Change search
Refine search result
123 101 - 124 of 124
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 101.
    Trifunovic, Sacha
    et al.
    ETH Zurich.
    Kouyoumdjieva, Sylvia T.
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Distl, Bernhard
    ETH Zurich.
    Pajevic, Ljubica
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Plattner, Bernhard
    ETH Zurich.
    A Decade of Research in Opportunistic Networks: Challenges, Relevance, and Future Directions2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 1, p. 168-173, article id 7823357Article in journal (Refereed)
    Abstract [en]

    Opportunistic networks are envisioned to complement traditional infrastructure-based communication by allowing mobile devices to communicate directly with each other when in communication range instead of via the cellular network. Due to their design, opportunistic networks are considered to be an appropriate communication means in both urban scenarios where the cellular network is overloaded, as well as in scenarios where infrastructure is not available, such as in sparsely populated areas and during disasters. However, after a decade of research, opportunistic networks have not yet been ubiquitously deployed. In this article we explore the reasons for their absence. We take a step back, and first question whether the use cases that are traditionally conjured to motivate opportunistic networking research are still relevant. We also discuss emerging applications that leverage the presence of opportunistic connectivity. Further, we look at past and current technical issues, and we investigate how upcoming technologies would influence the opportunistic networking paradigm. Finally, we outline some future directions for researchers in the field of opportunistic networking.

  • 102.
    Velayos, Hector
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Aleo, Victor
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Load balancing in overlapping wireless LAN cells2004In: 2004 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-7, IEEE , 2004, p. 3833-3836Conference paper (Refereed)
    Abstract [en]

    We propose a load-balancing scheme for overlapping wireless LAN cells. Agents running in each access point broadcast periodically the local load level via the Ethernet backbone and determine whether the access point is overloaded, balanced or under-loaded by comparing it with received reports. The load metric is the access point throughput. Overloaded access points force the handoff of some stations to balance the load. Only under-loaded access points accept roaming stations to minimize the number of handoffs. We show via experimental evaluation that our balancing scheme increases the total wireless network throughput and decreases the cell delay.

  • 103.
    Velayos, Hector
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Autonomic networking for wireless LANs2005Report (Other academic)
    Abstract [en]

    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 removingthe need for an Ethernet backbone. APs connected to different IP networkscan join the DS to form a single WLAN for users with link-layer mobility support. Two entities, portal and registry, are added to support selfconfiguration of access points, transport across the IP backbone and link layer mobility for stations. A novel feature of our DS design is the possibility that operators share some of their access points. Our proposed extensions are transparent to the stations; they do not require any modification to work with the new architecture.

  • 104.
    Velayos, Hector
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Karlsson, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Limitations of range estimation in wireless LAN2004In: Proceedings of 1st Workshop on Positioning, Navigation and Communication, WPNC'04, 2004Chapter in book (Other academic)
  • 105.
    Velayos, Hector
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Karlsson, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Multi-rate performance index for wireless LANs2004In: 2004 IEEE 15TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, VOLS 1-4, PROCEEDINGS, NEW YORK, NY: IEEE , 2004, p. 1154-1157Conference paper (Refereed)
    Abstract [en]

    The throughput per access point has been used as the main figure of merit in performance characterization of wireless LANs. The usefulness of throughput as a performance measure is limited because low throughput can be produced by either low offered traffic or by radio conditions that limit the data rates. In this paper, we propose the Multi-rate Performance Index as an additional figure of merit to characterize the performance of wireless LAN cells. It represents which bit rates are used in the cell, and therefore it identifies cells whose throughput is limited by radio conditions rather than offered traffic. We include several measurements in real cells to illustrate its utility in performance analysis.

