Earticle

The paper investigates the problem of a distributed robust relay beamforming in cognitive one-way relay networks with imperfect channel state information. We aim to the minimum the transmit power of relays, satisfying the SNR (signal-to-noise ratio) of the secondary users high a threshold and keeping the interference at primary users below an acceptable threshold. Because of the robust identity the optimal problem is a non-convex problem which is hard to be solved. In this paper we transform the non-convex problem into a convex one which can be solved efficiently by exploiting S-procedure and Schur complement theorem and relaxing the rank-one constrain. Then the robust beamforming vector can be obtained. Simulation results show that the proposed algorithm can solve the minimum problem with robust features efficiently and obtain satisfactory results.

Congestion in mobile ad hoc networks leads to transmission delays and packet losses and causes wastage of time and energy on recovery. In the current designs, routing is not congestion adaptive. Routing may let a congestion happen which is detected by congestion control, but dealing with congestion in this reactive manner results in longer delay and unnecessary packet loss and requires significant overhead if a new route is needed. This problem becomes more visible especially in large-scale transmission of heavy traffic such as multimedia data, where congestion is more probable and the negative impact of packet loss on the service quality is of more significance. Routing should not only be aware of, but also be adaptive to, network congestion. Routing protocols which are adaptive to the congestion status of a mobile ad hoc network can greatly improve the network performance. Many protocols which are congestion aware and congestion adaptive have been proposed. In this paper, we present a survey of congestion adaptive routing protocols for mobile ad hoc networks.

Mobile ad-hoc network is one of the most attractive fields for research. Any new node easily entered or left the network because of this property is easily thretend by the attack. A wormhole is one of the most crucial attack of MANET in this paper, we study lots of prevention and detection technique. In our propose work we work on trust and reputation mechanism and then secure network novelity of proposed work we proof by our outcomes.

With the development of IoT (interest of things) and network routing technology, IoT terminal data collection, integration and transmission technology improved significantly. Currently, research and use of IoT gradually widespread, but more of the terminal platforms were exploited for particular field. The versatility and compatibility of platform restrict its use and promotion. Based on the point, this paper aims to develop an IoT embedded system with flexible interface. Exploit the flexible interface with multi-sensor terminal access and ZigBee protocol to achieve MANET, sensor flexible access, low level of energy consumption, network isolation. The system has a high level of scalability and important value and practical significance to IoT application development.

Selective acknowledgment (SACK)-based retransmission and recovery mechanism has been implemented in most of current transmission control protocol (TCP) stacks. A new SACK-based loss recovery algorithm is defined in RFC6675 under standard track. Existing models in literatures on modeling TCP SACK, which usually use SACK-based retransmission and recovery mechanism, is no longer accurate for two reasons: 1) they ignore transmission of new packets before retransmission of the last loss; 2) they are based on the strategy that pipe is decreased by 2 upon receipt of a partial ACK, where pipe is the estimated number of outstanding packets. This paper develops a new method to derive the expected number of new packets transmitted between retransmission of the first loss and the last, proposes a model that estimates the expected number of packets transmitted during fast retransmission and recovery phase (FRR) and the corresponding expected duration based on RFC6675. The numerical results show that the proposed model can accurately estimate the expected number of packets transmitted during FRR and the corresponding expected duration based on RFC6675.

Wireless sensor network (WSN) is a new research area of computer science and technology and has a wide application future，more and more attention. It will be much market in application of military, health, home, environment, etc. In WSN, sensor devices have limited supply of energy. The sensor death due to dissipating battery energy is one of the fundamental design issues in WSNs. Hence, energy efficiency is argued to be the most important requirement for WSN. Aiming at the limitation of energy of wireless sensor network node, this paper presents a routing algorithm which is based on the ant’s capability of finding the best paths between a food source and their nests. The pheromone and the energy of the node and delay of the node were combined to affect the pheromone concentration in optimization．Simulation results show that it can balance energy consumption between nodes and prolong the lifecycle of the whole network.

