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Communication Networks and Services Research Conference, 2008. CNSR 2008. 6th Annual

Date 5-8 May 2008

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Displaying Results 1 - 25 of 101
  • [Front cover]

    Page(s): C1
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  • [Title page i]

    Page(s): i
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  • [Title page iii]

    Page(s): iii
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  • [Copyright notice]

    Page(s): iv
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  • Table of contents

    Page(s): v - xii
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  • Conference Program Committee Welcome Message

    Page(s): xiii
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  • Conference Program Organizing Committee

    Page(s): xiv
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  • Technical Program Committee

    Page(s): xv - xvi
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  • list-reviewer

    Page(s): xvii - xviii
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  • Keynote 1 - Algorithmic Methods for Sponsored Search Advertising

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  • Keynote 2 - Network Coding: A Revolution in the Making?

    Page(s): xx
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    Summary form only given. This paper presents an overview of the theory and application of linear network coding in packet networks is provided. The ideas are being applied to create new content dissemination protocols in the Internet and in wireless networks. It also sketches the problem of error-and erasure-correction in network-coded packet transmission systems. View full abstract»

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  • Keynote 3 - Distributed Pattern Matching

    Page(s): xxi
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    Summary form only given. Since the advent of P2P technology experts from industry and academia have proposed a number of search techniques - none of which is able to provide satisfactory solution to the conflicting requirements of search efficiency and flexibility. Structured search techniques, mostly DHT-based, are bandwidth efficient while semi(un)-structured techniques are flexible. But, neither achieves both ends. This paper introduces a generic framework called distributed pattern matching to address the search problem in distributed environments while achieving both search flexibility and efficiency. View full abstract»

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  • Transceiver Technologies for Impulse Radio Ultra Wideband (IR UWB) Wireless Systems

    Page(s): 3 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (393 KB) |  | HTML iconHTML  

    In this tutorial, with the above-described multipath problem as a key problem to solve, we will present in detail the following four technical subjects related to the transceiver design for the IR UWB systems: i) the effects of UWB antennas and related RF frontends on the multipath patterns of the received IR UWB signals; ii) the IEEE 802.15.4a multipath models for the applications of IR-UWB systems in various environments such as body-area networks and general indoor and outdoor settings (including residence, office complex, agricultural areas, farms, and industrial operation rooms and workshops); iii) general IR UWB modulation schemes such as pulse position modulation and pulse amplitude modulation; and iv) the existing IR UWB transceiver technologies, including selective rake receiver, transmitted reference/differential transceiver, single and multiple frequency-shifted reference transceiver, and code-shifted reference transceiver, and v) future development tendency for the IR UWB transceiver technologies. View full abstract»

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  • Next-Generation Broadband Networks

    Page(s): 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB) |  | HTML iconHTML  

    Broadband wireless access is viewed by many telephone and cable operators as a "disruptive" technology and rightly so. The broadcast nature of wireless transmission offers ubiquity and immediate access for both fixed and mobile users, clearly a vital element of quadruple play services involving voice, video, data, and mobility. Unlike wired access (copper, coax, fiber), a large portion of the deployment costs is incurred only when a subscriber signs up for service. The first part of the tutorial will provide a comparative assessment of the standards and technologies underpinning promising broadband wireless access solutions. Key standards include 802.16 (Wi-Max), 3G/4G/LTE, mobile digital TV broadcast, and 802.22 (wireless regional area network) with emphasis on the 802.16 standard. Key technologies include multimedia support, multiple antenna transmission, cognitive radio, and fixed-mobile convergence. View full abstract»

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  • Secure Communication in Next Generation Internet

    Page(s): 6 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (433 KB) |  | HTML iconHTML  

    In recent years, network security has emerged as one of the most important challenge for many organizations. The enormous proliferation of the Internet and emergence of unified data, voice and multimedia services are responsible for emerging communication models that are essential for successful business activity of any organization. However, the increasing numbers of sophisticated security threats have the potential to significantly impede productivity, disrupt business operations and result in loss of information. Therefore maintaining a secure network remains the top priority for most organizations. The aim of this tutorial is to discuss the major security issues faced by network managers and the solutions currently employed. View full abstract»

