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Communications and Information Technologies, 2006. ISCIT '06. International Symposium on

Date Oct. 18 2006-Sept. 20 2006

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Displaying Results 1 - 25 of 258
  • A Design Method of Criteria for Detecting the Number of Signals

    Page(s): 816 - 820
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4427 KB) |  | HTML iconHTML  

    This paper proposes a novel design method of criteria for detecting the number of signals superimposed in multichannel time-series. Based on probabilistic properties of difference in maximum log likelihood at infinite SNR, penalty functions in information theoretic criteria are designed by giving specific upper bounds of error probabilities. The proposed design method uses an approximation of probability distribution functions of the difference in maximum log likelihood. Finally, simulation results are shown to demonstrate flexible criteria for detecting the number of signals can be designed in the case that the number of available samples of observation vectors is small and also large View full abstract»

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  • Robust Constant-beamwidth Beamforming Based on Focusing Approach for Acoustic Imaging

    Page(s): 821 - 826
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6048 KB) |  | HTML iconHTML  

    Focused beamformer is an efficient broadband beamforming method due to the advantages like ability to operation in multipath environments and computational efficiency. However, the robustness of focused beamformer is not enough. To overcome the shortcoming, a novel robust broadband beamforming method based on focusing approach is presented in this paper to achieve constant beamwidth for acoustic imaging. The proposed method mainly combines the idea of robust Capon beamforming (RCB) in the focusing approach to get the more exact focusing transformation matrix and then reduce the focused data error. Thus it can greatly improve the robustness performance of focused beamformer. Simulation results show the feasibility of the proposed method View full abstract»

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  • Experimental Results of a New Method on Lessening The Grating Lobes' Effects in Phased Arrays

    Page(s): 827 - 830
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3396 KB) |  | HTML iconHTML  

    To design a phased array antenna, different criteria should be considered. Nulls must be placed toward the interferes' directions and the main beam should be focused on the desired user. To accomplish these conditions, several methods can be used. What is important in this paper is how additional roots can be added into AF1 polynomial to help main beam steering and reduce the grating lobes effects View full abstract»

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  • Determine the Irrelevance of Hidden Unit from the Validation Set

    Page(s): 831 - 834
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3784 KB) |  | HTML iconHTML  

    This paper proposes a method to determine the irrelevance of the hidden unit in the artificial neural network. Unlike other approaches, we calculate the sensitivity of the hidden unit from the validation set, instead of the training set. The advantage of using the validation set to calculate the sensitivity is that we never overestimate the relevance of hidden unit. In other words, we always remove the unit that has the least effect on the validation set error. As a result, the pruned neural network has the highest generalization when compared with other choices of removals. Our sensitivity is based on the activation difference of the output unit. This activation difference is the gap between the activation of output units when a particular hidden unit is present and when it is removed. We have applied our technique to two standard benchmark problems. The experimental results show that the proposed technique can correctly determine the least irrelevant hidden unit View full abstract»

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  • Ultrasonic Reflection Mode Tomography Using Frequency-Shift Method

    Page(s): 835 - 838
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3360 KB) |  | HTML iconHTML  

    Tomogram of the soft tissue can be reconstructed by using its projections resolved from the ultrasonic broadband pulsed waves which are passed through the tissue. While a data from ultrasonic transmission mode tomography cannot be used to image the character of soft tissue where shadowed by a bone, an ultrasonic reflection mode tomography is realized to be a solution for this. There are many ways to extract the projections, in most case the integrated attenuation coefficients of the tissue from the pulsed wave. Almost all of these methods were proved to implement with the transmission mode signal, but however, some adaptation may takes benefit from those method to implement with the reflection mode. We choose the frequency-shift method to be analyzed because its advantage in a computational viewpoint. The simple filtered backprojection algorithm was implemented to reconstruct the tomographic images of the soft tissue suffered by bone. The results are shown the successful of this method over the transmission mode tomography. Also the simulations for noisy data were analyzed View full abstract»

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  • Optimizing ACS for Big TSP Problems Distributing Ant Parameters

    Page(s): 839 - 842
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3835 KB) |  | HTML iconHTML  

