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Telecommunications, 2008. ICT 2008. International Conference on

Date 16-19 June 2008

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Displaying Results 1 - 25 of 105
  • A wireless network sensor and server architecture for legacy medical devices

    Publication Year: 2008 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (413 KB) |  | HTML iconHTML  

    Modern medical devices have the facility to output data such as device settings and readings. Such devices include vital signs monitors, ventilators and infusion pumps to name a few. Wirelessly networking these types of devices has the advantages of patient mobility, device mobility and central data storage. This has led us to develop wireless sensors, gateways, servers and clients to support legacy medical devices. In this paper we present results from a hospital usability trial of this newly developed technology. We present the final wireless sensor network architecture used in the trial which also supports other compatible sensors we have developed. This also includes the architecture detail that supports the addition of future medical devices. View full abstract»

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  • Channel assignment for multi-radio wireless mesh networks using clustering

    Publication Year: 2008 , Page(s): 1 - 6
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1098 KB) |  | HTML iconHTML  

    Wireless mesh networks (WMNs) are an emerging technology which provides broadband wireless access services. One of the challenges that still faces high performance WMNs is the capacity reduction due to interference of wireless links. In this paper, we address the problem of assigning channels to nodes in WMNs. For this, we introduce the cluster channel assignment (CCA) approach with the objective of reducing network interference to increase the overall network performance. A clustering approach is employed in order to reduce the complexity of channel assignment into local problems within clusters and taking the advantage of the possibility to reuse the channels in different clusters. View full abstract»

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  • Practical issues of power control in IEEE 802.11 wireless devices

    Publication Year: 2008 , Page(s): 1 - 5
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1951 KB) |  | HTML iconHTML  

    Power control techniques for IEEE 802.11 wireless networks have already gained much attention. Such techniques are particularly attractive because they can improve various aspects of wireless network operation such as interference mitigation, spatial reuse in dense wireless deployments, topology control, and link quality enhancement. However, until recently implementing such advanced power control using off-the-shelf wireless devices was not considered possible. For example, Abdesslem et al. [1] stated that ldquomany novel power control solutions cannot be efficiently implemented over existing IEEE 802.11 cardsrdquo. However, in this paper we demonstrate that power control is now feasible and can be implemented in current IEEE 802.11 cards with per-packet granularity and low power switching latency. View full abstract»

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  • Extending QoS support from Layer 3 to Layer 2

    Publication Year: 2008 , Page(s): 1 - 7
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3408 KB) |  | HTML iconHTML  

    This paper presents some of the results obtained by the application of Ethernet layer 2 quality of service in IP networks. IP networks traditionally provide quality of service in Layer 3. However, since there is an enormous existing Layer 2 infrastructure, todaypsilas networks could benefit from the deployment of Layer 2 quality of service and the cooperation between layer 2 quality of service and layer 3 quality of service. In this paper, experiments are suggested and conducted and a scheme is suggested for efficient cooperation between Layer 2 and Layer 3 QoS provisioning. View full abstract»

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  • Investigation of Mobile IPv6 and SIP integrated architectures for IMS and VoIP applications

    Publication Year: 2008 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2582 KB) |  | HTML iconHTML  

    Mobile IPv6 and SIP are protocols designed to support different types of mobility. Mobile IPv6 has been used to support mobility in IP networks and SIP has been used for voice over IP applications. It is the signalling protocol of the IP multimedia subsystem (IMS). In this paper both protocols have been simulated and compared in order to observe their performance for voice over IP (VoIP) applications. In this paper the architectures proposed by researchers in order to combine mobile IPv6 and SIP have also been investigated and compared to analyse their advantages and disadvantages. A network scenario, running mobile IPv6 and SIP for IMS, has also been simulated in order to evaluate the performance offered by the two protocols and to compare them with the results from the simulation of the pure mobile IPv6 and SIP architectures. The comparison shows that the combined scenario offers better performance similar to the one obtained using only mobile IPv6 with route optimization. The scenario simulated was also compared with the integrated architectures for mobile IPv6 and SIP that were investigated. View full abstract»