In mobile computing environments, storage service is becoming more and more important with the emerging of plenty of data-intensive applications. Although, many mobile storage systems have developed to deal with this situation, few of them take the energy-efficiency into consideration. In this paper, we presented an energy-efficient mobile storage platform, which is based on our previously developed Dependable Cloud-based Storage Platform for Mobile Computing (DCSP-MC). The key improvement of this mobile storage platform is that it takes the energy consumption of storage nodes into consideration. Extensive experiments are conducted to evaluate the performance of the proposed platform, and the results indicate that it can significantly improve the energy-efficiency of the underlying storage nodes, as well as providing desirable quality of service for mobile end-users.

In the existing literature for Information-Centric Networking (ICN) architectures improvement metrics are well researched and studied including the cache hit rate, origin server load reduction, and the reduction in the overall network footprint [1]. Metrics could be optimized using various aspects of caching including the content placement to make a decision which routers should cache the content on a request patch [2-5]. Impact of different ICN caching placement strategies on the main cloud TV performance metrics is deeply researched in this work, and results are presented. Seven cache placement algorithms are evaluated including four cache sizes of 1 GB, 10 GB, 100 GB, and 1 TB.

This paper first represent the basic conceptions of anonymous communication, then introduce the fundamentals in Anonymous Communication. Afterwards, we went deep to the classification of anonymous network topological, therefore we could get a better understanding on P2P anonymous communication system. We also systematically analyzes the existing node-select algorithms. Furthermore, we propose and implement a new node selection algorithm based on Dijkstra algorithm, named NSDA algorithm. We give a belief description about the backgrounds and design of NSDA Algorithm. The algorithm can combine the node properties with link properties to select node, which can adjust the system performancing and anonymity. In order to evaluate the NSDA algorithm, we have done experiments in Network Simulator 3, and we also explain the reason why we choose Network Simulator 3 as the simulate tool. In the end, we analyze the characteristics of NSDA algorithm according to the results of experiments.

A current sensing method based on giant magnetostrictive material (GMM) and fiber Bragg grating (FBG) was proposed, which not only combines the advantages of FBG such as wavelength encoding, compatibility with fiber and distributed measurement system realization, but also the advantages of GMM as large flexible coefficient, high electromechanical coupling coefficient and short response time. The minimal residual method was put forward to effectively identify the Jiles-Atherton model parameters of ferro-magnetic material. The parameters of the giant magnetostrictive ( Terfenol-D bar ) and the Jiles-Atherton model was established and optimized by using the Mathematica software. Then the optical fiber current test system with ferromagnetic loop was set up to investigate the current sensing properties of the sensor. The relationship between current excitation and GMM-FBG reflected wavelength was obtained, which provides basic support for further current sensing experiment research.

In order to provide personal guiding service to visitors in the Picture Gallery, a mobile visual search guiding system based on SIFT(Scale Invariant Feature Transform) is proposed in this paper. The visitors can achieve the paintings’ information using the camera function of the mobile phones when they enjoy the famous paintings in the Picture Gallery. The mobile search visual system proposed in this paper can identify the paintings in the server side so there are no extra performance requirements for the mobile phones. Firstly, the mobile visual search system was introduced. Then the system was designed and realized. The classification training was based on SVM (Support Vector Machine). The SIFT feature extraction algorithm was used to enhance the recognition rate. After the image retrieval, the geometric consistency check was employed to choose the best matching image. Finally, the experimental results verified the feasibility and practicability of this system. Compared with the present guiding systems, this system can communicate with the visitors conveniently and offer abundant and all-around information to the visitors. In addition, using this guiding system, any auxiliary devices are not needed to be installed in the Picture Gallery.

To deploy the MIMO technology in the heterogeneous networks, we analyzed the interference and energy efficiency of the system. The recent studies of the application of the MIMO technology in heterogeneous network is introduced first. Then, The system model, inter cell interference are analyzed. The mathematical model was proposed in the paper involving energy efficiency. Finally, the simulation results in the study indicates that the simple prevention can eliminate the interference and the ZF pre-encoding is equal to the MRT pre-encoding under limited conditions. The results show that the interference model and energy efficiency equation proposed in the study have a great application prospect.