  • 106.
    Velayos, Hector
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Statistical analysis of the IEEE 802.11 MAC service time2005In: Performance Challenges for Efficient Next Generation Networks, 2005, p. 2257-2266Conference paper (Refereed)
    Abstract [en]

    We present a statistical analysis of the IEEE 802.11 MAC service time. Our analysis complements the results from mathematical models, which focus on the mean delay. The location analysis shows that the service time's distribution is skewed: the mean is always larger than the median, and the mode is always the smallest. A deeper analysis of the mean illustrates its dependence on the number of stations in the cell, the offered load, the packet size and the bit rate. The analysis of variability includes the coefficient of variation of the service time and its cumulative distribution function. The high variability found indicates that the 95-percentile of the service time may be a more meaningful measure than the mean. Finally, the analysis of correlation demonstrates that the service time of a packet is not predictable from the service time of previous packets.

  • 107.
    Velayos, Hector
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Techniques to reduce IEEE 802.11b handoff time2004In: 2004 IEEE International Conference on Communications, Vols 1-7, IEEE , 2004, p. 3844-3848Conference paper (Refereed)
    Abstract [en]

    We analyze the link-layer handoff process in wireless LANs based on the IEEE 802.11b standard and suggest how to reduce its duration. Firstly, we divide the process into three phases: detection, search and execution. Our performance measurements indicate that the detection and search phases are the main contributors to the handoff time. We show that the link-layer detection time can be reduced to three consecutive lost frames. We also show that the search time can be reduced at least by 20% using active scanning with the two timers that control its duration set to 1 ms and 10.24 ms. Several simulations illustrate the achieved reduction in handoff time.

  • 108.
    Velayos, Hector
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Mas, Ignacio
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Distributed admission control for WLANs2005Report (Other academic)
  • 109.
    Velayos, Héctor
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    A Distribution System for Large Scale IEEE 802.11 Wireless LANs2008In: PROCEEDINGS OF THE 2008 16TH IEEE WORKSHOP ON LOCAL AND METROPOLITAN AREA NETWORKS / [ed] Gjessing S; Dobrota V; Papasopouli M; VanDerMerwe JE, 2008, p. 7-12Conference paper (Refereed)
    Abstract [en]

    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. AN 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.

  • 110.
    Velayos, Héctor
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Más, Ignacio
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Overload Protection for IEEE 802.11 Cells2006In: 2006 14th IEEE International Workshop on Quality of Service, IWQoS 2006, 2006, p. 149-158Conference paper (Refereed)
    Abstract [en]

    This paper presents a distributed admission control for the distributed coordination function of IEEE 802.11 wireless LANs that limits the risk of congestion collapse due to a high arrival rate of flows. This control scheme requires no modification to the current distributed coordination function; it works by performing a short, non-disturbing probe that estimates the MAC service time. The flow is admitted if the estimate is below a threshold. We show how the threshold may be adjusted dynamically to maintain an average packet loss rate below a configurable limit. We show via extensive simulations that the admission control avoids congestion due to flow arrivals and that it maintains the loss probability below the given threshold regardless of the offered load or number of stations. Our simulations also analyze the main drawback of our scheme: a reduction in the link utilization. The admission control efficiently protects cells from overload and it may offer soft QoS guarantees to multimedia flows without the need for scheduling or-polling mechanisms in IEEE 802.11.

  • 111.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Helgason, Ólafur
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    An Analytical Model for Pedestrian Content Distribution in a Grid of Streets2010Report (Other academic)
    Abstract [en]

    Mobile communication devices may be used for spreading multimedia data without support of an infrastructure. Such a scheme, where the data is carried by people walking around and relayed from device to device by means of short range radio, could potentially form a public content distribution system that spans vast urban areas. The transport mechanism is the flow of people and it can be studied but not engineered. The question addressed in this paper is how well pedestrian content distribution may work. We answer this question by modeling the mobility of people moving around in a city, constrained by a given topology. The model is supplemented by simulation of similar or related scenarios for validation and extension. Our conclusion is that contents spread well with pedestrian speeds already at low arrival rates into a studied region. Our contributions are both the results on the feasibility of pedestrian content distribution and the queuing analytic model that captures the flow of people.