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  • Ultra Mobile Broadband Technology Overview

    Page(s): 8 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    The 3GPP2 ultra mobile broadband (UMB) system is designed for robust mobile broadband access and is optimized for high spectral efficiency and short latencies using advanced modulation, link adaptation and multi-antenna transmission techniques. The UMB system uses OFDM as the main modulation technique. The Ultra Mobile Broadband standard UMB can operate in a wide range of deployments, thereby providing WWAN operators with a lot of flexibility in optimizing their network. The design objectives of UMB are to provide performance enhancements over existing cellular systems, while maintaining competitive edge over current and emerging wireless technology. View full abstract»

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  • MPEG-4 AVC Video Traffic Smoothing for Broadband Cable Networks

    Page(s): 13 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB) |  | HTML iconHTML  

    This paper presents a new rate-limited traffic smoothing algorithm for MPEG-4 AVC video traffic suitable for switched digital video cable deployments. It will be shown that the algorithm reduces bit rate variability and offers high buffer utilization. Such a smoothing algorithm can also minimize packet losses due to buffer overflows at the STB. View full abstract»

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  • Overall Performance Assessment of Energy-Aware Cooperative Techniques Exploiting Multiple Description and Scalable Video Coding Schemes

    Page(s): 18 - 24
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    In this paper we develop and analyze energy-efficient cooperative techniques for multimedia applications over wireless networks. The composite cellular-short-range network architecture is explored by using multiple description coding and scalable video coding schemes. In order to provide an overall and fair assessment of the schemes, different approaches are evaluated and discussed. The techniques are compared not only in terms of their energy gain with respect to noncooperative (autonomous) operation but also considering the quality of the delivered video signal. View full abstract»

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  • Short-Term MPEG-4 AVC Bandwidth Prediction for Broadband Cable Networks

    Page(s): 25 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    In this paper, we propose and evaluate the accuracy of a new traffic model that predicts, in the short term, the size of the B-frames of MPEG-4 AVC compressed video. To quantify the prediction accuracy, a model for the prediction error is also proposed. In a broadband cable network, the prediction model can be employed by a cable headend to provision video bandwidth efficiently or more importantly, reduce bit rate variability and bandwidth requirements via selective B-frame dropping, thereby minimizing buffering requirements and packet losses at the set top box. It will be shown that the model provides highly accurate prediction for a wide variety of video types, in particular, high action and regular movies encoded in high quality resolution. This is an important benefit since high motion MPEG videos demand the highest bandwidth and generate the widest range of bit rate requirements. Although the prediction model is very simple to implement, this paper also proposes two methods to simplify its operation further without sacrificing prediction accuracy. View full abstract»

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  • The Semantics of Mobile TV

    Page(s): 30 - 37
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    In order for a ubiquitous semantic Web-enabled global network to emerge, it is evident that many significant sub-domains must first evolve. A sub- domain, in this sense, can be thought of as a structured representation of a set of concepts and their associated attributes and terms within a given domain. Domains, which are a logical grouping of sub- domains, may span many different applications, Websites, portals, organizations or even industries. Domains must be capable of harmoniously exchanging data with others when requested, regardless of whether requests come from a human or a machine. This article will explain why one emerging domain - that of "Mobile TV" - is an appropriate if not prerequisite candidate domain for the semantic Web. View full abstract»

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  • Low Autocorrelation Fractional PTS Subblocking for PAPR Reduction in OFDM Systems

    Page(s): 41 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (406 KB) |  | HTML iconHTML  

    Partial transmit sequence (PTS) is a distortionless technique used to reduce the peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal. However, PTS has a relatively high computational complexity due to the computation of multiple inverse fast Fourier transforms (IFFTs). To reduce this complexity, fractional subblocking was introduced where a subset of inputs to identical inverse discrete Fourier transforms (IDFTs) (within an N-point IFFT) were used for subblocking. Unfortunately, the PAPR performance is degraded as the number of identical DFTs is increased. In this paper, we exploit the periodic autocorrelation function (ACF) of the PTS sequences to improve the PAPR performance with fractional subblocks. We show that a PAPR reduction is achieved which is better than with pseudo-random subblocking. View full abstract»

