In this paper, we propose an efficient geo-routing aware MAC protocol (GOAL) for underwater acoustic networks. It smoothly integrates self-adaptation based REQ/REP handshake, geographic cyber carrier sensing, and implicit ACK to perform combined channel reservation and next-hop selection. As a result, it incorporates the advantages of both a geo-routing protocol and a reservation-based medium access control (MAC) protocol. Specifically, with its self-adaptation based REQ/REP, nodes can dynamically detect the best next-hop with low route discovery cost. In addition, through geographic cyber carrier sensing, a node can map its neighbors' time slots for sending/receiving DATA packets to its own time line, which allows the collision among data packets to be greatly reduced. With these features, GOAL outperforms geo-routing protocols coupling with broadcast MAC. Simulation results show that GOAL provides much higher end-to-end reliability with lower energy consumptions than existing Vector-Based Forwarding (VBF) routing with use of a broadcast MAC protocol. Moreover, we develop a theoretical model for the probability of a successful handshake, which coincides well with the simulation results.

In this paper, a secure transmission scheme based on the artificial noise is proposed for D2D communications underlaying the full-duplex cellular network, and a secure power allocation scheme to maximize the overall secrecy rate of both the cellular user and D2D transmitter node is presented. Firstly, the full-duplex base station transmits the artificial noise to guarantee the secure communications when it receives signals of cellular uplinks. Under this secure framework, it is found that improving the transmission power of the cellular user or the D2D transmitter node will degrade the secrecy rate of the other, although will improve itself secrecy rate obviously. Hence, a secure power allocation scheme to maximize the overall secrecy rate is presented subject to the security requirement of the cellular user. However, the original power optimization problem is non-convex. To efficiently solve it, we recast the original problem into a convex program problem by utilizing the proper relaxation and the successive convex approximation algorithm. Simulation results evaluate the effectiveness of the proposed scheme. . He then received the M.S. degree in NDSC. He has been a faculty member of NDSC since 2014. His research interests include wireless location. KaizhiHuang received her B.E. degree in digital communication and M.S. degree in communication and information system from respectively. She has been a faculty member of NDSC since 1998, where she is currently a professor and director of the Laboratory of Mobile Communication Networks. Xinsheng Ji received the B.E. degree in Fudan University, Shanghai, China, in 1984, and received the M.S. degrees in PLA Information Engineering University, Zhengzhou, China, in 1991. He has been a faculty member of NDSC since 1988, where he is currently a professor and the chief engineer of NDSC. He has been a member of the Network and Communication (NaC) specialist group for China 863 High Technology Program and a senior member of China Institute of Communication. He was awarded as an outstanding expert of state in 2015. His major research interests include wireless communication network, security and signal processing.

In order to measure the magnetic field around electronic products, household appliances and industrial electrical equipment, this paper puts forward a new method which makes use of electromagnetic coupling design based on three-axis electromagnetic leakage. This method can overcome the disadvantage of traditional single-axis measurement which needs to get the total magnetic field after several times’ measurement. This paper designs three-axis electromagnetic leakage detector for circuit measurement, which is proved to be correct after circuit measurement experiment. It can easily detect 30-2K Hz leakage magnetic field of low frequency generated from electrical appliances products.Introduction.