A Secrecy Constrained Power Allocation for MIMO Wire-Tap Channels

Since a wireless transmission requires to access to a shared medium, the communication is susceptible to adversarial eavesdropping. This paper describes how eavesdropping can potentially be limited by resorting to waterfilling-like algorithms with additional constraints. A Gaussian wiretap channel (WTC) is considered in which a transmitter sends confidential messages to its reference receiver in the presence of a passive eavesdropper. We approach the problem from two different perspectives, focusing either on the rate of the main link or the secrecy level. Through numerical analysis, we show how the information-secrecy regions can be the means to evaluate the quality of the main link and the secrecy level, resulting from our algorithms application. Finally we analyze the case of interfering signals (induced by users sharing the same transmission resource) to show their effects on both information rate and secrecy, even in the case of an eavesdropper able to mitigate the interference.