By Topic

Communications, Computers and Signal Processing, 2007. PacRim 2007. IEEE Pacific Rim Conference on

Date 22-24 Aug. 2007

Filter Results

Displaying Results 1 - 25 of 157
  • [Front cover]

    Page(s): C1
    Save to Project icon | Request Permissions | PDF file iconPDF (355 KB)  
    Freely Available from IEEE
  • 2007 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing

    Page(s): nil1
    Save to Project icon | Request Permissions | PDF file iconPDF (343 KB)  
    Freely Available from IEEE
  • Copyright page

    Page(s): nil2
    Save to Project icon | Request Permissions | PDF file iconPDF (665 KB)  
    Freely Available from IEEE
  • Table of contents

    Page(s): nil3 - nil8
    Save to Project icon | Request Permissions | PDF file iconPDF (3990 KB)  
    Freely Available from IEEE
  • Author index

    Page(s): nil9 - nil18
    Save to Project icon | Request Permissions | PDF file iconPDF (1950 KB)  
    Freely Available from IEEE
  • Conference program

    Page(s): nil19
    Save to Project icon | Request Permissions | PDF file iconPDF (200 KB)  
    Freely Available from IEEE
  • Biologically-Based Signal Processing Chips with Emphasis on Telecommunication Defect Tracking and Reliability Estimation

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6859 KB) |  | HTML iconHTML  

    This paper provides observations and motivations to mimic biological information processing. Alternative bio-inspired systems definitions, basics, approaches, algorithms, and chip implementations will be illustrated to offer a base of choice for bio-based Intelligent Information Processing (IIP) systems. Hybrid biological and bio-based IIP are briefly presented. Two specific applications follow with embedded bio-based systems: Bio-chemical sensing and detection E-nose; and Track improvements In the reliability of the software used in telecommunication network deployments. The biologically-based processing discoveries gleaned from observing the spikes in the brain activity of monkeys, introduced the concept of plasticity in synapses used in our embedded Spiking Neural Network (SNN) system for the E-Nose The mathematical construct of a defect tracking classifier is nonlinear, and the event to be recognized involves a sequentially varying or non-stationary phenomenon for telecommunication defect tracking and reliability estimation. Thus, Adaptive Recurrent Dynamic Neural Network (ARDNN) system using wavelet function as the basis improved the failure event estimation of software defect tracking in telecommunications and reduced the error from 88% to L25-8%. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Topology Aggregation in PNNI Networks Part I: Link Aggregation

    Page(s): 8 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (173 KB) |  | HTML iconHTML  

    This paper and its sequel in Part II (node aggregation) present our work done in the deployment of topology aggregation techniques in the layer 2 infrastructure of AT&T's Global Network to deal with network growth. In Part I, use of PNNI link aggregation for new border-link additions is examined. This will cause an information loss with some impacts on routing. However, by aggregating multiple parallel border links between the same office pair, scaling in a large network can be achieved without compromising latency performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Framework for Opportunistic Allocation of Wireless Resources

    Page(s): 12 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    Wireless multi-hop, mesh networks are being considered as a candidate to backhaul data traffic from access networks to the wired Internet. To enhance system performance, scheduling algorithms for wireless mesh networks are desirable to take advantage of multi-user diversity resulted from time-varying channel condition and space-varying path loss. Although many existing scheduling algorithms or medium access protocols have been adopted for the wireless mesh networks, they do not perform well, given that the algorithms are devised for wireless access. In this paper, we study the computational complexity in finding the optimal schedule for a mesh network with time-division-duplexing (TDD) operations. We propose a novel heuristic distributed scheduling framework for wireless mesh networks with open definitions of utility function. Performance analysis shows that our proposed framework is of polynomial-time complexity. Simulation results compare our framework with the tree-structural approach, and reveal that our proposed framework is highly capable of selecting and scheduling links with high utility in a fully distributed manner. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Topology Aggregation in PNNI Networks Part II: Node Aggregation

    Page(s): 17 - 20
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    This paper and its part I (link aggregation) companion present our work done in the deployment of topology aggregation techniques in the layer 2 infrastructure of AT&T's Global Network to deal with network growth. In this paper, use of PNNI node aggregation for new node additions is examined. Two techniques are compared: simple and complex node representations. There is a tradeoff between accuracy in preserving the original topological features and compactness in representation to achieve scaling. While complex node is more accurate, it may require the use of link aggregation. Simple node scales well, but it may attract transit traffic. Our analysis of simple node suggests its use in offices with no major impact on latency performance. We illustrate with an application to regional hub offices with lots of links. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Multipath Flow Routing Approach for Increasing Throughput in the Internet

    Page(s): 21 - 24
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1538 KB) |  | HTML iconHTML  

