| 1. |
- Eklund, Johan, 1966-, et al.
(författare)
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Tuning SCTP failover for carrier grade telephony signaling
- 2010
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Ingår i: Computer Networks. - : Elsevier BV. - 1389-1286 .- 1872-7069. ; 54:1, s. 133-149
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Tidskriftsartikel (refereegranskat)abstract
- The Stream Control Transmission Protocol (SCTP) has not only been selected as the signaling transport protocol of choice in IETF SIGTRAN, the architecture that bridges circuit-switched and IP-based mobile core networks, but also plays a pivotal role in SAE/LTE, the next-generation UMTS/HSPA networks. To meet the redundancy requirements of telecom signaling traffic, SCTP includes a failover mechanism that enables rerouting of traffic from an unreachable network path to a backup path. However, the recommendations provided by IETF on how to configure the SCTP failover mechanism to meet telecom signaling requirements are kept quite general and leave much of the tuning to the telecom equipment vendor and/or operator. Several works by us and others have been carried out to study the effect of different SCTP parameters on the failover performance. The main contribution of this paper is that it gives a coherent treatment of how to configure the SCTP failover mechanism for carrier-grade telephony signaling, and provides practically usable configuration recommendations. The paper also discusses an alternate or complementary way of optimizing the SCTP failover mechanism by relaxing the exponential backoff that foregoes a retransmission timeout in SCTP. Some results showing significantly reduced failover times by use of this mechanism, with only marginal deteriorating effects on a signaling network, are discussed and analyzed in the paper. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Budzisz, Łukasz, et al.
(författare)
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A taxonomy and survey of SCTP research
- 2012
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Ingår i: ACM Computing Surveys. - New York : ACM Press. - 0360-0300 .- 1557-7341. ; 44:4, s. -36
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Tidskriftsartikel (refereegranskat)abstract
- The Stream Control Transmission Protocol (SCTP) is a relatively recent general-purpose transport layer protocol for IP networks that has been introduced as a complement to the well-established TCP and UDP transport protocols. Although initially conceived for the transport of PSTN signaling messages over IP networks, the introduction of key features in SCTP, such as multihoming and multistreaming, has spurred considerable research interest surrounding SCTP and its applicability to different networking scenarios. This article aims to provide a detailed survey of one of these new features—multihoming—which, as it is shown, is the subject of evaluation in more than half of all published SCTP-related articles. To this end, the article first summarizes and organizes SCTP-related research conducted so far by developing a four-dimensional taxonomy reflecting the (1) protocol feature examined, (2) application area, (3) network environment, and (4) study approach. Over 430 SCTP-related publications have been analyzed and classified according to the proposed taxonomy. As a result, a clear perspective on this research area in the decade since the first protocol standardization in 2000 is given, covering both current and future research trends. On continuation, a detailed survey of the SCTP multihoming feature is provided, examining possible applications of multihoming, such as robustness, handover support, and loadsharing.
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| 3. |
- Mesodiakaki, Agapi, et al.
(författare)
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Optimal User Association, Backhaul Routing and Switching off in 5G Heterogeneous Networks with Mesh Millimeter Wave Backhaul Links
- 2018
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Ingår i: Ad hoc networks. - : Elsevier. - 1570-8705 .- 1570-8713. ; 78, s. 99-114
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Tidskriftsartikel (refereegranskat)abstract
- Next generation, i.e., fifth generation (5G), cellular networks will provide a significant higher capacity per area to support the ever-increasing traffic demands. In order to achieve that, many small cells need to be deployed that are connected using a combination of optical fiber links and millimeter-wave (mmWave) backhaul architecture to forward heterogeneous traffic over mesh topologies. In this paper, we present a general optimization framework for the design of policies that optimally solve the problem of where to associate a user, over which links to route its traffic towards which mesh gateway, and which base stations and backhaul links to switch off in order to minimize the energy cost for the network operator and still satisfy the user demands. We develop an optimal policy based on mixed integer linear programming (MILP) which considers different user distribution and traffic demands over multiple time periods. We develop also a fast iterative two-phase solution heuristic, which associates users and calculates backhaul routes to maximize energy savings. Our strategies optimize the backhaul network configuration at each timeslot based on the current demands and user locations. We discuss the application of our policies to backhaul management of mmWave cellular networks in light of current trend of network softwarization (Software-Defined Networking, SDN). Finally, we present extensive numerical simulations of our proposed policies, which show how the algorithms can efficiently trade-off energy consumption with required capacity, while satisfying flow demand requirements.
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| 4. |
- Pieskä, Marcus, 1985-, et al.
(författare)
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TCP Performance over 5G mmWave Links - Tradeoff between Capacity and Latency
- 2017
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Ingår i: 2017 IEEE 13th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). - : IEEE. - 9781538638392 ; , s. 385-394
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Konferensbidrag (refereegranskat)abstract
- Recently, 5G systems started to explore the usage of mmWave bands both for access and backhaul. Cellular systems operating at such frequencies would achieve a significantly higher capacity than current systems due to the large frequency block available. Due to the propagation characteristics, highly directional mmWave links may frequently switch between Line-of-sight, Non Line-of-sight and outage if the beam is blocked by obstacles. Such intermittent connectivity combined with high throughput causes TCP to perform very badly. In this paper, we study the performance of several TCP variants over intermittent mmWave links. We focus on latency aspects, use ns-3 with extensions for mmWave links and evaluate the TCP performance with real Linux TCP stacks using the Direct Code Execution (DCE) framework. We also investigate the benefit of bufferbloat solutions such as CoDel, with different TCP variants. We investigate the impact of CoDels configuration parameters and different RTTs on TCP throughput, fairness and queueing delay. The problem of slow recovery of TCP after NLOS periods is less pronounced when multiple flows coexist under CoDel only if some of the flows have very short RTTs. However, under presence of NLOS, the fairness between different flows with different RTT values is reduced.
