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  • 1.
    Apanasevic, Tatjana
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Arvidsson, Niklas
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Hållbarhet och industriell dynamik.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Mobile payments: a proposal for a context-oriented approach based on socio-technical system theoryIngår i: Journal of Innovation Management, ISSN 2183-0606Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A recent review on mobile payment research by Dahlberg et al. (2015) concludes that there is a need to synthesise this research area by studying contexts in which innovation is done as well as to integrate different aspects of research. This article aims to provide a proposal for how to achieve such integration and context-orientation by building on previous studies as well as an additional review. Our systematic literature review of mobile payments research is focused on papers published during 2006–2016. The main objective is to examine how mobile payments research has been conducted from the methodological and theoretical perspectives. Our findings show that research on mobile payments is a multidisciplinary research. Three main themes, which are in line with previous studies, in research are: customer adoption, technological aspects, and business aspects. Moreover, research is mainly analytical based on deductive approach. To meet the challenge formulated in the previous research, we propose and apply a socio-technical system framework to achieve synthesis and context-specific consideration in future research on mobile payments.

  • 2.
    Apanasevic, Tatjana
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Mobile ticketing services in the Northern Europe: Critical business model issues2018Ingår i: Internet of Things Business Models, Users, and Networks, 2017 / [ed] Morten Falch, Copenhagen, Denmark: IEEE, 2018, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    Started as SMS ticketing, today, mobile ticketing services become a platform for combined mobility solutions that integrate mobile ticketing, bike renting, car sharing, and parking payment services. Mobile ticketing services provide a number of benefits for public transport companies and passengers, however, in some Northern European countries, the share of mobile ticket sales does not exceed 10 percent. In this paper, we analyse business models of three types of mobile ticketing services (SMS, in-app, and “Be-In Be-Out” (BIBO)) in order to identify factors that negatively affect wider penetration of mobile ticketing. In order to do so, we use STOF (Service, Technology, Organisation, and Finance) model. The research reveals that there are a number of challenges related to service, technology, and finance domains of mobile ticketing. Due to this, with the help of price policy, many public transport companies push choices of their customers towards use of plastic travel card.

  • 3.
    Apanasevic, Tatjana
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Mobile ticketing services in the Northern Europe Critical business model issues2017Ingår i: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Started as SMS ticketing, today, mobile ticketing services become a platform for combined mobility solutions that integrate mobile ticketing, bike renting, car sharing, and parking payment services. Mobile ticketing services provide a number of benefits for public transport companies and passengers, however, in some Northern European countries, the share of mobile ticket sales does not exceed 10 percent. In this paper, we analyse business models of three types of mobile ticketing services (SMS, in-app, and "Be-InBe-Out" (BIBO)) in order to identify factors that negatively affect wider penetration of mobile ticketing. In order to do so, we use STOF (Service, Technology, Organisation, and Finance) model. The research reveals that there are a number of challenges related to service, technology, and finance domains of mobile ticketing. Due to this, with the help of price policy, many public transport companies push choices of their customers towards use of plastic travel card.

  • 4.
    Apanasevic, Tatjana
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    The value of mobile ticketing from a public transport perspective2018Ingår i: Journal of Payments Strategy & Systems, Vol. 11, nr 4, s. 292-305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Within the field of mobile payments, the market segment for mobile ticketing services is expected to grow, driven by the public transport sector. Although a large number of studies have explored the value of mobile payments to customers (ie service end users), there is a lack of research exploring the value of mobile payment and mobile ticketing for business customers (ie transport companies and retailers). This paper aims to address this gap and to explore the kinds of value that mobile ticketing services create for public transport companies. The research considers mobile ticketing services in six Northern European countries. The research findings suggest that within the business-to-business context, mobile ticketing services create multiple dimensions of value, namely enhanced technical functionality; financial value; better working environment; operational value; and reputational and customer relationship value. For passengers, meanwhile, value takes the form of convenience and service enhancement. These benefits are factors driving adoption of mobile ticketing and mobile payment services by public transport companies.

  • 5.
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Bitcoin Price Prediction: An ARIMA ApproachManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Bitcoin is considered as the most valuable currency in the world. Besides being highly valuable, its value has also experienced a steep increase, from around 1 dollar in 2010 to around 18000 in 2017. Then, in recent years, it has attracted considerable attention in a diverse set of fields, including economics and computer science. The former mainly focuses on studying how it affects the market, determining reasons behinds its price fluctuations, and predicting its future prices. The latter mainly focuses on its vulnerabilities, scalability, and other techno-cryptoeconomic issues. Here, we aim at revealing the usefulness of traditional autoregressive integrative moving average (ARIMA)model in predicting the future value of bitcoin by analyzing the price time series in a 3-years-long time period. On the one hand, our empirical studies reveal that this simple scheme is efficient in sub-periods in which the behavior of the time-series is almost unchanged, especially when it is used for short-term prediction,e.g. 1-day. On the other hand, when we try to train the Arima model to a 3-years-long period, during which the bitcoin price has experienced different behaviors, or when we try to use it for a long-term prediction, we observe that it introduces large prediction errors. Especially, the ARIMA model is unable to capture the sharp fluctuations in the price, e.g. the volatility at the end of 2017. Then, it calls for more features to be extracted and used along with the price for a more accurate prediction of the price. We have further investigated the bitcoin price prediction using an ARIMA model trained over the whole dataset, as well as a limited part of the history of the bitcoin price, with length of w, as inputs. Our study sheds lights on the interaction of the prediction accuracy, choice of (p; q; d), and window size w.

  • 6.
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    On the DoF and Secure DoF of K-User MIMO Interference Channel with Instantaneous Relays2019Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Interference channel, in which multiple user pairs communicate over shared resources, is a building block of communications networks. Here, the K-user interference channel (IC) aided by J instantaneous relays (IRs), i.e. relays without delay, is considered. For KICJR networks, where K>2 and J>1, the DoF performance and achievable schemes have not been investigated in literature. Here, we devise a novel achievable scheme, called restricted interference alignment (RIA), which restricts the received interference from each source at each destination in a limited sub-space, and then, aligns the restricted interferences. Furthermore, we develop an analytical tool for finding a tight upper bound on DoF of KICJR networks by analyzing the properness of the interference alignment equations. Moreover, we develop linear beamforming design for sources and relays based on the mean square error (MSE) minimization, as an achievable scheme. The performance evaluation results show that the achievable sum DoF by using the proposed RIA scheme and the MSE-based beamforming design match well with the derived upper bounds. Furthermore, the results confirm that the achieved sum DoF using the RIA scheme outperforms the existing achievable schemes. Motivated by these promising results, we further investigate impact of IRs in providing physical layer security, i.e. achieving secure DoF in interference networks. Specifically, we derive a lower bound on the achievable secure DoF by devising an achievable scheme, called transmission in the null space (TNS). This scheme makes the cross channels rank deficient and enables sources to select their transmit filters in the constructed null spaces. Performance evaluation shows that by leveraging IRs, the secure DoF performance of interference networks could be increased significantly. The proposed analytical framework in this work for rank deficiency-powered DoF analysis is expected to also attract attention from other research areas, e.g. beamforming design for millimeter wave communications.

  • 7.
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Serving IoT Communications over Cellular Networks: Challenges and Solutions in Radio Resource Management for Massive and Critical IoT Communications2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Internet of Things (IoT) communications refer to the interconnections of smart devices, with reduced human intervention, which enable them to participate more actively in everyday life. It is expected that introduction of a scalable, energy efficient, and reliable IoT connectivity solution can bring enormous benefits to the society, especially in healthcare, wellbeing, and smart homes and industries. In the last two decades, there have been efforts in academia and industry to enable IoT connectivity over the legacy communications infrastructure. In recent years, it is becoming more and more clear that the characteristics and requirements of the IoT traffic are way different from the legacy traffic originating from existing communications services like voice and web surfing, and hence, IoT-specific communications systems and protocols have received profound attention. Until now, several revolutionary solutions, including cellular narrowband-IoT, SigFox, and LoRaWAN, have been proposed/implemented. As each of these solutions focuses on a subset of performance indicators at the cost of sacrificing the others, there is still lack of a dominant player in the market capable of delivering scalable, energy efficient, and reliable IoT connectivity. The present work is devoted to characterizing state-of-the-art technologies for enabling large-scale IoT connectivity, their limitations, and our contributions in performance assessment and enhancement for them. Especially, we focus on grant-free radio access and investigate its applications in supporting massive and critical IoT communications. The main contributions presented in this work include (a) developing an analytical framework for energy/latency/reliability assessment of IoT communications over grant-based and grant-free systems; (b) developing advanced RRM techniques for energy and spectrum efficient serving of massive and critical IoT communications, respectively; and (c) developing advanced data transmission/reception protocols for grant-free IoT networks. The performance evaluation results indicate that supporting IoT devices with stringent energy/delay constraints over limited radio resources calls for aggressive technologies breaking the barrier of the legacy interference-free orthogonal communications.

