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Computers and Communications, 2001. Proceedings. Sixth IEEE Symposium on

Date 5-5 July 2001

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  • Proceedings. Sixth IEEE Symposium on Computers and Communications

    Publication Year: 2001
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    Freely Available from IEEE
  • Efficient routing with quality-of-service requirements

    Publication Year: 2001 , Page(s): 326 - 331
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (490 KB) |  | HTML iconHTML  

    We present an efficient routing algorithm for quality-of-service (QoS) connections requiring deterministic end-to-end delay bounds. Such routing selects paths with enough resources to accommodate the connections and satisfies their QoS. We assume that the connection scheduling, connection admissibility and state advertisement at every node is based on the rate-controlled static priority (RCSP) algorithm. We provide conditions to efficiently find a path that satisfies the QoS constraints. The performance of the QoS routing algorithm can be seriously degraded if the states are outdated and/or has high advertisement overhead. We propose conditions coupled to the RCSP algorithm that provide efficient state updates. View full abstract»

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  • A delay-throughput performance improvement to the p/sub i/-persistent protocol

    Publication Year: 2001 , Page(s): 615 - 620
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (533 KB) |  | HTML iconHTML  

    The p/sub i/-persistent medium access protocol is an attractive solution for high-speed fiber-optic unidirectional bits networks. Sarkar (1996) investigated the delay versus throughput characteristics and fairness performance of the p/sub i/-persistent protocol, inducting the 1-persistent protocol. The main advantage of 1-persistent protocol over the p/sub i/-persistent protocol is the reduced mean packet delay (network-wide and also for individual stations), but the potential drawback of this protocol is the lack of fairness. In contrast, the p/sub i/-persistent protocol can provide good fairness in the sense that mean delays become almost station position independent, but the main drawback of this protocol is the inevitable increase in packet delay. We propose a new scheme, called p/sub i/-persistent/HH (p/sub i/-persistent protocol with hitch-hiking mechanism for slot pre-use) that can offer the combining advantages of 1-persistent and p/sub i/-persistent protocols (i.e. low mean delay and fairness). The low mean delay as well as fairness is achieved by introducing a special mechanism of slot pre-use, called hitch-hiking (HH). In this paper the p/sub i/-persistent/HH scheme is described and simulation results are presented to verify the projected performance. View full abstract»

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  • Author index

    Publication Year: 2001 , Page(s): 735 - 737
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    Freely Available from IEEE
  • Influence-based channel reservation scheme for mobile cellular networks

    Publication Year: 2001 , Page(s): 218 - 223
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    Channel reservation techniques have been extensively used in cellular networks in order to meet the quality of service (QoS) requirements. An influence-based channel reservation and call admission control scheme is proposed to provide the QoS guarantee in a mobile wireless network. The basic idea behind the proposed scheme is that a moving user; in addition to its requirements in the current cell, exerts some influence on the channel allocation in neighboring cells. Such an influence is related to the moving pattern of this user (speed and direction), and it can be calculated statistically. We first introduce the concept of the influence curve, which provides an estimate of the requirements that the ongoing calls in current cell will impose on a neighboring cell. Based on this concept we propose a channel reservation scheme that dynamically and adaptively adjusts the number of channels that should be reserved for handoff purposes in each cell. The proposed algorithm can be carried out in a distributed way: each cell collects its current traffic condition, calculates the influence and sends the results to all its neighbors periodically. The performance evaluation of the proposed scheme is achieved via analysis and simulation View full abstract»

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  • Wireless resource management using genetic algorithm for mobiles equilibrium

    Publication Year: 2001 , Page(s): 586 - 591
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    We propose an algorithm for controlling mobile users transmitter power and information bit rate cooperatively in CDMA networks. The active component of this scheme is called genetic algorithm for mobiles equilibrium (GAME). Based an an evolutionary computational model, the base station tries to achieve an adequate equilibrium between its users. Thereof each mobile can send its traffic with a suitable power to support it over the different path losses and interference. In the mean time, its battery life is being preserved while limiting the interference seen by neighbors. This optimization is based on each user traffic, required signal quality, the channel characteristics and users spatial distribution. A significant enhancement in signal quality and power level has been noticed through several experiments View full abstract»

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  • Performance of packetized layered space-time detection over wireless links

    Publication Year: 2001 , Page(s): 592 - 596
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB) |  | HTML iconHTML  

