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Dely, Peter
Publications (10 of 37) Show all publications
Dely, P., D’Andreagiovanni, F. & Kassler, A. (2015). Fair Optimization of Mesh-Connected WLAN Hotspots. Wireless Communications & Mobile Computing, 15(5), 924-946
Open this publication in new window or tab >>Fair Optimization of Mesh-Connected WLAN Hotspots
2015 (English)In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, Vol. 15, no 5, p. 924-946Article in journal (Refereed) Published
Abstract [en]

In Wireless mesh networks mesh access points (MAPs) forward traffic wirelessly towards users or Internet gateways. A user device usually connects to the MAP with the strongest signal, as such MAP should guarantee the best quality of service. However, this connection policy may lead to: (i) unfairness towards users that are distant from gateways; (ii) uneven distribution of users to MAPs; and (iii) inefficient use of network paths. We present a new model and solution approach to the problem of assigning users to MAPs and routing the data within the mesh network with the objective of providing max–min fair throughput. The problem is formulated as a mixed-integer linear programming problem (MILP). Because of the inherent complexity of the problem, real size instances cannot be solved to optimality within the time limits for online optimization. Therefore, we propose an original heuristic solution algorithm for the resulting MILP. Both numerical comparisons and network simulations demonstrate the effectiveness of the proposed heuristic. For random networks, the heuristic achieves 98% of the optimal solution. Network simulations show that in medium-sized networks, the number of users with at least 1Mbit/s minimum end-to-end rate increases by 550% when compared with the classical signal-strength based association.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keywords
wireless mesh networks, fairness, flow optimization
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-33203 (URN)10.1002/wcm.2393 (DOI)000351300900010 ()
Available from: 2014-07-07 Created: 2014-07-07 Last updated: 2018-01-11Bibliographically approved
Dely, P., Kassler, A., Chow, L., Bambos, N., Bayer, N., Einsiedler, H. & Peylo, C. (2014). BEST-AP: Non-intrusive estimation of available bandwidth and its application for dynamic access point selection. Computer Communications, 39, 78-91
Open this publication in new window or tab >>BEST-AP: Non-intrusive estimation of available bandwidth and its application for dynamic access point selection
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2014 (English)In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 39, p. 78-91Article in journal (Refereed) Published
Abstract [en]

The coverage area of Access Points CAPS) in Wireless Local Area Networks (WLANs) often overlaps considerably. Hence, a station can potentially associate with many APs. In traditional IEEE 802.11 systems, the station associates to the AP with the strongest signal. This strategy may result in load imbalance between APs and thus low overall network throughput. This paper proposes a new mechanism for selecting the "best" AP based on a novel available bandwidth estimation scheme. The available bandwidth provided by an AP depends mainly on the signal quality and the load on the wireless channel. Based on measurements we first analyze how those factors vary stochastically over time and motivate why a frequent estimation of available bandwidth is necessary. We then develop BEST-AP, a system for Bandwidth ESTimation of Access Points, which uses regular data traffic to estimate the available bandwidth from all APs in reach in a non-intrusive way, even if they are on a different channel. Based on OpenFlow, BEST-AP allows the station to be associated with multiple APs simultaneously and to switch between APs with low overhead. Using the available bandwidth estimates, the system exploits the "best" AP for longer duration while probing the less good APs for shorter durations to update the bandwidth estimations. The evaluation in a WLAN testbed shows that with background load created from real WLAN traces, the dynamic selection of APs improves the throughput of a station by around 81%, compared to a static selection. When the station is mobile, the throughput increases by 176% on average.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
WLAN, Handover, Mobility, Bandwidth estimation, Software defined networking
National Category
Computer and Information Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-41552 (URN)10.1016/j.comcom.2013.11.006 (DOI)000331504400009 ()
Available from: 2016-04-25 Created: 2016-04-11 Last updated: 2018-01-10Bibliographically approved
Dely, P., Kassler, A., Chow, L., Bambos, N., Bayer, N., Einsiedler, H., . . . Sanchez, M. (2013). A software-defined networking approach for handover management with real-time video in WLANs. Journal of Modern Transportation, 21(1), 58-65
Open this publication in new window or tab >>A software-defined networking approach for handover management with real-time video in WLANs
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2013 (English)In: Journal of Modern Transportation, ISSN 2095-087X, E-ISSN 2196-0577, Vol. 21, no 1, p. 58-65Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Springer, 2013
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-33201 (URN)10.1007/s40534-013-0007-x (DOI)
Available from: 2014-07-07 Created: 2014-07-07 Last updated: 2018-01-11Bibliographically approved
Chow, L., Collins, B., Bambos, N., Dely, P., Kassler, A., Peylo, C., . . . Bayer, N. (2013). Channel Aware Rebuffering for Wireless Media Streaming with Handoff Control. In: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM): . Paper presented at IEEE Global Communications Conference (GLOBECOM), DEC 09-13, 2013, Atlanta, GA (pp. 4434-4439). IEEE Press
Open this publication in new window or tab >>Channel Aware Rebuffering for Wireless Media Streaming with Handoff Control
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2013 (English)In: 2013 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE Press, 2013, p. 4434-4439Conference paper, Published paper (Refereed)
Abstract [en]

