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This paper builds on the assumption that in the future, UMTS, HIPERLAN-2 and DVB-T can be three (co-operating) components of a composite radio infrastructure that offers wideband wireless access to broadband IP-based services. Managing the resources of this powerful, composite-radio infrastructure in an aggregate manner, and multi-operator scenario, is a complex task. This paper presents an approach to the overall UMTS, HIPERLAN-2 and DVB-T network and service management problem, providing the internal operation of a system addressing this problem. Key points addressed are the development of an architecture that can jointly optimise the resources of the technologies in the composite radio environment, and the development of open interfaces with Service Provider mechanisms and the heterogeneous managed infrastructure. [ABSTRACT FROM AUTHOR]

This paper presents a QoS evaluation in a DiffServ experimental test-bed scenario. We implemented our field trial using prototypal routers running under Linux OS and we arranged them in order to make possible the interconnection with a remote island of a Multi-domain DiffServ network. The performance evaluation of Real-time applications presented in the paper will make clear how it is possible to provide "mission critical" applications with tool-quality level of service when appropriate algorithm and resource sharing are chosen and when these features are associated with a fair degree of aggregation. As a consequence the paper describes the results by means of a Mean Opinion Score (MOS) evaluation campaign to show how Real-Time applications (such as voice and video conferencing) may suffer for the lack of QoS. [ABSTRACT FROM AUTHOR]

A policy based management networking is a new paradigm used to achieve the network management. This paper presents a new policy based Mobile IP users management architecture based on a Common Open Policy Service (COPS) protocol which is currently deployed for QoS management. This paper introduces a new concept of terminal policy enforcement point (TPEP) which allows the terminal to interact with the network enforcing network policies defined by the network manager; it is a key feature of our architecture. The paper presents also the global architecture to support the mobile IP users requirements based mainly on two extensions of COPS protocol; COPS-SLS [1] for QoS negotiation and COPS-MU/MT [2] for policy based user and terminal mobility management. [ABSTRACT FROM AUTHOR]

The Virtual Home Environment (VHE) has been introduced as an abstract concept enabling users to access and personalize their subscribed services whatever the terminal they use and whatever the underlying network used. The European IST VESPER project (Virtual Home Environment for Service Personalization and Roaming Users) aims to provide an architectural solution and an implementation of the VHE, providing ubiquitous service availability, personalised user interfaces and session mobility, while users are roaming or changing their equipment. In this paper we present a multimedia delivery service, one of the trial services selected to demonstrate VHE features, showing its interconnection with the so far defined VESPER VHE architecture. [ABSTRACT FROM AUTHOR]

The UMTS-FDD system, one of the members of the ITU IMT-2000 third generation standard for terrestrial cellular systems, employs pruned Golay sequences to enable initial synchronisation of the mobile terminals to the network. In this paper a low complexity solution for initial synchronisation is proposed, which is able to counteract the performance degradation introduced by large frequency offsets occurring in the mobile station receiver. Simulation results are provided to validate the proposed solution. [ABSTRACT FROM AUTHOR]

This paper analyzes different packetization strategies that significantly improve the quality of H.263 coded video transmission in wireless local area networks (WLANs). We show that a considerable improvement can be obtained with the proper combination of error concealment techniques and transmission unit (TU) sizes. Moreover, we present performance evaluation results on critical system parameters for interactive video over Ad—Hoc WLANs, and propose a simple rule to specify TU sizes. We use Kinesis, a novel system architecture for packet video, as a software measurement tool to analyze the effects of packetization policies, distance, network offered load, and interference from co—located WLAN devices on overall video quality. Kinesis supports IP multicast extensions, overcoming delay issues introduced by the complex retransmission schemes in the IEEE 802.11 MAC sublayer, which are not acceptable for real—time services. It implements real—time transport protocol functions to manage synchronization and QoS, and performs software—only real—time H.263 video encoding. In this paper we address most common Ad—Hoc WLAN configurations, and present experimental results on Packet Error Rates, Frame Error Rates, frame delays and latency, and Peak Signal-to-Noise Ratio for well—known test video sequences. [ABSTRACT FROM AUTHOR]

