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  • 351.
    Della Penda, Demia
    et al.
    Ericsson AB, S-16480 Kista, Sweden..
    Abrardo, Andrea
    Univ Siena, Dept Informat Engn, I-53100 Siena, Italy.;Consorzio Nazl Interuniv Telecomunicaz, I-43124 Parma, Italy..
    Moretti, Marco
    Consorzio Nazl Interuniv Telecomunicaz, I-43124 Parma, Italy.;Univ Pisa, Dept Informat Engn, I-56122 Pisa, Italy..
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Distributed Channel Allocation for D2D-Enabled 5G Networks Using Potential Games2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 11195-11208Article in journal (Refereed)
    Abstract [en]

    Frequency channel allocation is a key technique for improving the performance of cellular networks. In this paper, we address the channel allocation problem for a 5G multi-cell system. We consider a heterogeneous network in which cellular users, micro-cell users, and device-to-device (D2D) communications coexist within the radio footprint of the macro cell. We maximize the aggregate transmission rate, exploiting channel diversity and managing both the inter-cell interference, typical of cellular networks and the intra-cell interference generated by the nonorthogonal transmissions of the small-cell and D2D users. By modeling the allocation problem as a potential game, whose Nash equilibria correspond to the local optima of the objective function, we propose a new decentralized solution. The convergence of our scheme is enforced by using a better response dynamic based on a message passing approach. The simulation results assess the validity of the proposed scheme in terms of convergence time and achievable rate under different settings.

  • 352.
    Demirel, Burak
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. University of Paderborn, Germany.
    Gupta, V.
    Quevedo, D. E.
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    On the Trade-Off between Communication and Control Cost in Event-Triggered Dead-Beat Control2016In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. PP, no 99, article id 7562376Article in journal (Refereed)
    Abstract [en]

    We consider a stochastic system where the communication between the controller and the actuator is triggered by a thresholdbased rule. The communication is performed across an unreliable link that stochastically erases transmitted packets. To decrease the communication burden, and as a partial protection against dropped packets, the controller sends a sequence of control commands to the actuator in each packet. These commands are stored in a buffer and applied sequentially until the next control packet arrives. In this context, we study dead-beat control laws and compute the expected linear-quadratic loss of the closed-loop system for any given event-threshold. Furthermore, we provide analytical expressions that quantify the trade-off between the communication cost and the control performance of event-triggered control systems. Numerical examples demonstrate the effectiveness of the proposed technique.

  • 353. Deng, Lei
    et al.
    Beltrán, Marta
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Arlunno, Valeria
    Zhao, Ying
    Caballero, Antonio
    Dogadaev, Anton
    Yu, Xianbin
    Llorente, Roberto
    Liu, Deming
    Tafur Monroy, I
    Fiber Wireless Transmission of 8.3-Gb/s/ch QPSK-OFDM Signals in 75–110-GHz Band2012In: Photonics Technology Letters, IEEE, Vol. 24, no 5, p. 383-385Article in journal (Refereed)
  • 354. Deng, Lei
    et al.
    Liu, Deming
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Arlunno, Valeria
    Zhao, Ying
    Caballero, Antonio
    Dogadaev, Anton K
    Yu, Xianbin
    Monroy, Idelfonso Tafur
    Beltran, Marta
    Llorente, Roberto
    42.13 Gbit/S 16qam-OFDM Photonics-Wireless Transmission in 75-110 GHz Band2012In: Progress In Electromagnetics Research, Vol. 126, p. 449-461Article in journal (Refereed)
  • 355. Deng, Lei
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Monroy, Idelfonso Tafur
    Tang, Ming
    Shum, Ping
    Liu, Deming
    Experimental demonstration of nonlinearity and phase noise tolerant 16-QAM OFDM W-band (75–110 GHz) signal over fiber system2014In: Journal of Lightwave Technology, Vol. 32, no 8, p. 1442-1448Article in journal (Refereed)
  • 356. Deng, Lei
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Yu, Xianbin
    Liu, Deming
    Monroy, Idelfonso Tafur
    Nonlinearity and Phase Noise Tolerant 75-110 GHz Signal over Fiber System Using Phase Modulation Technique2013In: National Fiber Optic Engineers Conference, 2013Conference paper (Refereed)
  • 357. Deng, Lei
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Zhao, Ying
    Othman, M Binti
    Jensen, Jesper Bevensee
    Zibar, Darko
    Yu, Xianbin
    Liu, Deming
    Monroy, Idelfonso Tafur
    2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON2012In: Optics express, Vol. 20, no 4, p. 4369-4375Article in journal (Refereed)
  • 358. Deng, Lei
    et al.
    Zhao, Ying
    Pang, Xiaodan
    RISE ACREO AB.
    Tang, Ming
    Shum, Ping
    Liu, Deming
    All-VCSEL Transmitters With Remote Optical Injection for WDM-OFDM-PON2014In: IEEE Photonics Technology Letters, Vol. 26, no 5, p. 461-464Article in journal (Refereed)
  • 359. Deng, Lei
    et al.
    Zhao, Ying
    Pang, Xiaodan
    RISE ACREO AB.
    Yu, Xianbin
    Jensen, J Bevensee
    Liu, Deming
    Monroy, I Tafur
    Colorless ONU based on all-VCSEL sources with remote optical injection for WDM-PON2011In: Photonics Conference (PHO), 2011 IEEE, 2011, p. 220-221Conference paper (Refereed)
  • 360. Deng, Lei
    et al.
    Zhao, Ying
    Pang, Xiaodan
    RISE ACREO AB.
    Yu, Xianbin
    Liu, Deming
    Monroy, Idelfonso Tafur
    Intra and inter-PON ONU to ONU virtual private networking using OFDMA in a ring topology2011In: Microwave Photonics, 2011 International Topical Meeting on & Microwave Photonics Conference, 2011 Asia-Pacific, MWP/APMP, 2011, p. 176-179Conference paper (Refereed)
  • 361.
    Derakhshanno, Homayoun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Voice over IP over GPRS2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Voice over IP (VoIP) technology has become prevalent today due to its lower cost than traditional telephony and its ability to support new value-added services. Additionally, the increasing availability of wireless internet access has led to research studies examining the combination of wireless network access with voice over IP. With the widespread availability of advanced mobile phones and Pocket PCs, the need for VoIP applications on these mobile platforms is tangible. To enable this, we need to evaluate the current wireless access technologies to see if they can support the necessary traffic and implement software to offer these VoIP services to users.