    ALOHA systems are some of the most attractive options for wireless applications which include packet transmission. However, despite their flexibility and simplicity, they present a very low channel throughput. The objective of this paper is to analyze the performance of such a protocol based layered space-time scheme over wireless communication links. A multiuser environment is hence considered in which each user carries only one transmit antenna. A generalization of Vertical-Layered Space-Time (V-BLAST) technique for BPSK modulation is then invoked to detect the transmitted signals through the use of multiple receive antennas at the base station. We asses in this paper the gain achieved by the proposed receiver; denoted by rT-BLAST, compared to the conventional V-BLAST system. We first consider the performance of this system over flat fading channels for a variety of system parameters. Then, throughput and delay performance are analyzed under different packetized traffics. It is demonstrated through simulation results that a significant improvement in system capacity, throughput and delay are achieved View full abstract»

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  • A predictive end-to-end QoS scheme in a mobile environment

    Publication Year: 2001 , Page(s): 534 - 539
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB) |  | HTML iconHTML  

    Mobility is one of the new services that have been introduced due to the development and popularity of the Internet. However, the Internet currently lacks quality of service support. This article presents an end-to-end QoS architecture for roaming terminals. This architecture is based on mobile IP reservation protocol (MIR), hierarchical mobile IP (HMIP) and Diffserv. MIR operates within the wireless environment inside a HMIP domain while Diffserv mechanisms provide end-to-end QoS. MIR addresses the problem of bandwidth and reservation in order to provide users of a shared medium with a guaranteed bandwidth. Resources are reserved in the cells where mobile nodes are likely to go View full abstract»

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  • Issues on the IP multicast service behaviour over the next-generation satellite-terrestrial hybrid networks

    Publication Year: 2001 , Page(s): 417 - 424
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB) |  | HTML iconHTML  

    Our main focus here is to study the IP multicast service behaviour over the next-generation of satellite-terrestrial hybrid networks for which we develop a general architecture and we enumerate their main characteristics. We first focus on the Internet Group Membership Protocol (IGMP) feedback implosion problem and we present the exponential feedback raise that able to provide sufficiently stable expectation values across a large group size. Then, we propose and compare different approaches that can be used to enable the multicast in the on-board satellite switch. We show that the approach based on maintaining a multicast beams table (MBT) containing the list of spot beams concerned by each multicast group is the most suitable approach because it allows an efficient and transparent integration of satellite links in the Internet. In fact, the on-board switch monitors the IGMP reports and queries sent over the satellite link and update the MBT entries. We also turn our attention to multicast routing protocols. We present some undesirable behaviour of DVMRP, PIM-DM, and PM-SM. For DVMRP and PIM-DM, we identify some configurations where the satellite receivers may receive duplicated packets and we propose a method to overcome this problem. We then develop a configuration policy of PIM-SM in hybrid networks concerning the choice of the list of rendezvous point (RPs) and the switching from the RP-routed tree to the shortest path tree View full abstract»

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  • Performance analysis of CDMA random access systems with heavy-tailed packet length distribution

    Publication Year: 2001 , Page(s): 597 - 602
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    This paper analyzes the performance of unslotted CDMA random access schemes with heavy-tailed packet length distribution. Most of the previous work cover the analysis of the system with Poisson process and for infinite population and infinite buffer size where the results mainly depend on the mean values of the traffic. We remove these assumptions and analyze the behavior of the system for the more general and realistic case of finite population, finite buffers and variable packet length. The emphasis is placed on the study of the effect of the heavy-tailed packet length on the system characteristics. Specifically, we show via analysis and simulation that even when the mean packet length is small the system can have bottlenecks due to the packet length characteristics, and therefore dynamic adaptation and control of the system is required View full abstract»

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  • Evaluating the energy-consumption reduction in a MANET by dynamically switching-off network interfaces

    Publication Year: 2001 , Page(s): 186 - 191
    Cited by:  Papers (13)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB) |  | HTML iconHTML  

    The design of energy-efficient routing algorithms is a fundamental problem in a mobile ad-hoc network (MANET) where battery energy is a limited resource. We evaluate a power-conserving algorithm, based on the RTS/CTS dialogue of the IEEE 802.11 standard which dynamically switches off the radio network interface card of nodes when they are neither transmitting nor receiving a packet. We evaluate the algorithm through simulations over four well-known routing algorithms: dynamic source routing (DSR), ad-hoc on demand distance vector (AODV), temporally-ordered routing algorithm (TORA), and destination-sequenced distance-vector routing (DSDV). The obtained results indicate that for all the evaluated routing protocols, the power savings are similar and range between 25 per cent and 60 per cent of the total energy View full abstract»

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  • Blind equalization of a class of IIR channel

    Publication Year: 2001 , Page(s): 573 - 579
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB) |  | HTML iconHTML  