  • 8.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Bria, Aurelian
    System and method for providing communication rules based on a status associated with a battery of a device2017Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The disclosure relates to communication systems and, more particularly, to a system and method for providing communication rules based on a status associated with a battery of a device.

  • 9.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Performance Evaluation and Optimization of LPWA IoT Networks: A Stochastic Geometry Approach2018Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, IEEE, 2018, artikel-id 8647881Konferensbidrag (Refereegranskat)
    Abstract [en]

    Leveraging grant-free radio access for enabling low-power wide-area (LPWA) Internet of Things (IoT) connectivity has attracted lots of attention in recent years. Regarding lack of research on LPWA IoT networks, this work is devoted to reliability modeling, battery-lifetime analysis, and operation-control of such networks. We derive the interplay amongst density of the access points, communication bandwidth, volume of traffic from heterogeneous sources, and quality of service (QoS) in communications. The presented analytical framework comprises modeling of interference from heterogeneous sources with correlated deployment locations and time-frequency asynchronous radio-resource usage patterns. The derived expressions represent the operation regions and rates in which, energy and cost resources of devices and the access network, respectively, could be traded to achieve a given level of QoS in communications. For example, our expressions indicate the expected increase in QoS by increasing number of transmitted replicas, transmit power, density of the access points, and communication bandwidth. Our results further shed light on scalability of such networks and figure out the bounds up to which, scaling resources can compensate the increase in traffic volume and QoS demand. Finally, we present an energy-optimized operation control policy for IoT devices. The simulation results confirm tightness of the derived analytical expressions, and indicate usefulness of them in planning and operation control of IoT networks.

  • 10.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Self-organized Low-power IoT Networks: A Distributed Learning Approach2018Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Enabling large-scale energy-efficient Internet-ofthings (IoT) connectivity is an essential step towards realization of networked society. While legacy wide-area wireless systems are highly dependent on network-side coordination, the level of consumed energy in signaling, as well as the expected increase in the number of IoT devices, makes such centralized approaches infeasible in future. Here, we address this problem by self-coordination for IoT networks through learning from past communications. To this end, we first study low-complexity distributed learning approaches applicable in IoT communications. Then, we present a learning solution to adapt communication parameters of devices to the environment for maximizing energy efficiency and reliability in data transmissions. Furthermore, leveraging tools from stochastic geometry, we evaluate the performance of proposed distributed learning solution against the centralized coordination. Finally, we analyze the interplay amongst energy efficiency, reliability of communications against noise and interference over data channel, and reliability against adversarial interference over data and feedback channels. The simulation results indicate that compared to the state of the art approaches, both energy efficiency and reliability in IoT communications could be significantly improved using the proposed learning approach. These promising results, which are achieved using lightweight learning, make our solution favorable in many low-cost low-power IoT applications.

  • 11.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Ozger, Mustafa
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Serving Non-Scheduled URLLC Traffic: Challenges and Learning-Powered StrategiesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Supporting ultra-reliable low-latency communications (URLLC) is a major challenge of 5G wireless networks. Whilst enabling URLLC is essential for realizing many promising 5G applications, the design of communications' solutions for serving such unseen type of traffic with stringent delay and reliability requirements is in its infancy. In prior studies, physical and MAC layer solutions for assuring the end-to-end delay requirement of scheduled URLLC traffic have been investigated. However, there is lack of study on enabling non-scheduled transmission of urgent URLLC traffic, especially in coexistence with the scheduled URLLC traffic. This study at first sheds light into the coexistence design challenges, especially the radio resource management (RRM) problem. It also leverages recent advances in machine learning (ML) to exploit spatial/temporal correlation in user behaviors and use of radio  resources, and proposes a distributed risk-aware ML solution for RRM. The proposed solution benefits from hybrid orthogonal/non-orthogonal radio resource slicing, and proactively regulates the spectrum needed for satisfying delay/reliability requirement of each traffic type. A case study is introduced to investigate the potential of the proposed RRM in serving coexisting URLLC traffic types. The results further provide insights on the interplay between the reliabilities of coexisting traffic, uncertainties in users' demands and channel conditions, and amount of required radio resources.

  • 12.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Masoudi, Meysam
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Optimized Resource Provisioning and Operation Control for Low-power Wide-area IoT NetworksManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Grant-free radio access is a promising solution for reducing energy consumption and access delay in low power wide-area (LPWA) Internet of Things (IoT) networks. This work is devoted to reliability modeling, battery-lifetime analysis, resource provisioning, and operation control for grantfreeIoT networks. Our modeling captures correlation in devices’locations, benefits from 3D (time/frequency/code) interference analysis, and enables coexistence analysis of multi-type IoT technologies. We derive the interplay amongst density of the access points, communication bandwidth, traffic volume, and quality of service (QoS) of communications. Deriving the interplay enables scalability analysis, i.e. it figures out the required increase in device's energy consumption (or access network’s resources) for compensating the increase in traffic volume or QoS demand. Our major contribution consists in deriving traffic loads and respective exchange rates in which, energy and cost resources of devices and the access network, respectively, could be traded to achieve a given level of QoS. We further indicate operation regions in which scaling a parameter turns from being a friend into a foe. Finally, we present energy- and cost-optimized operation control and resource provisioning strategies, respectively. The simulation results confirm tightness of the analytical expressions, and indicate the usefulness of them in planning and operation control of IoT networks.

  • 13.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Stefanovic, Cedomir
    Aalborg University.
    Popovski, Petar
    Aalborg University.
    Latency-Energy Tradeoff based on Channel Scheduling and Repetitions in NB-IoT Systems2018Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, artikel-id 8648024Konferensbidrag (Refereegranskat)
    Abstract [en]

    Narrowband Internet of Things (NB-IoT) is the latest IoT connectivity solution presented by the 3rd generation partnership project (3GPP). NB-IoT introduces coverage classes and offers a significant link budget improvement by allowing repeated transmissions by nodes that experience high path loss. However, those repetitions necessarily increase the energy consumption and the latency in the whole NB-IoT system. The extent to which the whole system is affected depends on the scheduling of the uplink and downlink channels. We address this question, not treated previously, by developing a tractable model of NB-IoT access protocol operation, comprising message exchanges in random-access, control, and data channels, both in the uplink and downlink The model is then used to analyze the impact of channel scheduling as well as the interaction of coexisting coverage classes, through derivation of the expected latency and battery lifetime for each coverage class. These results are subsequently employed in investigation of latency-energy tradeoff in NB-IoT channel scheduling as well as determining the optimized operation points. Simulations results show validity of the analysis and confirm that channel scheduling and coexistence of coverage classes significantly affect latency and battery lifetime performance of NB-IoT devices.

  • 14.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Popovski, Petar
    Stefanovic, Cedomir
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Grant-Free Radio Access for Cellular IoTManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Radio resource management (RRM) is a major factor affecting the delay, reliability, and energy consumption of Internet of Things (IoT) communications. This article is focused on grant-free access, a class of techniques suited to support massive IoT connectivity. Within the proposed scheme, the IoT devices transmit multiple replicas of the same packet. In addition to that, the receiver makes use of the random timing and frequency offsets in order to carry out Successive Interference Cancellation (SIC). The system performance is investigated by using a model based on stochastic geometry, leading to closed-form expressions for the key performance indicators, such as reliability and battery lifetime. The framework allows optimization of the number of replicas per device. This results in overall improvement of the energy consumption, delay and reliability, at the expense of more complex processing at the Base Station. The evaluation results indicate that the proposed data transmission and reception schemes can significantly prolong battery lifetime of IoT devices by removing the need for connection establishment and reducing the number of retransmissions. The obtained results also indicate existence of traffic-load regions, where grant-free radio access outperforms the grant-based one, which is used in LTE and NB-IoT systems. These results pave the way for enabling intelligent grant-based/free operation mode switching in 5G networks.