    In order to easily implement an IP-based service on GSM technology, we should use the GPRS service provided by the GSM operators. In this thesis, we evaluate Voice over IP service over GPRS in terms of feasibility and quality. Following this we ported a locally developed VoIP program to a Pocket PC (with GSM SIM-card support) which runs Microsoft’s Windows Mobile in order to provide suitable software as needed to offer the service from such a portable device.

  • 362. Dethise, A.
    et al.
    Chiesa, Marco
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Canini, M.
    Prelude: Ensuring inter-domain loop-freedom in SDN-enabled networks2018In: ACM International Conference Proceeding Series, Association for Computing Machinery , 2018, p. 50-56Conference paper (Refereed)
    Abstract [en]

    Software-Defined eXchanges (SDXes) promise to improve the interdomain routing ecosystem through SDN deployment. Yet, the nave deployment of SDN on the Internet raises concerns about the correctness of the interdomain data-plane. By allowing operators to deflect traffic from default BGP routes, SDN policies can create permanent forwarding loops that are not visible to the control-plane. We propose Prelude, a system for detecting SDN-induced forwarding loops between SDXes with high accuracy without leaking private routing information of network operators. To achieve this, we leverage Secure Multi-Party Computation (SMPC) techniques to build a novel and general privacy-preserving primitive that detects whether any subset of SDN rules might affect the same portion of traffic without learning anything about those rules. We then leverage this primitive as the main building block of a distributed system tailored to detect forwarding loops among any set of SDXes. We leverage the particular nature of SDXes to further improve the efficiency of our SMPC solution. The number of valid SDN rules rejected by our solution is 100x lower than previous privacy-preserving solutions, and provides better privacy guarantees. Furthermore, our solution naturally provides network operators with some insights on the cost of the deflected paths.

  • 363. Dethise, A.
    et al.
    Chiesa, Marco
    Université catholique du Louvain, Belgium.
    Canini, M.
    Privacy-preserving detection of inter-domain SDN rules overlaps2017In: SIGCOMM Posters and Demos 2017 - Proceedings of the 2017 SIGCOMM Posters and Demos, Part of SIGCOMM 201722 August 2017, Association for Computing Machinery (ACM), 2017, p. 6-8Conference paper (Refereed)
    Abstract [en]

    SDN approaches to inter-domain routing promise better traffic engineering, enhanced security, and higher automation. Yet, naïve deployment of SDN on the Internet is dangerous as the control-plane expressiveness of BGP is significantly more limited than the data-plane expressiveness of SDN, which allows fine-grained rules to deflect traffic from BGP's default routes. This mismatch may lead to incorrect forwarding behaviors such as forwarding loops and blackholes, ultimately hindering SDN deployment at the inter-domain level. In this work, we make a first step towards verifying the correctness of inter-domain forwarding state with a focus on loop freedom while keeping private the SDN rules, as they comprise confidential routing information. To this end, we design a simple yet powerful primitive that allows two networks to verify whether their SDN rules overlap, i.e., the set of packets matched by these rules is non-empty, without leaking any information about the SDN rules. We propose an efficient implementation of this primitive by using recent advancements in Secure Multi-Party Computation and we then leverage it as the main building block for designing a system that detects Internet-wide forwarding loops among any set of SDN-enabled Internet eXchange Points.

  • 364. Devlic, Alisa
    Extending CPL with context ontology2006Conference paper (Refereed)
    Abstract [en]

    Communication has always been an essential part of peo-ple's everyday life. Nowadays most of people would liketo be reachable on multiple devices at anytime, anyplace. As a consequence, there has been a need to know and exploit a user's availability for communication (so called presence information), so that he/she can control incoming callsand make the decision to accept this call or not based onthe user's current context. The appearance and acceptanceof Session Initiation Protocol (SIP) as a signalling protocol for next generation networks has opened the door for multiple services, such as Voice over IP (VoIP), chat, games,instant messaging, and other innovative communication services. Built on top of existing data communication networks, this has enabled easy integration of voice and data services. In this paper we present an idea on how to use the context information to enhance the power of existing SIP call control services, to enable users to have greater control over their incoming/outgoing calls. These services are implemented using Call Processing Language (CPL), a language to describe and control Internet Telephony Services. They are extended with context parameters to permit context-based decision making based on context ontology. We want to show how easy is to add new context parameters to the CPL and how complex criteria can be built using our solution.

  • 365.
    Devlic, Alisa
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    On Optimization of Quality of User Experience and Wireless Network Bandwidth in Video Content Delivery2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mobile video content today generates more than half of the mobile data traffic.The increasing popularity of mobile video on demand services poses great challenges to mobile operators and content providers. Frontmost, how to reduce the mobile video traffic load, while delivering high quality video content to mobile users without perceived quality degradations for the same (or cheaper) price? Battery lifetime represents another key factor of a user’s Quality of Experience(QoE). A lot of device energy is consumed by mobile network signalling and data transmission over new generation mobile communication systems. This thesis focuses on: (1) reducing the size of the video that is delivered to the enduser in the maximum achievable video quality, thus optimizing the wireless network bandwidth and the user-perceived QoE, and (2) reducing the energy consumption of a mobile device that is associated to data transfer over the radio interface, thus increasing the device’s battery lifetime. The main contributions have been given in providing the Over-the-Top video optimization and delivery schemes and recommendations on tuning their parameters in order to minimize the bandwidth and energy consumption of mobile video delivery, while maximizing the predictable user-perceived QoE. By preventing the video to be prefetched on low data rates and tuning the datarate threshold according to statistical properties of available data rates, we show that 20-70% of energy cost can be reduced by opportunistic prefetching, depending on the user’s pattern of available data rates. The data rate values ordered in time that have a large amount of serial correlation and low noise variance, or low average valueand high peak-to-mean ratio, are likely to yield the highest energy gains from content prefetching. Moreover, we show that energy gains are the largest when the threshold data rate is set close to an average data rate, due to the highest availability of data rates around this value, and for longer sleep time between the prefetching periods, which increases the probability of moving away from the areas with low data rates. Next, we focus on QoE-aware mobile video delivery solutions that are more bandwidth efficient without compromising the user-perceived video quality. They deliver a video over a varying data rate channel that is optimized for viewing on a mobile device in the highest perceptual video quality that can be achieved in the given video and network conditions. An optimized video consists of short segments in the minimum resolutions that satisfy the target perceptual video quality and have up to 60% reduced size compared to the video in the corresponding fixed video resolution, without perceptible quality difference. The delivery is performed by on demand download, context-aware prefetching, or in real time using the QoE-aware adaptive video streaming that runs over Dynamic Adaptive video Streaming over HTTP (DASH). By limiting the maximum bitrates of the requested video segments and using the remaining throughput to prefetch optimized video segments in advance of playout, we show that QoE-aware adaptive video streaming maintains a more stable perceptual video quality than DASH despite the fluctuations of the channel bandwidth, while using fewer number of bits, which improves a user-perceived QoE. The results of this thesis can help operators and content providers to reduce their costs and provide more content to their users at the same (or cheaper) price.