In wireless body-centric communications, either the transmitter or the receiver, or both are located in close proximity to the human body. Thus, the Line-of-Sight (LOS) components of the radio signal are particularly susceptible to shadowing caused by human body. In earlier, the effect of human body shadowing was studied using κ-μ fading channel, where the resultant dominant signal components due to body shadowing effect was characterized by log-normal distribution and Nakagami-m distribution in different experiments. In this context, this article provides a comprehensive comparison of two aforementioned methods of human body shadowing effects in wireless body-centric communications. Here, the dominant component characterized by log-normal distribution is mentioned as shadowed log-normal model, whereas the Nakagami-m distribution dominant component model is mentioned as shadowed Nakagami-m model. Different wireless body-centric communications scenarios, namely on-body, off-body, and body-to-body, are tested separately with these two distribution methods. MATLAB based simulations indicate that the shadowed Nakagami-m distribution provides better fit to the empirical results in comparison of shadowed log-normal distribution. Moreover, the probability density function of shadowed Nakagami-m model provides numerical advantages over shadowed log-normal model.

Machine selection is an important step in the process of manufacturing. The selection process needs to consider some selection attributes simultaneously from a set of candidate machines. The attribute weights are important for the result of machine selection problem, but the most used AHP method has the shortcoming. Thus this paper will develop a new weighting method based on the concept of group eigenvalue method. Then the new machine selection method is proposed by combining group eigenvalue method with TOPSIS method. Two practical examples demonstrate that the proposed method has more effectiveness and feasibility.

In this paper we investigate the high speed Tbps (Terabits per second) DWDM (Dense Wavelength Division Multiplexing) system optical network. In this system there is present 40 channels at transmitter section each having bit rate of 30Gbps to make a 1.2Tbps speed of system. The transmitting channel signal is passed through an optical fiber of link length 100 km along with DCF of length 8.37 km. At the receiver section signal is received by 40 receivers and check the receiving signal strength on the basis of Eye diagram i.e., by the values of Q-factor, BER and eye opening of the signal provided by eye diagram analyzer. The system covers a distance of 100 km with good and favorable results on the basis of Q-factor and BER.

In this paper, we investigate the interference scenario where multiple Device-to-Device (D2D) pairs reuse the spectrum resources allocated to one cellular user, and propose a novel algorithm for improving the signal-to-interference-plus-noise ratio (SINR) of D2D communication. We call this D2D SINR improvement algorithm as DSIA, and design it from the perspective of precoding and decoding. With the DSIA, each D2D pair involved in the network can obtain the corresponding precoding and decoding vectors which make the SINR of its receiver being maximized. In order to clearly describe the design procedure of the proposed algorithm, we first formulate an optimization problem with multiple variables to maximize the SINR of each D2D receiver, then simplify the objective function through mathematical derivation and seek out the relationship between the optimized variables which can transform the optimization problem to one of solving nonlinear equations, and finally propose the DSIA to work out the nonlinear equations. Numerical results show that the DSIA will enable D2D to achieve significant performance gains in terms of SINR and bit-error rate (BER) compared with the traditional spectrum orthogonal scheme.

Recently the in-band full-duplex in wireless communication has evolved into a mature technology since the self-interference cancellation technique is able to support full-duplex capability. Moreover, some researchers focus on the full-duplex media access control (MAC) protocol design for wireless local area networks (WLANs). However, it is assumed that all the node have full-duplex capability in most study of the full-duplex MAC, and it is not practical since stations (STAs) may be half-duplex in the network while access point (AP) has full-duplex capability. In this paper, a full-duplex MAC pro-tocol named interference aware full-duplex MAC (IAFM) is proposed for the next gen-eration WLANs on the assumption only AP has full-duplex capability. In IAFM protocol, there are three mode including direct scheduling mode for normal full-duplex transmis-sion, interference collection mode for interference collection usage and none full-duplex mode for legacy transmission. Beside, direct scheduling mode and interference collec-tion mode are described in detail, and none full-duplex mode obeys the legacy MAC pro-tocol in WLANs. The power control mechanism is also discuss in this paper. The simula-tion results shows that in saturation condition IAFM protocol with power control almost double the throughput of legacy MAC protocol in WLANs.

