Joint Decode-and-Forward and jamming for wireless physical layer security with destination assistance

A distributed wireless network with one source, one destination, one eavesdropper and multiple Decode-and-Forward (DF) relays is considered. A two-slot cooperative relaying scheme is proposed, in which relays help the source transmit to the destination while keeping the message as secret as possible from the eavesdropper. In the first slot, the source transmits a weighted combination of the information bearing signal and a noise signal. At the same time, the destination cooperates with the source in transmitting a noise signal with the purpose of confounding the eavesdropper. In the second slot, the `best' relay cooperates with the source to send a jamming signal along the null space of the destination channel. Optimal relay selection and also optimal power allocation among the first/second slot data signal and jamming noise is proposed. With the proposed transmission scheme, the system secrecy rate is shown to outperform the methods in literature and always benefits from increasing total power and larger number of relays.