  • 366. Devlic, Alisa
    et al.
    Erik, Klintskog
    Context retrieval and distribution in a mobile distributed environment2007Conference paper (Refereed)
    Abstract [en]

    Context-aware services are gaining momentum in mobile computing. To enable rapid development of context-aware services,context information has to be retrieved from the environment, modeled,processed, and distributed to these services. MIDAS is a European research project concerning 3G and beyond, which aims to dene and implement a platform to simplify and speed up the task of developing and deploying mobile applications and services. MIDAS context engine provides mechanisms to retrieve, model, synthesize, and distribute context information in a distributed, mobile environment. This paper presents a way to retrieve and distribute context information using context queries and triggers. A novel approach to perform context synthesis will be presented using operators.

  • 367.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Graf, A.
    Barone, P.
    Evaluation of context distribution methods via Bluetooth and WLAN: Insights gained while examining Battery Power Consumption2008In: MobiQuitous 2008 - 5th International ICST Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services, 2008Conference paper (Refereed)
    Abstract [en]

    In a traditional context-aware system, most context information is local to a device. However, we may need access to context information from outside the device. Increasingly mobile electronic devices are equipped with Bluetooth and/or WLAN network interfaces. Both of these technologies enable ad hoc discovery & networking. In this paper we evaluate the use of these technologies for context distribution within a local area (i.e., limited to a single hop). Using Bluetooth, we begin by discovering devices using Bluetooth's discovery protocol, collect their context information, create an XML file containing this information, and distribute this file to all discovered devices, such that every device now has the same context information. Next we perform the same discovery, collect, and distribute functions, but using WLAN. In each case we have performed the cycle of operations starting with a fully charged battery and continuing until the device was not able to utilize the selected wireless interface any longer. Finally we compare both approaches to context distribution in terms of battery power consumption. We observe that Bluetooth consumes 2-6 times more energy for transmission of a 1MB file to two devices than to discover these two devices. Furthermore, the transfer of this file is two times slower than WLAN, and we must unicast this file to each device. Multicasting via WLAN proved to be less energy consuming than the Bluetooth transmission, if data is to be sent to more than three users. In addition, the energy to discover 2 devices along with their services using Bluetooth consumed 52 times more energy than to receive the same amount of data via a WLAN multicast. Thus, this paper shows that it is more energy efficient to distribute context knowledge to other devices, than having each device learn this information itself. Finally, we give equations for calculating the battery power consumption of transmitting data using any protocol that runs over Bluetooth or over WLAN.

  • 368.
    Devlic, Alisa
    et al.
    Ericsson Research.
    John, Wolfgang
    Ericsson Research.
    Sköldström, Pontus
    A use-case based analysis of network management functions in the ONF SDN model2012In: European Workshop on SDN, 2012Conference paper (Refereed)
    Abstract [en]

    The concept of software-defined networking (SDN) recently gained huge momentum in the industry, driven mainly by IT companies interested in data center applications. In this paper, however, we apply SDN to the carrier domain, which poses additional requirements in terms of network management functions. As a specific use-case we take a virtualized carrier network shared by multiple customers. We consider the current SDN model as defined by the Open Networking Foundation (ONF), including the OpenFlow and OF-config protocols. Through a step-by-step discussion of the rocedures required to configure and manage the virtualized network, we analyze the applicability of the current SDN model as specified by the ONF. As a result, we identify shortcomings and propose necessary extensions to the ONF SDN model. The highlighted extensions include control network bootstrapping considerations, updates to the SDN and NOS model, and most importantly extensions of the OF-config management data model

  • 369.
    Devlic, Alisa
    et al.
    Ericsson Research.
    John, Wolfgang
    Ericsson Research.
    Sköldström, Pontus
    Carrier-grade Network Management Extensions to the SDN Framework2012In: 8th Swedish National Computer Networking Workshop SNCNW 2012 Stockholm, 2012Conference paper (Refereed)
    Abstract [en]

    The concept of software-defined networking (SDN)recently  gained  huge  momentum  in  the  industry,  driven  mainlyby  IT  companies  interested  in  datacenter  applications.  In  thispaper, however, we consider SDN applied in the carrier domain,which poses additional requirements on the network architecture,including  network  management  functions.  We  derive  concreterequirements  for  the  use-case  of  a  virtualized  multi-provideraccess/aggregation  network  based  on  carrier-grade  SDN.  Wethen provide initial architectural considerations for integrationof  network  management  extensions  to  the  SDN  framework  asdefined  by  the  Open  Networking  Foundation  (ONF).  Architec-tural considerations include definition of the required entities andtheir interactions. Finally, we apply the proposed architecture onthe access/aggregation network use-case, outlining procedures ofhow  the  network  management  extensions  can  enable  networkwide and node specific management & configuration