  • 15.
    Bai, Chumeng
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Evaluation and Improvement of Decentralized Congestion Control for Multiplatooning Application2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Platooning (fordonskonvojer) har potential att bli ett genombrott i öka vägkapaciteten och minska bränsleförbrukning, eftersom det tillåter en kedja av fordon att noga följa varandra på vägen. När antalet fordon ökar, kommer att plutoner följa varandra i vad som benämns multiplatooning (konvoj av fordonskonvojer). Många kooperativ intelligenta transportsystem (C-ITS) tillämpningar förlitar sig på regelbundet utbytte beacons bland fordon att förbättra traffiksäkerheten. Dock som antalet uppkopplade fordon ökar, kan nätverket bli överbelastat på grund av regelbundet utbytte beacons. Utan någon trängsel kontrollmetod, får därför säkerhet kritiska meddelanden såsom kooperativ medvetenhet meddelanden (CAMs) inte levereras i tid i höga fordon densitet scenarier. Både Europeiska institutet för telekommunikationsstandarder (ETSI) och Institute el och elektroniska tekniker (IEEE) har arbetat på olika standarder för att stödja vehicular kommunikation. ETSI definieras den decentraliserade överbelastning kontroll (DCC) mekanism som anpassar överföring parametrar (meddelande hastighet, överföra datahastighet och sändningseffekt, etc.) för att hålla kanalen belastningen under kontroll. ETSI DCC använder en tre-state maskin med RELAXED, ACTIVE och RESTRICTIVE stater. I denna avhandling har genomfört vi denna tre-state maskin genom att anpassa meddelande hastighet baserat på kanal upptagen förhållandet (CBR). Vi nämna detta meddelande-hastighet baserat tre-state machine DCC-3. DCC-3 har förmågan att kontrollera kanal belastning; Det har dock otillbörlighet och instabilitet problem på grund av de dramatiska parameterändringar mellan stater. Därför vi indelat det ACTIVE tillståndet för DCC-3 i fem undertillstånd och hänvisar till detta som DCC-7. Vi benchmarkade DCC-3 mot statiska leda (STB), dynamisk leda (DynB), linjära MEssage Rate integrerad kontroll (LIMERIC) och DCC-7 med olika utvärdering statistik med olika antal plutoner. Våra resultat från Plexe simulator visar att DCC-7 har bästa prestanda när man överväger alla utvärdering statistik, inklusive CBR, mellan receptionen tid (IRT), kollisioner, säker tid baserat och rättvisa. Vi fann dessutom använda Sändareffektstyrning kan avsevärt förbättra prestanda för CBR och kollision priser.

  • 16.
    Barbette, Tom
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS, Network Systems Laboratory (NS Lab).
    Katsikas, Georgios P.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS, Network Systems Laboratory (NS Lab).
    Maguire Jr., Gerald Q.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Kostic, Dejan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS.
    RSS++: load and state-aware receive side scaling2019Ingår i: Proceedings of the 15th International Conference on emerging Networking EXperiments and Technologies / [ed] ACM, Orlando, FL, USA: Association for Computing Machinery (ACM), 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    While the current literature typically focuses on load-balancing among multiple servers, in this paper, we demonstrate the importance of load-balancing within a single machine (potentially with hundreds of CPU cores). In this context, we propose a new load-balancing technique (RSS++) that dynamically modifies the receive side scaling (RSS) indirection table to spread the load across the CPU cores in a more optimal way. RSS++ incurs up to 14x lower 95th percentile tail latency and orders of magnitude fewer packet drops compared to RSS under high CPU utilization. RSS++ allows higher CPU utilization and dynamic scaling of the number of allocated CPU cores to accommodate the input load, while avoiding the typical 25% over-provisioning. RSS++ has been implemented for both (i) DPDK and (ii) the Linux kernel. Additionally, we implement a new state migration technique, which facilitates sharding and reduces contention between CPU cores accessing per-flow data. RSS++ keeps the flow-state by groups that can be migrated at once, leading to a 20% higher efficiency than a state of the art shared flow table.

  • 17.
    Besharat Pour, Shiva
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Li, Qi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Connecting Silos: Automation system for thesis processing in Canvas and DiVA2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    När digitaliseringens tid uppstår, så blir behovet av att integrera separata silor i ett synkroniserat anslutet system större. Denna avhandling fokuserar på Canvas Learning Management System (LMS) och Digitala vetenskapliga arkivet (DiVA) som är exempel på separata silor.

    Avhandlingen presenterar flera metoder för automatisering av dokumenthantering för examensarbeten. Projektet utnyttjar det faktum att eleverna kommer att skicka sin avhandling till sin examinator via Canvas. Canvas är den LMS-plattform som används av eleverna för att lämna in sitt kursarbete. När examinatorn godkänner avhandlingen kommer den att arkiveras i DiVA och eventuellt publiceras på DiVA. DiVA är ett institutionellt arkiv som används för forskningspublikationer och studentavhandlingar.

    När man manuellt arkiverar och publicerar studentuppsatser på DiVA måste flera fält fyllas i. Dessa fält ger metadata för själva avhandlingen. Innehållet i dessa fält (författare, titel, nyckelord, abstrakt, ...) kan användas vid sökning via DiVA-portalen. Även om det inte är en stor uppgift att skriva in denna metadata för en individuell uppsats så blir det en mycket tidskrävande process för många examensarbeten. Dessutom är det viktigt att ange dessa uppgifter korrekt, vilket är svårt när man manuellt utför den här uppgiften. Därför syftar detta avhandlingsprojekt till att automatisera denna process för framtida avhandlingar.

    Lösningen som presenteras i denna avhandling kommer att analysera PDF-dokument och använda annan information från LMS för att automatiskt skapa en fram- och baksida för avhandlingen och fylla i de nödvändiga DiVA-metadata. Grunden för införandet av denna data i ett kalendersystem för att ge ett meddelande om studentens presentation kommer också att ges. Dessutom kontrolleras uppgifterna för korrekthet.

    Manuell fyllning av DiVA-fält för att publicera avhandlingar har varit en ganska arbetsam och tidskrävande process. Således är det ofta en fördröjning innan en avhandling publiceras på DiVA. Därför ska detta projektet ge KTH ett automatiserat system att hantera avhandlingar och publicering på DiVA, samtidigt som det gör det mer effektivt och med färre fel. Korrektheten hos de extraherade metadatan kommer att utvärderas genom att jämföra resultaten med de tidigare inmatade metadatan för examensarbeten som redan ligger uppe på DiVA.  Den automatiska processen tar ungefär 50 sekunder att förbereda information för att publicera en avhandling till DiVA med ~ 71% noggrannhet jämfört med 1 timme och 34% noggrannhet i tidigare manuell metod.

  • 18.
    Cavdar, Cicek
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Gera, Damini
    Airbus, Ottobrunn, Germany..
    Ghosh, Ayan
    BT, Bristol, Avon, England..
    Hofmann, Sandra
    Airbus, Ottobrunn, Germany..
    Nordlow, Anders
    Ericsson, Stockholm, Sweden..
    Schupke, Dominic
    Airbus, Ottobrunn, Germany..
    Demonstration of an Integrated 5G Network in an Aircraft Cabin Environment2018Ingår i: 2018 IEEE/AIAA 37TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC), IEEE , 2018, s. 334-343Konferensbidrag (Refereegranskat)
    Abstract [en]

    The wireless communications finds many applications inside an aircraft cabin, in terms of Passenger and Crew Communications as well as Machine Type Communications (MTC). The aircraft cabin is a challenging environment and the different wireless technologies must be adequately tested and adapted to achieve maximum performance. In this regard, an aircraft environment has been analyzed in this paper for an in-cabin wireless system implementation and the measurement results have been further evaluated. This is an integrated system for the technologies of LTE, LAA and NB-IoT for the potential use-cases of Passenger Connectivity, On-Board Sensing, Cargo Tracking and Passenger Announcement. Results have then been summarized within the scope of this paper.

  • 19.
    Celik, Haris
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Feasibility and Performance of Dynamic TDD in Dense and Ultra-Dense Wireless Access Networks2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Meeting the seemingly never-ending increase in traffic over wireless networks presents a major challenge for future mobile network design. Given that much of the traffic is expected to be more time-varying and unpredictable, time division duplexing (TDD) is gaining increasing favorability in part thanks to its ability to better accommodate network-wide traffic variations. In order to account for traffic variations in individual cells on much shorter time scales, a more flexible variant called dynamic TDD has resurfaced as a promising technique to further improve resource utilization and performance. In dynamic TDD the traffic in each cell can be served immediately in either direction, but generates same-entity interference which is potentially more harmful. To avoid the much stronger downlink from saturating the uplink, this thesis considers dynamic TDD for dense and ultra-dense networks where transmission powers in the two directions are of comparable strength. Still, inter-cell interference remains an issue given the close proximity of some links. Because of the large number of cells comprising dense and ultra-dense networks, it is imperative that the interference management be both effective and scalable, which is the main focus of this thesis.

