Maximizing the minimum achievable secrecy rate in a two-user Gaussian interference channel

This paper studies a two-user Gaussian interference channel in which two single-antenna sources aim at sending their confidential messages to the legitimate destinations such that each message should be kept confidential from non-intended receiver. Also, it is assumed that the direct channel gains are stronger than the interference channel gains and the noise variances at two destinations are equal. In this regard, under Gaussian code book assumption, the problem of secrecy rate balancing which aims at exploring the optimal power allocation policy at the sources in an attempt to maximize the minimum achievable secrecy rate is investigated, assuming each source is subject to a transmit power constraint. To this end, it is shown that at the optimal point, two secrecy rates are equal, hence, the problem is abstracted to maximizing the secrecy rate associated with one of destinations while the other destination is restricted to have the same secrecy rate. Accordingly, the optimum secrecy rate associated with the investigated max-min problem is analytically derived leading to the solution of secrecy rate balancing problem.