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Local and Metropolitan Area Networks, 2008. LANMAN 2008. 16th IEEE Workshop on

Date 3-6 Sept. 2008

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Displaying Results 1 - 25 of 27
  • [Title page]

    Publication Year: 2008 , Page(s): i
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    Freely Available from IEEE
  • [Copyright notice]

    Publication Year: 2008 , Page(s): ii
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 2008 , Page(s): iii - v
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    Freely Available from IEEE
  • 2008 16th IEEE workshop on local and metropolitan area networks Referees

    Publication Year: 2008 , Page(s): vii
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    Freely Available from IEEE
  • Welcome!

    Publication Year: 2008 , Page(s): viii
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    Freely Available from IEEE
  • LANMAN 2008 Committees

    Publication Year: 2008 , Page(s): vi
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    Freely Available from IEEE
  • Greetings from the technical program committee chairs

    Publication Year: 2008 , Page(s): ix
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    Freely Available from IEEE
  • Deployment guidelines for highly congested IEEE 802.11b/g networks

    Publication Year: 2008 , Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB) |  | HTML iconHTML  

    Over the years, IEEE 802.11b/g wireless networks have been deployed in various locations such as hotels, airports and enterprises. Although IEEE 802.11b/g can be considered a mature technology, its deployment still presents challenges due to the limited number of non-overlapping channels available. This is particularly true in scenarios with a high density of users where a large number of APs covering roughly the same area is required. Through measurements we investigate different deployment scenarios, trying to provide a set of guidelines for the deployment of IEEE 802.11b/g networks so to minimize co-channel interference and maximize throughput. This, when the number of APs required to cover an area is larger than the number of non-overlapping channels available. In particular, we show how using partially overlapping channels causes lower retry rate and higher throughput than if deploying multiple APs on each of the non-overlapping channels. View full abstract»

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  • A distribution system for large scale IEEE 802.11 Wireless LANs

    Publication Year: 2008 , Page(s): 7 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (243 KB) |  | HTML iconHTML  

    We present extensions to the IEEE 802.11 WLAN architecture to facilitate the deployment and operation of large-scale networks. A new distribution system (DS) is designed to work across IP networks removing the need for an Ethernet backbone. APs connected to different IP networks can join the DS to form a single WLAN, with link-layer mobility support for users. Two entities, portal and registry, are added to support self-configuration of access points, transport across the IP backbone and link layer mobility for stations. These extensions are transparent to the stations; they do not require any modification to work with the new architecture. Our DS design allows operators to share access points. View full abstract»

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  • Practical evaluation of H.264 video streaming over IEEE 802.11e devices by cross-layer signaling

    Publication Year: 2008 , Page(s): 13 - 18
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (299 KB) |  | HTML iconHTML  

    Recent years have seen a growing demand for high quality multimedia traffic over wireless links. Due to the strong demands imposed to all the involved actors, several optimization techniques have been proposed and studied, mostly through theoretical analysis and simulation. In this article we focus on the practical evaluation of H.264 video streaming performance over IEEE 802.11e wireless devices. Measurement results present the effects of employing several key mechanisms which aim to improve the transmission quality over the wireless medium. A cross-layer signaling solution between the application and the MAC layers is implemented, in order to account for the different QoS characteristics of video and elastic traffic. In addition, network support for efficient multiqueue transmission is enabled in the Linux wireless card driver. Measurements also illustrate the effects of changing several H.264 and IEEE 802.11e parameters in the player and driver software. View full abstract»

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  • Measurement-based analysis of the performance of several wireless technologies

    Publication Year: 2008 , Page(s): 19 - 24
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (735 KB) |  | HTML iconHTML  

