resistant to jamming by adversary. It is well known technology to execute so called spread spectrum signals in order to prevent such attacks, especially under the conditions when enemy is superior i1n power against legitimate users. Moreover, adversary is able to estimate legitime signal parameter (type of modulation, duration of intervals ctr) However, such approach be vulnerable in the case of the use by adversary so called retransmitted interferences. The purpose of this article is to increase the efficiency of spread spectrum signals transmission under the action of retransmitted interference, the power of which exceeds the power of the legitimate signals. The essence of the proposed solution is to use spread spectrum phase-frequency modulated signals for information transmission, generated using independent unpredictable pseudorandom sequences that are different at the transmitted and non-transmitted frequencies. Instant phases are randomized independently for bit intervals at the transmitting side. Theoretically, using appropriated mathematical technique, the formula is derived for calculating of the bit error probability for the proposed system with different choice of its parameters. It is proved that for correctly selected parameters, the probabilities of bit errors are approaching to such values that occurs qcceptable to use next error correcting codes , which will ensure reliable delivery of important information. The scientific novelty of our method consists in the use an unpredictable pseudorandom sequence at a frequency that is not currently being transmitted, in a randomized phase shift at each bit interval when forming a broadband signal, as well as in optimizing the parameters for the proposed radio communication system, that improved significantly further use of error-correcting code. The theoretical significance consists in the correct proof of the formula for the bit error probabilities and further estimation the conditions for application of error correction codes. The practical significance lies in design of interference proof wireless communication system that after some further elaboration of synchronization system and error correction codes, can be applied in practice under very hard interference environment.