Earticle

A Software Defined Network (SDN) separates an existing network structure into a control plane and a data plane and centrally manages the network at the control plane. SDN is able to control the network in detail and operate efficiently by managing the traffic by flow unit. However, if the performance of the switches comprising the SDN varies greatly from one to another, it has a problem of delayed handling of traffic due to the bottleneck caused by an overhead concentration at the controller when the message exchanges between the low performance switch and the controller for flow table replacement increase in number. This research paper suggests a flow table management scheme, called Proactive-LRU, to alleviate this problem and compares its performance to that of the existing replacement algorithms such as LRU, LFU, and FIFO. Proactive-LRU scheme is a flow table management scheme that deletes the flow from all switches available within the forwarding path when a flow is deleted and reduces the number of message exchanges and the controller overhead. In order to compare the performance of the suggested scheme against that of the existing algorithms (FIFO, LRU, LFU), video traffic and web browsing traffic have been mixed in certain ratios in an SDN environment for the experiment. The analysis of the results showed that the number of message exchanges as well as the overhead and table overflow of switches in the suggested scheme were significantly reduced.

In order to improve signal reconstruction accuracy, a CoSaMP (Compressive Sampling Matching Pursuit) algorithm based on peak signal to noise ratio is proposed in allusion to the disadvantages of CoSaMP algorithm. Firstly, the discrete cosine wave transform is improved to initially estimate the signal sparseness; secondly, the optimum iteration number is determined according to the peak signal to noise ratio to gradually approach to the real sparseness of the signal for signal reconstruction; finally, the simulation experiment is adopted to analyze the algorithm performance. The result shows: compared with CoSaMP algorithm and other improved CoSaMP algorithms, the proposed algorithm can not only obtain more ideal reconstruction effect, but also improve the reconstruction success probability and reduce the reconstruction time, thus having higher reconstruction efficiency.

The matched filter is often used for the radar receiving terminal, but such application in wideband radar may cause complex system and high cost. The adoption of compressed sensing can not only remove the matched filter and the high-speed analog-digital converter, but also realize high-resolution radar imaging. In consideration of the sparseness of the radar target scene, a compressed sensing method used for chaotic radar is proposed in this article, wherein the chaotic frequency-modulated signal is generated by Bernoulli mapping and the randomness of such signal can be directly used for constructing the observation matrix. Meanwhile, the under-sampled echo signal can be used for radar scene reconstruction through the optimization technology. According to the simulation of stationary and non-stationary target radar scenes, compared with the matched filter processing technology, the proposed method has simple processing procedure and optimal performance, and the feasibility of this method is also verified by the simulation result.

Network Mobility Basic Support Protocol (NEMO-BSP), the existing IETF standard for mobile network support, signifies an important portion for future heterogeneous wireless access networks. The reason is to provide continuous Internet connectivity during movement of Mobile Router (MR) in NEMO. This paper conducted a quantitative analysis on the handoff delay component of NEMO-BSP as well as its existing enhancements, i.e., Fast NEMO (F-NEMO) handoffs, and an Extension of F-NEMO (EF-NEMO), using the numerical framework. The mathematical scenario includes two access routers, one local home agent and up to 20 MRs that interrelate by two different wireless access networks are mainly WiFi and WiMAX. The analysis offers quantitative outcomes of the performance enhancements achieved via the proposed improvements concerning handoff delay gain, packet loss, and packet loss ratio. The numerical results assist in understanding the influence of link switching delay, mobility rate, and radius on the handoff delay gain, packet loss, and packet loss ratio. The results of this analysis will also be aided to pick an appropriate mobility management scheme for Proxy NEMO environment.

In order to solve such problems as the difficult realization of accurate positioning and multidimensional dynamic elastic range measurement and the poor reading of positioning data caches during the range measurement process in wireless sensor network, a wireless sensor network positioning algorithm based on neighbor spin-hop iteration mechanism. Firstly, the neighbor clustering process is executed for the nodes in the wireless sensor network, namely: the first-order neighbor nodes and the second-order neighbor nodes are taken as the network neighborhood. Secondly, other network nodes are positioned according to the rejection and attraction conditions of the neighborhood radius, and meanwhile the iteration mechanism is adopted to realize error minimization so as to obtain the accurate position coordinate of the node. The simulation result shows: compared with currently widely applied two-dimensional non-iterative accurate positioning algorithms, such as RSLM algorithm and SOCP algorithm, the new algorithm is provided with clustering mechanism for accurate positioning and the error correction method based on iteration mechanism, thus to not only effectively reduce the node position error and improve positioning accuracy during multidimensional range measurement, but also improve network packet delivery ratio and reduce network control overhead.