  • 370.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Kamaraju, Pavan
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    QoE-aware optimization for video delivery and storage2015In: 2015 IEEE 16th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM) 2015, Boston, MA, USA, 2015, p. 1-10Conference paper (Refereed)
    Abstract [en]

    The explosive growth of Over-the-top (OTT) online video strains capacity of operators’ networks, which severely threatens video quality perceived by end users. Since video is very bandwidth consuming, its distribution costs are becoming too high to scale with network investments that are required to support the increasing bandwidth demand. Content providers and operators are searching for solutions to reduce this video traffic load, without degrading their customers’ perceived Quality ofExperience (QoE). This paper proposes a method that can programmatically optimize video content for desired QoE accordingto perceptual video quality and device display properties, while achieving bandwidth and storage savings for content providers, operators, and end users. The preliminary results obtained with Samsung Galaxy S3 phone show that up to 60% savings can be achieved by optimizing movies without compromising the perceptible video quality, and up to 70% for perceptible, but not annoying video quality difference. Tailoring video optimization to individual user perception can provide seamless QoE delivery across all users, with a low overhead (i.e., 10%) required to achieve this goal. Finally, two applications of video optimization: QoE-aware delivery and storage, are proposed and examined.

  • 371.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Kamaraju, Pavan
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Towards QoE-aware adaptive video streaming2016In: 2015 IEEE 23rd International Symposium on Quality of Service (IWQoS), IEEE, 2016, p. 75-76, article id 7404713Conference paper (Refereed)
    Abstract [en]

    This paper describes a novel QoE-aware adaptive video streaming method that enhances the viewing experience on mobile devices and reduces cellular network bandwidth consumed by Dynamic Adaptive Streaming over HTTP (DASH) by considering perceptual video quality and data rate channel conditions in the bitrate adaptation process. By streaming an optimized video for the particular video quality and channel conditions toa mobile device, we can improve the worst video qualities causedby DASH streaming and reduce quality variations using fewer number of bits.

  • 372.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Evaluation of energy profiles for mobile video prefetching in generalized stochastic access channels2014In: Mobile and Ubiquitous Systems: Computing, Networking, and Services: 10th International Conference, MOBIQUITOUS 2013, Tokyo, Japan, December 2-4, 2013, Revised Selected Papers, Springer, 2014, p. 209-223Conference paper (Refereed)
    Abstract [en]

    This paper evaluates the energy cost reduction of Over-The-Top mobile video content prefetching in various network conditions. Energy cost reduction is achieved by reducing the time needed to download content over the radio interface by prefetching data on higher data rates, compared to the standard on demand download. To simulate various network conditions and user behavior, a stochastic access channel model was built and validated using the actual user traces. By changing the model parameters, the energy cost reduction of prefetching in different channel settings was determined, identifying regions in which prefetching is likely to deliver the largest energy gains. The results demonstrate that the largest gains (up to 70%) can be obtained for data rates with strong correlation and low noise variation. Additionally, based on statistical properties of data rates, such as peak-to-mean and average data rate, prefetching strategy can be devised enabling the highest energy cost reduction that can be obtained using the proposed prefetching scheme.

  • 373.
    Dhainaut, Guillaume
    KTH, School of Electrical Engineering (EES), Communication Networks.
    A reverse proxy for VoIP: Or how to improve security in a ToIP network2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The need for security is crucial in Telephony over IP (ToIP). Secure protocols have been designed as well as specific devices to fulfill that need. This master thesis examines one of such devices called Session Border Controller (SBC), which can be compared to reverse proxies for ToIP. The idea is to apply message filters to increase security.

    This thesis presents the reasons of SBC existence, based on the security weaknesse sa ToIP network can show. These reasons are then used to establish a list of features which can be expected from a SBC and discuss its ideal placement in a ToIP network architecture. A test methodology for SBCs is established and used on the free software Kamailio as an illustration. Following this test, improvements of this software, regarding threats prevention and attacks detection, are presented and implemented.

  • 374. Dhaou, I. B.
    et al.
    Kondoro, A.
    Kelati, A.
    Rwegasira, D. S.
    Naiman, S.
    Mvungi, N. H.
    Tenhunen, H.
    Communication and security technologies for smart grid2017In: International Journal of Embedded and Real-Time Communication Systems, ISSN 1947-3176, E-ISSN 1947-3184, Vol. 8, no 2, p. 40-65Article in journal (Refereed)
    Abstract [en]

    The smart grid is a new paradigm that aims to modernize the legacy power grid. It is based on the integration of ICT technologies, embedded system, sensors, renewable energy and advanced algorithms for management and optimization. The smart grid is a system of systems in which communication technology plays a vital role. Safe operations of the smart grid need a careful design of the communication protocols, cryptographic schemes, and computing technology. In this article, the authors describe current communication technologies, recently proposed algorithms, protocols, and architectures for securing smart grid communication network. They analyzed in a unifying approach the three principles pillars of smart-gird: Sensors, communication technologies, and security. Finally, the authors elaborate open issues in the smart-grid communication network.

  • 375. Di Giglio, A.
    et al.
    Schiano, M.
    Ruffini, M.
    Payne, D.
    Doran, N.
    Achouche, M.
    Jensen, R.
    O’Sullivan, B.
    Pfeiffer, T.
    Bonk, R.
    Rohde, H.
    Talli, G.
    Yin, X.
    Wessaly, R.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Montalvo, J.
    Towards the distributed core for ubiquitous superfast broadband optical access2014In: 2014 European Conference on Networks and Communications (EuCNC), 2014, p. 1-5Conference paper (Refereed)
    Abstract [en]

    In this paper, we describe recent architectural and technological advances of the end to end optical network architecture proposed by the DISCUS project (the DIStributed Core for unlimited bandwidth supply for all Users and Services). The two main targets of DISCUS are the principle of equivalence in the access and the reduction of optical-to-electronic conversions in the metro-core network. Technological advances and techno-economic evaluation of Long-Reach Passive Optical Networks (LR-PON), as well as the optimal metro-core node architecture and the required network control plane framework are reported. Network infrastructure sharing challenges are also discussed.