    Ant colony algorithms are a group of heuristic optimization algorithms that have been inspired by ants foraging for food. In these algorithms there are some agents, the ants, that for finding the suitable solution, search the solution space. Ant colony algorithms have some parameters like relative pheromone importance on trail and pheromone decay coefficient that convergence and efficiency of algorithms is highly related to them. Usually desirable value of these parameters regarding the problem is determined through trial and error. Some approaches proposed to adapt parameter of these algorithms for optimizing them. The most important feature of the proposed algorithms are complication and time overhead. In this paper we have presented a simple and efficient approach based on distribution of ant parameters for optimizing ACS algorithm and by using different experiments efficiency of this proposed approach has been evaluated and we have shown that the presented concept is one of the most important reasons in success for parameter adapting algorithms View full abstract»

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  • A novel noninteracting Electronically Tunable Universal Filter

    Page(s): 843 - 846
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3625 KB) |  | HTML iconHTML  

    A noninteracting electronically tunable universal filter is proposed in this paper. The proposed circuit can simultaneously realize highpass, lowpass and bandpass transfer functions without changing the circuit topology. Also, the circuit is implemented by using four CCCIIs with controlled current gain and two grounded capacitors which is suitable for IC implementation. Moreover, the proposed circuit can be simply modified to achieve bandstop and all pass responses. The parameters omega, Q and H0 of the filter are independently tunable. The PSPICE simulation results show that the proposed filter performs its function property View full abstract»

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  • A Hybrid Approach to Intrusion Detection and Prevention for Business Intelligence Applications

    Page(s): 847 - 850
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5082 KB) |  | HTML iconHTML  

    In this paper, an application-based intrusion detection and prevention (ID/IP) system coupled with data mining and mobile agent technologies is introduced. Under this approach, the ID/IP system consists of a core engine with data sensor, detector, configuration device and alert and response device as its main components. The data sensors posting as designated agents are to gather information from their respective sources in real time. The information gathered by the respective agent is fed into the detector where correlation methods and data mining techniques are employed to analyze and identify any intrusive activity or event. Since information is gathered from various sources by the respective agent, different type of profiles representing normal behavior such as network traffic, users, systems, applications, transactions, alarms and alerts can be built, and deviation from these profiles are considered to be intrusion. A rating model is then used to evaluate the intrusive activities. When an intrusion or attack is detected by the detector and evaluated to have a rating below the threshold value, the configuration device changes the status of the ID/IP system to alert mode and signal the alert and response device to take the necessary actions. Subsequently, mobile response agents are used to carry out response mechanisms at the target and the source View full abstract»

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  • The LATIS Pervasive Patient Subsystem: Towards a Pervasive Healthcare System

    Page(s): 851 - 856
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7376 KB) |  | HTML iconHTML  

    The cost of maintaining a universal publicly-funded healthcare system has always been astronomical. Our collaborative effort is aimed at applying information technology into the healthcare system with the goal of making the delivery of medical services more effective and more efficient and, also to contribute to the reduction in the cost of such delivery. A pervasive healthcare system is aimed at providing complete healthcare services - that of the diagnostics, medical prescriptions, and the pervasive tracking of a patient. The last component provides medical service to a patient whether he is in or out of the hospital or medical clinic. This paper is aimed at presenting the last subsystem only. The architecture, along with its components, is presented, analyzed and simulated under different scenarios. Other aspects of artificial intelligence such as the application of multi-agent system and pervasive computing are also applied in the system View full abstract»

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  • Carbon nanotubes synthesized by plasma enhanced CVD: Preparation for measurements of their electrical properties for application in pressure sensor

    Page(s): 857 - 860
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4135 KB) |  | HTML iconHTML  

    Carbon nanotubes (CNTs) were synthesized in atmospheric pressure microwave plasma torch in the mixture of argon, methane and hydrogen on the silicon substrate with SiO2 overlayer and a thin top iron film serving as a catalyst. This deposition technique is unique because of its simplicity and high CNT growth rate but it is still under investigation as concerns exits around its reproducibility. CNTs were deposited with the future prospect of their applications or further characterization that might require CNTs in the form of suspension or powder. One of the research directions includes measurements of CNT electrical properties such as their current-voltage (I-V) characteristics. Preparation of solutions with well dispersed CNTs was studied using various liquids (distilled water, ethyl alcohol) and ultrasonication. Dried drops of these solutions were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in order to assess CNT appearance and dispersion. Electrical measurement chips with gold electrodes were prepared by electron lithography. CNTs were placed on the chips by dropping their solution and the I-V characteristics may be measured by contacting the electrodes bridged by CNTs View full abstract»