In this paper we present a scheme that enables a mobile user to perform a " QoS-conditionalized" handoff when moving to an overlapping area in Mobile IPv6. The idea is to use a QoS hop-by-hop option piggybacked in the binding messages for QoS signaling and conditional-ize a handoff upon the availability of sufficient resources along the new transmission path. Our scheme builds upon the hierarchical mobile IPv6 protocol and is especially suited for micro-mobility. It also enables the mobile node to flexibly choose among a set of available access points so that the mobile node can transmit packets through a route which offers satisfying QoS. [ABSTRACT FROM AUTHOR]

Quality of Service (QoS) for the Internet has been discussed for a long time without any major breakthrough. There are several reasons, the main one being the lack of a scalable, simple, fast and low cost QoS solution. A new QoS-framework, called resource management in differentiated services (RMD), aims to correct this situation. This framework has been published in recent papers and is extending the IETF differentiated services (diffserv) architecture with new admission control and resource reservation concepts in a scalable way. This paper focuses on proposing and investigating two resource reservation solutions on the problem of severe congestion situation within a diffserv-aware network utilizing an admission control scheme called Resource Mananagement in Diffserv (RMD). The different severe congestion solutions are compared using extensive simulation experiments. [ABSTRACT FROM AUTHOR]

It is widely recognized that the maximum number of heavy-tailed flows that can be admitted to a network link, while meeting QoS targets, can be much lower than in the case of markovian flows. In fact, the superposition of heavy-tailed flows shows long range dependence (self-similarity), which has a detrimental impact on network performance. In this paper, we show that long range dependence is significantly reduced when traffic is controlled by a Measurement-Based Admission Control (MBAC) algorithm. Our results appear to suggest that MBAC is a value added tool to improve performance in the presence of self-similar traffic, rather than a mere approximation for traditional (parameter-based) admission control schemes. [ABSTRACT FROM AUTHOR]

The CMPP (Circulant Modulated Poisson Process) modeling approach represents an appealing solution since it provides the integration of traffic measurement and modeling. At the same time, it maintains the Markovian hypothesis that permits analytical transient and steady-state analyses of queueing systems using efficient algorithms. These relevant features of CMPP approach has driven us to analyze in more details the fitting procedure when it is applied to actual broadband traffic. In the paper, investigating the estimation algorithm of model parameters, we emphasize the difficulty of CMPP in capturing the upper tail of marginal distribution of actual data, which leads to an optimistic evaluation of network performance. As shown in the paper, a simple relation exists between the number of significant eigenvalues obtained by the spectral decomposition and the peak rate that the CMPP structure is able to capture. The relation evidences the difficulties of CMPP to model actual traffic, characterized by long tailed distribution, as well as traffic data with the well accepted hypothesis of gaussian marginal. [ABSTRACT FROM AUTHOR]

Understanding the end-to-end packet delay dynamics of the Internet is of crucial importance since it directly affects the QoS (Quality of Services) of various applications, and it enables us to design an efficient congestion control mechanism. In our previous studies, we have measured round-trip time of the Internet, and have modeled its dynamics by the ARX (Auto-Regressive eXogenous) model using system identification. As input and output data for the ARX model, we have used the packet inter-departure time from a source host and the corresponding round-trip time variation measured by the source host. In the current paper, for improving the model accuracy, we instead use the packet transmission rate from the source host and the average round-trip time measured by the source host. Using input and output data measured in working LAN and WAN environments, we model the round-trip time dynamics by determining coefficients of the ARX model using system identification. Through numerical examples, we show that in LAN environment, the round-trip time dynamics can be accurately modeled by the ARX model. We also show that in WAN environment, the round-trip time dynamics can be accurately modeled when the bottleneck link is shared by a small number of users. [ABSTRACT FROM AUTHOR]