  • 376.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Ericsson Research, Sweden.
    Athanasiou, Georgios
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Institute of Communications and Computer Systems, National Technical University of Athens, Greece.
    Mekikis, Prodromos
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Signal Theory and Communications Dept., Technical University of Catalonia, Barcelona, Spain.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    MAC-aware routing metrics for the internet of things2015In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703XArticle in journal (Refereed)
    Abstract [en]

    The development of the internet of things (IoT) has significantly affected the concept of wireless networking. As the number of wireless devices is rising, new medium access control (MAC) and routing protocols have been developed to guarantee end-to-end network performance. When existing layered solutions are stacked together, there might be detrimental effects on the overall network performance. In this paper, an analysis of MAC and routing protocols for IoT is provided with focus on the IEEE 802.15.4 MAC and the IETF RPL standards. It is shown that existing routing metrics do not account for the complex interactions between MAC and routing, and thus novel metrics are proposed. This enables a protocol selection mechanism for selecting the routing option and adapting the MAC parameters, given specific performance constraints. Extensive analytical and experimental results show that the behavior of the MAC protocol can hurt the performance of the routing protocol and vice versa, unless these two are carefully optimized together by the proposed method.

  • 377.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Santucci, F.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Effects of Rayleigh-lognormal fading on IEEE 802.15.4 networks2013In: Communications (ICC), 2013 IEEE International Conference on, IEEE conference proceedings, 2013, p. 1666-1671Conference paper (Refereed)
    Abstract [en]

    The IEEE 802.15.4 communication protocol is a de-facto standard for wireless applications in industrial and home automation. Although the performance of the medium access control (MAC) of the IEEE 802.15.4 has been thoroughly investigated under the assumption of ideal wireless channel, there is still a lack of understanding of the cross-layer interactions between MAC and physical layer in the presence of realistic wireless channel models that include path loss, multi-path fading and shadowing. In this paper, an analytical model of these dynamics is proposed. The analysis considers simultaneously a composite Rayleigh-lognormal channel fading, interference generated by multiple terminals, the effects induced by hidden terminals, and the MAC reduced carrier sensing capabilities. It is shown that the reliability of the contention-based MAC over fading channels is often far from that derived under ideal channel assumptions. Moreover, it is established to what extent fading may be beneficial for the overall network performance.

  • 378.
    Di, Shuang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    USB Attached Network Performance: Uplink Performance2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    More and more people all over the world are using a USB modem to connect to the Internet. This is especially true in Sweden- which has the highest 3G coverage in Europe. Comparable to fixed broadband access, using a 3G USB modem is a wonderful experience for the customer. Increasingly, anywhere we can use our cellular phone is a place that we are able to access the Internet, even if we are traveling in a train, walking in a park, or sitting on the beach. This makes working on the move much easier. However, customers do not know if the network throughput, delay, and the cost of connectivity match their needs. Additionally, there is also the question of the time to connect to the network when there has not been some traffic for a period of time. However, the throughput, delay, and "time to connect" when using such a modem to connect to a wireless network depend on several factors. In this thesis we will examine these factors. More specifically, the thesis will analyze in detail the effects of using a USB attached network interface, in order to gain greater understanding of such an interface’s network performance. We have chosen to focus on the uplink, as it was expected to have a low throughput and it has not had as much attention as the downlink performance.

  • 379. Dietzel, C.
    et al.
    Antichi, G.
    Castro, I.
    Fernandes, E. L.
    Chiesa, Marco
    Université catholique du Louvain.
    Kopp, D.
    SDN-enabled traffic engineering and advanced blackholing at IXPs2017In: SOSR 2017 - Proceedings of the 2017 Symposium on SDN Research, 2017, p. 181-182Conference paper (Refereed)
    Abstract [en]

    While the clean slate approach proposed by Software Defined Networking (SDN) promises radical changes in the stagnant state of network management, SDN innovation has not gone beyond the intra-domain level. For the inter-domain ecosystem to benefit from the advantages of SDN, Internet Exchange Points (IXPs) are the ideal place: a central interconnection hub through which a large share of the Internet can be affected. In this demo, we showcase the ENDEAVOUR platform: a new software defined exchange approach readily deployable in commercial IXPs. We demonstrate here our implementations of traffic engineering and Distributed Denial of Service mitigation, as well as how member networks cash in on the advanced SDN-features of ENDEAVOUR, typically not available in legacy networks.

  • 380.
    Dimitriou, Eleftherios
    KTH, Superseded Departments, Teleinformatics.
    An Archive Robot for Video Mail1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today most of the real-time voice communications are carried over the Plain Old Telephone System (POTS). In the future that might well change. Research indicates a strong interest for developing the network to support real-time communications in a satisfactory way. Applications will be needed in this new world of IP (Internet Protocol) based communications.

    In this thesis we present an application called the Video Mail service. The Video Mail service can record and playback audio and video messages over the Internet using standard Internet telephony protocols. It is built on top of a more general platform called the Archive Robot. The Archive Robot provides the real-time functionality of the system. It is not explicitly designed to support the Video Mail service. Other services such as Conference Tool and Interactive Voice Response can also be supported.

    The Video Mail service was designed and implemented. Furthermore, this first prototype was used to evaluate the performance of the overall system.

  • 381.
    Dinc, Ergin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Vondra, Michal
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Multi-user Beamforming and Ground Station Deployment for 5G Direct Air-to-Ground Communication2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    On-board of aircraft is one of the last venues without high-speed connectivity, which makes it an important problem to address for both industry and academia. To this end, direct air-to-ground communications (DA2GC), where communication link is provided via direct link between aircraft and ground station, is a promising solution to provide high capacity and low latency backhaul capacity for aircraft. In this paper, we investigate the ground station deployment problem to provide 1.2 Gbps average backhaul capacity for each aircraft. The feasible operation points for the key network parameters: the number of ground stations, antenna array size, transmit power and bandwidth, are calculated. In addition, we propose a multi-user beamforming algorithm for dual-polarized hybrid DA2GC antenna arrays, and derive a tractable expression for the DA2GC cell throughput.

