Dynamic Coverage with Wireless Sensor and Actor Networks in Underwater Environment

This paper studies the problem of dynamic coverage with wireless sensor and actor networks(WSANs) in underwater environment.Different from most existing works,the WSANs consist of two kinds of nodes,i.e.,sensor nodes(SNs) which cannot move autonomously and actor nodes(ANs) which can move autonomously according to the performance requirement.The problem of how to coordinate two kinds of nodes to facilitate dynamic coverage in underwater environment is challenging due to their heterogeneous capabilities.To reduce redundancy of communication links and improve connectivity between ANs and SNs in underwater WSANs,a min-weighted rigid graph based topology optimization scheme is first developed,such that the underwater communication energy consumption can be saved.With the optimized topology,a dynamic coverage strategy is proposed to improve the coverage among SNs and ANs for underwater WSAN where underwater fluid motions are considered.Furthermore,it is proved that the network coverage area is connected by using the min-weighted rigid graph.Finally,simulation results are presented to show the effectiveness of the main results.

New Rural Community Construction or Retention Development:A Comparative Analysis of Rural Settlement Transition Mechanism in Plain Agriculture Area of China Based on Actor Network Theory

It is an important way to realize rural revitalization and sustainable development to guide rural settlement transition(RST)in an appropriate way.This paper uses actor network theory(ANT)to construct a theoretical framework for the study of RST.Taking two typical villages with different transition paths in rural areas of North China Plain as examples,this paper reveals the mechanism of RST and makes a comparative analysis.The results show that:1)after identifying problems and obligatory passage point,key actors recruit heterogeneous actors into the actor network by entrusting them with common interests,and realize RST under the system operation.2)Rural settlements under different transition paths have similarities in the problems to be solved,collective actions and policy factors,but there are differences in the transition process,mechanism and effect.The actor network and mechanism of RST through the path of new rural community construction are more complex and the transition effect is more thorough.In contrast,the degree of RST of retention development path is limited if there is no resource and location advantage.3)Based on the applicable conditions of different paths,this paper designs a logical framework of‘Situation-Structure-Behavior-Result’to scientifically guide the identification of RST paths under the background of rural revitalization.

DGR:dynamic gradient-based routing protocol for unbalanced and persistent data transmission in wireless sensor and actor networks

This paper is concerned with the routing protocol design for large-scale wireless sensor and actor networks (WSANs).The actor-sensor-actor communication (ASAC) strategy is first proposed to guarantee the reliability of persistent actor-actor communication.To keep network connectivity and prolong network lifetime,we propose a dynamic gradient-based routing protocol (DGR) to balance the energy consumption of the network.With the different communication ranges of sensors and actors,the DGR protocol uses a data load expansion strategy to significantly prolong the network lifetime.The balance coefficient and the routing re-establishment threshold are also introduced to make the tradeoff between network lifetime and routing efficiency.Simulation results show the effectiveness of the proposed DGR protocol for unbalanced and persistent data transmission.

A hybrid model for energy efficient spectrum sensing in cognitive radio

Purpose-Cognitive radio(CR)plays a very important role in enabling spectral efficiency in wireless communication networks,where the secondary user(SU)allows the licensed primary users(PUs).The purpose of this paper is to develop a prediction model for spectrum sensing in CR.Design/methodology/approach-This paper proposes a hybrid prediction model,called krill-herd whale optimization-based actor critic neural network and hidden Markov model(KHWO-ACNN-HMM).The spectral bands are determined optimally using the proposed hybrid prediction model for allocating the spectrum bands to the PUs.For better sensing,the eigenvalue based on cooperative sensing used in CR.Finally,a hybrid model is designed by hybridizing KHWO-ACNN and HMM to enhance the accuracy of sensing.The predicted results of KHWO-ACNN and HMM are combined by a fusion model,for which a weighted entropy fusion is employed to determine the free spectrum available in CRs.Findings-The performance of the prediction model is evaluated based on metrics,such as probability of detection,probability of false alarm,throughput and sensing time.The proposed spectrum sensing method achieves maximum probability of detection of 0.9696,minimum probability of false alarm rate as 0.78,minimum throughput of 0.0303 and the maximum sensing time of 650.08 s.Research implications-The proposed method is useful in various applications,including authentication applications,wireless medical networks and so on.Originality/value-A hybrid prediction model is introduced for energy efficient spectrum sensing in CR and the performance of the proposed model is evaluated with the existing models.The proposed hybrid model outperformed the other techniques.