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  • Modelling the power cost of security in Wireless Sensor Networks : The case of 802.15.4

    Publication Year: 2008 , Page(s): 1 - 8
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (571 KB) |  | HTML iconHTML  

    Pervasive applications and in particular Wireless Sensors Networks have very strict requirements in terms of power consumption. It is well known that radio activity is very expensive in terms of energy; we show here that intensive processing activities (as security) represent a major contribution to power budget. In this paper we extend our methodology for analyzing the impact of security related operations on power consumption and optimizing it. The analysis is based on experimental data and was validated with measurements on a real platform. View full abstract»

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  • Hybrid error concealment in image communication using data hiding and spatial redundancy

    Publication Year: 2008 , Page(s): 1 - 5
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB) |  | HTML iconHTML  

    Designed to diminish the artifacts caused by application of the state-of-the-art error concealment methods, a hybrid error concealment scheme is introduced. The proposed scheme stands out by using the inherent spatial redundancy of natural images along with a data hiding technique to obtain the information required for reconstruction of the lost parts of the image at the receiver. Furthermore, to maintain the quality of the received image in high packet loss conditions, an alternative scheme is proposed which will be activated in response to a receiverpsilas feedback reporting a high packet loss ratio. Our simulation results show that the proposed scheme outperforms the existing methods in terms of the quality of the received image and computational cost. View full abstract»

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  • Fuzzy biometric authentication in Home Networks for personalized users’ access

    Publication Year: 2008 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (581 KB) |  | HTML iconHTML  

    Thanks to the advances in communication and wireless technologies, many personal devices are able to interact within a new type of network called home networks (HNs). However, we need to protect the privacy of the users and secure their data during transfer. A number of works has been carried out recently to allow userspsila authentication within these networks using a biometric approach. In this paper, we propose a new biometric authentication method in HNs having broadband access to the Internet. The proposed solution employs the Fuzzy Vault biometric scheme and enables each user to access to his applicationspsila profiles in a personalized and secure manner. Our proposed solution brings additional privacy and does not disclose the biometric data of the users. This solution is consistent with the operator constraints regarding the performance and technical aspects. View full abstract»

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  • Can TCP metastability explain cascading failures and justify flow admission control in the Internet?

    Publication Year: 2008 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    This paper discusses implications of possible metastability of TCP-type fair bandwidth sharing under random flow arrivals/departures for understanding and defending the Internet against cascading failures. Cascading failures can be viewed as a process of network transition from desirable metastable mode with finite number of flows in progress to the congested mode. It is possible to eliminate or reduce the possibility of cascading failures with properly designed flow admission control which stabilizes the network in a close neighborhood of the desirable metastable state. View full abstract»

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  • Transmission power levels Prediction for Distributed Topology Control Protocols within parameterized scenarios

    Publication Year: 2008 , Page(s): 1 - 7
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    Distributed topology control protocols (DTCP) for wireless sensor networks (WSN) coordinate nodespsila decisions regarding their transmission ranges, in order to set up a network with a certain connectivity, while reducing nodespsila energy consumption and/or increasing network capacity. The key issue in DTCP is to choose the most suitable transmission power level (TPL) among those available for each sensor node in a distributed manner. We present a method to predict the TPLs for DTCP in realistic scenarios, which takes into account several propagation phenomena, such as barriers and multipath interference. To evaluate the effectiveness of our approach, we simulated the radio propagation pattern of a WSN in a scenario of multiple rooms. Our results suggested that our method allows to predict, with reasonable accuracy, the approximate TPLs distribution achieved by different DTCP approaches within a given parameterized scenario. View full abstract»

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  • Characterization of HTTP behavior on access networks in Web 2.0

    Publication Year: 2008 , Page(s): 1 - 6
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (638 KB) |  | HTML iconHTML  

