| 1. |
- Acatauassu, Diogo, et al.
(författare)
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Simple and Causal Copper Cable Model Suitable for G.fast Frequencies
- 2014
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Ingår i: IEEE Transactions on Communications. - 0090-6778. ; 62:11, s. 4040-4051
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Tidskriftsartikel (refereegranskat)abstract
- G.fast is a new standard from the International Telecommunication Union, which targets 1 Gb/s over short copper loops using frequencies up to 212 MHz. This new technology requires accurate parametric cable models for simulation, design, and performance evaluation tests. Some existing copper cable models were designed for the very high speed digital subscriber line spectra, i.e., frequencies up to 30 MHz, and adopt assumptions that are violated when the frequency range is extended to G.fast frequencies. This paper introduces a simple and causal cable model that is able to accurately characterize copper loops composed by single or multiple segments, in both frequency and time domains. Results using G.fast topologies show that, apart from being accurate, the new model is attractive due to its low computational cost and closed-form expressions for fitting its parameters to measurement data.
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| 2. |
- Acatauassu, Diogo, et al.
(författare)
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Simple and Causal Twisted-Pair Channel Models for G.fast Systems
- 2013
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- The use of a hybrid copper and fiber architecture is attractive in both fixed access and mobile backhauling scenarios. This trend led the industry and academia to start developing the fourth generation broadband system, which aims at achieving bitrates of 1 Gbps over short copper loops. In this context, accurate models of short twisted-pair cables operating at relatively high frequencies are key elements. This work describes new parametric cable models that incorporate four important characteristics: support of frequencies up to 200 MHz, few parameters, causal impulse responses and require relatively easy fitting procedures. The results show that the models achieve good accuracy for single segments, which are the expected topology for G.fast deployments.
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| 3. |
- Andersson, Jens A, et al.
(författare)
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Analytic Model for Cross-Layer Dependencies in VDSL2 access networks
- 2014
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Ingår i: 22nd International Conference on Software, Telecommunications and Computer Networks (SoftCOM), 2014. - 9781479964970 - 9789532900521 ; , s. 269-273
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Konferensbidrag (refereegranskat)abstract
- Recent changes in user employment of Internet based services, new deployment technologies for mobile networks as well as an ongoing realisation of fixed and mobile converged networks e.g. the EU FP7 project COMBO, are significant examples of enablers for increasing demands on DSL links. Investigating cross-layer dependencies between all layers in the OSI reference model becomes increasingly important. In this paper we present an analytical model and experimental results for the relation between impulse noise on a VDSL2 link and the effect this have on the network layer packet loss. We show how the packet loss rate is dependent not only on the disturbance signal level and periodicity but also on the link utilisation.
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| 4. |
- Andersson, Jens A, et al.
(författare)
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Impact of DSL link impairments on higher layer QoS parameters
- 2012
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Ingår i: Proceedings of SNCNW 2012. ; , s. 95-98
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Konferensbidrag (refereegranskat)abstract
- An increasing demand from e.g. real-time multimedia applications (IPTV, OTT) adds strains on especially DSL based access links. In this paper we argue why it is important to study DSL link impairments and their impact on QoS parameters on higher layers. We discuss the need for establishing methods for quality of service estimation with cross layer techniques and present some initial results.
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| 5. |
- Gosselin, Stéphane, et al.
(författare)
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Fixed and Mobile Convergence: Needs and Solutions
- 2014
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Konferensbidrag (refereegranskat)abstract
- The drivers of Fixed and Mobile Convergence (FMC) are discussed. A reference framework for FMC proposed by European project COMBO is then presented. Some use cases of FMC are described, showing the needs for mutualization and convergence of fixed and mobile broadband networks. Five network scenarios providing technical solutions to FMC use cases are proposed. They target an optimal and seamless quality of experience for the end user together with an optimized network infrastructure ensuring increased performance, flexibility, reduced cost and reduced energy consumption.
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| 6. |
- Höst, Stefan, et al.
(författare)
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Low complexity computation of the BT0 Hilbert twisted pair cable model
- 2010
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Ingår i: [Host publication title missing]. ; , s. 195-199
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Konferensbidrag (refereegranskat)abstract
- By use of the Hilbert transform the standardized BT0 twisted pair cable model can be rederived as a causal model with lower order, denoted BT0$_H$. In the present contribution the computational complexity of the BT0$_H$ model is decreased as the Hilbert transform is approximated with a look-up table implemented as a polynomial approximation. This results in a model of lower complexity than BT0$_H$ and lower order than the original BT0 model. Finally a comparison on causality of the considered models is presented.
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| 7. |
- Lindholm, Christin, et al.
(författare)
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A Case Study on Software Risk Analysis in Medical Device Development
- 2012
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Ingår i: Software Quality. Process Automation in Software Development/Lecture Notes in Business Information Processing. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1865-1348. - 9783642272127 ; 94, s. 143-158
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Konferensbidrag (refereegranskat)abstract
- Software failures in medical devices can lead to catastrophic situations. Therefore is it crucial to handle software related risks when developing medical devices. This paper presents the experiences gained from an ongoing case study with a medical device development organisation. This part of the study focuses on the two first steps of the risk management process, i.e. risk identification and risk analysis. The research is conducted as action research, with the aim of analysing and giving input to the organisation’s introduction of a software risk management process. The risk identification activities focus on user risks based on scenarios describing the expected use of the medical device in its target environment. Challenging problems have been found in the risk management process with respect to definition of the system boundary and system context, the use of scenarios as input to the risk identification and estimation of detectability used during risk assessment.
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| 8. |
- Lindholm, Christin, et al.
(författare)
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Software risk analysis in medical device development
- 2011
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Ingår i: Proceedings of the 37th EUROMICRO Conference on Software Engineering and Advanced Applications. - 9780769544885 ; , s. 362-365
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Konferensbidrag (refereegranskat)abstract
- The purpose of risk management in the development of safety-critical software is to eliminate or reduce harmful behaviour. In health-care it is essential to manage risk related to software due to its increased use in medical devices and other computer systems. This paper presents some of the experiences gained from an ongoing case study at a large hospital in Sweden. The study focuses on identification and analysis of risks using scenarios and how effective this approach is. The research is conducted as action research, with the aim of analysing and giving input to the organisation’s new software risk management process.
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| 9. |
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| 10. |
- Müller, Francisco, et al.
(författare)
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Optimizing Power Normalization for G.fast Linear Precoder by Linear Programming
- 2014
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Ingår i: 2014 IEEE International Conference on Communications, ICC 2014. - 9781479920037 ; , s. 4060-4065
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Konferensbidrag (refereegranskat)abstract
- The use of vectoring for crosstalk cancellation in the new ITU-T G.fast standard for next generation DSL systems becomes essential for efficient utilization of the extended bandwidth (up to 200 MHz). In VDSL2 (up to 30 MHz), a zero-forcing-based linear precoder is used in downstream which approaches single-line performance. However, at high frequencies, the linear precoder may amplify the signal power substantially since the crosstalk channel is much stronger than at lower frequencies. Performance could be significantly degraded by power normalization to keep the PSD below the mask. In this work, we extended a per-line power normalization scheme by linear programming (LP) optimization. By simulations using measured cable data it is shown how the LPbased scheme further improves the linear precoder and it is also capable of balancing the data rate between lines. Further, the simulations also show the non-linear Tomlinson-Harashima precoder performs better than the linear precoders.
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