Confidential communication in downlink beamforming

This paper deals with the problem of secure transmission in downlink beamforming. In this scenario, a base station, which usually serves information to an amount of users, wants to transmit a confidential message to one of the users. Focusing on the beamforming solution, we derive all possible weighted solutions. With this, each non-intended receiver has an importance factor and, therefore, the resulting beamformer is able to properly reconfigure its secure transmission varying the weighting factors. This derivation is done via multicriteria optimization, which allows us to transform a quasiconvex problem into a semidefinite one and, thus, reduce the computational complexity. Numerical results show the performance of the method.