Strong Secrecy in Wireless Network Coding Systems from Structured Interference

Wireless network coding (WNC) has been proposed for next generation networks. In this contribution, we investigate WNC schemes with embedded strong secrecy by exploiting structured interference in relay networks with two users and a single relay. In a practical scenario where both users employ finite, uniform signal input distributions we compute the corresponding strong secrecy capacity, and make this explicit when PAM modems are used. We then describe a simple triple binning encoder that can provide strong secrecy close to capacity with respect to an untrustworthy relay in the single antenna and single relay setting. An explicit encoder construction is described when M -PAM or M -QAM modulators are employed at the users’ transmitters. Lastly we generalize to a MIMO relay channel where the relay has more antennas than the users, and optimal precoding matrices are studied. Our results establish that the design of WNC transmission schemes with enhanced throughput and guaranteed data confidentiality is feasible in next generation systems.