  • 382. Ding, Zhiguo
    et al.
    Krikidis, Ioannis
    Rong, Beiyu
    Thompson, John S.
    Wang, Chao
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Yang, Sheng
    On Combating The Half-Duplex Constraint In Modern Cooperative Networks: Protocols And Techniques2012In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 19, no 6, p. 20-27Article in journal (Refereed)
    Abstract [en]

    A key issue that characterizes cooperative wireless networks is the half-duplex constraint (HDC), which refers to the inability of current modems to receive and transmit data in the same frequency at the same time. This hardware limitation results in inefficient use of system resources (bandwidth loss) as it requires dedicated bandwidth allocation for relay transmissions. Methods to overcome the HDC have been studied intensively in the literature of cooperative networks in recent years, and several approaches have been proposed. In this article we highlight four different techniques which combat the HDC by using existing technology. The first approach is non-orthogonal protocols, which allow the source to be active during relay transmissions. The second approach is the overlap of several relaying transmissions in order to mimic an ideal full-duplex operation. The third solution is the two-way relay channel where two sources exchange data via the assistance of a shared relay. Finally, the fourth approach incorporates cooperation on the "network" level and uses the cognitive radio concept to enable relay transmissions during silent periods of source terminals. These techniques summarize some of the most significant HDC solutions that cover both the physical and network layers.

  • 383. Dixit, A.
    et al.
    Lannoo, B.
    Colle, D.
    Pickavet, M.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Mahloo, Mozhgan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Efficient protection schemes for hybrid WDM/TDM Passive Optical Networks2012In: Communications (ICC), 2012 IEEE International Conference on, IEEE , 2012, p. 6220-6224Conference paper (Refereed)
    Abstract [en]

    Hybrid WDM/TDM Passive Optical Network (PON) is a promising candidate for next-generation optical access (NGOA) solutions as it is able to offer a high splitting ratio and consequently achieves a relatively low cost and power consumption on a per-user basis compared with other NGOA architectures. On the other hand, the end users require a certain level of connection availability while the operators need to reduce the failure impact (i.e. to avoid a huge number of end users being affected by any single failure). Therefore, by evaluating the connection availability and failure impact robustness we identify the most efficient parts to provide resilience in a hybrid WDM/TDM PON from an operator and an end-user perspective. Then, we select the appropriate protection schemes to construct some novel reliable architectures and analyze their reliability performance in urban and rural scenarios. In this way, this paper provides a comprehensive insight into the most relevant protection mechanisms for hybrid WDM/TDM PONs.

  • 384. Dixit, A.
    et al.
    Mahloo, Mozhgan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Lannoo, B.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Colle, D.
    Pickavet, M.
    Protection strategies for Next Generation Passive Optical Networks -22014In: 2014 International Conference on Optical Network Design and Modeling, 2014, p. 13-18Conference paper (Refereed)
    Abstract [en]

    Next Generation Passive Optical Networks-2 (NG-PON2) are being considered to upgrade the current PON technology to meet the ever increasing bandwidth requirements of the end users while optimizing the network operators’ investment. Reliability performance of NG-PON2 is very important due to the extended reach and, consequently, large number of served customers per PON segment. On the other hand, the use of more complex and hence more failure prone components than in the current PON systems may degrade reliability performance of the network. Thus designing reliable NG-PON2 architectures is of a paramount importance. Moreover, for appropriately evaluating network reliability performance, new models are required. For example, the commonly used reliability parameter, i.e., connection availability, defined as the percentage of time for which a connection remains operable, doesn’t reflect the network wide reliability performance. The network operators are often more concerned about a single failure affecting a large number of customers than many uncorrelated failures disconnecting fewer customers while leading to the same average failure time. With this view, we introduce a new parameter for reliability performance evaluation, referred to as the failure impact. In this paper, we propose several reliable architectures for two important NG-PON2 candidates: wavelength division multiplexed (WDM) PON and time and wavelength division multiplexed (TWDM) PON. Furthermore, we evaluate protection coverage, availability, failure impact and cost of the proposed schemes in order to identify the most efficient protection architecture.

  • 385.
    Do, Tan Tai
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Optimal Transmission for the MIMO Bidirectional Broadcast Channel in the Wideband Regime2013In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 61, no 20, p. 5103-5116Article in journal (Refereed)
    Abstract [en]

    This paper considers a transmit strategy for an AWGN MIMO bidirectional broadcast channel in the wideband regime. In order to characterize the boundaries of the wideband capacity and energy per bit regions, the transmit strategy at the relay is designed to maximize the weighted wideband rate sum. A closed form of the optimal transmit covariance matrix is derived, which shows that a single beam transmit strategy is optimal. The transmit strategies for some special cases are also analyzed. The fairness versus energy efficiency tradeoff is then discussed. In addition, an extension to multipair MIMO bidirectional broadcast channel is studied in which we show that serving a certain pair with full power is optimal in the sense of maximizing the achievable weighted wideband rate sum. Finally, a discussion on the conjecture of the minimum energy per bit for multi-pair systems is provided.

  • 386.
    Do, Tan Tai
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Achievable energy per bit for the multi-pair MIMO bidirectional broadcast channel2012In: European Wireless, 2012. EW. 18th European Wireless Conference, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents a transmit strategy for the AWGN multi-pair MIMO bidirectional broadcast channels in the wideband regime. An achievable wideband rate region and an achievable energy per bit region are provided. The transmit covariance matrix at the relay has been designed in order to maximize the wideband weighted rate sum. A closed form of the optimal matrix is derived, which shows that a single beam transmit strategy is optimal. In addition, an energy efficiency versus fairness analysis is considered. Lastly, some discussions on the minimum energy per bit are given.

  • 387.
    Do, Tan Tai
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Optimal transmission for the MIMO bidirectional broadcast channel in the wideband regime2011In: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, 2011, p. 356-360Conference paper (Refereed)
    Abstract [en]

    This paper presents an optimal transmit strategy for multiple antennas bidirectional broadcast channels in the wideband regime. The transmit covariance matrix at the relay has been designed in order to maximize the wideband weighted sum rate. A closed form of the optimal matrix is derived, which shows that a single beam transmit strategy is optimal. The transmit strategies for some special cases, the wideband capacity region, and the minimum energy per bit versus fairness issues are also discussed.

