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Intelligent Signal Processing and Communications Systems (ISPACS), 2011 International Symposium on

Date 7-9 Dec. 2011

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Displaying Results 1 - 25 of 164
  • [Title page]

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  • [Copyright notice]

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  • International steering's message

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  • General chair and Co-Chairs' message

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  • Capacity of WCDMA links with hetorgenous traffic

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (249 KB) |  | HTML iconHTML  

    The soft capacity of the commercial WCDMA systems is defined as the average load that assures that the instantaneous load in the system stays below a target threshold with a high probability. In military communication systems each user link is required to have assured availability and hence the capacity has to be based on assured availability of each link rather than on an aggregate measure such as the system load factor. In this paper we derive the uplink capacity of WCDMA links based on link availability requirements for each user with a heterogeneous mix of user traffic, channel characteristics and orthogonality conditions. We use a unique approach by formulating and solving the capacity problem as an eigenvalue/eigenvector problem. Numerical examples are presented to illustrate the impact of various factors such as heterogeneous traffic and orthogonality conditions on capacity. View full abstract»

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  • Object segmentation from sparse views of wide-baseline images

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1033 KB) |  | HTML iconHTML  

    In this paper, we propose an automatic approach to segment object from multiple sparse views of wide-baseline images. Depth and occlusion information recovered from multiple views assist the object initialization and segmentation processes. The initial object patch is extract based on a saliency map incorporating the depth and locality cues. We then formulate the object segmentation task as an energy minimization problem, which is solved by graph cut optimization. Based on the basic energy function, local background modeling, adaptive data fusion and 3D graph construction are developed to make the segmentation toward better results. Experimental results on self-recorded images and the benchmarks demonstrate the efficiency and robustness of the proposed approach. View full abstract»

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  • A nonlinear classifier using an evolution of Cellular Automata

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (577 KB) |  | HTML iconHTML  

    Generalized Multiple Attractor Cellular Automata (GMACA) is a special class of Cellular Automata (CA) for nonlinear pattern classification however the disadvantages of GMACA are: there is only one rule vector for classification, a search space for constructing an appropriate graph is exponential growth, and the complexity of classification is O(n2). For this reason, this paper proposed Two-Class Classifier Generalized Multiple Attractor Cellular Automata with artificial point (2C2-GMACA+). It utilizes two-class classifier architecture basis that enables to process two classes at a time. Moreover, exploring an appropriate pivotal point (artificial point) is offered in order to reduce the complexity of classification and search space. The experiments on error correcting capability show that the performance of classification on 2C2-GMACA+ is more superior to GMACA. View full abstract»

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  • An error-correction scheme with Reed-Solomon codec for CAN bus transmission

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB) |  | HTML iconHTML  

    This paper presents an error-correction scheme to enhance the performance of typical CAN bus. The proposed scheme uses Reed-Solomon (R-S) codec to calculate the parity for the transmission of typical CAN bus. Compared with prior work in terms of Hybrid Automatic Repeat Request (HARQ) scheme for CAN bus transmission, the proposed scheme does not modify the standard CAN protocol but insert an R-S codec unit as an error-correction between Electronic Control Unit (ECU) and CAN bus. In other words, the focus of our proposed scheme is not on modifying the fixed CRC codec of the standard structure, but on increasing the performance based on an additional enhancement module. Experimental results show that the execution time of standard CAN bus can be reduced by the proposed scheme for almost half of transmission time on typical design, while accompanying very minor cost when errors are not correctable or without errors. View full abstract»

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  • An adaptive correlation-based group recommendation system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2082 KB) |  | HTML iconHTML  

    An adaptive correlation-based group recommendation system or recommender is proposed which takes the members' interactions into account. Thus, the proposed method can predict members' relationships by acquiring the correlations between a group and its members. With the predicted correlations, each member's weight can be estimated. Finally, the group's ratings of those non-rated items can be predicted by merging members' ratings and their estimated weights. Without complex computation, the proposed group recommendation system can achieve accurate predictions of the group's ratings. Therefore, it suits for helping a group to make decisions since its members have different opinions for selecting multimedia contents. View full abstract»