    In the current Internet, hotspots arise because traffic tends to be routed along shortest hop paths sharing common links, leading to congestion on these links and underutilization on others. Current routing protocols are not able to exploit the path redundancy that exists in the Internet. To improve overall throughput and network utilization, we propose a multipath flow routing overlay system, coupled with network sensors that provide realtime information about overlay links, to distribute traffic more efficiently over the network. In particular, we focus on improving the throughput performance of large file transfers over TCP/IP-based internets. Files are dynamically split into multiple flows, which are then distributed over the network by the multipath flow routing overlay. We have implemented such a routing overlay using the Click modular software router and studied its performance on the Emulab network emulation testbed. We present performance results, which show that the multipath routing overlay can dramatically increase TCP throughput under a variety of network scenarios. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of Multiple Trees on Path Discovery for Beacon-Based Routing Protocols

    Page(s): 25 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    Routing in Mobile Ad-hoc Networks (MANETS) has proved to be an extremely challenging research problem due to the high frequency of link changes in wireless mobile environments. Most known routing protocols struggle to maintain complex routing structures, e.g., N spanning trees, or use expensive (from the perspective of communications cost) methods for path discovery. These methods incur extreme communications costs in most MANET deployments. In this paper, we investigate the performance of a relatively unstudied class of routing protocols which we refer to as Beacon-Based Routing Protocols. This class of protocols maintain minimum routing structures and use these structures to boot strap path discovery. In a well defined sense, this class of routing protocols achieves optimal performance with respect to minimizing the communications costs associated with on-demand routing. We specifically investigate the impact of multiple tree implementations for path discovery and analyze their impact on the effectiveness of optimal path discovery. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An efficient evolutionary algorithm for multiobjective optimization problems

    Page(s): 30 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    An efficient evolutionary algorithm (EA) for the multiobjective optimization problems is proposed. To reduce the computational cost, a variant of k-d tree is used in our approach to preserve all nondominated solutions. Our experiments demonstrate that the algorithm outperforms the other popular multiobjective EA's, especially for the higher dimensional cases. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ontology-Driven Development of Intelligent Educational Systems

    Page(s): 34 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    Despite the opportunities to improve software development though the use of ontologies, there have been few reports giving guidelines for developing such systems based on real case studies. This paper explores what approach to Ontology-driven Software Development (ODD) would be suited for the development of intelligent educational systems such as Athabasca University's eAdvisor -an intelligent academic advising system. With the goal of exploiting synergies with proven software engineering practices to meet the needs of both those who develop the system and those who govern projects, baseline processes for ODD of eAdvisor have been developed. Initial analysis of the feasibility of these baseline processes from performance and complexity viewpoints took place using qualitative analysis of focused interviews. ODD is especially appropriate for the development of intelligent systems with an ontology-based architecture and can leverage familiar and proven software engineering tools and techniques. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Transformation from RDF Documents and Schemas to Relational Databases

    Page(s): 38 - 41
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (145 KB) |  | HTML iconHTML  

    At present, resource description framework (RDF) documents and schemas (RDFS) are used to describe information in the semantic Web. Many research works regard the RDF/RDFS documents as databases and proposed data manipulations for them. This research paper takes a different approach. In order to easily manipulate the database, RDF/RDFS documents are transformed into relational database format so that relational languages, data management and business intelligence facilities which are readily available can be exploited. A conceptual meta schema that describes RDF/RDFS documents and the corresponding meta table are presented together with illustrated examples. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Clustering Algorithm for Short Documents Based On Concept Similarity

    Page(s): 42 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (149 KB) |  | HTML iconHTML  

    In recent years, there has been an increasing interest in data clustering of short documents. Existing works consider seldom the concept similarity between the words, so the quality of clustering is often very low. This paper proposes a new document-clustering algorithm based on concept similarity in Chinese text processing. Different from tradition method, the algorithm converts text into a words vector space model at first; it splits words into a set of concepts at second; 3rd, it gets the similarity between words through computing the inner products between concepts; 4th, it computes the similarity of text based on the similarity of words. Finally, through two-phased steps, the algorithm finishes the clustering of a specified set of document. The extensive experiments prove the validity and performance of the algorithm. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Novel Reduction Method Based On Attributes Similarity In Chinese Traditional Medicine Prescriptions

    Page(s): 46 - 49
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (150 KB) |  | HTML iconHTML  

    According to the similarity among data attributes, this paper proposes a reduction method of high dimensional data. Different from the existed algorithms, this method takes attributes as basic vectors in high dimensions space, and data tuples as vector sum of attributes vectors. With the transcendental concept similar information between attributes, the weight computing is defined as formulas of attribute vectors and their projects on each other, and the final result is gotten from three simplifying algorithms which are proposed in this paper. The paper analyzes the new method, and compares reduced results between different algorithms. This method is successfully applied in automatic induction of Chinese traditional medicine prescription. The extension experiments prove the validity of the method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Improved Multiscale Normal-Mesh-Based Image Coder

    Page(s): 50 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (895 KB) |  | HTML iconHTML  