Satellite link characteristics cause reduced performance in TCP data transfers. In this paper we present SaTPEP, a TCP Performance Enhancing Proxy which attempts to improve TCP performance by performing connection splitting. SaTPEP monitors the satellite link utilization, and assigns to connections window values that reflect the available bandwidth. Loss recovery is based on Negative Acknowledgements. The performance of SaTPEP is investigated in terms of goodput and fairness, through a series of simulation experiments. Results obtained in these experiments, show significant performance improvement in presence of available bandwidth and at high error rates. [ABSTRACT FROM AUTHOR]

The Differentiated Services (DiffServ) architecture has been proposed as a scalable solution for providing service differentiation among flows. Towards the enhancement of this architecture, new mechanisms for admission control and a new set of network services are proposed in this paper. Each network service is appropriate for a specific type of traffic and is realized through its own network mechanisms, which are the Traffic Classes. Traffic Classes provide the traffic handling mechanisms for each Network Service and are composed of a set of admission control rules, a set of traffic conditioning rules and a per-hop behavior (PHB). Different traffic-handling mechanisms are proposed for each network service and are implemented with the use of the OPNET simulation tool. A large-scale network is used as a reference topology for studying the performance and effectiveness of the proposed services. [ABSTRACT FROM AUTHOR]

We consider, in this paper, the call admission control (CAC) problem in a multimedia cellular network that handles several classes of traffic with different resource requirements. The problem is formulated as a Semi-Markov Decision Process (SMDP) problem. It is too complex to allow for an exact solution for this problem, so, we use a real-time neuro-dynamic programming (NDP) [Reinforcement Learning (RL)] algorithm to construct a dynamic call admission control policy. A broad set of experiments shows the robustness of our policies compared to the classical solutions such as Guard Channel [ABSTRACT FROM AUTHOR]

Research of web-servers has recently addressed the problem of content distribution coupled with quality of service (QoS). Due to the explosive growth of services offered over the Internet, novel mechanisms are needed for IP based service delivery to scale in a client-transparent way. This paper addresses the above problem considering also utilization of available processing power of servers. Many developed caching systems dedicate a fixed portion of the processing power for higher QoS services leading to lowered overall throughput of the server system. Here we introduce and simulate a QoS aware caching scheme that offers lower response delay for higher quality services and additionally optimizes utilization of the available processing power. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of minimizing the routing delay in ad hoc on-demand routing protocols through optimizing the Time-to-Live (TTL) interval for route caching. An analytical framework is introduced to compute the expected routing delay when the source node has a cached route with a given TTL value. Furthermore, a numerical method is proposed to determine the optimal TTL of a newly discovered route cached by the source node. We present simulation results that support the validity of our analysis. [ABSTRACT FROM AUTHOR]

The World-wide Web (WWW) works now as the infrastructure over the Internet for multimedia applications. Internet radio is one of those applications and its growth is explosive. We have started operating an Internet Radio station with streaming music services since April 2000. An Internet radio can broadcast music over the network regardless of such geographic restrictions as the traditional radio systems have. There are some problems and services due to the Internet. This paper reports our operation as well as the issues. We propose our idea on some novel radio services as well. [ABSTRACT FROM AUTHOR]

In this paper we propose a new router architecture that combines both flexibility and performance. This router architecture aims at combining the best of two worlds: the commercial routers, which have a proven track for stability and performance but lack the flexibility of routers with open source operation system. The latter is particularly flexible because the source code is accessible for analysis and modification purposes as opposed to the traditional commercial routers, whose software can be altered by their manufacturers only. [ABSTRACT FROM AUTHOR]

Multicast state scalability is among the critical issues which delay the deployment of IP multicast. In our previous work, we proposed a scheme, called aggregated multicast to reduce multicast state. The key idea is that multiple groups are forced to share a single delivery tree. We presented some initial results to show that multicast state can be reduced. In this paper, we develop a more quantitative assessment of the cost/benefit trade-offs. We introduce metrics to measure multicast state and tree management overhead for multicast schemes. We then compare aggregated multicast with conventional multicast schemes, such as source specific tree scheme and shared tree scheme. Our extensive simulations show that aggregated multicast can achieve significant routing state and tree management overhead reduction while containing the expense of extra resources (bandwidth waste and tunnelling overhead, etc.). We conclude that aggregated multicast is a very cost-effective and promising direction for scalable transit domain multicast provisioning. [ABSTRACT FROM AUTHOR]