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  • Performance analysis of adaptive step-size least mean modulus-Newton algorithm

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    This paper first reviews least mean modulus-Newton (LMM-Newton) algorithm for complex-domain adaptive filters. The LMM-Newton algorithm is effective in making the convergence of an adaptive filter with a highly correlated input as fast as that for the LMM algorithm with a White & Gaussian filter input. However, the filter convergence for the LMM-Newton algorithm is still much slower than for the LMS algorithm. Then, the paper introduces a generalized error modulus (“p-modulus”) and proposes a new adaptive step-size (ASS) control algorithm to be combined with the LMM-Newton algorithm to further improve the convergence speed. Analysis of the ASS-LMM-Newton algorithm is developed for calculating transient and steady-state behavior. Through experiment with simulations and theoretical calculations of filter convergence, we find that the filter convergence is almost the same for any value of p of “p-modulus.” We demonstrate effectiveness of the proposed ASS-LMM-Newton algorithm, while preserving the robustness of the LMM algorithm against impulsive observation noise. Good agreement between simulated and theoretical convergence validates the analysis. View full abstract»

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  • Steganalysis using difference images and bit-plane splitting

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1039 KB) |  | HTML iconHTML  

    Steganalysis, in contrast to steganography, is a method that focuses on detecting secret messages hidden in carrier media. In this paper, a blind steganalysis method for digital images is proposed. We describe the statistical characteristics of the difference image, and the statistical characteristics of the images in bit-plane to exploit features. Then we use the multi-layer perceptron (MLP) to classify images. Extensive experimental results show that the proposed method is efficient than some previous methods. View full abstract»

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  • Joint estimation of frequency offset and channel parameters for MIMO-OFDM systems with PAPR reduction precoder

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1817 KB) |  | HTML iconHTML  

    Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is very sensitive to the carrier frequency offset (CFO), which not only affects the channel estimation but also the selection of a minimum error probability based precoder for peak-to-average power ratio (PAPR) reduction such that the system performance will degrade. This paper presents the joint scheme of CFO) and channel estimation in the MIMO-OFDM systems with the minimum error probability based precoder for reducing PAPR. First, a minimum error probability based precoding matrix to reduce the PAPR of OFDM signals is designed. The CFO and CIR estimators based on the expectation maximization (EM) algorithm with an iterative scheme are developed to execute the estimations. To reduce computational complexity, a simpler coarse CFO estimator is carried out before the fine estimation so that a more accurate and faster convergent estimate can be attained. Simulation results show that the CFO estimator with a coarse initial estimate not only has an excellent performance at reduced computational complexity, but also makes the CIR estimation achieve almost ideal performance. View full abstract»

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  • Interference mitigation in femtocell CDMA networks through time reuse partitioning

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (804 KB) |  | HTML iconHTML  

    A two-tier network composed of conventional macrocellular networks and emerging multi-femtocell networks offers extended indoor coverage and higher data rates while off oading the traffic through high speed backhaul network. This network can also reduce the power useage signif cantly via available short range radio communication. As the femtocell shares the same frequency band with underlying macrocell, the cross tier interference needs to be mitigated. The inter-femtocell and cross tier interference near femtocell boundary may unacceptably degrade the system performance. In this paper, we propose to use time reuse portioning to mitigate downlink inter-femtocell interference as well as cross tier interference and the present results to show performance improvement by employing the time reuse partitioning in CDMA networks. View full abstract»

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  • Designing triangular filters for Continuous Phase Modulation (CPM) receivers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1597 KB) |  | HTML iconHTML  