    Wireless technologies have rapidly evolved and are becoming ubiquitous. An increasing number of users attach to the Internet using these technologies; hence the performance of these wireless access links is a key point when considering the performance of the whole Internet. In this paper we present a measurement-based analysis of the performance of an IEEE 802.16 (WiMAX) client and an UMTS client. The measurements were carried out in a controlled laboratory. The wireless access links were loaded with traffic from a multi-point videoconferencing application and we measured three layer-3 metrics (one-way-delay, IP-delay-variation and packet loss ratio). Additionally we estimate the performance of a WiFi and Ethernet client as a reference. Our results show that Ethernet and WiFi have comparable performances. Both the WiMAX and the UMTS links exhibited an asymmetric behavior, with the uplink showing an inferior performance. We also assessed the causes of the discretization which appears in the jitter distributions of these links. View full abstract»

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  • New prioritization schemes for QoS provisioning in 802.11 wireless networks

    Publication Year: 2008 , Page(s): 25 - 30
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    Due to the unreliable nature of the wireless medium, provisioning of quality of service (QoS) in wireless LANs is far more complicated than in wired networks. In order to address this challenge, IEEE 802.11e defines a framework for QoS support where packets are prioritized based on their traffic characteristics. In this paper, we propose two new QoS support schemes. One is based on a ldquouser centricrdquo approach and the other on a ldquopacket content basedrdquo approach. The new mechanisms, in addition to the traffic itself, take into consideration the identification of the station that generates the traffic or the content of the traffic. Therefore, they use a second prioritization level on top of the one that is implemented in IEEE 802.11e. In the ldquouser centricrdquo approach, the mechanism defines groups of stations based on their MAC addresses and assigns different priorities to different groups. Under this classification, stations are served based on the prioritization of the group they belong. Among stations with same priority, traffic is scheduled based on the priorities given by 802.11e. On the other hand, in the case of the ldquopacket content basedrdquo approach, the mechanism defines groups of words or phrases with their respective priority. A packet that includes words of a specific group is scheduled based on the priority that the particular content defines. The new schemes are simple yet efficient, since they are adapted to the realistic needs of todaypsilas WiFi networks. In order to evaluate the performance of these proposed schemes, we implement them using open source drivers in a Linux platform. We run experiments in a medium-size testbed. Experimentation results clearly demonstrate the performance superiority of the new schemes, as compared to the legacy IEEE 802.11e. View full abstract»

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  • Collaborative setting of RTS/CTS in multi-rate multi-BSS IEEE 802.11 wireless LANs

    Publication Year: 2008 , Page(s): 31 - 36
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (177 KB) |  | HTML iconHTML  

    Despite the fact that the Request-To-Send/Clear-To-Send (RTS/CTS) protocol significantly reduces collisions and retransmissions due to the hidden node problem, it is well known that it adds considerable overhead specially with small payload packets. The IEEE 802.11 standard defined a manageable parameter, RTS threshold, above which a data packet should be preceded with RTS/CTS handshake. In this paper, we propose new dynamic criteria for setting the RTS/CTS mechanism. We believe that RTS/CTS settings should consider the characteristics of userspsila traffic, data rates, activities and locations. While most of the algorithms proposed for controlling RTS/CTS have been investigated under single transmission rate for all users, we evaluate our criteria in a multi-rate scenario. We validate our ideas using both synthetic and real traces as well as real experiments. View full abstract»

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  • Optimizing the channel load reporting process in IEEE 802.11k-enabled WLANs

    Publication Year: 2008 , Page(s): 37 - 42
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB) |  | HTML iconHTML  

    IEEE 802.11 k is an extension of the IEEE 802.11 specification for radio resource measurements. In an IEEE 802.11 k-enabled wireless LAN, an access point or other network element may request from a client or another access point to monitor and report the load of a channel. We call the latter a channel monitoring station. In this paper we propose a mechanism for a channel monitoring station to efficiently derive accurate values of channel load.We especially focus on optimizing the duration of channel monitoring and thus minimize the impact on applications. Note that such mechanisms are critical for the success of new sharing regimes such as cognitive radio and open spectrum access. View full abstract»