The paper concerns device discovery in multi-hop networks of Bluetooth devices. We start from the observation that forming a Bluetooth scatternet (i.e., a multi-hop wireless topology) requires each pair of neighboring nodes to have a "symmetric" knowledge of each other, i.e., if node u knows node v then node v knows node u. We investigate the use of the Bluetooth procedures for device discovery (inquiry procedures) in order to guarantee the needed symmetric knowledge for scatternet formation. Through the use of simulations we observed that despite the long time required for each node to become aware of the presence of all its neighbors, the Bluetooth topologies obtained by using the devices discovered after just 6 seconds are connected. The average number of neighbors of each node and the average route length are also consistently close to the values that we would obtain if all the neighbors of a device were discovered. [ABSTRACT FROM AUTHOR]

In this paper we present a protocol for reliable multicast within a group of mobile hosts that communicate with a wired infrastructure by means of wireless technology. The protocol tolerates failures in the wired infrastructure, i.e., crashes of stationary hosts and partitions of wired links. The wireless coverage may be incomplete and message losses could occur even within cells, due to physical obstructions or to the high error rate of the wireless technology, for example. Movements of mobile hosts are accommodated efficiently because they do not trigger any interaction among stationary hosts (i.e., there is no notion of hand-off). We evaluate by simulation the impact of fault-tolerance on the performance of the protocol in normal operating conditions, i.e., in the absence of failures. The results obtained show that the increase in the average latency experienced by messages is limited to few milliseconds. [ABSTRACT FROM AUTHOR]

In this paper we propose an architecture for an output queued switch based on the mesh of trees topology. After establishing the equivalence of our proposal with the output queued model, we analyze its features, showing that it merges positive features of the input queued switches (specially their implementability) with all the characteristics typical of output queued ones. Moreover, such an architecture is able to easily and efficiently manage multicast traffic, which is becoming extremely important in networks with traditional communication services integrated in. [ABSTRACT FROM AUTHOR]

This paper presents an efficient algorithm for Monte-Carlo simulation of time blocking probabilities for multi-layer multicast streams with the assumption that blocked calls are lost. Users may join and leave the multicast connections freely, thus creating dynamic multicast trees. The earlier published algorithms are applicable to small networks or networks with few users. The present simulation algorithm is based on the inverse convolution method, and is the only effective way to handle large systems, known to the author. [ABSTRACT FROM AUTHOR]

The main contribution of this paper is a new online routing algorithm, called Dynamic Online Routing Algorithm (DORA), for dynamic setup of bandwidth guaranteed paths in MPLS networks. The goal of DORA is to accept as many network path setup requests as possible by carefully mapping paths with reserved bandwidth evenly across the network. The key operation behind DORA is to avoid routing over links that: 1) have high potential to be part of any other paths, and 2) have less residual bandwidth available. We compare DORA against other existing constraint-based routing algorithms based on two performance metrics: path setup rejection ratio and percentage of successful reroutes. Our result shows that DORA performs better than the other algorithms in both metrics. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of pricing-based distributed resource allocation via scheduling in a communication network. Introducing the temporal aspect in the resource allocation problem presents new challenges e.g. in accounting for the durations and deadlines of the resource requests. Dynamic real-time pricing concepts are discussed for the decentralized sharing of network resources. A numerical example illustrates the benefit of congestion based pricing in a dynamic communication network. The quality of service that results from decentralized resource allocation is studied from the point of view of a power-controlled wireless network. The model is based on a dynamic noncooperative game and is related to recent work on centrally optimal (Pareto-optimal) distributed dynamic resource allocation. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the issue of dimensioning Internet access lines for elastic traffic. This is important for Internet service providers (ISPs) because over-dimensioning wastes precious bandwidth resources, while under-dimensioning generally leads to less satisfactory quality of service (QoS) perceived by subscribers. Our discussion is based on the M/G/R processor sharing model which characterizes TCP traffic at flow level. Our analysis demonstrates the impact of a number of key factors (and their relations) on the dimensioning procedure. We consider two dimensioning methods based on different QoS criteria. It is found that the method based on the delay factor is superior in that both the average delay (throughput) and blocking performance targets can be satisfied. Numerical and theoretical analyses also illustrate that significant multiplexing gain can be achieved for elastic flows and this gain increases with burstiness. [ABSTRACT FROM AUTHOR]