    In the first part we focus on scalable radio resource management (RRM). We show that non-cooperative dynamic TDD is feasible for indoor ultra-dense deployment and highlight the benefit of employing beamsteering at both the base station (BS) and user equipment (UE) to mitigate interference distributively, especially at high load. Recognizing that beamsteering is better suited for higher frequencies and high data rate applications, we proceed to investigate the efficacy of receive-side interference management in the form of successive interference cancellation (SIC). Being that the interference distribution is different in dynamic TDD, we show that it suffices to cancel only strongest interferer at the UE side and the two strongest interferers at the BS. The combined benefit of SIC and dynamic TDD in reducing delay for low-rate traffic is also displayed. Next, we introduce limited inter-cell information exchange in order to leverage the resource allocation in the medium access control (MAC). To minimize the amount of information exchange and preserve scalability, a scheduling framework is proposed that relates real-time traffic to inter-BS interferences measured offline and mapped to the individual activation probability of each BS. The proposed scheme is shown to perform well with respect to comparable scalable schedulers when interference is high, and optimally when interference is low.

    In ultra-dense networks it is expected that some BSs might not have a UE to serve. In the second part, we therefore introduce cooperation to utilize the otherwise idle BSs to improve network performance. To mitigate both same- and other-entity interference, zero forcing (ZF) precoding is employed where not only downlink UEs but also uplink BSs are included in the beamforming. Results show that both uplink and downlink performance improves at low and medium load, and that it is possible to trade performance in the two directions at high load.

  • 20.
    Celik, Haris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Sung, Ki Won
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Efficacy of Successive Interference Cancellation in Dynamic TDD Cellular NetworksManuskript (preprint) (Övrigt vetenskapligt)
  • 21.
    Celik, Haris
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Sung, Ki Won
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Success Probability of Successive Interference Cancellation in Random Wireless NetworksManuskript (preprint) (Övrigt vetenskapligt)
  • 22.
    Chang, Peiliang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cross-Layer Energy-Efficient Mobile Network Design2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    För att säkerställa en hållbar utveckling av framtidens mobilnät är det avgörande att förbättra energieffektiviteten i dem. Denna avhandling ägnas därför åt utformningen av energieffektiva mobilnät. En designmetod över lagren antas, där resurshanteringen i MAC-lagret, nätverkslagret samt servicelagret optimeras för att förbättra energieffektiviteten. Problemet att optimera MAC-lagrets resursallokering i nedlänk i NOMA-system med flera bärare för att maximera systemets energieffektivitet samtidigt som användarnas QoS-krav uppfylls betraktas först. Den optimala effektfördelningen över delbärare och över användare som delar en delbärare föreslås. Genom att utnyttja lösningsstrukturen för den optimala effektallokeringen mellan användare som delar en delbärare, utvecklas en suboptimal lösning för delbärartilldelning, vilket gynnsamt minimerar den behövda effekten för att serva alla användare med erforderlig QoS. Förutom att optimera kanaltilldelningen och effektfördelningen i en enda cell, studeras även länkschemaläggningen i ett flercellsscenario för att hantera mellancellsstörningar. En skalbar och distribuerad lösning för länkschemaläggning föreslås för att orkestrera sändning och DTX-mikrosömn av flera basstationer så att både mellancellsstörningar och energiförbrukning minskas. I nätverkslagret optimeras driften av basstationens sovande för att förbättra mobilnätets energieffektivitet utan att för den delen försämra användarnas QoS. Spektral- och energieffektiviteten i mobilnät där basstationer är aktiverade med DTX studeras först under olika trafikbelastningar. Det visar sig att när nätverksbelastningen ökar, så minskar länkspektraleffektiviteten medan nätverksspektraleffektiviteten ökar. När det gäller nätverksenergieffektiviteten så kommer den antingen att först öka och sedan minska, eller alltid öka i takt med att nätverksbelastningen ökar. Den optimala nätverksbelastningen för att maximera nätverksenergieffektiviteten beror på effektförbrukningen hos basstationer i DTX-viloläge. Baserat på resultaten från ovanstående studie undersöks sedan den kombinerade optimeringen av cell-DTX och djupsömn för att maximera nätverksenergieffektiviteten. En skalningslag för sändningseffekt föreslås som säkerställer att fördelningen av den mottagna effekten förblir oförändrad när fler basstationer kopplas om till djupsömn. Genomsnittliga resursutnyttjandet och överbelastningssannolikheten för basstationer som ej är i djupsömnläge härleds också. Baserat på dessa resultat erhålls ett möjligt intervall på andelen basstationer i djupsömnläge. Slutligen härleds den optimala andelen basstationer i djupsömnläge för att maximera nätverksenergieffektiviteten samtidigt som användarnas QoS-krav uppfylls. Till sist optimeras resurstilldelningen i tjänstelagret för kantnodsberäkning (eng. edge computing), i syfte att förbättra energieffektiviteten i mobilnäten. Vi studerar avvägningen mellan servicefördröjning och energiförbrukning i beräknings- och kommunikationsdelsystemen, och visar att belastningen i delsystemen bör balanseras. Att öka resurserna hos det högt belastade delsystemet kan avsevärt minska resurserna för andra delsystem. En algoritm föreslås för att ta reda på den optimala beräkningshastigheten och optimala antalet aktiva basstationer som minimerar den totala energiförbrukningen samtidigt som kraven på genomsnittlig servicefördröjning säkerställs.

  • 23.
    Chang, Peiliang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Energy-Efficient Resource Allocation in Multi-Carrier NOMA SystemsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    5G cellular networks are expected to support heterogeneous services with the same level of energy dissipation as current cellular networks. As a key enabler of 5G [1], the energy efficiency performance of non-orthogonal multiple access (NOMA) is of paramount importance. In NOMA systems, the system performance, e.g., spectral efficiency and energy efficiency are largely affected by resource allocation, i.e., sub-carrier assignment and power allocation. This paper studies the joint sub-carrier assignment and power allocation for the downlink transmission of multi-carrier NOMA systems to maximize the system energy efficiency (SEE). We first formulate an energyefficiency maximization problem while assuring the connectivity requirements of all users. The original optimization problem is a mixed integer programming problem and is NP hard. In order to develop optimal solutions with low complexity, the formulated problem is decomposed into three sub-problems: sub-carrier assignment, power allocation across sub-carriers and power allocation among users sharing the same sub-carrier. Given subcarrier assignment, we first obtain the optimal power allocation among users on one sub-carrier and then the optimal power allocation across sub-carriers. To find the optimal sub-carrier assignment, a greedy search solution based on the intrinsic structure of the transmitted power is proposed to minimize the overall required power to support the connectivity requirements of all users. Numerical simulations are implemented to validate the analytical findings. The results show that our proposed algorithms achieve better system energy efficiency and lower user blocking rate than the state-of-the-art solutions in the literature.

  • 24.
    Chang, Peiliang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Interference-aware Distributed Control of Cell Discontinuous Transmission2018Ingår i: 2018 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    As a main enabler for the next generation (5G) cellular networks, network densification faces challenges in intercell interference and energy consumption. Cell discontinuous transmission (DTX) can be employed to reduce both energy consumption of base stations (BSs) and inter-cell interference. In this paper we study the control problem of cell DTX in dense small cell networks (DSCNs). We firstly formulate the network energy efficiency optimization problem. Then a centralized heuristic DTX control algorithm is presented. In order to address the issues of complexity and scalability of the centralized solution, an interference-aware distributed DTX control algorithm is proposed. Discussions on algorithm complexity and implementation are provided. The proposed algorithms are evaluated with numerical simulations. Results show that at high load region, the proposed algorithms can not only enhance network capacity by reducing inter-cell interference by up to 60% but also increase network energy efficiency by switching BSs into micro-sleep mode by 67%.

  • 25.
    Chang, Peiliang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Optimal Operation of Base Stations With Deep Sleep and Discontinuous TransmissionIngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Traffic-aware base station (BS) sleeping is a promising approach to increase the energy efficiency (EE) of cellular networks. Both deep sleep and discontinuous transmission (DTX)can be applied to improve network EE. This paper studies the optimal BS operation when both deep sleep and DTX are employed. Queuing theory and stochastic geometry theory are jointly applied to model network performance considering both traffic dynamics and stochastic channel quality. We firstly propose a scaling law of transmit power that assures network coverage. Then, we characterize the resource utilization of active BSs when various percent-ages of BSs are switched into deep sleep, and analyze the overload probability of the remaining active BSs. Finally, we investigate the impact of BS deep sleep and DTX micro sleep on network EE. Both analytical and simulation results show that there is a trade-off between deep sleep and DTX micro sleep. Switching BSs into deep sleep would increase the load of the remaining active BSs and reduce their energy saving achieved with DTX. When the power consumption of BS in DTX micro-sleep mode is considerably low, switching BSs into deep sleep might increase the overall energy consumption, and it is not always the best practice to switch as many BSs into deep sleep as possible to maximize network EE.

