To achieve secure communication in heterogeneous cryptography systems, we present a heterogeneous hybrid signcryption scheme. The proposed scheme allows a sender in an identity-based cryptography system to send multi-message to multi-receiver in a certificateless cryptography system with different master keys. At the same time, all users are mapped to a distinct pseudo-identity for conditional identity privacy preservation. A trusted authority could trace the real identity when necessary. Compared with existing schemes, the proposed scheme is more practical for actual applications. In addition, the proposed scheme has indistinguishability against adaptive chosen ciphertext attacks and existential unforgeability against adaptive chosen message attacks under the random oracle model.

SUMMARYUser cooperative is a powerful tool to combat fading and to increase robustness for communications over wireless channels. For cooperative relaying communications, the outage probability and the expected rate (throughput) can be greatly improved when the superposition coding relaying (SC-relaying) strategy is employed. Under the assumption of high signal-to-noise ratio (SNR), this work contributes to a comprehensive investigation on the outage probability and the throughput of cooperative relaying communications system with only two-level rate SC. Through strict mathematical process and deduction, the approximated close-form expressions of the outage probabilities and the throughput of system are obtained for the first time. Based on the results, the impact of power and channel allocation fractions on system performance is carried out. With the aim of maximal throughput, a set of optimal solutions of system parameters are obtained by employing difference evolution arithmetic. The comparative numerical analyses show that the approximation results are feasible and correct.

To achieve insights about the impact of amplified loop interference, we consider a dual-hop fullduplex (FD) massive multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying system in terms of achievable ergodic rates for each user pair as well as spectrum and energy efficiencies. It is assumed that the base station (or relay) is equipped with M Rx receive antennas and M Tx transmit antennas, while all sources and destinations have a single antenna. For such FD massive MIMO AF relaying systems, the closedform expressions of the lower bounds of achievable ergodic rates are derived first with a finite number of receive and transmit antennas at base station. Then, the asymptotic performance analysis is performed by considering three different power-scaling schemes: 1