Packet/frame 'rebuffering' in wireless video streaming typically considers only connectivity from the mobile terminal to its network access point (AP). However, in the presence of multiple APs with the possibility of handoffs, the overall wireless environment should be considered. We develop a model capturing joint rebuffering & handoff dynamics in wireless video streaming, and design a new channel-aware joint rebuffering & handoff control scheme, aiming to minimize the long-run average cost of video jitters and freezes. We first characterize the optimal control in the general case of multiple wireless APs/channels and multiple states per channel. Subsequently, we evaluate the system performance in key important cases, using experimental traces of wireless channel data. We explore the relationship between optimal rebuffering thresholds and overall channel dynamics, and evaluate the associated joint handoff control. The performance results demonstrate the importance of jointly managing rebuffering and handoff controls to achieve high-performance wireless video streaming.

Place, publisher, year, edition, pages
IEEE Press, 2013
Series
IEEE Global Telecommunications Conference (Globecom), ISSN 1930-529X
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-38681 (URN)000357299604089 ()978-1-4799-1353-4 (ISBN)
Conference
IEEE Global Communications Conference (GLOBECOM), DEC 09-13, 2013, Atlanta, GA
Available from: 2015-11-23 Created: 2015-11-23 Last updated: 2018-01-10Bibliographically approved
Dely, P., Vestin, J. & Kassler, A. (2013). CloudMAC - Using OpenFlow to Process 802.11 MAC Frames in the Cloud. PIK - Praxis der Informationsverarbeitung und Kommunikation, 36(1), 53
Open this publication in new window or tab >>CloudMAC - Using OpenFlow to Process 802.11 MAC Frames in the Cloud
2013 (English)In: PIK - Praxis der Informationsverarbeitung und Kommunikation, ISSN 0930-5157, Vol. 36, no 1, p. 53-Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Walter de Gruyter, 2013
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-33220 (URN)10.1515/pik-2012-0068 (DOI)
Available from: 2014-07-08 Created: 2014-07-08 Last updated: 2018-01-11Bibliographically approved
Zola, E., Barcelo-Arroyo, F., Dely, P. & Kassler, A. (2013). Expected Bit Rate for Terminals Moving According to the Random Waypoint Model in a WLAN Cell. In: : . Paper presented at IEEE: Wireless and Mobile Networking Conference (WMNC)23-25 april Dubai United Arab Emirates. IEEE conference proceedings
Open this publication in new window or tab >>Expected Bit Rate for Terminals Moving According to the Random Waypoint Model in a WLAN Cell
2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The IEEE 802.11 standard defines the different bit rates and modulation schemes to which a WLAN device may adapt according to the channel quality. User mobility may also have an impact on the available bit rate. This paper presents a study of the bit rate evolution along time for devices that move according to the Random Waypoint mobility pattern in WLAN cells. Simulation has been applied in order to obtain statistical results that permit to characterize the evolution of the bit rate behavior along time and to compute average results in the ideal case (without interference) and in the presence of interfering devices. Our results can be useful in the solution of optimization problems in which decision on where to connect must be taken based on some minimum guaranteed bit rate. They also can be useful in the design of inter and intra-cell handover methods and load balancing schemes.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2013
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-33219 (URN)10.1109/WMNC.2013.6549015 (DOI)978-1-4673-5615-2 (ISBN)978-1-4673-5614-5 (ISBN)
Conference
IEEE: Wireless and Mobile Networking Conference (WMNC)23-25 april Dubai United Arab Emirates
Available from: 2014-07-08 Created: 2014-07-08 Last updated: 2018-01-11Bibliographically approved
Zola, E., Dely, P., Kassler, A. & Barcelo-Arroyo, F. (2013). Robust Association for Multi-radio Devices under Coverage of Multiple Networks. In: : . Paper presented at International Conference on Wired/Wireless Internet Communications - WWIC, June 5-7 St Petersburg, Russia. Springer Berlin/Heidelberg