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| 5. |
- Yedugundla, Kiran, 1982-, et al.
(författare)
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Probe or Wait : Handling tail losses using Multipath TCP
- 2017
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Ingår i: 2017 IFIP Networking Conference (IFIP Networking) and Workshops. - : IEEE. - 9783901882944
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Konferensbidrag (refereegranskat)abstract
- Packet losses are known to affect the performance of latency sensitive Internet applications such as media streaming and gaming. Transport protocols recover from packet loss in order to provide reliable end-to-end communication and improve user experience. The efficiency of loss recovery mechanisms influences the completion time of flows, and thus also the application performance as perceived by the end user. In this paper we focus on state-of-the-art loss recovery mechanisms for TCP and Multipath TCP. We use controlled tail loss scenarios to evaluate the performance of loss recovery mechanisms and, based on the observations, we propose an enhanced tail loss recovery mechanism for Multipath TCP, to improve the loss recovery time. Our experiment results, using the Linux Multipath TCP implementation, show consistent end-to-end latency performance improvement in considered scenarios.
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| 6. |
- Hassan, Mahdi Mohammad, 1977-, et al.
(författare)
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Testability and Software Robustness : A Systematic Literature Review
- 2015
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Ingår i: 2015 41st Euromicro Conference on Software Engineering and Advanced Applications. - Funchal, Madeira, Portugal : IEEE. - 9781467375856 ; , s. 341-348
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Konferensbidrag (refereegranskat)abstract
- The concept of software testability has been researched in several different dimensions, however the relation of this important concept with other quality attributes is a grey area where existing evidence is scattered. The objective of this study is to present a state-of-the-art with respect to issues of importance concerning software testability and an important quality attribute: software robustness. The objective is achieved by conducting a systematic literature review (SLR) on the topic. Our results show that a variety of testability issues are in focus with observability and controllability issues being most researched. Fault tolerance, exception handling and handling external influence are prominent robustness issues in focus.
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| 7. |
- Alay, Özgü, et al.
(författare)
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Experience : An open platform for experimentation with commercial mobile broadband networks
- 2017
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Ingår i: MobiCom '17 Proceedings of the 23rd Annual International Conference on Mobile Computing and Networking. - New York : Association for Computing Machinery (ACM). - 9781450349161 ; , s. 70-78
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Konferensbidrag (refereegranskat)abstract
- Open experimentation with operational Mobile Broadband (MBB) networks in the wild is currently a fundamental requirement of the research community in its endeavor to address the need of innovative solutions for mobile communications. Even more, there is a strong need for objective data about stability and performance of MBB (e.g., 3G/4G) networks, and for tools that rigorously and scientifically assess their status. In this paper, we introduce the MONROE measurement platform: an open access and flexible hardware-based platform for measurements and custom experimentation on operational MBB networks. The MONROE platform enables accurate, realistic and meaningful assessment of the performance and reliability of 11 MBB networks in Europe. We report on our experience designing, implementing and testing the solution we propose for the platform. We detail the challenges we overcame while building and testing the MONROE testbed and argue our design and implementation choices accordingly. We describe and exemplify the capabilities of the platform and the wide variety of experiments that external users already perform using the system
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| 8. |
- Atxutegi, Eneko, et al.
(författare)
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TCP behaviour in LTE : impact of flow start-up and mobility
- 2016
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Ingår i: Wireless and Mobile Networking Conference (WMNC), 2016 9th IFIP. - : IEEE. ; , s. 73-80
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Konferensbidrag (refereegranskat)abstract
- Nowadays, more than two billion people uses the mobile internet, and it is expected to rise to almost 4 billion by 2020. Still, there is a gap in the understanding of how TCP and its many variants work over LTE. To this end, this paper evaluates the extent to which five common TCP variants, CUBIC, NewReno, Westwood+, Illinois, and CAIA Delay Gradient (CDG), are able to utilise available radio resources under hard conditions, such as during start-up and in mobile scenarios at different speeds. The paper suggests that CUBIC, due to its Hybrid Slow- Start mechanism, enters congestion avoidance prematurely, and thus experiences a prolonged start-up phase, and is unable to efficiently utilise radio resources during shorter transmission sessions. Still, CUBIC, Illinois and NewReno, i.e., the loss-based TCP implementations, offer better throughput, and are able to better utilise available resources during mobility than Westwood+ and CDG – the delay-based variants do.
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| 9. |
- Berthold, Stefan
(författare)
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Inter-temporal Privacy Metrics
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Informational privacy of individuals has significantly gained importance after information technology has become widely deployed. Data, once digitalised, can be copied, distributed, and long-term stored at negligible costs. This has dramatic consequences for individuals that leave traces in the form of personal data whenever they interact with information technology, for instance, computers and phones; or even when information technology is recording the personal data of aware or unaware individuals. The right of individuals for informational privacy, in particular to control the flow and use of their personal data, is easily undermined by those controlling the information technology.The objective of this thesis is to study the measurement of informational privacy with a particular focus on scenarios where an individual discloses personal data to a second party which uses this data for re-identifying the individual within a set of other individuals. We contribute with privacy metrics for several instances of this scenario in the publications included in this thesis, most notably one which adds a time dimension to the scenario for modelling the effects of the time passed between data disclosure and usage. The result is a new framework for inter-temporal privacy metrics.
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| 10. |
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