We present a possible way to extend queuing theory to account for interactions between adjacent queues in a packet-switched network. The interaction between queues arises because of the influence of the routing protocol on each switching decision and the stochastic nature of packet lengths and inter-arrival times. Both the methodology and the analysis tools are adaptations of methods of statistical mechanics and are presented in outline here. The justification for their use lies in experimental evidence given in [1,2,3] that aggregate, core-network IP traffic exhibits quasi-Markovian properties. In this paper, we focus on the interaction between pairs of queues, either in a cascaded arrangement, or connected to the same switching fabric, in the presence of an idealised routing protocol. [ABSTRACT FROM AUTHOR]

Many remote computers need to be securely connected to their organization main network through a public IP network (e.g. Internet). Our purpose is to integrate as seamlessly as possible remote networks in the organization network, i.e. to put these in exactly the same situation as if they were located inside the organization. After summarizing the state of the art, the paper presents a solution based on RSIP, to dynamically allocate an IP address of the organization to a host of the remote network requesting an external access. Security is provided by IPSec. We compare this solution with a former proposal based on DHCP and show that the two solutions are very close but that RSIP brings us closer to an ideal situation but at an extra cost. [ABSTRACT FROM AUTHOR]

In order to provide the guaranteed mobile QoS (Quality- of- service) for arriving multi-class calls, we need to minimize the dropping rate of handoff calls while at the same time controlling the blocking rate of new calls. This paper proposed a new multi-class call admission control mechanism that is based on dynamically formed reservation pool for handoff requests. The simulation results show that the individual QoS criteria of multi-class traffic such as the handoff call dropping probability can be achieved within a targeted objective and the new call blocking probability is constrained to be below a given level. The proposed scheme is applicable to channel allocation of multi-class calls over high-speed multimedia wireless networks. [ABSTRACT FROM AUTHOR]

Explicit Congestion Notification (ECN) for IP networks has received considerable attention in recent years, and has been shown to improve TCP goodput. Previous studies have centered on scenarios in which TCP with ECN (TCP/ECN) traffic competes with ECN-unaware traffic. This paper presents case studies in which moderately short flows are all ECN-capable, and compare them with the corresponding cases where the flows are ECN-unaware, running over drop tail and Random Early Detection routers. Using transmission overhead metrics, we show that TCP/ECN uses network resources more efficiently. We also consider the case of battery-operated devices and show that TCP/ECN is more power conserving than standard TCP. An unexpected outcome of our experiments is that goodput does not improve in an all-TCP/ECN environment. [ABSTRACT FROM AUTHOR]

Current quality source-adaptive schemes for multicast multilayered video rely on merging capabilities at special nodes in the network as a means of combining feedback from the whole set of receivers. These strategies reduce network load and avoid feedback implosion at the source. In this paper, we examine how to provide optimal feedback for such schemes. The optimal feedback is achieved when state information from the whole set of receivers is represented in every incoming feedback packet at the source. We show that the choice of a suitable merging time window in the intermediate nodes coupled with a periodical transmission of feedback packets by the receivers leads to near-optimal feedback. [ABSTRACT FROM AUTHOR]