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  • Network planning for disaster recovery

    Publication Year: 2008 , Page(s): 43 - 48
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (245 KB) |  | HTML iconHTML  

    Disaster recovery and business continuity issues are becoming fundamental in networks since the importance and social value of digital data is continuously increasing. On the one hand, there is an obvious need of backing up data for resilience against major failures; in many situations the process of storing backup data is also enforced by the law. On the other hand, providing services that allow the migration of applications in real-time through virtualization techniques is becoming a mandatory feature in several business situations. In this paper we analyze the problems and the challenges of off-site data replication and virtual machine migration. In particular, we discuss the issue of optimizing network planning to support disaster recovery and business continuity. ILP (Integer Linear Programming) formulations for the optimization problem are presented with different objective functions. Heuristics are also proposed and analyzed taking into account both network cost minimization and fault recovery efficiency. View full abstract»

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  • Cross-layer failure restoration techniques for a robust IPTV service

    Publication Year: 2008 , Page(s): 49 - 54
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    Broadcast TV distribution over an IP network requires stringent QoS constraints, such as low latency and loss. The main challenge to achieving these QoS objectives is how to design the network to respond to network failures. Streaming content in IPTV is typically delivered to the distribution points on the IP backbone using IP multicast, and in the case being considered, with protocol independent multicast source specific mode (PIM-SSM). A proven failure restoration technique at the IP layer is link-restoration using MPLS or layer-2 fast reroute (FRR). Link-based FRR creates a pseudo-wire or tunnel in parallel to the IP adjacencies (links) along the forwarding path used by the PIM tree. For each such tunnel both a primary and backup path are defined. The backup path is Layer-1-disjoint from the physical link and when the link fails, the pseudo-wire can be rapidly restored. Thus, single link failures are transparent to the interior gateway protocol (IGP). Although one may choose the back-up pathpsilas IGP link weights to avoid traffic overlap during any single link failure, multiple failures may still cause traffic overlap with FRR. We present a cross-layer restoration approach that combines both FRR-based restoration for single link failure and ldquohitlessrdquo (i.e., without loss) PIM tree reconfiguration algorithms to prevent traffic overlap when multiple failures occur. View full abstract»

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  • Distributed sampling for on-line SLA assessment

    Publication Year: 2008 , Page(s): 55 - 60
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB) |  | HTML iconHTML  

    New business infrastructures over the Internet pose a new set of traffic constraints. In particular, multimedia and interactive contents require guarantees of bandwidth and delivery time. The broad deployment and real-time nature of this class of applications require the provisioning of specific resources in the network to guarantee a certain level of quality of service (QoS). QoS techniques need ways of obtaining feedback about the status of the QoS enabled paths, for example, for checking the fulfilment of service level agreements (SLA). A possible technique for obtaining such feedback is by passively monitoring the network traffic. The issue with traffic monitoring is the additional bandwidth needed by the control traffic generated by the different collection points in order to synchronise its acquired QoS metrics. Moreover, passive monitoring at line speed is an expensive process both in terms of resource consumption and price. However, some of these requirements can be significantly reduced by using traffic sampling. This paper presents a novel methodology for intra-domain on-line distributed QoS monitoring, which makes an efficient use of the network resources by employing distributed sampling mechanisms. The proposal is validated by performing real tests on an European-wide testbed. Our results show that the sampling technique can significantly reduce the traffic overhead, while obtaining very accurate estimations of the One Way Delay performance metric. View full abstract»

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  • Maximizing packet loss monitoring accuracy for reliable trace collections

    Publication Year: 2008 , Page(s): 61 - 66
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (263 KB) |  | HTML iconHTML  