    Three modifications to the normal-mesh-based image coder of Jansen, Baraniuk, and Lavu are proposed, namely, the use of a data-dependent base mesh, an alternative representation for normal/vertical offsets, and a different scan-conversion scheme based on bicubic interpolation. Experimental results show that our proposed changes lead to improved coding performance in terms of both objective and subjective image quality measures. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Lossless Compression of Error Diffused Images by Coding Multi-Level Images Having Least Entropy

    Page(s): 54 - 57
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (122 KB) |  | HTML iconHTML  

    A lossless compression of an error-diffused image by lossless coding of entropy-minimized multi-level image, which can produce given halftone image at the receiver side, is studied. Through the study, block-type error diffusion is introduced to consider the two-dimensional entropy, and both of entropy-based prioritisation method and prediction-error-based prioritisation method in inverse halftoning procedure are proposed and compared. The result shows that the restored image by proposed methods has about 40% less entropy than that of the original multi-level image, but 50-70% larger than that of halftone image. However through the simulation of pseudo high resolution images, it was expected that the proposed method could even show less entropy than that of the bi-level image in higher resolution cases. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Lossless Compression of Mammographic Images by Chronological Sifting of Prediction Errors

    Page(s): 58 - 61
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (550 KB) |  | HTML iconHTML  

    Mammography is a low dose x-ray technique that's used to create an image of the breast. It is an efficient way for early detection of any cancerous changes and malignancy of lumps. Mammographic images are usually archived and in many cases are transferred on Internet. Therefore, compression of these images has attracted the attention of many researchers. In this paper an efficient method is proposed for lossless compression of mammographic images. Gradual compression of prediction errors in an iterative manner is the basic idea of the proposed method. The simulation results were compared with standard image compression routines such as JPEG-LS, JPEG2000, JBIG and PNG. The superiority of the proposed method was shown for compression of mammographic images. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient Fractal Image Coding Using Adaptive Domain Pool Reduction Technique

    Page(s): 62 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    Fractal image coding was the scope of heavy research during the last decade. It has proved its efficiency as an image coding technique. However, its asymmetric nature has limited its use especially for real time applications. In this paper, a new fast fractal image coding technique will be presented. The proposed technique enhances the encoding time using spatial local activities of the image trying to overcome the major drawback of fractal image coding. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Robust Wireless Image Communications Using Combined SPIHT/OFDM Technique

    Page(s): 66 - 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB) |  | HTML iconHTML  

    In this paper, we propose a combined SPIHT/OFDM coding scheme for transmission of image/video over wireless fading channels. The proposed system implements a rate control algorithm as the image coding scheme and an adaptive modulation OFDM system as the communication coding scheme. We evaluate the system over uncorrelated Rayleigh fading channel. Simulation results for Peak Signal-to-Noise Ratio (PSNR) of the received image at different rates are presented which demonstrate the contribution of our algorithm over this challenging channel. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wireless Ad-hoc Networks Using Cooperative Diversity-based Routing in Fading Channel

    Page(s): 70 - 73
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB) |  | HTML iconHTML  

    We propose new routing scheme, Cooperative Diversity-based Routing (CDR) which utilize the cooperative space diversity for power saving and for performance enhancement of wireless ad-hoc networks. The end-to-end performance of the proposed routing, CDR, is analyzed based on the Haenggi's link model. The improved performance is compared with Multi-hop Relay Routing (MRR) by analytical methods. When the required outage probability is 1times10-3 at the destination node in ad-hoc networks with 7 nodes, we noticed that each node can save power consumption by 21.5 dB in average, by using our proposed CDR compared to MRR. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of the Channel Access Mechanism in IEEE 802.11 Wireless Local Area Networks

    Page(s): 74 - 77
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (981 KB) |  | HTML iconHTML  

    IEEE 802.11 wireless network has spread widely during the past few years. This type of network employees a carrier-sense multiple access with collision-avoidance (CSMA/CA) scheme with exponential backoff procedure. In this paper, we present a performance analysis of IEEE 802.11 channel access mechanism. The analysis captures the details of the Distributed Function Coordination (DCF), such as the contention window size, inter-frame spacing, and packet exchange sequence, and obtains the throughput for such a network with multiple number of stations. The throughput is obtained when the station packet load varies. Two packet access mechanism, namely, the basic access mechanism and the RTS/CTS access mechanism are considered in the throughput analysis. Simulation results are presented to verify the analysis. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Framework for Evaluating Video Transmission over Wireless Ad Hoc Networks

    Page(s): 78 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (167 KB) |  | HTML iconHTML  

    We propose a framework that facilitates the transmission of video over multi-hop wireless networks by using various routing techniques for route establishment. We denote this framework by ad hoc EvalVid. This framework allows the performance of different routing techniques to be studied under different network conditions. The results of our study show that 1) dynamic manet on demand (DYMO) routing protocol can still deliver good quality of video streams under extreme network conditions, 2) ad hoc on demand distance vector (AODV) routing protocol is best suited for large-sized networks with light loads and 3) optimized link state routing protocol (OLSR) is likely not suitable for real-time video transmission. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.