Earticle

There are many problems in security of Internet of Things (IOT) crying out for solutions, such as RFID tag security, wireless security, network transmission security, privacy protection, information processing security. This article is based on the existing researches of network security technology. And it provides a new approach for researchers in certain IOT application and design, through analyzing and summarizing the security of ITO from various angles.

A quadrifilar helix antenna (QHA) operating at 0.94GHz is designed and realized in this paper. The designed QHA consists of four helical conductors which are excited in phase quadrature by employing a Wilkinson divider which shows good performance in return loss and transmission characteristic. According to the designed parameters of the helices and Wilkinson divider, a QHA is fabricated and measured. The measured results demonstrate that the designed QHA has a resonant frequency of 0.94GHz and relative good performances including low voltage standing wave ratio (VSWR), broad beam width and approximate circular polarization are achieved. The designed QHA has simple structure and is suitable for practical application.

Wireless sensor networks are power constrained since nodes operate with limited battery energy. In order to maximize the lifetime of sensors networks, traffic should be sent via a route and different traffic applications that can be avoid nodes with low energy. In this paper, we analyze the performance of Zigbee home automation network under different traffic applications (such as constant bit rate (CBR), variable bit rate (VBR), and file transfer protocol (FTP)) by considering energy consumption parameter. The simulation results represent the impact on power consumption due to these different traffic applications in transmit mode, receive mode and idle mode. Energy consumed in transmits, receive and idle mode, for FTP application is low as compare to VBR and CBR. In terms of energy consumption FTP overall performs better than other traffic application since low power consumption corresponds to high efficiency.

In this paper an adaptive wavelet kernel based on density SVM approach for P2P traffic classification is presented. The model combines the multi-scale learning ability of wavelet kernel and the advantages of support vector machine. Mexican hat wavelet function is used to build SVM kernel function. The wavelet kernel function is tuned adaptively according to the density of samples around support vectors for several times during the training process. The experimental results show that the presented model can improve classification accuracy while reducing the number of support vectors and has better performance for solving P2P traffic classification.

This paper describes four cascade coplanar transmission line structures built into the quad flat pack (QFP) lead frame for high-frequency system in package (SiP) applications. Adjacent ground leads are used to provide return paths in a coplanar configuration, thereby minimizing impedance mismatch. Due to the complexity level in QFP structure, full-wave electromagnetic simulations have been performed to extract the S-parameter. Time Domain Reflectometry (TDR) is also used to help in understanding the contributing to the SiP structure. The SiP has also been fabricated and good correlation with electromagnetic simulations is also achieved.

The rapid development of various kinds of aerospace application systems requires the appropriate high-accuracy time and frequency standard. In order to establish suitable time and frequency standard in aerospace, based on the establishment of aerospace satellite visual model, we simulate the satellite visual time of 3-layer satellite constellation, including GEO satellite(Geostationary Earth Orbit), IGSO (Inclined GeoSynchronous Orbit)satellites and MEO(Medium Earth Orbit) satellites. The visual features of this satellite constellation have been gained. Combining with the major influencing factors of satellite clock offset error, we study the layered aerospace time synchronization architecture and give the advantage of the architecture and the choice of time synchronization method. Starting from the establishment of the time synchronization link demand, we simulate the variation range of intersatellite distance of the layered aerospace time synchronization architecture, and give budget results of GEO-GEO link in laser band and GEO-IGSO and GEO-MEO links in S-band and Ku-band. The results show that GEO-GEO link can achieve to more than 3Gb/s data transmission rate on condition that the transmitting power is 0.5W, the antenna diameter is only 20cm; if the S-band transmission rate is in excess of 2Mb/s, when the antenna is 1m in diameter, the transmitting power needed is about 50W. In the Ka-band, 1m antennas only need 1W transmitting power to provide an intersatellite data transmission rate higher than 2Mb/s. Research results serves as reference for the establishment of layered aerospace time synchronization architecture and improvement of time synchronization precision.

Mobile ad-hoc networks (MANETs) face a number of challenges, in particular due to its dynamic network topology. A self organizing framework can overcome the problems associated with changing topology and dynamic behavior of mobile nodes thus routing has become a great challenge to these types of networks. Such a framework can be created by using connected dominating set (CDS). But the choice of misbehaving node as CDS will inversely affect the network performance. A misbehaving node may disturb the network by denying packet forwarding. In this paper we propose a new reputation based routing protocol using CDS (Connected Dominating Set). The proposed weight heuristic is applied to each node in network for selecting CDS based on uses the reputation value in order to selective forwarders detection. Reputation refers to the opinion of one node about another node. Hence only well behaving and good quality nodes are selected as a dominant node for CDS construction. Through simulation results proves that the proposed method performs well compared to MPR selection approach in OLSR.