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  • An Augmented Security Protocol for WirelessMAN Mesh Networks

    Page(s): 861 - 865
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5336 KB) |  | HTML iconHTML  

    IEEE standard 802.16 is a broadband wireless access technology in wireless metropolitan access network (WMAN). It promises to provide wireless broadband access to homes, businesses and core telecommunication networks worldwide. Security is a critical concern to the success of IEEE standard 802.16. There has been extensive work on improving the security of IEEE standard 802.16 for both fixed and mobile networks in PMP mode, but thus far there is scarcity of research on security in IEEE 802.16 mesh mode. This paper presents a synopsis of the IEEE 802.16 mesh topology, overviews its security architecture and analyzes weaknesses in the existing privacy and key management protocol. It proposes an augmented privacy and key management (APKM) protocol that provides defense against the security threats present in a wireless environment View full abstract»

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  • Digital Signature on Mobile Devices based on Location

    Page(s): 866 - 870
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4845 KB) |  | HTML iconHTML  

    With rapid growing of wireless and mobile technologies, mobile devices are part and parcel of our lives. Nowadays GPS (Global Positioning Service) technology is combined with mobile devices. People use some Internet applications, e.g. mobile fund transfer, e-commerce, game online and theatre booking. These applications should support digital signature service for more security. Because mobile device is low-computation capability and limited battery life, it is not suitable to use digital signature protocols, which are based on asymmetric cryptographic algorithm, with mobile devices. And it does not use advantage of GPS technology. We present "location based digital signature on mobile devices" with geo-encryption to generate digital signature. This method reduces the burden on mobile devices, the computation time of the requester by almost 98%, compared with Abe-Fujisaki's RSA-based partially blind signature and decreases communication between sender and receiver View full abstract»

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  • Channel Detection and Estimation Based on the PSD Estimation for OFDM System

    Page(s): 871 - 874
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3110 KB) |  | HTML iconHTML  

    OFDM is a promising technique for achieving high-speed data transmission in future cellular system and WLAN system, and the channel detection and the channel estimation are very important for subchannel allocation and channel equalization. The PSD estimation could be imposed to obtain accurate signal estimation. In this paper, a channel detection algorithm and a channel estimation algorithm based on the PSD are presented. The results of simulation prove that the detected CSI error based on the PSD estimation is less than that of the LS estimation and the MMSE estimation, and the performance of OFDM system under the condition of channel equalization based on the PSD & LS channel estimation is better than that of the LS channel estimation and the MMSE estimation View full abstract»

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  • Noise Correlation-Aided Iterative Decoding for Magnetic Recording Channels

    Page(s): 875 - 880
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8365 KB) |  | HTML iconHTML  

    In this paper, three noise correlation-aided iterative decoding schemes are proposed for magnetic recording channels, where the correlation is imposed by the equalizer's spectral shaping effect. The first approach exploits the noise' correlation in the form of linear prediction-aided detection by increasing the number of detector trellis states invoked by the Bahl, Cocke, Jelinek, and Raviv (BCJR) detection algorithm. In the second approach, we have extended the first technique by employing both previous and future correlated noise samples in order to attain noise estimates. In order to achieve this objective, the classic BCJR algorithm has to be modified for the sake of additionally exploiting future noise samples. The third approach is designed for reducing the decoding complexity by applying the Viterbi algorithm (VA) to assist the detector in finding the encoded sequences associated with the survivor paths in the detector's trellis, without increasing the number of trellis states. We will demonstrate that for the classic PR4-equalized Lorentzian channel, the proposed schemes are capable of offering a performance gain in the range of 1.1-3.7 dB over that of a benchmark turbo decoding system at the BER of 10-5 and at a recording density of 2.86 View full abstract»

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  • Research on the Received Signal Strength Indication Location Algorithm for RFID System

    Page(s): 881 - 885
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4817 KB) |  | HTML iconHTML  

