Security Gap of Coded Transmit Antenna Selection Systems with Frame Scrambling

Abstract

In this work, we evaluate physical layer security through security gap. We consider a network composed of two legitimate nodes and one passive eavesdropper, all of them provided with multiple antennas. We also consider the transmit antenna selection (TAS) scheme along with frame scrambling at the transmitter to provide an instantaneous advantage for the legitimate users over the eavesdropper, while both legitimate and malicious receivers operate under maximum ratio combining (MRC). By considering a quasi-static fading scenario, we evaluate (analytically and through numerical results) the security gap in terms of both outage probability and frame error rate (when using convolutional codes), as a function of the number of antennas at each node. Our results show that, either adopting the FER or the outage probability as the performance metric, it is possible to achieve negative security gaps using a feasible number of antennas.