    We examine some properties associated with twice oversampled IIR channels, and suggest a novel blind equalization scheme. We note that a twice oversampled IIR channel is equivalent to a single-channel feedback section in cascade with a two-channel feedforward section. We propose a two-step blind identification procedure for this class of channel, the performance of which we demonstrate by simulation. We note that such a procedure has particular application to channels with short feedback and long feedforward sections. We examine the nature of a Tomlinson-Harashima precoder, and show how a similar two-step blind identification can be applied when the precoder has a dynamics limited input View full abstract»

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  • Trade-offs between tariffs and QoS in mobile telephony networks: an integrated design approach

    Publication Year: 2001 , Page(s): 546 - 553
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB) |  | HTML iconHTML  

    We present an analytical approach for the joint optimization of quality of service (in terms of call blocking probability) and tariffs for a mobile telephony network. The analytical approach is based on the combination of traditional telecommunication system design techniques and econometric approaches for profit maximization View full abstract»

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  • Variable redundancy coding for mobile channels

    Publication Year: 2001 , Page(s): 580 - 584
    Cited by:  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    Mobile data channels carry different communication services with different data formats and rates. In modern CDMA systems as in UMTS, such different data rates and services are carried in a fixed frame. This results with some free data gaps in the frame. A novel coding concept called variable redundancy coding (VRC) to replace the currently used bit repetition for filling such gaps is presented. The key idea behind the proposed VRC is simple: instead of repeating bits to match the channel rate, block code redundancy bits are stuffed in the free gaps. Such VRC bits particularly improve the frame error rate (FER) and at the same time fill the free gaps. This results in a more efficient overall channel throughput, as the data throughput depends mainly on the frame error rate and on the ARQ strategy employed. A particular VRC technique based on the burst error correcting Fire code is presented and is shown to be effective to optimize the overall system performance View full abstract»

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  • Integrated performance evaluating criteria for network traffic control

    Publication Year: 2001 , Page(s): 438 - 443
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB) |  | HTML iconHTML  

    The performance-evaluating criterion is one of the most important issues for the design of network traffic control strategy and algorithms. The design will be varied with the evaluating criterion. Because the network traffic control strategy has multiple performance objects, how to reach multiple objects simultaneously is one difficult problem. This paper provides a set of integrated performance evaluating criteria from the network traffic control model, and the criteria integrates several objects, such as the network performance, user's QoS requirement and system fairness. Then it is discussed and analyzed in details. Moreover, the integrated performance evaluating criteria can be applied to performance evaluation and improvement in network traffic control strategy and algorithms View full abstract»

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  • Defense against man-in-the-middle attack in client-server systems

    Publication Year: 2001 , Page(s): 9 - 14
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB) |  | HTML iconHTML  

    The deployment of several client-server applications over the Internet and emerging networks requires the establishment of the client's integrity. This is necessary for the protection of copyright of distributed material and, in general, for protection from loss of “sensitive” (secret) information. Clients are vulnerable to powerful man-in-the-middle attacks through viruses, which are undetectable by conventional anti-virus technology. We describe such powerful viruses and show their ability to lead to compromised clients, that cannot protect copyrighted or “sensitive ” information. We introduce a methodology based on simple hardware devices, called “spies”, which enables servers to establish client integrity, and leads to a successful defense against viruses that use man-in-the-middle attacks View full abstract»

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  • Enabling the progressive multicast service deployment

    Publication Year: 2001 , Page(s): 178 - 183
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB) |  | HTML iconHTML  

    The IP multicast architecture was not widely deployed because multicast address allocation is difficult and there is no scalable solution to inter-domain multicast routing. Hence, there is an interest in developing protocols that allow the progressive deployment of the multicast service by supporting unicast clouds. This paper proposes HBH (hop-by-hop multicast routing protocol). HBH adopts the source-specific channel abstraction to simplify address allocation and implements multicast distribution using recursive unicast trees. In this model, data packets have unicast destination addresses. Therefore, HBH supports pure unicast routers transparently. The branching-nodes recursively create packet copies to implement the distribution. HBH constructs a shortest-path tree even in the presence of asymmetric unicast routing. Consequently, HBH provides best routes in asymmetric networks, and is suitable for an eventual implementation of QoS-based routing. Additionally HBH reduces tree bandwidth consumption in asymmetric networks when compared to other approaches. The results obtained from simulation support our statements View full abstract»

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  • A throughput analysis of reliable multicast protocols in an active networking environment

    Publication Year: 2001 , Page(s): 151 - 158
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    Reliable multicast protocols have gained popularity with active services contribution where routers implement additional functionalities. Contributing mainly to feedback implosion problems, retransmission scoping and cache of data, these active protocols open new perspectives for achieving high throughput and low latencies on wide-area networks. We define generic protocols with active services and present a throughput analysis of the various mechanisms proposed in existing protocols, i.e. active reliable multicast (ARM) and active error recovery (AER). The main contribution consists in the analysis of the local recovery facility with different NACK suppression strategies and the potential of the subcast feature. Some insights on dimensioning active networks are also provided View full abstract»