Open this publication in new window or tab >>Robust Association for Multi-radio Devices under Coverage of Multiple Networks
2013 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2013
Series
Lecture Notes in Computer Science, ISSN 0302-9743
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-33218 (URN)10.1007/978-3-642-38401-1_6 (DOI)978-3-642-38400-4 (ISBN)
Conference
International Conference on Wired/Wireless Internet Communications - WWIC, June 5-7 St Petersburg, Russia
Available from: 2014-07-08 Created: 2014-07-08 Last updated: 2018-01-11Bibliographically approved
Dely, P., Kassler, A., Einsiedler, H., Bayer, N. & Peylo, C. (2013). Software Defined Networking for the Management and Operation of WLANs. Deutsche Telekom, 2
Open this publication in new window or tab >>Software Defined Networking for the Management and Operation of WLANs
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2013 (English)Other (Other (popular science, discussion, etc.))
Place, publisher, year, pages
Deutsche Telekom, 2013
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-26784 (URN)
Available from: 2013-03-28 Created: 2013-03-28 Last updated: 2018-06-26Bibliographically approved
Dely, P., Kassler, A., Bayer, N., Einsiedler, H., Peylo, C., Chow, L., . . . Miguel, S. (2012). A Software Defined Networking Approach for Handover Management with Real-Time Video in WLANs. In: : . Paper presented at HMWC'2012 - The 1st International Workshop on High Mobility Wireless Communications, November 10-12, 2012, Chengdu, China.
Open this publication in new window or tab >>A Software Defined Networking Approach for Handover Management with Real-Time Video in WLANs
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2012 (English)Conference paper, Published paper (Refereed)
National Category
Computer Sciences
Identifiers
urn:nbn:se:kau:diva-16132 (URN)
Conference
HMWC'2012 - The 1st International Workshop on High Mobility Wireless Communications, November 10-12, 2012, Chengdu, China
Available from: 2012-12-11 Created: 2012-12-11 Last updated: 2018-01-12Bibliographically approved
Dely, P. (2012). Architectures and Algorithms for Future Wireless Local Area Networks. (Doctoral dissertation). Karlstad: Karlstads universitet
Open this publication in new window or tab >>Architectures and Algorithms for Future Wireless Local Area Networks
2012 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

Future Wireless Local Area Networks (WLANs) with high carrier frequencies and wide channels need a dense deployment of Access Points (APs) to provide good performance. In densely deployed WLANs associations of stations and handovers need to be managed more intelligently than today.

This dissertation studies when and how a station should perform a handover and to which AP from a theoretical and a practical perspective. We formulate and solve optimization problems that allow to compute the optimal AP for each station in normal WLANs and WLANs connected via a wireless mesh backhaul. Moreover, we propose to use software defined networks and the OpenFlow protocol to optimize station associations, handovers and traffic rates. Furthermore, we develop new mechanisms to estimate the quality  of a link  between a station and an AP. Those mechanisms allow optimization algorithms to make better decisions about when to initiate a handover. Since handovers in today’s WLANs are slow and may disturb real-time applications such as video streaming, a faster procedure is developed in this thesis.

Evaluation results from wireless testbeds and network simulations show that our architectures and algorithms significantly increase the performance of WLANs, while they are backward compatible at the same time.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2012. p. 227
Series
Karlstad University Studies, ISSN 1403-8099 ; 2012:53
Keywords
WLAN, IEEE 802.11, network management, software defined networking, OpenFlow, optimization, handover, mobility
National Category
Communication Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-15393 (URN)978-91-7063-464-2 (ISBN)
Public defence
2012-12-14, 1B306, 11:00 (English)
Opponent
Supervisors
Available from: 2012-11-23 Created: 2012-10-30 Last updated: 2012-11-23Bibliographically approved
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