Guaranteeing Secrecy using Artificial Noise

TLDR

The broadcast nature of the wireless medium makes communication vulnerable to eavesdropping, and the channel state information is publicly known, so secrecy does not depend on CSI. This paper studies secret communication between two nodes over a fading wireless medium with a passive eavesdropper. The authors assume the transmitter and its helpers have more antennas than the eavesdropper and achieve secrecy by allocating power to artificial noise that degrades the eavesdropper’s channel, considering both a multi‑antenna transmitter and a relay‑based scheme that mimics multiple antennas.

Abstract

The broadcast nature of the wireless medium makes the communication over this medium vulnerable to eavesdropping. This paper considers the problem of secret communication between two nodes, over a fading wireless medium, in the presence of a passive eavesdropper. The assumption used is that the transmitter and its helpers (amplifying relays) have more antennas than the eavesdropper. The transmitter ensures secrecy of communication by utilizing some of the available power to produce 'artificial noise', such that only the eavesdropper's channel is degraded. Two scenarios are considered, one where the transmitter has multiple transmit antennas, and the other where amplifying relays simulate the effect of multiple antennas. The channel state information (CSI) is assumed to be publicly known, and hence, the secrecy of communication is independent of the secrecy of CSI.