  • 26.
    Chang, Peiliang
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Resource Provision for Energy-Efficient Mobile Edge Computing2018Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, IEEE Communications Society, 2018, artikel-id 8648008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile Edge Computing (a.k.a Fog computing) is recently proposed to provide computing service for delay-sensitive mobile applications. Despite various benefits, deploying edge servers in cellular networks would increase their energy consumption. In this paper, we investigate the provision of resources, including both communication and computation resources, of Mobile Edge Computing (MEC) systems to improve their energy efficiency (EE). In a MEC system, both the communication subsystem, which allows mobile users to access Internet and offload their computing tasks, and the computation subsystem, which accomplishes the offloaded computing tasks, affect the service latency and consume energy. Modelling the whole system as tandem queues, we study the trade-offs between these two subsystems on energy consumption and service latency. Based on the analysis results, we propose an algorithm to determine the optimal provision of both communication and computation resources to minimize the overall energy consumption without sacrificing the performance on service latency. Numerical results are provided to validate our analytical findings.

  • 27.
    Eneroth, Nathanael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Securing LBO VoLTE roaming with multiple Escrow Agents: A dynamic approach to distribute cryptographic keys to Escrow Agents2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Den fjärde generationens mobila bredband, Long-Term Evolution (LTE), möjliggör användandet av höghastighetsinternet över Internet Protocol (IP). Dagens trådlösa infrastrukturer banar väg för ett fritt och lättillgängligt digitalt samhälle där alla kan vara uppkopplade samtidigt. För att uppnå global trådlös infrastruktur måste mobilabonnenten ha möjlighet att utnyttja flera andra trådlösa nätverk än det nätverk som teleoperatören binder dem till. Därför utgör fri roaming en viktig del i utvecklingen av framtidens globala trådlösa infrastrukturer.

    Local Breakout (LBO) Voice over Long-Term Evolution (VoLTE) är en roamingarkitektur som gör det möjligt för en mobilabonnent att kopplas upp från en teleoperatörs nät till en annans. LBO kräver att kontrollsignaler och användardata skickas mellan flera operatörer innan trafiken når sitt mål, och därmed utsätts mobilabonnenten för laglig avlyssning av elektronisk information på flera platser samtidigt.

    Det här examensarbetet undersöker möjligheten att använda Multimedia Internet KEYing (MIKEY) och Secure Real-Time Transport Protocol (SRTP) för att kryptera mediatrafik i VoLTE. Under arbetets gång utvecklas och utvärderas en Law Enforcement Monitoring Provider (LEMP). LEMP är placerad i en mobiltelefon och distribuerar delar av krypteringsnycklar till flera betrodda tredje parter (till flera escrow agents). Detta gör det möjligt att uppfylla kraven för laglig avlyssning av elektronisk information även när flera teleoperatörer avlyssnar användardata och kontrollsignaler. Resultatet visar att distribueringstiden primärt beror på nätverkslatens, och inte på den tid det tar att fördela krypteringsnyckeln i mindre delar. Därför kan den här metoden användas i praktiken.

  • 28.
    Friðriksson, Vilhelm
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Container overhead in microservice systems2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Containers har blivit populärare under de senaste åren tack vare deras förmåga att ge högre flexibilitet, högre tillförlitlighet och dynamisk skalbarhet för företagsprogramvarusystem.  För att fullt ut kunna använda containers har programutvecklarna för avsikt att bygga sin programvara med hjälp av mikroservicearkitekturen, vilket innebär att programvaran delas upp i mindre enheter istället för att arbeta på en enda stor kodbas för hela projektet. Dessa mikroservices kan distribueras i sina egna containers istället för den traditionella virtuella maskininstallationen, där en server måste konfigureras med alla nödvändiga beroenden.  Att flytta sig från monolitisk mjukvaruarkitektur till containeriserade microservices kommer att få prestandaförsämringar på grund av ökade nätverksanrop mellan tjänster och container-overhead. Integrationen måste därför noggrant planeras för att fullt ut utnyttja containeruppsättningen och minimera overhead. Syftet med detta avhandlingsprojekt var att mäta hur mycket overhead kan förväntas på grund av containers i en företagsmiljö. Genom att använda en kombination av virtuella maskiner och Dockercontainers, implementerades ett microservices-system med fyra olika implementeringsstrategier och systemets prestanda mättes genom att analysera anropens svarstid under olika belastningar. Tjänsterna gjordes för att köras på en enda server och på flera servrar, med och utan Docker.  Prestandamätningarna visade att systemet var sämre i alla fall när Docker användes. Dessutom, visade resultaten att Docker kan ha signifikant negativ inverkan på prestanda när det är tung belastning på systemet.

  • 29.
    Hofmann, Sandra
    et al.
    Airbus, Munich, Germany.
    Megas, Vasileios
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS.
    Ozger, Mustafa
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Schupke, Dominic
    Airbus, Munich, Germany.
    Fitzek, F. H. P.
    Tech Univ Dresden, Deutsch Telekom Chair Commun Networks, Dresden, Germany.
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Datavetenskap, Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Combined Optimal Topology Formation and Rate Allocation for Aircraft to Aircraft Communications2019Ingår i: IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2019, artikel-id 8761882Konferensbidrag (Refereegranskat)
    Abstract [en]

    Providing broadband in-flight Internet connectivity to aircraft is challenging. Today's options include satellite communications (SC) and direct air-to-ground communication (DA2GC). To overcome data rate, delay and cost limitations of SC and coverage limitations of DA2GC, one can extend DA2GC with air-to-air communication (A2AC) by enabling multi-hop communication. To investigate the A2AC performance, we construct a mixed integer linear programming (MILP) problem of DA2GC and A2AC, jointly considering interference in topology formation and flow assignment. Our objective is to maximize the number of aircraft that can be connected with a given specific minimum data rate threshold. The evaluation is performed for low aircraft density scenarios over the North Atlantic. We show that in the investigated scenarios, over 90 % of aircraft can have at least 50 Mbps, some being up to 1600 kilometers away from the closest base station (BS). Furthermore, we identify antenna capabilities as an important factor for A2AC performance.

  • 30.
    Hossain, M. Istiak
    et al.
    KTH.
    Laya, Andres
    KTH.
    Militano, Francesco
    Ericsson Res, Bangalore, Karnataka, India..
    Iraji, Sassan
    Aalto Univ, Aalto, Finland..
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Reducing Signaling Overload: Flexible Capillary Admission Control for Dense MTC over LTE Networks2015Ingår i: 2015 IEEE 26TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE , 2015, s. 1305-1310Konferensbidrag (Refereegranskat)
    Abstract [en]

    The increasing adoption of Machine-Type Communication (MTC) applications on existing Long Term Evolution (LTE) brings new challenges for traditional signaling mechanism and system capacity. MTC is related to high number of devices; which represents a challenge when performing control and signaling procedures required for getting resource grant, since these processes are inefficient compared to the actual resource usage for small data transmissions. Solutions based on device grouping propose a static grouping approach, which does not perform well in low load scenario. This paper introduces the notion of a flexible admission/connection that can give granular group device control to Core network. With the proposed approach devices can be grouped for a certain period of time under supervision and control of a gateway and they can be ungrouped when there is no need for grouping them together. In this way, a finer control can be achieved on prioritizing certain services and load balancing. Our simulation results demonstrate significant signaling reduction by using this simple scheme compared to conventional connection procedure.