    Network traces are a valuable source of information for modeling and analysis of network behavior and for the evaluation of network protocols. These crucial activities should be supported with reliable traffic traces. Reliable packet capturing facilities should be devoted to avoid losing packets and at the very last, report when packets have been lost with the highest accuracy possible. This paper describes a methodological approach to maximize the accuracy in the packet loss monitoring. The approach lies on the monitoring of appropriate statistical indicators directly from Ethernet hardware. These indicators become the enablers for the collection of metadata traces in parallel with the standard trace collections. The resulting meta-traces are proposed as a mechanism to monitor packet loss accuracy at the packet level as they provide the means to identify the exact location and amount of the packet loss in the collected traces files. We describe an evaluation use case of our approach with commodity hard- and software. The conclusion drawn from our experimental set up configuration is that it is possible to maximize the accuracy of the packet loss monitoring for reliable trace collections at affordable costs. View full abstract»

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  • Enabling Seamless Internet Mobility

    Publication Year: 2008 , Page(s): 67 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (171 KB) |  | HTML iconHTML  

    Mobility is a requirement not appropriately addressed by the original design of the Internet since an IP address has two fundamentally different tasks. It specifies a network location (for routing) and serves as an application identifier. A plethora of suggestions have been made to overcome this, e.g., Mobile IP and HIP. Yet, each of the proposed solutions has drawbacks such as requiring fundamental changes to the Internet architecture or relying on triangular routing. We propose the Seamless Internet Mobility System (SIMS) for enabling seamless IP network layer mobility. Our goals are (1) to enable mobility even for users that do not have a permanent IP address and therefore cannot rely on a Mobile IP home agent; (2) to impose no overhead for applications initiating network traffic in the current network; (3) to preserve sessions that started in any previously visited network location; (4) to be robust, scalable, and easily deployable in the current Internet; (5) address the economics of roaming between different administrative domains. The key ideas are to allow any new connection to use the current IP address and to take advantage of the heavy-tailed nature of connections. This implies that after a network change only a small number of connections need to be retained. View full abstract»

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  • Explorative analysis of one-way delays in a mobile 3G network

    Publication Year: 2008 , Page(s): 73 - 78
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    In this paper we investigate the dynamics of one-way delays in an operational mobile core network. Our final goal is to develop anomaly detection schemes for the packet delay process in order to reveal network and equipment problems. This requires a preliminary exploration of the delay distribution in the core network, which we undertake in this study. We present one-way delay measurements extracted from passive traces captured at an operational General Packet Radio System (GPRS)/Universal Mobile Telecommunications System (UMTS) network. We find that queuing is the only source of delay at Gateway GPRS Support Nodes (GGSN), while for Serving GPRS Support Nodes (SGSN) the mobility and flow-control further complicate the characterization of the ldquonormalrdquo delay behavior. Moreover, the presence of unwanted traffic has an impact on the delay statistics and should be taken into account. We find that information about actual bandwidth conditions in the Radio Network may be inferred by investigating packet delays in the core network. Our explorative results are promising about the possibility of leveraging one-way delay measurement for troubleshooting in such networks. View full abstract»

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  • Evaluation of dynamic bandwidth allocation algorithms for G-PON systems using a reconfigurable hardware testbed

    Publication Year: 2008 , Page(s): 79 - 84
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (365 KB) |  | HTML iconHTML  

    The capabilities of passive optical networks (PONs) are strongly influenced by the quality of the used dynamic bandwidth allocation (DBA) algorithm. DBA algorithms control the assignment of available upstream bandwidth to the users connected to the PON. In an oversubscribed environment, that poses a challenge regarding the selection of an appropriate DBA algorithm. Therefore, DBA algorithms are subject of continuous research. To support efficient development and realistic evaluation of DBA algorithms, an FPGA-based hardware evaluation platform is presented. It supports fast implementation and evaluation of both hardware- and software-based algorithms. The evaluation process is featured by software tools, which are used to control stimulus creation. Furthermore, the results of changes in simulated user traffic can be analyzed on a connected workstation. View full abstract»

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  • Rethinking the timescales at which congestion-control operates