    A novel filter design method has been proposed for implementing linear Continuous Phase Modulation receivers. The design is based on the observation of all possible waveform tracks at the receiver. A piece-wise approximation is subsequently used to obtain a triangular filter which can be efficiently implemented in hardware. The resulting filters have shown excellent bit error rate performances in comparison with the existing CPM receivers. For improved bit error rate performances a modified CPM frequency pulse is also proposed. View full abstract»

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  • An efficient 2×2 Tchebichef moments for mobile image compression

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB) |  | HTML iconHTML  

    Currently mobile digital image applications transmit a lot of images back and forth. Image compression is needed to reduce transmission payload at the expense of lower quality. At the same time, mobile devices are only expected to be equipped with lower computing power and storage. They need an efficient compression scheme especially for small images. The standard JPEG using discrete Cosine transform is a popular lossy image compression. Alternatively, this paper introduces 2×2 Tchebichef moments transform for the efficient image compression. In the previous research, larger sub-block discrete Tchebichef moments have been used extensively for image compression. The comparisons between JPEG compression and 2×2 Tchebichef moments image compressions shall be done. The preliminary experiment results show that 2×2 Tchebichef moments transform has the potential to easily perform better than JPEG image compression. The 2×2 Tchebichef moments provides an efficient and compact support for image compression. View full abstract»

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  • Resistance against power analysis attacks on adiabatic dynamic and adiabatic differential logics for smart card

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1608 KB) |  | HTML iconHTML  

    Numerous articles and patents on the masking of logic gates in CMOS logic styles have been reported, however, less information is available with regards to comparing the single-rail and dual-rail on masking input logic values. This paper investigates single-rail and dual-rail logic families that have been developed by the logic designers for secure logic implementations in cryptographic system. The novelty of this work is that we evaluate the dynamic logic and differential logic for one-phase 2-inputs logic in adiabatic mode in SPICE simulation. We analyze the power consumption of logic circuit along 16 possible transitions of 2-inputs logic during one cycle. The power traces show that adiabatic differential logic families are masking the input logic values, because they consume constant power during pre-charge and evaluation phases that enables the circuit to resist against power analysis attacks. Based on our results, we deduce that adiabatic differential logic families are promising candidates for further development to obtain a far more robust secure logic for countermeasure against power analysis attacks in smart card. View full abstract»

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  • A pentagonal slot antenna with two-circle stack patch for WLAN/WiMAX

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1780 KB) |  | HTML iconHTML  

    This paper presents a dual wideband slot antenna for WLAN/WiMAX operation. The proposed antenna consists of a radiating pentagonal slot and an exciting two-circle stack patch with a CPW feed. The input impedance matching has been also improved by inserting two slot stubs at the central feed line. The measurement results show the frequency range from 2.3 to 3.75 GHz of the first band and from 4.8 to 6.5 GHz of the second band, which are adequate wide bandwidths for WLAN/WiMAX operations. The radiation patterns of the proposed antenna are nearly omnidirectional in xz plane for all frequency bands. Therefore, this antenna is a good candidate for various short range wireless communication applications. View full abstract»

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  • Performance of the MIMO CS-PRP-OFDM systems with complementary codes

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (709 KB) |  | HTML iconHTML  

    This paper presents a new transceiver framework of the MIMO-OFDM systems, with the space-time block code (ST-BC). Unlike the conventional Pseudo-Random Postfix (PRP) - OFDM in our proposed framework the null samples of zero-padding (ZP)-OFDM is replaced by known cyclic postfix sequence (CPS), weighted by a pseudo-random (PR) scalar. Since the CPS is implemented by the cyclic-shift (CS) complementary code (CC) sequences, the proposed transceiver scheme is referred to as the MIMO CS-PRP-OFDM systems. By exploring the useful property of CC sequences, convolved with channel information, the receiver design associated with the semi-blind channel estimation of the proposed MIMO CS-PRP-OFDM systems is affected only by the background noise. It avoids the interference of the transmitted signals, and yields achieving better system performance, in terms of symbol error rate, compared with the conventional PRP-OFDM based systems, with less complexity. This is especially true when the signal-to-noise ratio is increased. View full abstract»