  • 31.
    Hossain, Mohammad Istiak
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cellular-Internet-of-Things Enablers:: A Techno-Economic Study of Wide Area Networks Connectivity and Platform Solutions2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Internet of Things (IoT) services are gradually attaining the expected service growth rate estimated by market actors. New connectivity paradigms, like the low-power wide-area network (LPWAN), have emerged to address the immediate challenges of IoT connectivity service. In addition, a plethora of new connectivity and application platforms have been developed to support IoT services. Until now, the majority of IoT services have been small scale deployments or trials. The overall cost-effectiveness and scalability aspects of IoT service provisioning are still not well understood. Hence, the growth of IoT services requires attention from a multidisciplinary perspective to address the cost-efficient scalability of IoT communication and service platforms.The technical part of this thesis focuses on the impact of multiplicity on the physical random access channel (PRACH) performance. We investigate the performance limitations of the initial access resource allocation, considering the multiplicity effect on physical layer signature detection to ensure uniform accessibility of devices. The performance evaluation reveals that MAC-protocol designed for PRACH needs to consider the realistic impact of multiplicity on signature detection. Then, we propose an efficient algorithm to detect multiplicity with a higher confidence factor. We also investigate the trade-off of random-access collision and resource allocation utilisation to meet the IoT resource utilisation requirements. We propose a pool-based resource allocation procedure that uses supervised learning to optimise the performance of early data transmission (EDT). Our analysis suggests that with this approach, EDT can handle delay constraint IoT services efficiently.The economic part of the thesis addresses the cost-structure and scalability aspects of both connectivity and platform solutions. The overall research question is: "What factors are driving the costs of IoT connectivity and platform services and why?" We have developed a framework for cost structure analysis of IoT services. We present cost structure breakdown analysis for both IoT connectivity and IoT platform services. The evaluation results discuss conditions when a platform service provider should choose a platform as a service (PaaS), and when on-premises platform deployment is viable.The technical study contributes to shaping the assessment metrics of the random-access algorithm selection. This study proposes solutions to support heterogeneous IoT solutions in cellular-IoT systems. Furthermore, the study demonstrates the potential of supervised learning to optimise resource allocation. The proposed algorithm assures service scalability in terms of user density for massive-IoT, and delay constraint IoT use cases.The economic study is helpful for telecom managers and IoT service providers to understand the cost breakdown of IoT connectivity and platform solutions under a different scenario. The cost driver of different IoT communication technologies like LPWAN, LPLAN, and C-IoT can be estimated at a high level. The framework provides a comparison base which is helpful for the actors in the IoT domain to analyse and compare different service provisioning options.

  • 32.
    Hossain, Mohammad Istiak
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Zander, Jens
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Collision Multiplicity Detection: Challenges, Solutions, and Impacts on Cellular Random Access2020Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    In cellular and cellular-IoT systems, random access has the utmost importance as it is the gatekeeper that assures conflict-free access to radio resources. The main drawback of the legacy protocols lies at the collision resolution procedure as the base station (BS) is blind to the collision multiplicity and collided devices rely on the BSs for contention resolution. While contention resolution over the random access channel (RACH) is mature in the literature, most studies are following optimistic assumptions in which the full collision impact at the receiver is neglected, and a simplified model of partially overlapping packets is considered. This work is devoted to the investigation of a more realistic model of collision in cellular networks with the aim to investigate challenges and potential solutions in preamble detection in collision scenarios. The simulation results show that besides previously well-known challenges in dealing with collisions, the occurrence of collisions significantly increases the probability of false preamble detection.

  • 33.
    Hossain, Mohammad Istiak
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Islam, Raihan Ul
    Luleå University of Technology.
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Andersson, Karl
    Luleå University of Technology.
    Early Data Transmit in Cellular-IoT: A Supervised Learning Approach to Optimized Resource Pool Allocation2020Ingår i: Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    3GPP introduced Early Data Transmit (EDT) protocol in release-15 to address Internet of things (IoT) services signaling cost and connection delay due to RRC connectivity procedure. EDT enables data transmission in MSG3 wherein traditional RACH procedure, a collision is realized at MSG3 reception. Traditional preventive approach (access class barring) may control the device access rate, but that does not always adequate to solve hidden collision due to the receiver’s limitation and devices power control mechanism. The present work aims at solving the problem by allocating extra resources pool for potential collided devices. The allocated resource of the pool is optimized based on an artificial neural network (ANN) based learning algorithm. The performance evaluation result shows that the learning-based resource allocation radically increases the data transmission success rate with EDT.

  • 34.
    Hossain, Mohammad Istiak
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Kumar, Niroop
    KTH.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Techno-Economic Framework for IoT Service Platform:: A Cost-Structure Aspects of IoT Service ProvisioningIngår i: IEEE Internet of Things Journal, ISSN 2327-4662Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A plethora of Internet of Things (IoT) platforms are available in the market today. Most of the IoT platforms are used mainly for service prototyping. Cost-efficient service scalability on any platform is still an unresolved concern that, so far, has been addressed qualitatively. A quantitative method for IoT platform economics is missing in the literature. In this paper, we propose a generic framework to address this gap. Our proposed framework covers the dimensioning of the platform's software and hardware to envisage the design, deployment, and operation cost of platform services. Then, we use the framework to perform a quantitative study of platform rollout in three platform business contexts. Our analysis shows the applicability of different deployment and platform integration choices. Our results suggest that storage and energy are the main cost drivers for platforms' hardware scalability, where the main cost driver is the intensity of the sensors' message transmission rate. Additionally, our use-case based study suggests that platform as a service (PaaS) is only beneficial for actors who have limited scale or niche market need.

  • 35.
    Hossain, Mohammad Istiak
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Lin, Lu
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    A Comparative Study of IoT-Communication Systems Cost Structure: Initial Findings of Radio Access Networks Cost2018Ingår i: 11th CMI International Conference, 2018: Prospects and Challenges Towards Developing a Digital Economy within the EU, PCTDDE 2018 / [ed] Williams, I, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 49-55, artikel-id 8624853Konferensbidrag (Refereegranskat)
    Abstract [en]

    This techno-economic study introduces a framework to study the deployment cost of IoT radio access network and to compare the cost and capacity of LPWAN, LPLAN, and Cellular-IoT systems. There are a plethora of Communication technologies available today. Small rollout and pilot projects are visible for most of the IoT connectivity technologies. However, The economic viability of cellular and non-cellular IoT connectivity technologies are not definite. The primary objective of this work is to analyze the cost structure of SigFox, LoRaWAN, NB-IoT, and WiFi-HaLow. In this paper, we study an urban scenario with the consideration of an Greenfield and Brownfield actor to understand the technology selection strategy of communication service prodvider's perspective. One of our findings indicates that the maintenance cost is the key cost driver for IoT radio access networks. We also point out certain bounds where a technology is potentially cost-effective.

  • 36.
    Hossain, Mohammad Istiak
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Comparison of LPWAN Technologies: Cost Structure and Scalability2019Ingår i: Telecommunications Policy, ISSN 0308-5961, E-ISSN 1879-3258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    — Pilot rollouts of Cellular-IoT (C-IoT) networks just started to take place this year. In the coming years, commercial deployment will take place. However, among the plethora of low power wide area network (LPWAN) technologies, the cost-effectiveness of C-IoT is not certain for IoT service providers, small and greenfield operators.  Today, there is no known public framework for the feasibility analysis of IoT communication technologies.

    Hence, this paper first presents a generic framework to assess the viability of cellular and non-cellular LPWAN technologies. Then, we applied the framework in eight deployment scenarios to analyze the prospect of LPWAN technologies like Sigfox, LoRaWAN, NB-IoT, LTE-M, and EC-GSM. We consider the inter-technology interference impact on LoRaWAN and Sigfox scalability. Our results validate that large rollout with a single technology is not cost-efficient. Also, our analysis suggests the viability of an IoT communication Technology may not be linear to cost efficiency.

  • 37.
    Hossain, Mohammad Istiak
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    IoT-Communications as a Service: Actor Roles on Indoor Wireless Coverage2017Ingår i: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet of Things (IoT) is anticipated as a 'game changer' for communication service providers. Numerous IoT devices will deploy in areas where humans already inhabit. It is increasing the importance of indoor area coverage to support IoT services. This again brings the historically important questions, 'what roles an actor play and who will control the indoor coverage?' In this paper, we discuss the business actors' roles in IoT indoor service context. We identify the possible roles and activities needed to provide end-to-end indoor IoT services. Additionally, we analyze the actors' roles in IoT ecosystem. We compare the actors' roles in the context of the suitable technology and deployment choices. Our identification of roles and initial analysis shows the impact of technology and rollout choices over network business strategy. With our presented analysis, we evaluate the possible paths for mobile network operators (MNOs) on low-power wide area (LPWAN) or low-power wireless local area (LPWLAN) network deployment.

  • 38.
    Jan, Jonathan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Collecting Data for Building Automation Analytics: A case study for collecting operational data with minimal human intervention2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Ungefär 40 % av den totala energikonsumtionen i E.U. och U.S.A. förbrukas av fastigheter. Om de delar av fastigheten som är ineffektiva enkelt kunde identifieras, skulle det underlätta fastighetsförvaltarnas arbete i att göra byggnader mer energisnåla. Detta har i sin tur potential att minska kostnader och byggnaders ekologiska fotavtryck.