Mobile devices are increasingly becoming famous in the current times. Limited computing resources are still a hindrance for resource intensive computations. Several frameworks have been established to enable cloud -based mobile augmentation (CMA) approach be followed by mobile applications. CMA has a strategy of dynamic outsourcing resource intensive tasks to the external resources. CMA’s state of art mobile augmentation model employs resource- rich clouds to increase, enhance and optimize mobile device. Augmented mobile devices in the cloud are geared towards extensive computations and storage of big data beyond the device capabilities with little or no traceable footprint and vulnerabilities. CMA has made efforts towards exploiting various cloud- based computing resources especially the distant clouds and proximate mobile nodes to augment mobile devices. Task scheduling is one of the approaches that are well elaborated using computations in this paper that is employed to reduce execution time.

With the continuous improvement of the transmission rate and the quality of wireless communications services, the need for a wireless communication network structure to adjust. The traditional rules of cellular networks no longer meet the high-density, large number of people for high-speed data transmission. Heterogeneous network can solve the problem of network coverage and network-efficient transport, but because of the heterogeneous network dense arrangement of the network, so the introduction of a number of inter-cell interference, especially at the edge of the cell. To solve this problem, we use collaborative tools of game theory, to be distributed among the power cells to determine the coverage of each pico cell. But the need to optimize collaboration between cells, select the number and scope of the coordinated cell. Simulation results show that the proposed algorithm can effectively improve the transmission rate of the system, eliminating the interference between cells.

In view of the problem of AS-R autonomous wheeled mobile robot obstacle avoidance, a rapid convergence of sonar and binocular stereovision sensor distance information in order to detect and avoid obstacle algorithm is proposed in this paper. The algorithm first uses binocular camera (CCD) to get three-dimensional image of the real environment, through the stereo matching and V-disparity method which is used to calculate disparity map, then obstacles is extracted by Hough lines detection algorithm, finally we will get information about obstacles and sonar return information with T-S fuzzy neural network fusion, then it will output walking controlled decisions. Experimental results proved that the algorithm is effective and practical.

Wireless technology is continuously evolving, and the development of new versions of adaptive protocols and mechanisms are at their peak to achieve high performance in network-based applications and services. LTE networks offer broadband wireless access to users who can benefit from high data rate applications such as video streaming. However, the high energy consumption of these applications has not been considered. The end user quality of experience (QoE) of video delivery over a radio network is mainly influenced by the radio parameters in the radio access network. This paper will present a multiple framework QoE model for video delivery over LTE, denoted as MQoE that measures the overall perceived quality of mobile video delivery from subjective user experience and objective system performance. We propose a QoE-based energy efficient mechanism to reduce smartphones’ power consumption. We have done a series of experiments to verify the efficiency of this model. Experiment results show that MQoE has significant improvement at energy efficiency

MANET is multi-hop network which is a decentralized and infrastructure-less network that includes collection of mobile nodes that are self configurable and co-operates with each other for transmission of data. It has dynamic nature in terms of topology. Due to this dynamic nature of topology and no fixed infrastructure in MANET, these nodes have to be dependent on each other for transmission of data and thus are prone to packet drop attacks like Blackhole, grayhole attack. These attacks hinder the smooth transmission of data between nodes and hampers effective communication. In this paper, a new mechanism Traffic Light Trust Based (TLTB) is proposed to detect both Blackhole attacks and Grayhole attacks. This mechanism works after modification in the standard AODV routing protocol and Watchdog mechanism. This mechanism uses color scheme to define trust level of a node or any path. Just like traffic light it includes three colors to depict the level of trust. AODV routing protocol packets are modified to include new fields for application of proposed trust mechanism. These Solutions are compared with Light-weight Trust Based (LTB) and EDRI mechanism for Normalized Control load, Packet Delivery Ratio, accuracy in Blackhole and Grayhole detection and reliability of paths.

In order to improve universality of detection effect of complex network covert channel, coarsening clustering of channel is achieved, based on clustering algorithm, with hierarchical clustering in this article, then recognition detection of two-stage channel refinement is carried out in coarsening clustering results of each layer based on density clustering. Clustering method of multilayer covert channel is designed based on density, the effectiveness of proposed method is verified by carrying out contrast experiment on density clustering method, entropy method and  evaluation method; in the end, experiments of simulation example demonstrate that such algorithm is able to quickly and accurately detect covert channel of complex network when the noise is not higher than 20%.