    The traffic generated by the hypertext transfer protocol has a dominating position in current Internet traffic. The analyzing and characterizing of HTTP traffic is significant for understanding the nature of Internet traffic. Many studies on HTTP traffic were carried out when HTTP 1.1 appeared. Along with the prevailing of Web 2.0 the research on new features of HTTP traffic becomes a new issue in network measuring. In this paper comprehensive characterization of both the user behavior and the transportation feature on HTTP traffic are discussed. The characterization of HTTP behavior at HTTP conversation, TCP connection and Web flow level is parsed based on data collected on-line from access link of an institutepsilas LAN with more than 1500 users. The HTTP request and response length, temporal characteristics of HTTP message, and the interval of TCP connections as well as Web flows are discussed in detail. Some transformations of the investigated characterization caused by the influence of Web 2.0 are discovered in the experiment contrasting with previous result. View full abstract»

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  • Adaptive transmit power window control for channel state based packet transmissions in CDMA cellular downlink communications

    Publication Year: 2008 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1641 KB) |  | HTML iconHTML  

    This paper proposes an adaptive transmit power window control scheme based on location of mobile stations and traffic load for channel state based transmissions to enhance the system performance in CDMA cellular downlink packet communications. The proposed scheme constrains the downlink packet transmissions by employing a transmit power window individually given to each mobile station. The size of the transmit power window is controlled by using the optimum threshold value for each traffic load point. This optimum threshold value is selected with regard to the mobile locations and the traffic load. Computer simulations show that the proposed scheme improved the delay performance and fairness of service compared with the conventional scheme. View full abstract»

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  • Spam over Internet telephony: Prototype implementation

    Publication Year: 2008 , Page(s): 1 - 6
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2079 KB) |  | HTML iconHTML  

    This paper presents a prototype implementation of the reputation-based spam detection scheme, first presented in. Different components were developed, in particular the reputation manager (RM) that collects the appropriate information from the contact lists of the SIP subscribers and builds a social network. The latter provides the possible paths that might exist between any two SIP subscribers. This social network is endowed with a metric that allows to assign reputation values to the mentioned paths. Based on these scored paths, a decision is taken for accepting or rejecting calls. The result of our implementation is a working mechanism that tolerates zero false acceptance and an average of 4% false rejection. Our work demonstrates the scalability of the suggested solution as well as the feasibility of using the reputation concept for detecting SIP spam. View full abstract»

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  • Secure Wi-Fi sharing at global scales

    Publication Year: 2008 , Page(s): 1 - 7
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (217 KB) |  | HTML iconHTML  

    The proliferation of broadband Internet connections has lead to an almost pervasive coverage of densely populated areas with private wireless access points. To leverage this coverage, sharing of access points as Internet uplinks among users has first become popular in communities of individuals and has recently been adopted as a business model by several companies. However, existing implementations and proposals suffer from the security risks of directly providing Internet access to strangers. In this paper, we present the P2P Wi-Fi Internet Sharing Architecture PISA, which eliminates these risks by introducing secure tunneling, cryptographic identities, and certificates as primary security concepts. Thus, PISA offers nomadic users the same security that they expect from a wired Internet connection at home. Based on its three fundamental mechanisms, PISA achieves a flexibility which opens significant advantages over existing systems. They include user mobility, anonymity, service levels with different performance and availability characteristics, and different revenue models for operators. With this combination of key features, PISA forms an essential basis for global, seamless, and secure Wi-Fi sharing for large communities. View full abstract»

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  • Extension design of PLS codes in DVB-S2 based satellite broadcasting system

    Publication Year: 2008 , Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1222 KB) |  | HTML iconHTML  

    DVB-S2 based satellite broadcast system benefits from adaptive coding and modulation (ACM) for improving the bandwidth efficiency, which yields physical layer signaling (PLS) codes in the head of the physical frame. However, with the increasing types of ACM, the reserved assignable PLS codes will be soon exhausted. In this paper, the extension design of PLS codes is proposed, which will meet the requirement of the large number of ACM. On the other hand, compared with the traditional design, the extension design has equivalent performance without suffering from intolerable degradation. View full abstract»

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  • Trellis design of APSK in satellite broadcasting

    Publication Year: 2008 , Page(s): 1 - 7
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3320 KB) |  | HTML iconHTML  