    I dagens fastighetsautomationssystem samlas data in varje sekund, men på grund av att det saknas ett standardiserat sätt att beskriva den på, är det skillnad på att ha tillgång till data och att faktiskt kunna använda sig av den. Heterogeniteten gör att det blir både kostsamt och tidskrävande för fastighetsförvaltare att samla in data från sina fastigheter.

    Fastighetsförvaltare kan inte åtgärda något det inte kan se. Därför är det viktigt att underlätta möjligheten för visualisering av data från olika typer av fastighetsautomationssystem. Att lyckas med detta har potential att ge positiva effekter både när det gäller hållbarhet och ekonomi. I den här uppsatsen är författarens mål att komma fram till en hållbar, kostnads- och tidseffektiv integrationsstrategi för fastighetsförvaltare som vill få bättre insikter hur effektiv deras byggnad faktiskt är. Forskningsarbetet inleds med en litteraturstudie för att finna tidigare och pågående försök att lösa detta problem. Några initiativ för standardisering av semantiska modeller för att beskriva data inom fastighetsautomation hittades. Två av dessa, Brick och Project Haystack, valdes ut. En byggnad, och ett fastighetsautomationssystem testades i en pilotstudie.

    Resultaten från studien pekar på att data från fastighetautomationssystem kan integreras med en analysplattform, och en så kallad ETL-process, efter de engelska orden: extract, transform, load; presenteras för att uppnå det målet. Hur tidseffektivt data kan taggas och transformeras beror på det nuvarande kontrollsystemets datalagringsformat och om information om dess struktur är adekvat. Det noteras att det inte finns någon garanti till att få åtkomst till kontrollsystemets databas, eller information om dess struktur, därför presenteras även alternativa tekniker, däribland BACnet/IP och Open Platform Communications (OPC) Unified Architecture. 

  • 39.
    Karapantelakis, Athanasios
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Challenges for ICT Business Development in Intelligent Transport Systems2017Ingår i: 2017 JOINT 13TH CTTE AND 10TH CMI CONFERENCE ON INTERNET OF THINGS - BUSINESS MODELS, USERS, AND NETWORKS / [ed] Falch, M, Institute of Electrical and Electronics Engineers (IEEE), 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Intelligent Transportation Systems (ITS) are a product of convergence of Information and Communication Technology (ICT) and transport industries, with an aim to improve safety, mobility and efficiency of transportation. Ubiquitous, fast and inexpensive wireless communication and increasing vehicle computation, storage and sensing capabilities, are technological enablers for ITS. Notwithstanding technological maturity, the real challenge rises from the change the ITS market brings to the business of ICT players, as development of ITS services requires cooperation of multiple actors across industries. For ICT players, this signifies a departure from rigid telecom-era business models to a more networked structure of collaboration with other players. In this paper, we identify key business challenges that ICT players face in ITS market, by analysis of two ITS use cases.

  • 40.
    Katsikas, Georgios P.
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Network Systems Laboratory (NS Lab). RISE SICS.
    Barbette, Tom
    University of Liege.
    Kostic, Dejan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Network Systems Laboratory (NS Lab).
    Steinert, Rebecca
    RISE SICS.
    Maguire Jr., Gerald Q.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Metron: NFV Service Chains at the True Speed of the Underlying Hardware2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present Metron, a Network Functions Virtualization (NFV) platform that achieves high resource utilization by jointly exploiting the underlying network and commodity servers’ resources. This synergy allows Metron to: (i) offload part of the packet processing logic to the network, (ii) use smart tagging to setup and exploit the affinity of traffic classes, and (iii) use tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers’ fastest cache(s), with zero inter-core communication. Metron also introduces a novel resource allocation scheme that minimizes the resource allocation overhead for large-scale NFV deployments. With commodity hardware assistance, Metron deeply inspects traffic at 40 Gbps and realizes stateful network functions at the speed of a 100 GbE network card on a single server. Metron has 2.75-6.5x better efficiency than OpenBox, a state of the art NFV system, while ensuring key requirements such as elasticity, fine-grained load balancing, and flexible traffic steering.

  • 41.
    Khosravi, Sara
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Shokri-Ghadikolaei, Hossein
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Petrova, Marina
    Efficient Beamforming for Mobile mmWave Networks2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    We design a lightweight beam-searching algorithmfor mobile millimeter-wave systems. We construct and maintaina set of path skeletons, i.e., potential paths between a user and theserving base station to substantially expedite the beam-searchingprocess. To exploit the spatial correlations of the channels, wepropose an efficient algorithm that measures the similarity ofthe skeletons and re-executes the beam-searching procedure onlywhen the old one becomes obsolete. We identify and optimizeseveral tradeoffs between: i) the beam-searching overhead andthe instantaneous rate of the users, and ii) the number of usersand the update overhead of the path skeletons. Simulation resultsin an outdoor environment with real building map data show thatthe proposed method can significantly improve the performanceof beam-searching in terms of latency, energy consumption andachievable throughout.

  • 42.
    Kim, Donggu
    et al.
    Korea Adv Inst Sci & Technol, Sch Elect Engn, Daejeon 34141, South Korea..
    Yang, Yanpeng
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Kang, Joonhyuk
    Korea Adv Inst Sci & Technol, Sch Elect Engn, Daejeon 34141, South Korea..
    Cooperation Strategies for Partly Wireless C-RAN2018Ingår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, nr 6, s. 1248-1251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This letter presents a variant of cloud radio access network (C-RAN) architecture, which we term partly wireless C-RAN (PW-CRAN). It is characterized by extra radio nodes connected through the existing remote radio heads. Because of the newly connected nodes and the consequent additional delay, the operation of PW-CRAN requires different approaches compared with that of the typical C-RAN. Specifically, the effect of delayed channel state information on the suitability of network cooperation should be identified. To tackle this problem, we introduce two representative cooperation strategies and evaluate the performance with regard to the delay via simulations. Numerical results suggest that it is better to exclude the extra nodes from cooperation if they incur excess delay. Furthermore, whether the delay is deemed excessive depends on the interference environment. Hence, we provide quantified guidelines on the cooperation strategy of PW-CRAN.

  • 43.
    Kwon, Younggap
    et al.
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea.;Agcy Def Dev, Daejeon 305600, South Korea..
    Park, Hyunsung
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea..
    Oh, Jintaek
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea..
    Miao, Guowang
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Hwang, Taewon
    Yonsei Univ, Sch Elect & Elect Engn, Seoul 120749, South Korea..
    Energy-Efficient Routing and Link Adaptation for 2D Wireless Relay Networks in the Wideband Regime2018Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, nr 11, s. 7325-7339Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discuss the globally optimal energy-efficient design of a 2D relay network. Different from the existing routing protocols on energy saving, which finds the minimal energy route for a given data rate, the proposed algorithm jointly optimizes routing and data rate to maximize energy efficiency (EE) defined as the achievable data rate per power consumption. We propose a low-complexity algorithm to circumvent the huge complexity of the exhaustive search for the network EE maximization and prove its global optimality. Moreover, the proposed algorithm is implemented in a distributed fashion because each relay needs to send its routing information only to the relays in its adjacent tiers, which significantly reduces the signaling overhead of the centralized implementation. Our analysis on the worst-case complexity in a fading channel shows that the complexity of the proposed algorithm increases linearly while that of the exhaustive search increases exponentially as the tier index increases. Simulation results confirm that the proposed algorithm outperforms the existing routing protocols on energy saving and achieves the globally optimal network EE at a significantly lower complexity than the exhaustive search.

  • 44.
    Laya, Andrés
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Lundberg, Stefan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Network-centric business models for health, social care and wellbeing solutions in the internet of things2018Ingår i: Scandinavian Journal of Management, ISSN 0956-5221, E-ISSN 1873-3387, Vol. 34, nr 2, s. 103-116Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this multiple case study we analyze solutions based on connected devices in the context of health, social care and wellbeing. Based on the consideration that a solution is a combination of services and products, we build on the notion that business models can be studied at a firm-level and also at a network-level. The network-level analysis is used to motivate the reasons why solutions emerging at the intersection of the healthcare and the ICT industries benefit from collaboration among different actors. We conclude that the firm- and the network-level development of business models provide alignment in the business network and are useful to establish the relation that technological component have with overall solutions. Our findings suggest that some component bring novelty in the final offer without affecting the ongoing operation, while other component aim at improving the internal working processes, with minimal effects on the final offer to end users. We discuss the benefits of a network-level perspective for each case.