To curb the impact and transmission of worms and virus for simple mass action incidence rate in computer networks, SI1I2RS (Susceptible, Infectious due to worm, Infectious due to virus, Recovered and Susceptible) model have been formed. Basic reproduction number, endemic equilibrium state and their stability are discussed for the simple mass action incidence. For locally and globally asymptotically stability of the infection free equilibrium state, Liapunov function is used. Numerical methods have been used to solve and simulate the system which will help us to understand the attacking behavior and transmission dynamics of malicious object in computer network, and efficiency of antivirus software.

Missing data is a common phenomenon in the data collection process of wireless sensor network (WSN), and the missing data imputing is an important issue of WSN stream data mining. Currently WSN missing data imputing method has little considered about the dynamic characteristics of internal data time structure during the data collection process, which makes data imputing difficult to reflect the real monitoring change objectively. In order to analyze the internal structure and dynamics of WSN time sequence data systematically, with the equivalence relation of the monitored object the time domain can be regarded as a series of integral time granule (ie atomic time point set), a wireless sensor network timing information system (WTIS) is established. The system can reason logically at different time granularity, and a multiple optimal time granularity strategy of WTIS based on hierarchical successive approximation approach is proposed. Finally, based on the research, a multiple optimal time granularity WSN missing data clustering imputing algorithm is proposed. Compared with traditional fixed time granularity missing data imputing algorithm, experiments show that the algorithm can lower error rate when imputing WSN missing data.

A wireless cattle health monitoring system to measure health and psychological parameter of cattle has been developed using environmental temperature and humidity, body temperature, rumination, heartbeat, and sweat sensors. The system developed is capable to analyze stress level of cattle’s with reference to THI (Thermal Humidity Index). System is developed according to IEEE1451.1, 1451.2, and 802.15.4 standards. The ATmega16 controller and zigbee has been used to develop the wireless sensor and receiver nodes. LabVIEW is used as a real time data logger for monitoring the output of various sensors over the PC. This real time data monitoring is much inexpensive technique for monitoring of health of livestock. Power consumption of the device has been kept minimum. The device is successfully designed, made, and tested.

How to schedule multiple sensing units of a sensor to cover multiple targets becomes a new challenging problem. This problem is formulated as an integer linear programming problem for maximizing the network lifetime. We propose a novel energy-efficient target coverage algorithm to solve this problem based on clustering architecture. First of all, the network probability model is established and the subordinate relation between sensor nodes and the target nodes is presented. Secondly, a series of probability is computed and the related theorems and reasoning are also proven. Thirdly, effective coverage for the monitoring region is achieved through scheduling mechanism of nodes themselves, thus the purpose of increasing network lifetime can be realized. Finally, experimental results show that the proposed algorithm could achieve complete coverage for networks of different scale, and increase the network lifetime. It possesses the good quality of effectiveness and stability.

The paper proposes a clustering algorithm for wireless sensor network based on hypergraph. Under the hypergraph model, a wireless sensor network is mapped to a hypergraph. Then a hierarchical iterative clustering algorithm is applied to the hypergraph, thus dividing the hypergraph into multiple parts. A cluster head is selected from each part. In order to improve the partitioning process, a new modularity function is proposed. Compared with the classic clustering algorithm LEACH, simulation shows that our algorithm performs better in energy consuming and network lifetime.

In this paper OFDM-PON downstream transmission is demonstrated over different length of fiber at Remote Node (RN) for different m-QAM mapped OFDM signal (m = 4 and16) transmission from the central office (CO) for data rates (10 Gbps) using coherent detection at the user end or optical network unit (ONU). Investigation is performed with different number of sub-carriers back to back optical signal to noise ratio (OSNR) along with transmitted and received constellation diagram for m-QAM mapped coherent OFDM downstream transmission at different speed over different transmission distance. Simulation results suggest the different length and data rate that can be used for different m-QAM mapped coherent detection OFDM downstream transmission and the proposed system may be implemented in Next Generation high speed PONs (NG- PONs).