Cooperative Jamming for Physical Layer Security in Hybrid Satellite Terrestrial Relay Networks

To integrate the satellite communications with the LTE/5G services, the concept of Hybrid Satellite Terrestrial Relay Networks(HSTRNs) has been proposed. In this paper, we investigate the secure transmission in a HSTRN where the eavesdropper can wiretap the transmitted messages from both the satellite and the intermediate relays. To effectively protect the message from wiretapping in these two phases, we consider cooperative jamming by the relays, where the jamming signals are optimized to maximize the secrecy rate under the total power constraint of relays. In the first phase, the Maximal Ratio Transmission(MRT) scheme is used to maximize the secrecy rate, while in the second phase, by interpolating between the sub-optimal MRT scheme and the null-space projection scheme, the optimal scheme can be obtained via an efficient one-dimensional searching method. Simulation results show that when the number of cooperative relays is small, the performance of the optimal scheme significantly outperforms that of MRT and null-space projection scheme. When the number of relays increases, the performance of the null-space projection approaches that of the optimal one.

Enhancing physical-layer security via big-data-aided hybrid relay selection

The explosive growth in data trac presents new challenges to the new generation of wireless communication systems,such as computing capabilities,spectrum eciency and security.In this paper,we use the network structure,which is adaptable for the big data trac,to improve the security of wireless networks.Speci cally,a big-data aided hybrid relay selection scheme is designed and analyzed to enhance physical layer security.First,considering the ideal situation that an eavesdropper's CSI(Channel State Information)is known to the legal nodes,we propose an optimal hybrid relay selection scheme consisting of the optimal mode selection scheme and the optimal relay selection scheme.In this case,we analyze the upper bound of an eavesdropper's capacity in FD(Full-Duplex)mode and the secrecy outage probabilities of the optimal HD(Half-Duplex),FD,and hybrid relay selection schemes.Through the analysis of data,it is clear that the mode selection is decided by the self-interference of the FD technique.However,the instantaneous CSI of an eavesdropper is dicult to obtain due to the passive characteristic of eavesdroppers in practice.Therefore,a more practical hybrid relay selection scheme with only the channel distribution information of an eavesdropper is further studied,where a weighting factor is employed to guarantee that the hybrid mode is no worse than either the FD mode or HD mode when the self-interference grows.Finally,the simulation results show the improved security of our proposed scheme.

Performance evaluation of DHRR-RIS based HP design using machine learning algorithms

Reconfigurable Intelligent Surfaces(RIS)have emerged as a promising technology for improving the reliability of massive MIMO communication networks.However,conventional RIS suffer from poor Spectral Efficiency(SE)and high energy consumption,leading to complex Hybrid Precoding(HP)designs.To address these issues,we propose a new low-complexity HP model,named Dynamic Hybrid Relay Reflecting RIS based Hybrid Precoding(DHRR-RIS-HP).Our approach combines active and passive elements to cancel out the downsides of both conventional designs.We first design a DHRR-RIS and optimize the pilot and Channel State Information(CSI)estimation using an adaptive threshold method and Adaptive Back Propagation Neural Network(ABPNN)algorithm,respectively,to reduce the Bit Error Rate(BER)and energy consumption.To optimize the data stream,we cluster them into private and public streams using Enhanced Fuzzy C-Means(EFCM)algorithm,and schedule them based on priority and emergency level.To maximize the sum rate and SE,we perform digital precoder optimization at the Base Station(BS)side using Deep Deterministic Policy Gradient(DDPG)algorithm and analog precoder optimization at the DHRR-RIS using Fire Hawk Optimization(FHO)algorithm.We implement our proposed work using MATLAB R2020a and compare it with existing works using several validation metrics.Our results show that our proposed work outperforms existing works in terms of SE,Weighted Sum Rate(WSR),and BER.

A Novel Cooperative Multi-Stage Hyper-Heuristic for Combination Optimization Problems

A hyper-heuristic algorithm is a general solution framework that adaptively selects the optimizer to address complex problems.A classical hyper-heuristic framework consists of two levels,including the high-level heuristic and a set of low-level heuristics.The low-level heuristics to be used in the optimization process are chosen by the high-level tactics in the hyper-heuristic.In this study,a Cooperative Multi-Stage Hyper-Heuristic(CMS-HH)algorithm is proposed to address certain combinatorial optimization problems.In the CMS-HH,a genetic algorithm is introduced to perturb the initial solution to increase the diversity of the solution.In the search phase,an online learning mechanism based on the multi-armed bandits and relay hybridization technology are proposed to improve the quality of the solution.In addition,a multi-point search is introduced to cooperatively search with a single-point search when the state of the solution does not change in continuous time.The performance of the CMS-HH algorithm is assessed in six specific combinatorial optimization problems,including Boolean satisfiability problems,one-dimensional packing problems,permutation flow-shop scheduling problems,personnel scheduling problems,traveling salesman problems,and vehicle routing problems.The experimental results demonstrate the efficiency and significance of the proposed CMS-HH algorithm.