    Received signal strength indication (RSSI) location algorithm is studied in this paper. Simulation platform of radio frequency identification (RFID) location system is also constructed. The affection by different number of reference tags with detection power-level is studied. Tracing location information of mobile tags and the layout of simulation area to effect location error are also investigated. The simulation results illustrate that RSSI algorithm based on RFID with active tag is a viable and cost-effective candidate for indoor location sensing View full abstract»

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  • Manet Node Based Mobile Gateway with Unspecific Manet Routing Protocol

    Page(s): 886 - 889
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4195 KB) |  | HTML iconHTML  

    Integrating mobile ad hoc network (Manet) with Internet will facilitate the trend to an all-IP wireless environment. In this paper, we propose a novel integration mechanism of Internet and Manet. In the architecture, Manet nodes (with or without mobile IP support) access the Internet using the mobile hosts with mobile IP as the gateways. It is superior to fixed gateway architecture. We develop the mobile gateway registration, discovery, advertisement and invalidation algorithm in that infrastructure. The problem of load-balance for multi-gateway can be alleviated with those algorithms. In addition, our technology does not rely on any specific Manet routing protocol View full abstract»

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  • COSR: Cooperative On-Demand Secure Route Protocol in MANET

    Page(s): 890 - 893
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5014 KB) |  | HTML iconHTML  

    Now, an ad hoc network works well rely on other nodes in the network for discovering route and forwarding data packets. Most routing protocols are based on the assumption of cooperation and no cheat. If there are malicious nodes to attack network, these protocols would be broken down. In this paper, we propose the cooperative on-demand secure route (COSR) protocol to against the main passive route attacks. COSR measures node-reputation (NR) and route-reputation (RR) by contribution, capability of forwarding (CoF) and recommendation to detect malicious nodes. Furthermore, COSR uses reputation to balance load to avoid hot-point in the network. In this paper, we provide definition and formula of NR and RR. Moreover, we present improvement of DSR by reputation model to discover optimum route View full abstract»

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  • A Comparative Study of Random Waypoint and Gauss-Markov Mobility Models in the Performance Evaluation of MANET

    Page(s): 894 - 899
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5988 KB) |  | HTML iconHTML  

    A mobile ad hoc network (MANET) is a network consisting of a set of wireless mobile nodes that communicate with each other without centralized control or established infrastructure. The mobility model represents the moving behavior of each mobile node (MN) in the MANET that should be realistic. It is a crucial part in the performance evaluation of MANET. Random waypoint mobility model is the only mobility model that has been widely used in the simulation study of MANET despite some unrealistic movement behaviors such as sudden stop and sharp turn. Whilst Gauss-Markov mobility model has been proved that it can solve both of these problems. This paper presents a comparative simulation study of random waypoint and Gauss-Markov mobility models on the performance study of MANET that uses ad-hoc on-demand distance vector (AODV) as the routing protocol. The results show that both mobility models are not different in case each MN is moving at human running speed. Therefore, it is suggested to use random waypoint mobility model because of its less computational overhead comparing to Gauss-Markov mobility model. When the speed of MNs is as high as fast automobiles, the performance result using random waypoint mobility model is significant different from Gauss-Markov mobility model. Therefore, Gauss-Markov mobility model should be used instead. Moreover, different levels of randomness setting have no effect on the accuracy of throughput and end-to-end delay View full abstract»

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  • Global Data Allocation Based on User Behaviors in Mobile Computing Environments

    Page(s): 900 - 905
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6389 KB) |  | HTML iconHTML  

    In this paper, we utilize user behaviors to do global data allocation in mobile computing environments. The issue we addressed here is to allocate right data at the right location for whole users in the environments. User behaviors include user moving patterns and user request patterns. By utilizing the information stored at the servers in the environments, we devise four algorithms focus on different views respectively-average hit ratio, average communication cost, and average response time. According to the data allocation schemes derived from these algorithms, we conduct several experiments to evaluate them and compare them pro and con View full abstract»

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  • Study of Biasing Effects on Coupled Microstrip Lines Characteristics

    Page(s): 906 - 909
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3627 KB) |  | HTML iconHTML  

