Generalized multiple-access relay channel with confidential messages

In this paper, we propose information theoretic schemes that achieve the rate-equivocation regions for the multiple-access relay channel with confidential messages. This channel consists of two users that play the role of eavesdropper for each other´s message and a relay that helps them to have a reliable and secure communication. The relay can itself be an eavesdropper of the users messages. The first coding scheme used for achievability is noise forwarding strategy and the second is the combination of noise forwarding with the compress and forward strategy. In the first one, relay cooperates with the users to have a confidential communication by sending codewords independent of the secret messages. In the second one, in addition to sending independent codewords, relay also sends compressed version of the received signals. Using these schemes, we derive the inner bounds for the capacity-equivocation region of the described model.