  • 45.
    Liu, Fei
    et al.
    Rhein Westfal TH Aachen, Inst Networked Syst, D-52072 Aachen, Germany..
    Petrova, Marina
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Dynamic Power Allocation for Downlink Multi-Carrier NOMA Systems2018Ingår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, nr 9, s. 1930-1933Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, the performance of optimal dynamic power allocation (PA) is analyzed for downlink multi-carrier non-orthogonal multiple access (MC-NOMA) systems. We study the PA optimization problem with a pair of users and weighted-sum-rate utility. A novel low-complexity algorithm is designed to solve the problem with a closed-form PA expression. The analytical data rate performance is derived and verified by simulation results. The numerical results indicate that a large difference in user channel states improves performance by enhancing the user diversity gain in NOMA systems. Moreover, the channel diversity gain can be achieved by multi-carrier transmission and increases with the number of subcarriers. Finally, the number of subcarriers for dynamic PA in MC-NOMA systems is discussed for practical applications.

  • 46.
    Liu, Fei
    et al.
    Rhein Westfal TH Aachen, Inst Networked Syst, D-52072 Aachen, Germany..
    Petrova, Marina
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Performance of Proportional Fair Scheduling for Downlink PD-NOMA Networks2018Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, nr 10, s. 7027-7039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we present an analytical model for performance analysis of dynamic proportional fair scheduling (PFS) in downlink power-domain non-orthogonal multiple access (PD-NOMA) networks. In order to develop a tractable model of analytical performance, we relax the condition in the PFS optimization problem and assume an ideal NOMA system with an arbitrary number of multiplexed users per frame. We derive a closed-form solution of the optimal power allocation for the relaxed problem and design a low-complexity algorithm for joint power allocation and user set selection. With this optimal solution, the transmission performance in the ideal NOMA system is proved to be an upper bound. Based on our derivation, we develop an analytical model of the upper bound throughput performance. The analytical performance is used to estimate user data rates and overall throughput in practical NOMA systems. We conduct system-level simulations to evaluate the accuracy of our data rate estimation. The simulation results verify our analysis of the upper bound performance of PFS in NOMA systems and confirm that using its analytical results for data rate estimation guarantees high accuracy. The impact of partial and imperfect channel state information on the estimation performance is investigated as well.

  • 47.
    Ly, Steven
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Dynamic Pricing Communication2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Parkering har sedan länge varit ett stort område, vilket enkelt innebär att ett fordon lämnas på en plats. Parkering har för det mesta haft ett sekundärt syfte från att äga en bil. Men eftersom antalet bilägare ökar, ökar även parkeringsbehovet. Om det inte finns tillräckligt med parkeringar för att kunna tillfredsställa behovet, leder det till en ökad trafikträngsel. Trafikträngsel skapar både miljöproblem och säkerhetsproblem. Den huvudsakliga metoden för att påverka parkeringsbehovet har varit genom att skapa lägre en efterfrågan. Efterfrågan har sänkts genom att justeringar av parkeringsavgifter. Då efterfrågan på senaste tiden har ökat markant, räcker de traditionella parkeringsavgifterna inte längre till. För att lösa problemen, har många bolag och organisationer börjat jobba mot en dynamisk prissättning.

    Dynamisk prissättning använder sig av en prisstrategi som sätter parkeringsavgifterna i realtid baserat på den nuvarande efterfrågan och tillgång. Däremot har parkeringsindustrin i nuläget inte de nödvändiga kommunikationskanalerna som krävs för att anta en dynamisk prissättning. Examensarbetets huvudsyfte har varit att utveckla ett protokoll som gör det möjligt att dela parkeringsrelaterade data så som: plats-, ockuperings- och tariffdata. Huvudmålet med protokollet är att det senare ska kunna bli en standard i parkeringsindustrin. På grund av tidsbegränsningar, har den största fokusen av utvecklingen lagt på stöd för tariffdata. Därmed kan inte protokollet antas som den fullständiga lösningen för dynamisk prissättning. Dock, kan protokollet ses som en delvis lösning, då det med protokollet är möjligt att korrekt dela med sig av tariffdata.

    Evalueringen visade att det gick, med hjälp av det utvecklade protokollet, att beskriva flera sorters tariffer utan att förlora någon viktig information. Tariffer som gick att beskriva används för bland annat: gatu-, infarts- och boendeparkeringar. Ett framtida projekt blir att utveckla och färdigställa protokollet för fullt stöd av plats- och ockuperingsdata. Ytterligare har det diskuterats om att den fortsatta utvecklingen av protokollet, ske som öppen källkod (open-source).

  • 48.
    Mahmood, Aamir
    et al.
    Mid Sweden Univ, Dept Informat Syst & Technol, S-85170 Sundsvall, Sweden..
    Hossain, Aftab M M
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS.
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Gidlund, Mikael
    Mid Sweden Univ, Dept Informat Syst & Technol, S-85170 Sundsvall, Sweden..
    Energy-Reliability Aware Link Optimization for Battery-Powered IoT Devices With Nonideal Power Amplifiers2019Ingår i: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 6, nr 3, s. 5058-5067Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we study cross-layer optimization of low-power wireless links for reliability-aware applications while considering both the constraints and the nonideal characteristics of the hardware in Internet-of-Things (IoT) devices. Specifically, we define an energy consumption (EC) model that captures the energy cost-of transceiver circuitry, power amplifier (PA), packet error statistics, packet overhead, etc.-in delivering a useful data bit. We derive the EC models for an ideal and two realistic nonlinear PA models. To incorporate packet error statistics, we develop a simple, in the form of elementary functions, and accurate closed-form packet error rate approximation in Rayleigh block-fading. Using the EC models, we derive energy-optimal yet reliability and hardware compliant conditions for limiting unconstrained optimal signal-to-noise ratio (SNR), and payload size. Together with these conditions, we develop a semianalytic algorithm for resource-constrained IoT devices to jointly optimize parameters on physical (modulation size, SNR) and medium access control (payload size and the number of retransmissions) layers in relation to link distance. Our results show that despite reliability constraints, the common notion-higherorder M-ary modulations are energy optimal for short-range communication-prevails, and can provide up to 180% lifetime extension as compared to often used OQPSK modulation in IoT devices. However, the reliability constraints reduce both their range and the energy efficiency, while nonideal traditional PA reduces the range further by 50% and diminishes the energy gains unless a better PA is used.

  • 49.
    Masoudi, Meysam
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Yavuz, E. A.
    Ericsson AB, Stockholm, Sweden.
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Grant-Free Radio Access IoT Networks: Scalability Analysis in Coexistence Scenarios2018Ingår i: IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers Inc. , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    IoT networks with grant-free radio access, like SigFox and LoRa, offer low-cost durable communications over unlicensed band. These networks are becoming more and more popular due to the ever-increasing need for ultra durable, in terms of battery lifetime, IoT networks. Most studies evaluate the system performance assuming single radio access technology deployment. In this paper, we study the impact of coexisting competing radio access technologies on the system performance. Considering K technologies, defined by time and frequency activity factors, bandwidth, and power, which share a set of radio resources, we derive closed-form expressions for the successful transmission probability, expected battery lifetime, and experienced delay as a function of distance to the serving access point. Our analytical model, which is validated by simulation results, provides a tool to evaluate the coexistence scenarios and analyze how introduction of a new coexisting technology may degrade the system performance in terms of success probability and battery lifetime. We further investigate solutions in which this destructive effect could be compensated, e.g., by densifying the network to a certain extent and utilizing joint reception.

  • 50.
    Masoudi, Meysam
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Azari, Amin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Yavuz, Emre Altug
    Ericsson AB, Stockholm, Sweden.
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Grant-free Radio Access IoT Networks:Scalability Analysis in Coexistence Scenarios2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    IoT networks with grant-free radio access, likeSigFox and LoRa, offer low-cost durable communications overunlicensed band. These networks are becoming more and morepopular due to the ever-increasing need for ultra durable, interms of battery lifetime, IoT networks. Most studies evaluatethe system performance assuming single radio access technologydeployment. In this paper, we study the impact of coexistingcompeting radio access technologies on the system performance.Considering K technologies, defined by time and frequencyactivity factors, bandwidth, and power, which share a set of radioresources, we derive closed-form expressions for the successfultransmission probability, expected battery lifetime, and experienceddelay as a function of distance to the serving access point.Our analytical model, which is validated by simulation results,provides a tool to evaluate the coexistence scenarios and analyzehow introduction of a new coexisting technology may degrade thesystem performance in terms of success probability and batterylifetime. We further investigate solutions in which this destructiveeffect could be compensated, e.g., by densifying the network toa certain extent and utilizing joint reception.

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