    An accurate method for evaluating the effects of biasing potential on the quasi-static even and odd mode propagation characteristics of coupled microstrip lines is given. In this method the equivalent circuits theory simulate the quasi-static theory for the coupled microstrip lines. The depletion layer capacitance is determined using parallel plate waveguide model. The techniques used here are constructed from the standard transmission line model voltage and current as well as field lines distribution. The elements of the series branch impedance of the equivalent circuit can be found by solving for the current distribution on the conductor given the magnetic potential. The shunt admittance components are determined by using conformal transformation formulas. It is found that the bias potential has great effects on the propagation characteristics of coupled microstrip lines as well as the phase angle of microstrip phase shifter View full abstract»

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  • Studying The Effects of High Order Roots of Array Factor Polynomial On Phased Array's Beamwidth

    Page(s): 910 - 915
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4347 KB) |  | HTML iconHTML  

    Phased array antennas must scan a wide range of space and find the proper direction to send/receive the allocated data. It is desired to find the user directions and also interferer directions to aim the main beam of the array into the desired user and place nulls along interferer directions. There is always a trade off between the number and size of elements and the pattern beamwidth. This article shows how high order roots of array factor can assist in narrowing the overall beamwidth. For this purpose a computer program was written in MATLAB and the simulation results is included View full abstract»

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  • Radiation Characteristics of a Vertically Rectangular Slot at Arbitrary Location on Conducting Spherical Cavity

    Page(s): 916 - 921
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5249 KB) |  | HTML iconHTML  

    This paper presents the dyadic Green's function approach for analyzing a vertical-aligned rectangular slot antenna which can be located at arbitrary latitude on a conducting spherical cavity. Some investigations on characteristics of the antenna, such as radiation patterns, are considered. The characteristics of the antenna are also pointed out when the slot length and cavity size are changed. Finally, numerical results of the derived dyadic Green's function approach are compared with that of the classical vector potential approach View full abstract»

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  • Distortion Analysis of Ultra Wideband Pulse Waveforms with Meander Line Antenna

    Page(s): 922 - 925
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4665 KB) |  | HTML iconHTML  

    In this paper, the distortion of ultra wideband (UWB) pulse waveforms with meander line antenna (MLA) is analyzed. The rectangular passband, modulated rectangular and modulated Gaussian waveforms, which satisfied the Federal Communications Commission (FCC) definition of UWB signal and FCC spectral masks for the indoor and outdoor limits, are considered. The frequency transfer function of MLA is evaluated by using measurement scheme. The correlation coefficient of each waveform at the specific angle is illustrated. From the results, we can see the distortion effect of each waveform caused by MLA along the specific angle View full abstract»

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  • Hybrid Error Concealment Using Linear Interpolation

    Page(s): 926 - 931
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6346 KB) |  | HTML iconHTML  

    In this paper we extend the previous work (B.N. Chen and Y. Lin, 2006) and propose a hybrid error concealment algorithm using linear interpolation for error-prone video transmission channel. In the proposed hybrid algorithm, the selective motion field interpolation (SMFI) is first employed to conceal the erroneous macroblock. The spatial and temporal boundary-matched errors are then used to check whether the SMFI conceals the erroneous macroblock properly. If the temporally recovered macroblock is reconstructed incorrectly, the spatial error concealment using linear interpolation is employed to conceal the damaged macroblock instead of SMFI. The proposed hybrid algorithm employs the linear interpolation on both spatial and temporal error concealment and the computational complexity is reasonably low. It possesses benefit of easy implementation and can achieve better performance subjectively as well as objectively over other error concealment techniques. Simulation was conducted on the H.263 codec and the experimental results reveal that the proposed algorithm significantly outperforms other concealment techniques View full abstract»

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  • Optimization Of The Deblocking Filter In H.264 Codec For Real Time Implementation

    Page(s): 932 - 936
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4427 KB) |  | HTML iconHTML  

    Blocking artifacts are visible in the decoded frames of most video coding standards at low bit rate coding. Latest video coding standard H.264/AVC uses an in-loop deblocking filter to remove the blocking artifacts. The main drawback of this filter is its high implementation complexity. In this paper, we propose an in-loop deblocking filter to remove the blocking artifacts. In the proposed method, the maximum and minimum values among the six pixels across an edge are computed to decide whether the pixels of the block should be filtered or not. For intra frames, again the block is classified as smooth or mildly textured region. Depending on the classification of the block, the appropriate filter is applied to that block. The main advantage of the proposed method is its low complexity compared to JM 9.8 (H.264 software). A performance comparison of the proposed method and the current method is presented View full abstract»

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