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  • Design and implementation of a low cost BJTs comb generator

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1200 KB) |  | HTML iconHTML  

    Design and implementation of a low cost comb generator based on a BJT switching circuit are proposed in this work. The proposed comb generator can produce multiple harmonics with excellent amplitude flatness up to 2 GHz. The output power of each harmonic is -35 dBm at the low frequency end and -41 dBm at the high frequency end. The input of the proposed comb generator is driven by a 10 MHz square wave with ±2.5V amplitude. View full abstract»

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  • A Social Network-based serendipity recommender system

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (829 KB) |  | HTML iconHTML  

    The appearing of the internet brings a large amount of information, this makes searching and filtering difficult. Therefore, a kind of special data mining technique appeared, it called Recommender System. Most research of recommender system always provides the most relevant items for users or items. However, recommendations from traditional recommender system may not satisfy the new human beings because users may already know these relevant items from other information sources. We believe that there are still some unsearched but less relevant items useful for users. On the other hand, because social network has grown very quickly, we think that there are some very useful interactive information that recommender systems can use to provide recommendations. Therefore, we propose a Social Network-based Serendipity (SNS) recommender system that uses interactive information from the social network to find out which items are interesting for users but hard to discover by themselves. View full abstract»

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  • CFTA-based current multiplier/divider circuit

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1208 KB) |  | HTML iconHTML  

    In this paper, the design of a simple analog current-mode multiplier/divider circuit using only two current follower transconductance amplifiers (CFTAs) is presented. With the selection of the applied input currents, the proposed circuit can perform four-quadrant current multiplication, division and current-controlled current amplification, all from the same circuit configuration. The circuit is also insensitive to ambient temperature variations. Additionally, the CFTA non-ideality effects and the non-ideal gain and parasitic component effects on the proposed circuit are studied. The performances of the realized circuit are examined by PSPICE simulations. View full abstract»

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  • A novel contrast enhancement method using differential gray-levels histogram

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1426 KB) |  | HTML iconHTML  

    Histogram equalization (HE) is a simple and effective method for contrast enhancement as it can automatically define the gray-levels transformation function based on the distribution of gray-levels included in the image. HE fails to produce satisfactory results for a broad variety of low-contrast images because the HE does not use a spatial feature included in the input image. This paper proposes a novel contrast enhancement method using not only the conventional histogram but also the differential gray-levels histogram of the input image. The differential gray-levels histogram contains edge information of the input image. Edge information is one of the important spatial features of the image. We can identify the regions where are desired to be emphasized by using both the conventional histogram and the differential gray-levels histogram. Thus, for example, the proposed method can emphasize the objects which are buried in shadow or saturation regions efficiently. View full abstract»

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  • A novel adaptive prediction structure for multiview video coding

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1668 KB) |  | HTML iconHTML  

    The prediction structure of multi-view video coding (MVC) is expected to support temporal random access, high compression efficiency and low computational complexity. Since the characteristic of multi-view video (MVV) sequences change from sequence to sequence, the fixed prediction structure of Joint Multi-view Video Coding (JMVC) is difficult to cope with various characteristics of multi-view video sequences. To gain better coding performance, an adaptive prediction structure for MVC (APS_MVC) based on temporal and inter-view correlation is proposed in this paper. MVV sequences are partitioned into three categories according to their temporal and inter-view correlation. Consequently, three different MVC prediction structures are developed. The best fit prediction structure is automatically selected according to the temporal and inter-view correlation of the encoded sequence. Experimental results have shown that the proposed APS_MVC outperforms Scalable Prediction Structure Scheme for MVC (SPS_MVC) on reducing computational complexity, improving random access ability, and decreasing decoding picture buffer (DPB) size by about 41%, 30%, and 35% on average, respectively. View full abstract»

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