With the growing popularity of cloud computing, more and more users outsource their private data to the cloud. To ensure the security of private data, data owners usually encrypt their private data before outsourcing the data to the cloud server, which brings incommodity of data operating. This paper proposes a scheme for similar search on encrypted images. In the setup phase, image owner extracts feature vectors to represent the images as usual image retrieval system does. Then, the feature vectors are transformed by an invertible matrix, which not only protect the information of feature vector but also support similarity evaluation between the vectors. The encrypted vectors and image identifies are used to construct inverted index, which is finally uploaded along with the encrypted image to the cloud. In the search phase, with a query image, the authorized image user extracts and encrypts feature vector to generate the trapdoor. The trapdoor is submitted to the cloud and can be used to calculate the similarity with the transformed feature vectors. The encryption on features does not degrade the result accuracy. Moreover, the image owner could update the encrypted image database as well as the secure index very easily.

Botnet is most widespread and occurs commonly in today's cyber attacks and they become one of the most serious threats on the Internet. Most of the existing Botnet detection approaches concentrate only on particular Botnet command and control (C&C) protocols and structures, and can become ineffective as Botnets change their structure and C&C techniques. In this paper, we proposed a new general detection strategy. This proposed strategy was based on degree distributions of node and anomaly net flows, and combined data mining technology. In this scheme, we first constructed accurate traffic profile based on packet behavioral mode, and then introduced dialog flow to draw traffic profile of node. Finally we set up degree distributions of node and group and applied the degree distributions of node as input of data mining, which were then classified and distinguished to obtain reliable results with acceptable accuracy. The advantages of our proposed detection method is that there is no need for prior knowledge of Botnets such as Botnet signature and the accuracy of the experiment results is as much as 99%. The FP rate and the FN rate can be controlled within 3%, the best is almost 0.

Localization has been identified as a key and challenging topic in Wireless Sensor Networks (WSNs), especially for the applications requiring the accurate position of the sensed information. DV-Hop is a typical range-free node localization algorithm in WSNs; the localization cost and hardware requirements are not high and localization accuracy of sensor nodes is still low under certain circumstances. Based on the main reasons of the error DV-Hop algorithm, an improved algorithm is proposed in this paper which reduces the location error without requiring additional hardware. The proposed algorithm uses Received Signal Strength Indicator (RSSI) to give the hop count a correction value. In the proposed algorithm the hop count is no longer positive integer number, and can be positive real number. With this new idea, the distance between sensor nodes can be more accurately computed that that of in DV-Hop localization algorithm. Since the distance between sensor nodes estimation is a key issue in localization for WSNs, the proposed algorithm achieves better performance as compared with DV-Hop algorithm. Simulations are performed and the results show that the enhanced DV-Hop algorithm outperforms the DV-Hop algorithm in term of localization accuracy.

Enhanced distributed channel access (EDCA) is used for transmitting good quality of service of multimedia traffic in wireless local area network (WLAN). Applications like Constant bit rate (CBR), file transfer protocol (FTP) and voice over internet protocol (VoIP) are used in wireless LAN network. Audio data is assign as high priority (AC_VO) and other such as CBR & FTP type of data are assigned as low priority (AC_BE) in IEEE 802.11b network. G.711 provides a very good perceived audio quality in comparison to other audio CODECs. The G711 codec is used in VoIP call with 20 msec of audio data. In this paper, analysis of the effects on CBR& FTP traffic with increased call rate of VOIP and payload sizes of CBR & FTP traffic in WLAN environment for real time applications are made. Jitter buffer used in RTP protocol is improving the quality of service (QoS) of multi traffic in comparison to RTP protocol without jitter buffer.

Low earth orbit (LEO) satellite has the advantages of global coverage, low propagation delay and low path losses, etc. Combined with orthogonal frequency division multiplexing (OFDM) transmission, LEO satellite system can support very high capacity suitable for wideband multimedia traffic. This paper analyzes the channel model and throughput for LEO OFDM satellite communication system. First, several channel models for LEO satellite system are expounded with simulations because channel model is the basis of throughput analysis. Second, the beam model and the signaling model for LEO satellite are introduced. Considering high speed movement of LEO satellite, channel fading and the channel quality information (CQI), link throughput is simulated. Finally, compared with MF-TDMA system, simulation results demonstrate that OFDM system outperforms the former because its feasibility and superiority in throughput.

Interference alignment scheme, because of non ideal channel, can cause interference to primary user increases, it is worse at the same time the user's transmission rate, aiming at this problem, this paper studies the multiple antenna system is a kind of cognitive radio interference can achieve full multiplexing gain alignment method, analyses the interference alignment method under the condition of imperfect channel state information of the optimal transmission problem, and according to this problem, put forward the iteration method of interference alignment schemes, the simulation results show that this method is compared with the previous beam forming algorithm, and can obtain more transmission rate, improve the capacity of the time the user's system.

