A Secret-key-aided scheme to secure transmissions from single-antenna RF-eh source nodes

Abstract

We propose a two-phase artificial-noise-aided scheme to power a single-antenna energy-harvesting source node (Alice) and secure her transmissions to a multiple-antenna legitimate destination (Bob) in the presence of a multiple-antenna eavesdropper (Eve). A one-time pad (OTP) encryption scheme is used to ensure the security of the source's information signal. In our proposed scheme, Bob sends a secret key to Alice then Alice uses an OTP encryption scheme to secure her transmissions. If Alice can correctly decode the secret key and has stored enough energy to ensure reliable information transmission (i.e., ensure no outages on her link to Bob), she sends her data packet to Bob. To secure the key signal from the eavesdropper, Bob uses a hybrid fast-fading and slow-fading multiplicative artificial-noise scheme. Power allocation between the multiplicative noise and the desired signal and time allocation between the two transmission phases are investigated.