Secure compute-and-forward transmission with artificial noise and full-duplex devices

We consider a wiretap channel with an eavesdropper (Eve) and an honest but curious relay (Ray). Ray and the destination (Bob) are full-duplex (FD) devices. In order to prevent Ray from getting information on the secret message, we consider the scaled compute-and-forward (SCF) where scaled lattice coding is used in the transmission by both the source (Alice) and Bob in order to allow Ray to decode only a linear combination of the two messages. At the same time Ray transmits artificial noise (AN) to confuse Eve. When Ray relays the decoded linear combination, Alice and Bob are transmitting AN against Eve. With respect to existing literature the innovations of this paper are: a) Bob and Ray are FD devices; b) Alice, Ray and Bob transmit also AN; and c) the channel to Eve is not known to Alice, Bob and Ray. For this scenario we derive bounds on both the secrecy outage probability and the achievable secrecy-outage rates.