    Publication Year: 2008 , Page(s): 85 - 90
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    The efficiency of TCP congestion-control in achieving high throughput is quite poor in high-speed, lossy, and dynamic-bandwidth environments. The main culprit is the slow bandwidth-search process used by TCP, which may take up to several thousands of round-trip times (RTTs) in searching for and acquiring the end-to-end spare bandwidth. While several alternate protocols have been proposed to speed up the search process, these still take hundreds of RTTs for doing so. In this paper, we argue that the sluggishness of existing protocols stems from two limiting design decisions that help a transfer remain non-intrusive to competing transfers. We argue that these legacy design decisions can be done away with if we limit the impact of probing for spare bandwidth. We use this idea to design a new approach for congestion-control that allows TCP connections to boldly search for, and adapt to, the available bandwidth within a single RTT. Our approach relies on carefully orchestrated packet sending times and estimates the available bandwidth based on the delays experienced by these. We instantiate our new protocol, referred to as RAPID, using mechanisms that promote efficiency as well as queue-friendliness. Our experimental evaluations indicate that RAPID: (i) converges to an updated value of bandwidth within 1-2 RTTs; (ii) helps maintain fairly small queues even in high-speed networks; and (iii) has negligible impact on regular TCP traffic. The benefits of our approach are especially significant on lossy links and those with rapidly-changing bandwidth. View full abstract»

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  • Analyzing channel assignment with rearrangement in multi-channel wireless line networks

    Publication Year: 2008 , Page(s): 91 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (403 KB) |  | HTML iconHTML  

    In this paper, we analyze the blocking performance of a channel assignment scheme in a multi-channel wireless line network. We assume that the existing calls in the network may be rearranged on different channels to accommodate an incoming call. The analysis is limited to single-hop calls with different transmission ranges. Through extensive simulations, we demonstrate that the developed analytical model closely approximates the values obtained through simulations. View full abstract»

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  • Implementation of a cooperative MAC protocol using a software defined radio platform

    Publication Year: 2008 , Page(s): 96 - 101
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    Cooperation in wireless networks has shown significant performance gains in comparison to legacy wireless networks. Cooperative wireless protocols achieve such efficiency by enabling cooperation among nodes to exploit spatial diversity. CoopMAC is a medium access control (MAC) protocol that enables cooperation by using an intermediate node as a helper to a direct communication under poor channel conditions. The helper is typically located in a position where it experiences a good channel with both the source and destination. Therefore, it increases the efficiency of the communication by forwarding a packet from the source to the destination using high transmission rates. In an earlier attempt, we demonstrated the benefits of cooperation at the MAC layer by implementing the CoopMAC protocol using an open source wireless driver platform. However, due to some limitations posed by the hardware, the full potential of the protocol could not be explored. In this paper, we proceed with a complete implementation of the cooperative MAC protocol using an OFDM based software defined radio (SDR) platform. We investigate the benefits of the SDR approach, describe the details of the implementation, as well as the experiments we run in order to evaluate the protocol. Experimental results show that CoopMAC can easily be implemented and can lead to a significant improvement in the performance of wireless networks. View full abstract»

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  • Address and traffic dynamics in a large enterprise network

    Publication Year: 2008 , Page(s): 102 - 107
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3421 KB) |  | HTML iconHTML  

    Despite the centrally-managed nature of and critical infrastructure provided by enterprise networks, analyses of their characteristics have been limited. In this paper we examine the dynamics of enterprise networks from two distinct perspectives, namely traffic and addressing. Using a large packet trace spanning approximately 3.5 weeks coupled with diverse other data sources, we pose and answer a series of questions pertinent to understanding the aforementioned aspects of todaypsilas enterprise networks. Our analysis results reveal characteristics regarding the geographical spread of traffic observed at a site in the enterprise network, the validity of the client-server model and mobility patterns within the Enterprise. Finally, we discuss the implications of our findings for tasks such as network management and dimensioning. View full abstract»

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