A New Physical-layer Security Measure - Secrecy Pressure

The information-theoretic techniques can ensure security in communication regardless of the computational power of the attackers. The requirements for applying such techniques require: 1) an advantage over the eavesdroppers' quality of reception and 2) the location information on the eavesdropper. Traditionally, the performance of a secure communication link is measured using the metrics of secrecy capacity or outage probability, which are both related to the relative quality of the legitimate link compared with that of the eavesdropper link. In this paper, we present a new metric, called secrecy pressure, which measures the security level of the surface/environment where the legitimate link is embedded but is independent of the position of the eavesdropping node. The metric can be also visualized as a secrecy map. The analytical results show how the optimization of the secrecy pressure measure can lead to decide the optimum transmit antenna orientation and/or the position and power of an additional interfering node (friendly jammer).