  • 112.
    Vukadinovic, Vladimir
    et al.
    Disney Research Zürich.
    Helgason, Ólafur
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    An analytical model for pedestrian content distribution in a grid of streets2013In: Mathematical and computer modelling, ISSN 0895-7177, E-ISSN 1872-9479, Vol. 57, no 11-12, p. 2933-2944Article in journal (Refereed)
    Abstract [en]

    Mobile communication devices may be used for spreading multimedia data without support of an infrastructure. Such a scheme, where the data is carried by people walking around and relayed from device to device by means of short range radio, could potentially form a public content distribution system that spans vast urban areas. The transport mechanism is the flow of people and it can be studied but not engineered. We study the efficiency of pedestrian content distribution by modeling the mobility of people moving around in a city, constrained by a given topology. The model is supplemented by simulation of similar or related scenarios for validation and extension. The results show that contents spread well with pedestrian speeds already at low arrival rates into a studied region. Our contributions are both the queuing analytic model that captures the flow of people and the results on the feasibility of pedestrian content distribution.

  • 113.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Multicast Scheduling with Resource Fairness Constraints2009In: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196, Vol. 15, no 5, p. 571-583Article in journal (Refereed)
    Abstract [en]

    Integration of multicast and unicast data in future radio access networks will be necessary in order to improve the resource efficiency and provide new services. Such integration requires new and efficient resource sharing mechanisms. These mechanisms need to be optimized to provide the best possible trade-off between resource efficiency and fairness. In this article, we consider a case where streaming multicast users are multiplexed together with elastic unicast users on a common time-slotted channel. We derive a system model to study the performance of various resource allocations strategies under proportional and resource fairness constraints. Fairness is directly defined in terms of the users' utilities rather than of the throughputs they are assigned to. We also describe an extension of the well-known unicast proportional fair scheduler to the multicast scenario. Through extensive simulations we demonstrate the performance of this scheduler for various traffic loads and multicast group sizes.

  • 114.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Optimal resource sharing for integration of unicast and multicast data on TDM radio channels2007In: 2007 5TH INTERNATIONAL SYMPOSIUM ON MODELING AND OPTIMIZATION IN MOBILE, AD HOC AND WIRELESS NETWORKS AND WORKSHOPS, NEW YORK: IEEE , 2007, p. 154-161Conference paper (Refereed)
    Abstract [en]

    Future integration of multicast and unicast data on time-slotted radio channels will require efficient resource sharing mechanisms. These mechanisms need to be optimized to provide the best possible performance for the users. In this paper, we consider the case where members of a video streaming multicast group share the common resources with unicast users on a HSDPA-like TDM channel. We define performance metrics and derive a system model to study the user performance for various resource allocations under fairness constraints. Our results show that the performance gains of resource-optimal multicast could be substantial and should be exploited in practical scheduling schemes.

  • 115.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Spectrum and Energy Efficiency of Mobility-Assisted Podcasting in Cellular Networks2010In: MobiOpp '10 Proceedings of the Second International Workshop on Mobile Opportunistic Networking, Association for Computing Machinery (ACM), 2010, p. 51-57Conference paper (Refereed)
    Abstract [en]

    We consider a wireless podcasting service for mobile users. That service can be provided by mobile operators in their coverage areas. Our focus is on dense urban environments. The latency and throughput requirements of the podcasting service are flexible and, therefore, podcast contents do not need to be delivered to all users via the operator’s network: they can be relayed from one user to another in a store-carry-and-forward fashion. Hence, mobility of users can be used as a supplementary transport mechanism to off-load the operator’s network and relieve strain on scarce spectrum resources. In this paper, we evaluate the achievable throughputs and spectrum savings of the mobility-assisted wireless podcasting for various mobility patterns and user densities in an area. We also estimate the energy consumption of the mobility-assisted podcasting for the case when Bluetooth radios are used for peer-to-peer communication.

  • 116.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Trade-offs in bit-rate allocation for wireless video streaming2006In: ACM MSWiM 2005: Proceedings of the Eighth ACM Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems, 2006, Vol. 2006, p. 349-353Conference paper (Refereed)
    Abstract [en]

    One of the central problems in video transmission over lossy channels is the choice of source and channel coding rates to allocate the available transmission rate optimally. In this paper, we present a structural distortion model for video streaming over time-varying fading channels. Based on this model we study the average video distortion for various bit-rate allocation strategies and channel conditions. We argue that sensitivity to channel variations should be one of the selection criteria when choosing an optimal bit-rate allocation. We demonstrate that a simple bitrate allocation strategy, which aims to minimize current distortion, is not necessarily optimal in terms of time-average distortion. System robustness is crucial for the streaming performance when frequent allocation updates are not feasible. It is achieved at the expense of higher source distortion in the encoder.