  • 388.
    Do, Tan Tai
    et al.
    Electronic & Radio Engineering, KyungHee University.
    Park, Jae Cheol
    Electronic & Radio Engineering, KyungHee University.
    Song, Iickho
    Kim, Yun Hee
    Electronic & Radio Engineering, KyungHee University.
    Cross-layer design of multiple antenna multicast combining AMC with truncated HARQ2010In: Annales des télécommunications, ISSN 0003-4347, E-ISSN 1958-9395, Vol. 65, no 11-12, p. 803-815Article in journal (Refereed)
    Abstract [en]

    Combining adaptive modulation and coding with truncated hybrid automatic request, this paper presents a cross-layer design for multiple antenna multicast over a common radio channel. In the design, the modulation and coding scheme of a multicast packet is selected based on the minimum signal-to-noise ratio (SNR) in the multicast group in such a way that the constraint on the packet loss rate is satisfied for all users in the group. A general expression for the throughput of the proposed design is derived in frequency-flat fading channel environment and specific results in Rayleigh, Nakagami, and Rician fading channels are provided. It is shown that the proposed multicast design provides a significant throughput gain compared to the unicast counterpart, in particular, in the mid- to high SNR region. It is also shown that a larger value of the diversity order, Nakagami parameter, and Rician factor is more beneficial to multicast than to unicast.

  • 389.
    Do, Tan Tai
    et al.
    Electronics & Radio Engineering Department, KyungHee University.
    Park, Jae Chul
    Electronics & Radio Engineering Department, KyungHee University.
    Kim, Yun Hee
    Electronics & Radio Engineering Department, KyungHee University.
    Cooperative diversity for wireless multicast transmission with truncated ARQ2009In: 2009 9th International Symposium on Communications and Information Technology, ISCIT 2009, 2009, p. 947-948Conference paper (Refereed)
    Abstract [en]

    This paper proposes a cooperative diversity protocol with truncated automatic repeat request (ARQ) for multicast transmission. The proposed method employs SNR threshold-based selective relaying for distributed space time block coding for retransmission. Numerical results will show that the proposed method with optimal SNR threshold improves the error and throughput performance remarkably.

  • 390.
    Do, Tan Tai
    et al.
    Electronics & Radio Engineering Department, KyungHee University.
    Park, Jae Chul
    Electronics & Radio Engineering Department, KyungHee University.
    Kim, Yun Hee
    Electronics & Radio Engineering Department, KyungHee University.
    Song, Iickho
    Cross-Layer Design of Adaptive Wireless Multicast Transmission with Truncated HARQ2009In: 2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, 2009, p. 1879-1883Conference paper (Refereed)
    Abstract [en]

    This paper presents a cross-layer design of adaptive modulation and coding (AMC) with truncated hybrid automatic repeat request (HARQ) for one-to-many multicast transmission, in order to increase the spectral efficiency under the quality-of-service (QoS) constraints. For adaptive transmission over the channel common to the multicast group users, the AMC mode is chosen with the minimum SNR among the users to guarantee the target performance of all users. In the meanwhile, the minimum SNR required to support an AMC mode is aggressively designed by allowing retransmission with HARQ schemes. For the proposed design, we derive the average packet error rate, average number of transmission, and spectral efficiency and provide the performance numerically obtained. Numerical results show that the cross-layer design for multicast provides a significant performance gain at a small number of retransmissions as in unicast. In particular, it is observed that AMC design with HARQ is more beneficial in the low SNR region where multicast performs worse than unicast

  • 391. Dogadaev, Anton
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Deng, Lei
    Ruepp, Sarah
    Dittmann, Lars
    Christiansen, Henrik
    Experimental and simulation analysis of the W-band SC-FDMA hybrid optical-wireless transmission2014In: IEEE Photonics Conference (IPC), San Diego, CA, USA, 2014, p. 77-78Conference paper (Refereed)
  • 392. Dolfi, M.
    et al.
    Morosi, S.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Del Re, E.
    Energy efficient optimization of a sleep mode strategy in heterogeneous cellular networks2017In: EuCNC 2017 - European Conference on Networks and Communications, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7980740Conference paper (Refereed)
    Abstract [en]

    As base stations (BS) are responsible for the large amount of energy consumed in cellular networks, energy efficient BS sleep mode techniques have the potential to save a significant amount of energy. However, assuming that BSs are able to alternate between sleeping and active states as frequently as possible may have a negative impact on network reliability, shortening BS lifetime. In this paper we propose a multiobjective optimization framework aimed at minimizing the power consumption and number of BS sleep mode switchings in heterogeneous cellular networks (HetNet), by jointly considering Quality of Service (QoS) requirements. We focus on the HetNet scenario in which macro and micro cells coexist. The Mixed Integer Quadratic Programming (MIQP) optimization technique is used to minimize the power consumption together with the number of BS sleep mode operations of both macro and micro cells. The trade-off between power consumption, sleep mode switchings and performance of the network is shown for different energy saving solutions. Results show that the proposed optimization can guarantee QoS target throughput for users and significant reduction of 50% for macro and 73% for micro BS respectively daily number of switchings, while still achieving 8% savings in terms of daily energy consumption.

  • 393. Dombrowski, Christian
    et al.
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Reducing Outage Probability over Wireless Channels Under Hard Real-Time Constraints2011Conference paper (Refereed)
  • 394. Dombrowski, Christian
    et al.
    Junges, Sebastian
    Katoen, Joost Pieter
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Model-Checking Assisted Protocol Design for Ultra-Reliable Low-Latency Wireless Networks2016Conference paper (Refereed)
    Abstract [en]

    Recently, the wireless networking community is getting more and more interested in novel protocol designs for safety-critical applications. These new applications come with unprecedented latency and reliability constraints which poses many open challenges. A particularly important one relates to the question how to develop such systems. Traditionally, development of wireless systems has mainly relied on simulations to identify viable architectures. However, in this case the drawbacks of simulations – in particular increasing run-times – rule out its application. Instead, in this paper we propose to use probabilistic model checking, a formal model-based verification technique, to evaluate different system variants during the design phase. Apart from allowing evaluations and therefore design iterations with much smaller periods, probabilistic model checking provides bounds on the reliability of the considered design choices. We demonstrate these salient features with respect to the novel EchoRing protocol, which is a token-based system designed for safety-critical industrial applications. Several mechanisms for dealing with a token loss are modeled and evaluated through probabilistic model checking, showing its potential as suitable evaluation tool for such novel wireless protocols. In particular, we show by probabilistic model checking that wireless tokenpassing systems can benefit tremendously from the considered fault-tolerant methods. The obtained performance guarantees for the different mechanisms even provide reasonable bounds for experimental results obtained from a real-world implementation.