Demand for mobile network access is having a huge increase nowadays. Cellular networks are being deployed to cope with a high number of users. Several IP micro-mobility protocols have been proposed to handle routing and handoffs inside cellular networks. In this paper the HAWAII micro-mobility protocol is analyzed by means of an analytical model. A detailed description of the handoff procedure is given and illustrated by means of traces obtained from simulation. Several of the system details are taken into account in the analytical model. This allows us to investigate the influence of various system parameters (e.g. cell overlap area, beacon latency, forwarding buffer capacity, etc.) on the system performance for constant bit rate (UDP) traffic. The results are validated by means of simulation results obtained with the network simulator (ns). [ABSTRACT FROM AUTHOR]

This paper analyzes mobile agent performance in network management, comparing it with the client-server model used by the SNMP (Simple Network Management Protocol). Response time results show that the mobile agent performs better than the SNMP when the number of managed elements ranges between two limits determined by the number of messages that pass through a backbone and by the mobile agent size that grows with the variables collected on the network elements. [ABSTRACT FROM AUTHOR]

The flow control algorithms currently used in the Internet have been tailored to share bandwidth between users on the basis of the physical characteristics of the network links they use rather than the characteristics of their applications. This can result in a perception of poor quality of service by some users even when adequate bandwidth is potentially available, and is the motivation for seeking to provide differentiated services. In this paper, stimulated by current discussion on Web mice and elephants, we explore service differentiation between persistent and short-lived flows, and between file transfers of different sizes. In particular, we seek to achieve this using decentralized algorithms that can be implemented by end-systems without requiring the support of a complex network architecture. The algorithms we propose correspond to a form of weighted processor sharing and can be tailored to approximate the shortest remaining processing time service discipline. [ABSTRACT FROM AUTHOR]

Bluetooth enables portable electronic devices to communicate wire-lessly via short-range ad-hoc networks. Initially Bluetooth will be used as a replacement for point-to-(multi)point cables. However, in due course, there will be a need for forming multihop ad-hoc networks over Bluetooth, referred to as scatternets. This paper investigates the capacity assignment problem in Bluetooth scatternets. The problem arises primarily from the special characteristics of the network and its solution requires new protocols. We formulate it as a problem of minimizing a convex function over a polytope contained in the matching polytope. Then, we develop an optimal algorithm which is similar to the well-known flow deviation algorithm and that calls for solving a maximum-weight matching problem at each iteration. Finally, a heuristic algorithm with a relatively low complexity is developed. [ABSTRACT FROM AUTHOR]

The modeling of Internet topology is of vital importance to network researchers. Some network protocols, and particularly multicast ones, have performances that depend heavily on the network topology. That is why the topology model used for the simulation of those protocols must be as realistic as possible. In particular a protocol designed for the Internet should be tested upon Internet-like generated topologies. In this paper we provide a comparative study of three topology generators. The first two are among the latest available topology generators and the third is a generator that we have created. All of them try to generate topologies that model the measured Internet topology. We check their efficiency by comparing the produced topologies with the topology of a recently collected Internet map. [ABSTRACT FROM AUTHOR]

We address the logical topology design problem (LTD) in WDM transport networks under static traffic assumptions. We start with one of the standard MILP formulations of the LTD problem that aims at optimizing the network congestion. We propose an improvement to this model that additionally optimizes the average hop count. We then derive a new MILP model that compels the traffic to be atomically routed. This last model enables fair comparisons of solutions obtained with MILP formulations and with metaheuristic algorithms. The latter allow us to deal with large size networks whereas the former are limited by their computational complexity. In this paper Tabu Search is used to tackle the LTD problem. We compare and discuss the logical topologies computed by the various methods described in the paper. [ABSTRACT FROM AUTHOR]