  • 117.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Trade-Offs in Bit-Rate Allocation for Wireless Video Streaming2009In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 11, no 6, p. 1105-1113Article in journal (Refereed)
    Abstract [en]

    One of the central problems in wireless video transmission is the choice of source and channel coding rates to allocate the available transmission rate optimally. In this paper, we present a structural distortion model for video streaming over time-varying fading channels. Based on the model, we study the end-to-end distortion for various bit-rate allocation strategies and channel conditions. We show that the robustness to channel variations is crucial for the streaming performance when frequent bit-rate adaptations are not feasible. It is achieved at the expense of higher source distortion in the encoder. Our findings are illustrated on a practical problem of distortion-optimal selection of transport formats in an adaptive modulation and coding (AMC) scheme used in HSDPA.

  • 118.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Video Streaming in 3.5G: On Throughput-Delay Performance of Proportional Fair Scheduling2006In: 14th IEEE International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems, 2006. MASCOTS 2006, IEEE Computer Society, 2006, p. 393-400Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the performance of the proportional fair scheduler, which has been proposed for the emerging 3.5G radio access systems. It maximizes the spectral efficiency of the systems, which is a strong incentive for network providers to use it. Our goal is to investigate whether the proportional fair scheduler also provides benefits to the streaming users. Focus is on the throughput-delay trade-offs associated with video streaming over HSDPA. Special attention is devoted to defining appropriate performance measures and creating a realistic simulation environment. Our results indicate that the opportunistic scheduling faces major difficulties in providing the user-level performance in cases where streaming flows constitute a significant share of the traffic load.

  • 119.
    Vukadinovic, Vladimir
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Video Streaming Performance under Proportional Fair Scheduling2010In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 28, no 3, p. 399-408Article in journal (Refereed)
    Abstract [en]

    In this paper, we study the performance of the proportional fair scheduler, which has been proposed for some of the emerging radio access systems. It maximizes the spectral efficiency of the systems, which is a strong incentive for network providers to use it. Our goal is to investigate how the proportional fair scheduling affects the performance of streaming users. Focus is on the throughput-delay trade-offs associated with proportional fair scheduling in CDMA/HDR systems. Special attention is devoted to defining appropriate performance measures and creating a realistic simulation environment. Our results indicate that the opportunistic scheduling may face difficulties in providing the user-level performance in cases where streaming flows constitute a significant share of the traffic load.

  • 120.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Mitigating Denial of Service Attacks using Anonymity Networks: Relationship Anonymity-Communication Overhead Trade-offManuscript (preprint) (Other academic)
    Abstract [en]

    Denial-of-service attacks are a significant threat to mission critical communication infrastructures, e.g., to industrial control systems. They are relatively easy to perpetrate, as an attacker that has access to communication links or equipment could observe the source and destination addresses for every message, and can identify and discard the messages exchanged between particular communication participants. Mix networks and anonymity networks could render these attacks more difficult by providing anonymous communication via relaying. Nevertheless, relaying introduces overhead and increases the end-to-end message delivery delay, which in practice must often be low. Hence, an important question is how to optimize anonymity for limited overhead and delay. In this paper we address this question by studying two anonymity networks: MCrowds, an extension of Crowds, which provides unbounded communication delay and Minstrels, which provides bounded communication delay. We derive exact and approximate analytical expressions for the relationship anonymity for these systems. Using MCrowds and Minstrels we show that, contrary to intuition, increased overhead does not always improve anonymity. We investigate the impact of the system's parameters on anonymity and on the optimal anonymity network parameters, and the sensitivity of anonymity to the misestimation of the number of attackers.