In this letter, we propose a novel two-way amplify- and-forward (AF) relay selection scheme over independent flat Nakagami-m fading channels. In the proposed schemes, two users first sequentially broadcast their respective information to all the relays. Then, the Nth best-relay perform AF protocol on the received signals sent from the two users and forward them to both users. The Nth best-relay is selected to optimize the end-to- end performance of the system transmission. The performance of the proposed system is quantified by deriving the lower bound of the overall outage probability and average symbol error rate (SER). The effectiveness of our proposed selection scheme and analytical results is verified by simulations.

Through analyzing and researching the cross-layer model proposed in traditional literatures for the data transmission in wireless sensing networks and the improved version thereof, the problem of the inaccurate data slot selection is found in current cross-layer data transmission mechanism. Then, mini-slot is adopted to improve data frame structure and reduce data transmission conflict ratio, thus to reduce network throughput and energy consumption at the same time. Moreover, the slot function selection process and the mathematical derivation process are provided for the multi-hop network. However, due to the limited experimental conditions at present, the improvement for test site selection, experiment size, etc. can be achieved in future.

A data transmission scheme based on cluster is proposed for data transmission of VANETs. Firstly, the selection scheme of cluster head CH is designed. The optimal CH is selected by calculating the utility function of CCHs, which combines node degree (NOD), available resource and mobile information of CHs and CMs, including the characteristic requirements of different user applications. According to the simulation results, the proposed scheme’s performance can be improved in terms of throughput, data transmission delay, successful transmission rate and overhead.

This paper present a review on the data aggregation techniques in WSNs. Data aggregation techniques have become an major part of WSNs to overcome the problem of flooding at the base station. Also data aggregation techniques reduce the communication cost of WSNs; because it reduces the redundant data by aggregation. Various data aggregation techniques have been considered in this paper. The data aggregation results in reduction of redundant data therefore reduce the amount of data transmission packets size which will reduce the energy consumption in each round. This paper ends with the shortcoming of data aggregation techniques.

The vibration signal is one of the significant signals that reflects the fault. In allusion to the shortcomings of traditional signal analysis method in the high-frequency and non-stationary signal analysis, the wavelet theory and approximate entropy algorithm are introduced into the signal analysis in order to propose a new vibration signal analysis (WTAEAVSA) method in this paper. In the proposed WTAEAVSA method, the wavelet transform technology is used to reduce the noise and decompose the low and high frequency vibration signal in order to obtain the signal characteristics of different frequency bands. Then the approximate entropy algorithm is used to determine the complexity and irregular degree of vibration signal in the different scale and different frequency band, so as the non-stationary characteristics of vibration signal are extracted. At last, some simulated signals with time-domain and frequency-domain from the normal signal are used to test the characteristics of the proposed WTAEAVSA method. The simulation results show that the proposed WTAEAVSA method can extract the characteristic vector from vibration signal, visually and sharply reflect the changes of the mechanical states.

Nowaday, the worldwide applications of RFID technologies have contributed to the development of supply chain system. However, to be confronted with various security and privacy issues in lightweight RFID protocols, the security analysis of lightweight ownership transfer (OT) protocols has become an important task. First and foremost, the passive attacker can further break down the security and privacy of three new published lightweight RFID protocols. Subsequently, the proposed protocol is designed to prevent the traceability attacks. Then, it is significant for us to show how to prove strong forward untraceable and backward untraceable of the improved scheme in security model.

Keeping the network coverage and maintaining high connection are the goal of the wireless sensor networks (WSN). Therefore, network coverage becomes the focus of research, then an Energy aware-based complete coverage and highly connectivity scheme is proposed in this paper, which named EACC. In EACC scheme, firstly, the relationship between overlapping area of two sensor nodes’ sensing area and distance between them is analyzed, and results show that overlapping area is non-linearly reduced with the increase of distance. Secondly, each cluster head (CH) makes use of the coverage area and residual energy of nodes to determine whether the node is the active node or sleep node. Moreover, in order to maintain the connectivity, any one node is in another node communication range. Finally, compared with similar schemes, extensive simulations results show that EACC scheme outperforms other schemes.

In the process of coverage for multiple targets, due to the existence of a large number of redundant data make the effective monitoring area coverage decreased and force the network to consume more energy. Therefore, this paper proposes a multi-target k-coverage preservation protocol. First of all, establish the affiliation between the sensor nodes and target nodes through the network model, present a method to compute the coverage expected value of the monitoring area; secondly, in the network energy conversion, using scheduling mechanism in sensor nodes to attain the network energy balance, and achieve different network coverage quality through different nodes energy conversion. Finally, simulation results show that NMCP can effectively reduce the number of active nodes meeting certain coverage requirements and then improve the network lifetime.