Although many research efforts have been devoted to the network congestion against an increase of the Internet traffic, there has been a little concern on improvement of the performance of Internet hosts in spite of the projection that the bottleneck is now being shifted from the network to hosts. We have proposed SSBT (Scalable Socket Buffer Tuning), which is intended to improve the performance of Web servers by maintaining their resources effectively and fairly, and validated its effectiveness through the simulation and implementation experiments. In the current Internet, however, a significant amount of Web document transfer requests are through HTTP proxy servers. Accordingly, in this paper, we propose a new resource management scheme for proxy servers to improve their performance and to reduce Web document transfer time via the proxy servers. Our proposed scheme has the following two components. One is an enhanced E-ATBT, which is an enhancement version of our previous SSBT for proxy servers by taking account of different characteristics among TCP connections. The other is a scheme that manages persistent TCP connections at proxy servers to avoid newly arriving TCP connections from being rejected due to lack of resources. We validate an effectiveness of our proposed scheme through simulation experiments, and confirm that it can manage proxy server resources effectively. [ABSTRACT FROM AUTHOR]

Forward Error Correction (FEC) is an attractive solution for recovering from packet losses in real-time applications. However, in many such applications, due to delay constraints, complex FEC schemes that may enable to approach the Shannon channel capacity cannot be used. In those cases, much simpler FEC schemes are implemented, in which a compressed copy of a packet is concatenated to some subsequent packet. In this paper we analyze the utility gained by such schemes in the case where losses are due to queueing congestion in the network. Loss probabilities in presence of FEC are obtained using sophisticated tools based on Ballot theorems. Our explicit expressions allows us to study numerically several approaches for adding FEC. [ABSTRACT FROM AUTHOR]

This work proposes new power-saving strategies for mobile access to the Web. User mobility is a key factor in the evolution of Web services. Unfortunately, the legacy approach for Web access is very inefficient when applied to mobile users. One of the critical issues is the inefficient usage of energetic resources when adopting the legacy TCP/IP architecture for Web access from mobile devices. In this paper we address this problem by proposing a new architecture, namely PS- Web, which works at the transport layer and exploits some knowledge about the application behavior. PS-Web is transparent with respect to the application and independent from the sub-network technology. We implemented a prototype of PS-Web. Experimental results provided by this prototype have shown that a relevant energy savings (about 70% on average) can be achieved with respect to the legacy TCP/IP approach. Furthermore, power saving is obtained without a significant degradation in the QoS perceived by the users. Specifically, PS-Web introduces almost neglible additional delays (with respect to the legacy approach) in the downloading of a Web page. [ABSTRACT FROM AUTHOR]

Different from Immediate Request (IR) service in packet-switched networks, admission control for Advance Reservation (AR) service is more complex - the decision points include not only the start time of the new connection, but also the instants that the new connection overlaps with connections already admitted in the system. Traditional approach on advance reservation considers only a fixed scheduled period. When overtime occurs (often quite approaching the end of the originally scheduled service period) depending on network load and resource usage, the service may easily be disrupted due to insufficient resources available. Examples include the broadcasting of sports events and business video-conference calls. In this paper, we study the problem of admission control and resource management for AR service with uncertain service duration. The objective is to maximize user satisfaction in terms of service continuity and guarantee of QoS while minimizing reservation cost and call blocking probability of the AR service. An innovative two-leg admission control and bandwidth management scheme is proposed. Service continuity, user utility and reservation cost functions are proposed here to evaluate user's satisfaction and the efficiency of resource allocation. Simulation results are presented. [ABSTRACT FROM AUTHOR]

In this paper we consider some models for contention resolution in cable networks, in case the contention pertains to requests and is carried out by means of contention trees. More specifically, we study a number of variants of the standard machine repair model, that differ in the service order at the repair facility. Considered service orders are First Come First Served, Random Order of Service, and Gated Random Order of Service. For these variants, we study the sojourn time at the repair facility. In the case of the free access protocol for contention trees, the first two moments of the access delay in contention are accurately represented by those of the sojourn time at the repair facility under Random Order of Service. In the case of the blocked access protocol, Gated Random Order of Service is shown to be more appropriate. [ABSTRACT FROM AUTHOR]

This paper introduces a technique for applying packet arrival rate based queue management to class based scheduling algorithms. This enables a DiffServ architecture with very low packet latency, loss, and high link utilisation. Simulation results demonstrate that the proposed technique outperforms the current weighted random early drop (WRED) and weighted fair queue (WFQ) architecture. [ABSTRACT FROM AUTHOR]