  • 121.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Mitigating Gray Hole Attacks in Industrial Communications using Anonymity Networks: Relationship Anonymity-Communication Overhead Trade-offManuscript (preprint) (Other academic)
    Abstract [en]

    Gray hole attacks are a significant threat to mission critical communication infrastructures, such as industrial control systems. They are relatively easy to perpetrate, as an attacker that has access to communication links or equipment could observe the source and destination addresses for every message, and can identify and discard the messages exchanged between particular communication participants. Anonymity networks could render these attacks more difficult by providing anonymous communication via relaying. Nevertheless, relaying introduces overhead as it increases end-to-end message delivery delay and introduces additional traffic, which both in practice must often be low. Hence, an important question is how to optimize anonymity for limited overhead. In this paper we address this question by studying two anonymity networks: MCrowds, an extension of Crowds, which provides unbounded communication delay and Minstrels, which provides bounded communication delay. We derive exact analytical expressions for the relationship anonymity for these systems. Using MCrowds and Minstrels we show that, contrary to intuition, increased overhead does not always improve anonymity. We investigate the impact of the system’s parameters on anonymity and on the optimal anonymity network parameters, and the sensitivity of anonymity to the misestimation of the number of attackers.

  • 122.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    On the Trade-off between Relationship Anonymity and Communication Overhead in Anonymity Networks2011In: IEEE International Conference on Communications, 2011Conference paper (Refereed)
    Abstract [en]

    Motivated by protection and privacy in industrial communication networks, in this paper we consider the trade-off between relationship anonymity and communication overhead. We consider two anonymity networks: Crowds, which has unbounded communication delay and Minstrels, proposed in this paper, which provides bounded communication delay. While Crowds hides the sender's identity only, Minstrels aims at hiding the receiver's identity as well. However, to achieve bounded communication delay it has to expose the sender's identity to a greater extent than Crowds. We derive exact and approximate analytical expressions for the relationship anonymity for these systems. While Minstrels achieves close to optimal anonymity under certain conditions, our results show that, contrary to expectations, increased overhead does not always improve anonymity.

  • 123.
    Vuković, Ognjen
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Traffic Analysis Attacks in Anonymity Networks: Relationship Anonymity-Overhead Trade-off2013Report (Other academic)
    Abstract [en]

    Mix networks and anonymity networks provide anonymous communication via relaying, which introduces overhead and increases the end-to-end message delivery delay. In practice overhead and delay must often be low, hence it is important to understand how to optimize anonymity for limited overhead and delay. In this work we address this question under passive traffic analysis attacks, whose goal is to learn the traffic matrix. For our study, we use two anonymity networks: MCrowds, an extension of Crowds, which provides unbounded communication delay and Minstrels, which provides bounded communication delay. We derive exact and approximate analytical expressions for the relationship anonymity for these systems. Using MCrowds and Minstrels we show that, contrary to intuition, increased overhead does not always improve anonymity. We investigate the impact of the system's parameters on anonymity, and the sensitivity anonymity to the misestimation of the number of attackers.

  • 124.
    Yavuz, Emre A.
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Karlsson, Gunnar
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Poster: Collective Mobile Sensing for Wireless Network Performance Monitoring2011In: Proc. ACM Annual International Conference on Mobile Systems, Applications and Services, 2011, p. 411-Conference paper (Refereed)
    Abstract [en]

    Rapid growth of mobile wireless industry has generated numerous challenges for service operators. The provisioning of increasing demand in capacity and higher quality of service can be met with redimensioning of networks which makes a priori network planning difficult. We propose a network performance monitoring system to which all mobile devices contribute by voluntarily submitting periodical reports on the availability and quality of network access that they experience at their current geographical locations. Network performance measures such as signal strength, coverage, call block/drop statistics and operator service capabilities are reported to a server with a network status information database as experienced by mobile devices. The proposed database will indicate areas with lack of coverage, insufficient capacity, and high interference, which may serve as cues for operators to upgrade/retune their infrastructure equipment and for regulators to take action against operators that do not fulfill commitments made to their subscribers.

123 101 - 124 of 124
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf