Secure transmissions in wireless multiuser networks using message correlation

Due to the openness of wireless multiuser networks, the private information transmitted in uplink or downlink is vulnerable to eavesdropping. Especially, when the downlink transmissions use nonorthogonal multiple access (NOMA) techniques, the system further encounters interior eavesdropping. In order to address these security problems, we study the secret communication in multiuser networks with both uplink and downlink transmissions. Specifically, in uplink transmissions, the private messages transmitted in each slot are correlated, so any loss of the private information at the eavesdropper will prevent the eavesdropper from decoding the private information in later time slots. In downlink transmissions, the messages are correlated to the uplink information. In this way, any unexpected users who lose the expected user's uplink information cannot decode its downlink information. The intercept probability is used to measure security performance and we analyze it in theory. Finally, simulation results are provided to corroborate our theoretical analysis.