Secure Communication Using Interference Cancellation Against Multiple Jammers

In the area of physical-layer security for wireless communications, jamming is one of the methods that a malicious agent uses to actively attack legitimate nodes. The jammers make interference to hinder the legitimate transmissions. It can use the constant, random, or reactive mode with fixed or varied signals. We formulate a general model for all jamming modes and signal types. We propose novel methods to eliminate the interfering signals and securely estimate the needed signals for a network model with two legitimate nodes who are exchanging information via a relay. The method for the varied signal is generalized into a theorem such that it can be also used in a scenario different from the security scenario. We exploit the ratios of the channel between each jammer and a certain antenna of a receiver to the channel between that jammer and the rest of antennas of that receiver to estimate the needed signals. It is then applied in the two-way relay scenario to demonstrate the efficiency of the proposed schemes. The numerical results show that the secrecy rate of the proposed schemes are higher than that of the corresponding conventional schemes.