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Mobile devices have become high-value attacked targets since they contain numerous private or business information. Android, the most popular mobile computing platform, also known for its openness, is facing various threats from system vulnerabilities to malicious applications. After analyzing Android's security model and threat, we summarize the technic possibility for remote or physical attacks,...
It analyzed three troposphere mapping functions, Niell Mapping Function (NMF), Vienna Mapping Function 1 (VMF1) and Global Mapping Function (GMF), and its parameters selection and characteristics paralleled. Also it presented the thumb rule in troposphere mapping function and designed a two way time transfer method based on troposphere mapping functions. Besides it studied the station height errors...
Wireless sensor network (WSN) applied on bridge health monitoring has attracted considerable attention for its advantages such as self-organization, micro-structure, low cost and high flexibility. The performances of WSNs are extremely correlated with application scenarios and even the same protocol may results in an obvious performance difference on various applications. However, no one has studied...
A wireless sensor network is composed of randomly dispersed nodes capable of collecting and transmitting physical data to a central node. Communication protocols are responsible for maintaining the routs in the network as well as for ensuring reliable inter-node communication. The main focus of this work is to analyze the performance of both reactive routing protocols mainly Ad hoc On Demand Distance...
Due to the limitation of the energy, the performances and applications were constrained of the pure batteries powered wireless sensor networks (WSNs). WSNs with energy harvesting extracting energy from the surrounding environment, supplement energy to the sensor nodes, can be significant prolong the lifespan of WSNs, or even make WSNs running for perpetual. In order to determine the node energy harvesting...
Block diagonalization (BD) is a well-known linear precoding scheme for multi-user multiple-input multiple-output (MU-MIMO) downlink transmission. BD precoding achieves good performance but results in high computational complexity overheads due to two singular value decomposition (SVD) operations for each user. By replacing the first SVD operation with a less complex solution, the QR decomposition...
To study the electromagnetic environment above the board of ship when high-altitude nuclear electromagnetic pulse (HEMP) radiated to it, a new method based on signal reconstruction is presented. By adopting FFT method, the HEMP signal is decomposed into a sum of sine continuous waves of different frequencies, and the amplitude response of the ship at each frequency, namely the amplitude spectrum can...
Self-organizing desynchronization in wireless sensor networks leads to near-optimal time-division multiple access (TDMA) behavior in the network's steady-state, without requiring a coordinator node. In order to increase bandwidth utilization, desynchronization can be extended to multi-channel MAC protocols. In this paper, we proposed a new protocol for the medium access control layer of IEEE 802.15...
This article presents a novel simple and compact triple band RFID reader antenna for handheld applications. The antenna is a microstrip antenna and fed by a feeding strip. By cutting a rectangular slot on the radiation patch to change the surface currents distribution, and then adjusting the dimensions and position of the rectangular slot to achieve a tri-band antenna. Radiation patch and the ground...
In the process of designing of the Micro mouse, we often need to spend a large quantity of time on debugging of the maze search algorithm. Research works on modularizing design with mathematical model can helps to modulate the maze environment and the moving model of Micro mouse, thus we can carry out the simulation of maze search algorithm, as well as other functions such as the compiling of the...
Recent years wireless networks have witnessed an explosive growth in enhanced multimedia broadcast and multicast service (eMBMS). Scalable video coding (SVC) streaming is a mainstream coding in eMBMS. In this paper we present a novel eMBMS user cooperative erasure recovery mechanism based on network coding where SVC streaming and layer network coding are broadcasted by source node. Local cooperative...
This paper analyzes the polling principle of IEEE802.ll PCF, and researches on the key parameters such as the system of the average queue length and average waiting time. In this paper, it presents a new dynamic polling access protocol based on priority (DPQWMAP protocol). The simulation results show that the protocol reduces the average waiting time of the whole system by the cluster head dynamically...
For cognitive radio (CR), compressed sensing (CS) techniques have been utilized for spectrum sensing in order to alleviate the high signal acquisition costs in the wideband regime. However, the compressed spectrum reconstruction will fail owing to the non-sparsity of the spectrum when the primary (licensed) users (PU or LU) occupy most subchannels. In this paper we study the problem of detecting spectrum...
According to the spectrum sensing problem under the short of collaborative users and low SNR, a cooperative sensing algorithm based on bistable stochastic resonance (BSR) is presented in this paper. First, decomposition and recombination (DAR) are adopted to increase the dimensions of matrix. Depending on the kind of decompositions, it can be divided into order-DAR and interval-DAR, which have a different...
Spectrum sensing in a wideband regime for cognitive radio network (CRN) faces considerably technical challenge due to the constraints on ADCs, especially in the presence of primary user emulation attack (PUEA) where some malicious users try to impersonate the primary user (PU) to prevent other secondary users (SUs) from accessing the idle spectrum. To address this issue, an eigenvalue-based compressive...
Differential frequency hopping (DFH) was believed to be an effective FH technique for increasing data rate of FH communication system. Cognitive radio (CR) users can use the CR technology to sense the surrounding RF environment, search for available spectrum resources and access spectrum dynamically. The cognitive radio technology and applied mathematics are introduced in DFH. And the Latin squares...
In this paper, the convergence-enhanced subspace channel estimation technique is investigated for MIMO-OFDM systems. The perturbation of noise subspace is inversely proportional to the number of OFDM symbols. Using the block circular property of the channel matrix, we propose the cyclic repetition method (CRM) to generate a group of equivalent signals for each OFDM symbol. The subspace channel estimation...
In this paper, we propose a ROI (Region of Interest)-based rate and computing resource allocation algorithm for H.264/AVC video coding, targeting at the wireless video communication applications on mobile devices. The proposed algorithm includes three modules: ROI detection, computing resource allocation, and bit rate allocation. A saliency-map-based scheme is performed to detect the ROI. Considering...
In recent years, the Android operating system for mobile terminals has developed very quickly. A variety of mobile devices which are using Android operating system are more than 60% in the domestic market share. With the number of Android application raising fast, a variety of information leakage, malicious chargeback, failure of operating system events occurred frequently; the safety of Android system...
With the gradual research on authentication issues, many researchers began to apply chaotic maps. Chaos theory has many good properties. It can achieve fast computing, and the time of encryption and decryption can be shortened to ensure smooth communication. Meanwhile, smart card technology is becoming a more practical technology. It has capabilities of security, confidentiality and identification,...
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