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  • QoS using delay-synchronized dynamic priority scheduling

    Publication Year: 2001 , Page(s): 276 - 281
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB) |  | HTML iconHTML  

    Controlled-load service that provides acceptable quality of service to adaptive real-time applications without making absolute guarantee is extensively considered, owing to its higher resource utilization than guaranteed service. Enhancement of utilization strongly relies on traffic scheduling method adaptable to a varying traffic load, and admission control algorithms that do not depend on worst-case traffic behavior. We propose a new scheduling scheme called delay-synchronized dynamic priority (DSDP), which exploits node synchronization of a multi-hop network by dynamically altering the priority of a packet to offset the deviation from its expected arrival time. Additionally, we develop a measurement-based admission control algorithm that uses existing traffic measurements under the DSDP scheme for controlled-load service View full abstract»

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  • Testing distributed real time systems using a distributed test architecture

    Publication Year: 2001 , Page(s): 648 - 654
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB) |  | HTML iconHTML  

    We present a method for testing real-time distributed systems. More precisely, we propose: (1) a model for specifying distributed real-time systems, (2) a simple and practical test architecture, and (3) a procedure for distributing test sequences View full abstract»

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  • Multicast for small conferences

    Publication Year: 2001 , Page(s): 145 - 150
    Cited by:  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB) |  | HTML iconHTML  

    This paper describes a concept to support scalable multicast communications for small audio/video conferencing groups on the Internet. The solution presented in this paper is based on extensions of IPv6 and the session description protocol (SDP). A goal of the concept called multicast for small conferences (MSC) is the smooth deployment in the Internet View full abstract»

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  • Formal validation of a multicast transport protocol

    Publication Year: 2001 , Page(s): 642 - 647
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB) |  | HTML iconHTML  

    The past years have seen the emergence of cooperative applications that require the exchange of high volumes of data among remote cooperating parties. With the purpose of providing a scalable communication solution for this kind of applications, multicast transport protocols have been proposed in the literature, because point to point communications lead to wasting too much bandwidth, in particular if one wants to guarantee a certain level of reliability. In this paper, we study a multicast transport protocol, scalable probabilistic reliable multicast (SPRM), and show how a formal description technique, RT-LOTOS, has been successfully applied to identify some flaws in this complex multi-parties protocol. It is shown how the same approach may also be used for performance evaluation, and we compare our results with other models based on queuing theory View full abstract»

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  • A novel fuzzy approach to estimate cell loss probability for self similar traffic in ATM networks

    Publication Year: 2001 , Page(s): 260 - 265
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB) |  | HTML iconHTML  

    Estimating cell loss probability (CLP) in real time for achieving satisfactory call admission control (CAC) remains an important research problem. In estimating CLP which is often specified to be less than 10 -9, fuzzy based techniques have been found to be more promising than crisp statistical techniques. In this paper, we propose a novel fuzzy logic algorithm based on the α-cuts of equivalence relations to estimate CLP in real time for self-similar ATM networks. The α-cuts of fuzzy sets are used to construct the membership functions of the input and output variables and to induce necessary fuzzy rules. The proposed fuzzy approach is validated by comparing the estimated values of CLP with the theoretical values. The new approach not only estimates accurate real time CLP, but also achieves it by using fewer theoretical data View full abstract»

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  • A new fairness criterion and its realization by using a new scheduling algorithm in the Internet

    Publication Year: 2001 , Page(s): 444 - 449
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB) |  | HTML iconHTML  

    A new fairness criterion (logarithmic proportional fairness) is introduced in this paper. Under the control of this criterion, the tradeoff among fairness, network utility and total delay can be achieved in the Internet. This paper also presents a new scheduling algorithm-logarithmic proportional fair queueing scheduling algorithm (LPFQ, in short). By using this scheduling algorithm in routers, the logarithmic proportional fairness criterion and punishment to misbehaving flows can be implemented in the Internet. The theoretical analysis and simulation results prove their validity View full abstract»

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  • A service-component testing method and a suitable CORBA architecture

    Publication Year: 2001 , Page(s): 655 - 660
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB) |  | HTML iconHTML  

    This paper presents a method for service-component testing and a suitable CORBA test architecture. This test environment allows the service validation from its components and is a close step towards the execution of the obtained tests on a CORBA environment. Two aspects are relevant: the test of components and the test architecture. The testing method for components is new: it is based on the generation of partial graphs and avoids the combinatorial explosion of number of states of the global system. The test architecture on a CORBA platform is also new, since there are few works on testing based on these environments. As an application we present a case study on a real conference call service View full abstract»

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