Sink mobility has been widely used to reduce the energy consumption of sensor nodes, which can prolong the lifetime of nodes in wireless sensor networks (WSNs). Researchers found that sink mobility can improve the stability, throughput and lifetime of the very large-scale WSNs. However, sink mobility also causes issues such as data latency and communication overhead. With these properties sink mobility remains more research efforts under different requirements. In this paper we present a survey of energy efficient strategies in WSNs with mobile sink. Firstly, we investigate the existing issues in WSNs. Then we focus on the problem of energy efficient data gathering strategy with mobile sink and present some existing solutions. Finally, we conclude this paper with some potential extensions which need to be further explored.

In the Internet of Things (IoT), a gateway and a set of IoT devices (IoTDs) form a star-topology and the IoTDs compete between them for sending uplink communication during short time slots. Therefore, in this paper, we propose a novel multiple access protocol with time-slot reservation that can increase the success rate of the uplink data transmission with collision avoidance in the IoT. Further, using a modem calculator tool from the LoRa Alliance, we evaluate the system performance of the low power wide area network which is designed for sensors and applications in terms of equivalent bitrate, time on air, and Tx energy consumption for the uplink of the IoTDs.

The LNCR-IDS for the mobile Ad-HOC network is put forward for the problem that the redundancy clusters are adverse to energy saving because leaf node independent clusters exist in the CHS and cluster partition in the traditional mobile Ad-Hoc network containing IDS. Firstly, make analysis on the traditional random cluster partition method and find that the method easily results in the problem of redundancy partition, put forward the new method which carries out cluster partition starting from the leaf node, try to solve the problem of redundancy of cluster partition, so as to lower the energy consumption; secondly, make analysis on the realization of algorithm, construct the algorithm of single node elimination and give the process of cluster partition via simple analysis example in allusion to the proposed method; finally, carry out simulation comparison with the existed algorithm via the experimental platform created, the proposed algorithm should be about 30% less than the comparing algorithm in the number of clusters, which is beneficial to the improvement of network service life.

Node localization algorithm of NLOS (Non-line-of-sight) environment based on PSO (particle swarm optimization) is proposed aiming at NLOS range error. PSO algorithm is quoted in wireless sensor network localization. First of all, the parameter of PSO algorithm is improved and nonlinear adjustment to inertia weight is made to boost convergence rate of algorithm, at the same time, target value is in rank ordering to decrease calculated quantity. Simulation results demonstrate that proposed algorithm reduced error influence of NLOS and improved location accuracy.

In this paper, we propose an Energy Harvesting aware Entropy-based Routing protocol, called EHER, in mobile ad-hoc wireless sensor networks. The main features and contributions of this paper are as follows. First, we use physical layer information of RF-energy harvesting when routes are selected in network layer. Second, we use energy aware entropy based mesh route selection strategy adaptively to efficiently support route stability. Third, we use a direction-guided line using location information to support energy saving for the establishment of routing routes in the given networks. The performance evaluation using OPNET shows that the proposed routing protocol can efficiently support PDR, average and minimum remaining energy of nodes, and the lifetime of routes and networks, respectively.

In allusion to such problem as unsatisfactory accuracy of the traditional laser communication LTE channel estimation algorithm, an LTE-OFDM multi-layer channel estimation algorithm based on least square 2D spread spectrum is proposed in this paper. Firstly, 2D spread spectrum estimation is adopted to design the weighted 2D spread spectrum estimation algorithm framework under multi-layer time-frequency domain LTE-OFDM resource model; secondly, in order to improve the accuracy of 2D spread spectrum estimation, the linear least square algorithm is adopted for weight parameter estimation and 2D spread spectrum power normalization; finally, through the comparison in the simulation calculation example, it is indicated that the proposed algorithm is superior to the standard 2D spread spectrum algorithm and the linear least square algorithm in the aspect of channel estimation effect.

With the flight environment becoming more and more complex, how to avoid the moving threat for the UAV under the dynamic environment and complete the mission become a key problem. With the idea of guidance, using the method of dimension reduction, the dynamic guidance obstacle avoidance method in three dimensional spaces is given. Considering the collision avoidance completion time and the UAV’s maneuverability, the parameters range of obstacle avoidance navigation law are deduced. Simulation results show the validity of the algorithm.

The recognition of handwritten mathematical documents is a very important field which is interested in identifying the text, graphics or notations and in extracting information. In this paper the focus will be on the handwritten mathematical text recognition and we are going to present all the necessary steps in our system (preprocessing, text lines segmentation, mathematical symbols segmentation and symbols recognition).