Conventional distribution of real-time multimedia data uses multicasting or a series of relays and tunnels for unicast networks. The former is a capability not popularly enabled by a lot of networks while the static relays cannot readily adapt to changing network conditions and are potential bottlenecks in a heavily accessed system. This paper proposes a dynamic overlay framework for streaming multimedia data over heterogeneous networks. The overlay comprises a self-improving tree which is built from client relays on the fly and a lightweight server to manage the tree. The overlay provides a better QoS than conventional relays as it monitors the network and re-configures the tree to adapt to changing environments. Clients can switch parents for better QoS. The robustness of the tree is improved by using a spiral mechanism and failure of the lightweight server will not impact the data distribution functionality of the existing tree. [ABSTRACT FROM AUTHOR]

AMnet provides a framework for flexible and rapid service creation. It is based on Programmable Networking technologies and uses active nodes (AMnodes) within the network for the provision of individual, application-specific services. To this end, these AMnodes execute service modules that are loadable on-demand and enhance the functionality of intermediate systems without the need of long global standardization processes. Placing application-dedicated functionality within the network requires a flexible signaling protocol to discover and announce as well as to establish and maintain the corresponding services. AMnet Signaling was developed for this purpose and will be presented in detail within this paper. [ABSTRACT FROM AUTHOR]

A class of contention-type MAC protocols (e.g., CSMA/CA) relies on random deferment of packet transmission, and subsumes a deferment selection strategy and a scheduling policy that determines the winner of each contention cycle. This paper examines contention-type protocols in a noncooperative an ad-hoc wireless LAN setting, where a number of stations self-optimise their strategies to obtain a more-than-fair bandwidth share. Two scheduling policies, called RT/ECD and RT/ECD-1s, are evaluated via simulation It is concluded that a well-designed scheduling policy should invoke a noncooperative game whose outcome, in terms of the resulting bandwidth distribution, is fair to non-self-optimising stations. [ABSTRACT FROM AUTHOR]

This paper studies and discusses the presence of LRD in network traffic after classifying flows into traffic aggregates. Following DiffServ architecture principles, generic QoS application requirements and the transport protocol in use, a classification criterion of Internet traffic is established. Using fractal theory, the resulting traffic classes are analysed. The Hurst parameter is estimated and used as a measure of traffic burstiness and LRD in each traffic class. The traffic volume per class and per interface is also measured. The study uses real traffic traces collected at a University of Minho major backbone router in different periods of network activity. [ABSTRACT FROM AUTHOR]

This paper provides an overview of development of telecommunications in Slovenia. Major systems, networks and services are briefly considered. The combination of own generic research and critical mass of knowledge had and still has a very positive influence the on development of telecommunications in Slovenia. We propose a two-level network architecture consisting of a simplified data forwarding plane and service control plane. Future technological development and the proposed role of Slovenia as a regional telecommunications hub are presented. [ABSTRACT FROM AUTHOR]

In the 3rd generation multimedia communication world and in the 3GPP standardization consortium, SIP protocol appears to be the preferred signaling protocol. However, the need to communicate with non-SIP based network, e.g. H.323 from ITU-U, is still a reality. The need can be satisfied with the introduction of network gateways (also named Inter-Working Function). One of the open issues about SIP-H.323 interworking is the address resolution, in other words, the automatic forwarding of a SIP call to an H.323 user. The paper proposes a SIP network architecture which can interoperate with H.323 networks, safeguarding the existing software/hardware components, as SIP terminal clients or SIP server proxies or IWF gateways. [ABSTRACT FROM AUTHOR]

This paper presents a performance analysis of a fair sharing mechanism for PC-based software routers, required when the I/O bus and not the CPU is the bottleneck. The mechanism involves changes to the OS kernel and assumes the existence of certain NIC functions, but does not require any changes to the PC hardware architecture. [ABSTRACT FROM AUTHOR]