    Amplitude phase-shift keying (APSK), especially 16APSK and 32APSK modulations, have been efficiently applied into satellite broadcasting and communications, such as DVB-S2, which endows the system with high spectrum efficiency and transmission rate. However, fewer design about the trellis coding and modulation based on APSK has been reported so far. In this paper, the symmetric and asymmetric TCM for 16APSK and 32APSK have been proposed and investigated. The proposed symmetric scheme has been proved more than 2dB gain in AWGN channel compared with the relatively low modulation schemes, e.g. 8PSK vs. 16APSK and 16APSK vs. 32APSK, which can be considered as a good alternative if the system works beneath the demodulation threshold of the relatively low modulation schemes. Moreover, the asymmetric TCM scheme is proposed in fading channel to achieve additional more than 1dB gain. View full abstract»

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  • On ARQ feedback intensity of the IEEE 802.16 ARQ mechanism

    Publication Year: 2008 , Page(s): 1 - 6
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (134 KB) |  | HTML iconHTML  

    The IEEE 802.16 standard defines the ARQ mechanism as a part of the MAC layer. The functioning of the ARQ mechanism depends on a number of parameters. The IEEE 802.16 specification defines them but it does not provide concrete values and solutions. We ran simulation scenarios to study how the ARQ feedback intensity impacts the performance of application protocols. The simulation results reveal that a low ARQ feedback intensity results only in a marginal improvement. Though it is possible to optimize the ARQ feedback intensity, it is reasonable to rely upon more frequent ARQ feedback messages as they do not result in a performance degradation. At the same time, ARQ connections, which work on top of HARQ, can delay the ARQ feedbacks up to the ARQ retry timeout to optimize the performance. View full abstract»

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  • A novel method of association based service handover in broadcast networks

    Publication Year: 2008 , Page(s): 1 - 7
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    Current broadcast networks such as digital video broadcasting for handheld (DVB-H) do not provide a direct approach for handovers but rely on a bidirectional mobile network such as universal mobile telecommunications system (UMTS) for the handover. In this paper, we present a novel method which can be used for handover without the support of a bi-directional mobile network. Furthermore, our method can also be used for associating services between broadcast and non-broadcast networks. In this article we compare this novel method with existing methods of service delivery. We demonstrate the efficiency of this method by comparing the overhead in a DVB-H network. Furthermore, we apply our method in the convergence of DVB-H and multimedia broadcast multicast service (MBMS) to achieve a seamless service handover by associating the services between these two networks. The simulation results demonstrate the improvements in the setup delay time for different burst sizes and bitrates while transferring the service from one network to another. View full abstract»

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  • Statistical modelling and experimental verification for wideband MIMO mobile-to-mobile channels in urban environments

    Publication Year: 2008 , Page(s): 1 - 6
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (589 KB) |  | HTML iconHTML  

    A three-dimensional reference model for wideband multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) channels is reviewed. To validate the reference model, an experimental MIMO M-to-M channel-sounding campaign was conducted for M-to-M vehicular communication with vehicles travelling along surface streets of a metropolitan area. The measured data is processed and the first- and second-order channel statistics obtained from the reference model and from the empirical measurements are compared. The close agreement between the analytically and empirically obtained channel statistics confirms the utility of the proposed reference model. View full abstract»

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  • A Fair Service and Dynamic Round Robin scheduling scheme for CICQ switches

    Publication Year: 2008 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (366 KB) |  | HTML iconHTML  

    The limitations in complexities and extensibilities of CICQ switchespsila scheduling policies are first analyzed. Then, based on this analysis, the guidelines for designing high extensible scheduling policies and the concept of virtual channel are proposed. Based on the guidelines and virtual channel, it comes up with a dynamic round robin scheduling algorithm-FDR (fair service and dynamic round robin), which is simple, high efficiency and fair service. FDR is based on round robin mechanism and its complexity is O(1). It allots the scheduling share for each virtual channel according to its current states. Thus, FDR has good dynamic and real-time performance, and it can adapt to unbalanced traffic load network environment. Simulation results under SPES show that FDR performs good delay, throughput and anti-burst performance, which can be applied in high performance routing and switching devices. View full abstract»