Based on cognitive self-organizing network transmission delay larger and larger interference to primary user receiver problem, put forward a method of spectrum joint routing selection, this method is effective to consider the transmission delay and the main user interference at the receiving end, mainly from < 1 > bandwidth available probability; < 2 > sent via link the number of bits of variance; < 3 > spread spectrum characteristic; < 4 > primary user receiver protection; < 5 > spectrum sensing five aspects to consider. Cognitive users of the information interaction with on-demand routing discovery process started, and to establish collaborative perception nodes along the route cluster, using the routing maintenance message to maintain the nodes in the cluster. At the same time on the cognitive network capacity maximization as the goal, put forward to jointly design spectrum collaborative perception and channel allocation. The simulation results prove the effectiveness of the method.

This paper proposes a method to deal with holes healing problems in wireless hybrid sensor networks. With recent advances in mobile platforms, hybrid sensor networks including static and mobile sensors are becoming very popular technology. In this paper, we investigate the coverage hole healing efficiency and propose a method to improve the efficiency. Specifically, mobile sensors can dynamically move to the un-coverage areas, improving both the coverage rate and the quality of service in WSN applications. During the process of mobile sensors moving, obstacles may exist in the environment. In order to reach the anticipated destination effectively, mobile sensors need to find an obstacle-free path for movement. To do this, we proposed an obstacle-free and geographic-free decentralized dispatch scheme (OGDD) to select and navigate the mobile sensors to participate the healing work. Experimental results reveal that the proposed scheme can be efficiently executed.

BGP is currently the most popular inter-domain routing protocol used in the Internet, providing stable and secure interconnection schemes for operators, and has a wealth of routing control mechanisms. BGP chooses its route depending on the attribute information contained in the update messages received from its neighbors. It allows each AS to choose their own routing policy, which may result too long convergence time to make packets lost in the application layer. Purely modifying the MRAI timer may reduce the convergence time at some degree, but may also bring some negative impacts like broadcast storms. In this paper, we proposed a BGP fast convergence mechanism by modifying the timer depending on the message type based on the concept that the bad news travels slowly while the good news travels quickly in the Internet. By simulating our mechanism on the SSFnt, we draw the conclusion that it can greatly reduce the convergence time, as well as reducing the redundant packets to some extent.

It is of great significance to manage and maintain EPON (Ethernet Passive Optical Network) effectively by discovering devices running in EPON network and relationships between devices automatically. After analyzing the characteristics of EPON network and basic principle of topology discovery, a topology discovery scheme is proposed, which is designed and implemented based on WebNMS framework to discover topology automatically in EPON network. The test results show that the scheme can discover topologic structure of EPON network quickly and precisely.

Mobile ad hoc networks (MANETs) are mobility sensitive and battery power constraint network. The link breaks frequently, hampers the continuity of data transmission. Most of the research work is targeted to find a feasible route from a source to a destination without considering its link breakage possibilities and its after effects. So proper route management is required. Thus, route discovery using cross layer approach routing protocol with Fuzzy logic (RDCLRP-FUZZY) is proposed in this paper. The route is refurbished through route discovery using adaptive hello warning message (HWM). The proposed scheme is investigated for mobility and traffic. Simulations are run on qualnet 5.0. Results are compared with basic AODV. It is illustrated that the route failure is reduced by 90% which is most important aspect for real time communication. The reduction of route failure improves the performance of the network. The novel part of the proposed work is route maintenance through route discovery. This reduces route failure frequency and flooding in the network.

Multipath routing protocols improve the load balancing and quality of service in WSN and also provide reliable communication. This paper investigates various multi-path routing protocols of the WSN in the literature and illustrates its benefits. The main elements of these schemes and their classifications based on their attributes have been also discussed. A comparison of these protocols which are of great help to understand the properties and limitations of existing solutions have been done in the following study.

Conversely to the fully connected case, it has been proved in theory that interference alignment (IA) can be achievable in a partially connected multi-cell multiple input and multiple output (MIMO) interfering broadcast channels (IBC) network of arbitrary size efficiently. For this applicable significance, based on the L-interfering MIMO IBC model, we present three iterative IA algorithms to solve the alignment problem for this type of model in this paper. Then we discuss the feasibility conditions and the computational complexity of the algorithms. Simulations show that, with a finite antenna number per transmitter and receiver pair between base station (BS) and user, the proposed algorithms can achieve the optimal degrees of freedom (DoF) and can be applied to a partially connected MIMO IBC network with arbitrary number of cells and users per cell.