Degraded multiple-access channel with confidential messages

In this paper, we study the degraded multiple-access channel (MAC) with confidential messages, where two users transmit their confidential messages (no common message) to a destination, and each user obtains a degraded version of the output of the MAC. Each user views the other user as a eavesdropper, and wishes to keep its confidential message as secret as possible from the other user. Measuring each users uncertainty about the other users confidential message by equivocation, the inner and outer bounds on the capacity equivocation region for this model have been provided. The result is further explained via the binary and Gaussian examples.