  • 395. Dombrowski, Christian
    et al.
    Petreska, Neda
    Görtzen, Simon
    Schmeink, Anke
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Energy-efficient multi-hop transmission for machine-to-machine communications2013In: 2013 11th International Symposium and Workshops on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, WiOpt 2013, 2013, p. 341-348Conference paper (Refereed)
    Abstract [en]

    Emerging machine-to-machine communication scenarios are envisioned to deal with more stringent quality-of-service demands. This relates mainly to outage and latency requirements, which are for example for safety-critical messages quite different than for traditional applications. On the other hand, it is widely accepted that machine-to-machine communication systems need to be energy-efficient because of the widespread use of battery-powered devices, but also due to their huge deployment numbers. In this paper, we address these issues with respect to multi-hop transmissions. Specifically, we deal with minimizing the consumed energy of transmitting a packet with end-to-end outage and latency requirements. We account for the cases in which the system can utilize solely average channel state information, or in addition obtain and profit from instantaneous channel state information. The developed solution is based on convex optimization. It is shown numerically that despite accounting for the energy consumption of acquiring instantaneous channel state information, especially as the outage and latency requirements become tough, it is by up to 100 times more energy efficient to convey a packet with instantaneous than with average channel state information.

  • 396.
    Dominique, Torkel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Push services based on SIP2001Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Session Initiation Protocol (SIP) is the most potential protocol for Real Time IP communication, for example IP telephony, today. This M.Sc. thesis project aim to create a solution for information providers to push information to a large numbers of users, using the SIP protocol and a number of proposed extensions to SIP. The system will be built on a SUBSCRIBE/NOTIFY mechanism similar to the one used for instant messages and presence. This system can be used for companies to build information push services (i.e. News, Traffic information, etc.) or to push commercial advertisement.

    The reason to use the SIP protocol for this is that SIP has already solved the addressing problem by introducing email-like addresses that follow the user when he moves around in the system. This is perfect for the push service that wants to reach the user wherever he is.

  • 397.
    Domínguez Sánchez, Carlos
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Speaker Recognition in a handheld computer2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Handheld computers are widely used, be it a mobile phone, personal digital assistant (PDA), or a media player. Although these devices are personal, often a small set of persons can use a given device, for example a group of friends or a family.

    The most natural way to communicate for most humans is through speech. Therefore a natural way for these devices to know who is using them is for the device to listen to the user’s speech, i.e., to recognize the speaker based upon their speech.

    This project exploits the microphone built into most of these devices and asks whether it is possible to develop an effective speaker recognition system which can operate within the limited resources of these devices (as compared to a desktop PC). The goal of this speaker recognition is to distinguish between the small set of people that could share a handheld device and those outside of this small set. Therefore the criteria is that the device should work for any of the members of this small set and not work for anyone outside of this small set. Furthermore, within this small set the device should recognize which specific person within this small group is using it.

    An application for a Windows Mobile PDA has been developed using C++. This application and its underlying theoretical concepts, as well as parts of the code and the results obtained (in terms of accuracy rate and performance) are presented in this thesis. The experiments conducted within this research indicate that it is feasible to recognize the user based upon their speech is within a small group and further more to identify which member of the group is the user. This has great potential for automatically configuring devices within a home or office environment for the specific user. Potentially all a user needs to do is speak within hearing range of the device to identify themselves to the device. The device in turn can configure itself for this user. 

  • 398. Donde, Shrinish
    Optimal Robot Localisation Techniques for Real World Scenarios2019Conference paper (Other academic)
    Abstract [en]

    The following paper is a thorough review of our research based on the localisation of robots. It is an attempt to segregate the techniques, to locate the accurate position of robots in different environments and to discuss the superlative methods to localise such robots or in some cases an unmanned vehicle. The paper is divided into three real world problem statements and a thorough analysis of the best technique amongst other is made, for all the three conditions namely underwater, indoor and space, based on a number of parameters such as the cost, accuracy, efficiency, implementation of the technique and the environmental conditions around the robot. The primary reason to select these problem statements is due to the recent trends of research in these domains. Each of the technique has been chosen after discarding several previously applied techniques and an effective approach has been put forward for localising the robots in different areas.

  • 399. Dordlofva, Bengt
    et al.
    Karlsson, Magnus
    Larsson, Per
    Larsson, Thomas
    Zetterberg, Per
    KTH.
    Arrangement for Frequency Planning in Cellular Systems1999Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The invention relates to an arrangement for frequency planning in cellular systems using a mix of wide and narrow antenna beams. The arrangement employs a dual frequency reuse for the respective wide and narrow antenna beams. According to the invention, a first frequency group is allocated to a cluster with a reuse distance sufficient for narrow beam channels and a second frequency group is allocated to a larger cluster with a reuse distance sufficent for wide beam channels. The second frequency group is a subdivision of and contained in the first frequency group. The second frequency group is the only frequency group available for wide beam channels, while all the frequencies of the two groups are available for the narrow beams channels. Generally, the wide beams are used for control channels and the narrow beams are used for traffic channels. A frequency planning in accordance with the invention makes it possible to use narrow beam traffic channels more efficiently compared to known state of the art methods which results in improved trunking efficiency.

  • 400.
    Dreier, Dennis
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Smart City Concepts in Curitiba - innovation for sustainable mobility and energy efficiency: Project NEWSLETTER, January 20162016Other (Other (popular science, discussion, etc.))
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