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  • Improved Compensation of HPA Nonlinearities Using Digital Predistorters with Dynamic and Multi-dimensional LUTs

    Page(s): 46 - 52
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (459 KB) |  | HTML iconHTML  

    Orthogonal frequency division multiplexing (OFDM) has been widely adopted in communications systems due to its high spectral efficiency and resistance to multipath fading and impulse noise. However, because of its large peak-to-average power ratio (PAPR), OFDM is highly sensitive to nonlinear distortion. In wireless systems, where to achieve acceptable power efficiency, the high power amplifiers (HPAs) operate near the saturation point, OFDM signals cause spectral regrowth leading to prohibitively high levels of adjacent channel interference (ACI). This paper investigates two signal predistortion techniques that attempt to mitigate these effects. The first approach assumes the HPA is memoryless, meaning that the output only depends on the current input. A predistorter using a one-dimensional (1-D) look up table (LUT) which has non-uniform bin spacing in amplitude is proposed. This non-uniform spacing allows the LUT to produce a better estimate of the inverse gain characteristic of the HPA. The second approach attempts to utilizes a two- dimensional (2-D) LUT which is capable of linearizing amplifiers with memory effects where the amplifier gain has a dependency on the short-term average power of the input signal. Multiple LUTs are constructed over the range of the input signal with each LUT being employed over a specific range of short-term average power. View full abstract»

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  • A Sub-optimal Eigenvalue-Based Adaptive Modulation Scheme for Broadband MIMO-OFDM Systems

    Page(s): 53 - 58
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    The ability to provide high data rate is a key measure in 3GPP long term evolution (LTE). Multiple input multiple output (MIMO) has emerged as an technique that increases the data rates in 3G systems. In this paper we study MIMO-OFDM system based on adaptive modulation and investigate the preceding technology. We present a method for adaptive modulation based on eigenvalues and a preceding matrix will be used at the transmitter according to singular value decomposition. A low complexity ratio-based algorithm with good performance is proposed to decide which modulation scheme to be used. The achieved results show that the proposed scheme outperforms basic beamforming with adaptive modulation. View full abstract»

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  • The Effect of Coding on OFDM and Single Carrier Transmission with Decision Feedback Equalizer

    Page(s): 59 - 63
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    Single carrier transmission (SCT) is a competing technique for orthogonal frequency division multiplexing (OFDM) in broadband wireless systems (BWS). Recent developments in frequency domain equalization (FDE) using decision feedback equalization (DFE) have greatly improved the system based on the single carrier (SC) technique. This paper presents the comparison of the effect of coding on OFDM and SCT with DFE. SC-linear equalizer (SC-LE) and SC-DFE techniques are compared with OFDM-cyclic prefix (OFDM-CP), OFDM-zero padding (OFDM-ZP). BER performance of these four techniques are compared with the coded version of the each. 1/2 rate conventional code and Viterbi decoding are used to simulate the coding gain. A wireless local area network (WLAN) system was simulated for frequency selective fading channel model with and without Inter symbol interference (ISI) encounter. Moreover CP and ZP variants of both OFDM and SC-DFE are simulated to compare the coding gains. More coding gain is comparatively achieved by the SC-DFE when ISI is encountered and by the OFDM when ISI is not encountered. View full abstract»

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  • Analysis of Threats to the Security of EPC Networks

    Page(s): 67 - 74
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    Detecting and responding to security and privacy threats to Electronic Product Code (EPC) and Radio Frequency IDentification (RFID) technologies are becoming major concerns of information security researchers. However, and before going further in these activities, an evaluation of the threats in terms of importance must be done. We present such an evaluation. Our analysis of the threats is based on a methodology proposed by the European Telecommunications Standards Institute (ETSI). According to this methodology, we rank the threats to EPC networks in order of relevance. This assessment is intended to prioritize threats for future research on appropriate countermeasure mechanisms. View full abstract»

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