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  • A new service differentiation scheme: Size based treatment

    Publication Year: 2008 , Page(s): 1 - 5
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6743 KB) |  | HTML iconHTML  

    The increase of real-time applications as well as the vast usage of portable wireless devices has led to a corresponding increase of real-time traffic with strict bandwidth and delay requirements. In order to satisfy the requirements of various applications we typically use service differentiation. However, as new real-time applications are created, their portion of the total traffic increases, thus making more and more difficult to satisfy completely their requirements. In this paper we propose a new scheme, which is based on the axiom that dasiadifferent types of applications typically utilize different packet sizespsila. With size based treatment (SBT) different packet sizes are dropped with different probability by the queue. Small sized packets can benefit and transmit on higher rates, increasing the total system fairness. View full abstract»

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  • Securing mobile IP communications using MOBIKE protocol

    Publication Year: 2008 , Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    Mobile IP is used to manage the mobility of the Internet mobile users, and to keep their connectivity while they move from place to place. The security of mobile IP considering can be divided into two aspects, first in registration process, second, when connected parties exchange data with each other. In this article, after a brief study on the existing approaches used for securing mobile IP connections and after pointing to their problems, a new method will be introduced. This method is based on using IPsec security mechanism in conjunction with MOBIKE protocol. It will be pointed out that by using this proposed approach, the security of mobile IP connections will be achieved with respect to both two mentioned aspects. And also it is shown that most of the problems of existing approaches are eliminated in this method. View full abstract»

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  • Cross-layer congestion control mechanism for SCTP over EGPRS network

    Publication Year: 2008 , Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (379 KB) |  | HTML iconHTML  

    In this paper we propose a cross-layer algorithm between SCTP and RLC/MAC. Our approach proposes an analytical model of SCTP layer bandwidth variations according to EDGE link layer bandwidth changes. Tunable functions are proposed depending on the couple (MCS,BLER). This modeling is based on an effective cross-layer modeling, which adapts the congestion window size evolution to the radio transmission channel state. We introduce a congestion control mechanism modification consisting of restriction to the slow start phase. This cross-layer optimization allows congestion avoidance at transport layer caused by radio interface quality degradations. Our goal, in this study, is to provide a means that gives an optimal interaction model between transport layer (SCTP) and link layer (RLC/MAC EDGE), in order to improve network reliability. View full abstract»

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  • LDPC codes for binary asymmetric channels

    Publication Year: 2008 , Page(s): 1 - 7
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (199 KB) |  | HTML iconHTML  

    In this paper we examine the use of low-density parity-check (LDPC) codes in binary asymmetric channels. The problem is interesting since in some types of binary input fading multiple access channels (MAC) without channel state information (CSI), which use the successive decoding scheme, some of the users may experience asymmetric channels. It is well known that the successive decoder is a set of single user decoders and since there is no CSI at the receiver, the corresponding single user channels may be asymmetric in general. In that case the rate of interest of the user with the asymmetric channel is achieved by an unbalanced input distribution of the binary input. We are interested in constructing LDPC codes for these channels that approach the desired rate tuple in the capacity region. A convenient way of making the output distribution unbalanced is by introducing a mapper at the output of the encoder. Here we explain the method of mapping and its effect on the iterative decoding and derive closed form expressions for the upper bound of the probability of error. View full abstract»

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  • Simulation of energy efficient communication from flying sensors to a grid of base stations on the ground

    Publication Year: 2008 , Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (481 KB) |  | HTML iconHTML  

    In the field of mobile wireless communication, energy efficient protocols are crucial in order to ensure a widespread use of wireless technologies. These protocols determine the sending strategy, i.e. the decision when, where and how much data is transmitted, as well as the packet size and field strength of the sending antenna. We defined a model for the energy household of smart sensors, who are able to store the digitalized data and forward it to a base station at defined times, depending on the energy consumption. In this paper we present the sending strategy which is used in this model, as well as simulations we performed in order to test our sending strategy. View full abstract»

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