| 1. |
- Forsström, Stefan, 1984-, et al.
(author)
-
Specialanpassade kurser för yrkesverksamma ingenjörer : Erfarenheter och upplevelser
- 2023
-
In: Bidrag från den 9:e utvecklingskonferensen för Sveriges ingenjörsutbildningar. - : Mälardalens universitet. - 9789174856200 ; , s. 348-353
-
Conference paper (other academic/artistic)abstract
- I dagens samhälle blir det allt viktigare att fortbilda sig under hela sitt yrkesverksamma liv. För att möta efterfrågan på det livslånga lärandet har Mittuniversitetet utvecklat och genomfört ett antal kurser som riktar sig mot yrkesverksamma ingenjörer. Detta arbete presenterar våra erfarenheter av att ge dessa kurser, med en tyngdpunkt på studenternas upplevelser. Syftet med detta är att bygga upp en vetenskaplig bas för vad vi gör som är bra, men även vad som kan förbättras och förändras. Målsättningen är att göra dessa specialanpassade kurser riktade mot yrkesverksamma ingenjörer så givande och flexibla som möjligt. Våra initiala resultat visar bland annat att studenternas negativa upplevelser ofta var kopplade till antagningsförfarandet och det praktiska genomförandet av kurserna. Man hade svårigheter med att hitta hur man skulle registrera sig på kursen och att tidsramen för registrering kunde vara ett problem. Läroplattformen uppfattades som svår att överblicka och det förekom även viss otydlighet gällande var undervisningen skulle äga rum. Den positiva responsen i utvärderingarna gällde främst det faktiska kursinnehållet, då man ansåg att uppgifter och kursmaterial var givande. Vidare uppskattades kursupplägget, att man kunde kombinera studierna med arbete. Framledes kommer vi att fortsätta med dessa utvärderingar i takt med att kurserna ges, och därefter anpassa vårt mottagande och kommunikationen med studenterna. Även kursupplägget ses över kontinuerligt via den återkoppling vi mottar.
|
|
| 2. |
- Beltramelli, Luca, et al.
(author)
-
Energy efficiency of slotted LoRaWANcommunication with out-of-band synchronization
- 2021
-
In: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662.
-
Journal article (peer-reviewed)abstract
- Although the idea of using wireless links for covering large areas is not new, the advent of Low Power Wide area networks (LPWANs) has recently started changing the game. Simple, robust, narrowband modulation schemes permit the implementation of low-cost radio devices offering high receiver sensitivity, thus improving the overall link budget. The several technologies belonging to the LPWAN family, including the well-known LoRaWAN solution, provide a cost-effective answer to many Internet-of-things (IoT) applications, requiring wireless communication capable of supporting large networks of many devices (e.g., smart metering). Generally, the adopted medium access control (MAC) strategy is based on pure ALOHA, which, among other things, allows to minimize the traffic overhead under constrained duty cycle limitations of the unlicensed bands. Unfortunately, ALOHA suffers from poor scalability, rapidly collapsing in dense networks. This work investigates the design of an improved LoRaWAN MAC scheme based on slotted ALOHA. In particular, the required time dissemination is provided by out-of-band communications leveraging on Radio Data System(FM-RDS) broadcasting, which natively covers wide areas both indoor and outdoor. An experimental setup based on low-cost hardware is used to characterize the obtainable synchronization performance and derive a timing error model. Consequently, improvements in success probability and energy efficiency have been validated by means of simulations in very large networks with up to 10000 nodes. It is shown that the advantage of the proposed scheme over conventional LoRaWAN communication is up to 100% when short update time and large payload are required. Similar results are obtained regarding the energy efficiency improvement, that is close to 100% for relatively short transmission intervals and long message duration; however, due to the additional overhead for listening the time dissemination messages, efficiency gain can be negative for very short duration of message fastly repeating.
|
|
| 3. |
- Beltramelli, Luca, et al.
(author)
-
Hybrid MAC Mechanism for Energy Efficient Communication in IEEE 802.11ah
- 2017
-
In: Proceedings of the 2017 IEEE International Conference on Industrial Technology (ICIT). - : IEEE. - 9781509053209 ; , s. 1295-1300
-
Conference paper (peer-reviewed)abstract
- Many applications for machine-to-machine (M2M) communications are characterized by large numbers of devices with sporadic transmissions and subjected to low energy budgets. This work addresses the importance of energy consumption by proposing a new Medium Access Control (MAC) mechanism for improving the energy efficiency of IEEE 802.11ah, a standard targeting M2M communication. We propose to use the features of IEEE 802.11ah MAC to realize a hybrid contention-reservation mechanism for the transmission of uplink traffic. In the proposed mechanism, any device with a buffered packet will first notify the Access Point (AP) during a contention phase before being given a reserved timeslot for the data transmission. We develop a mathematical model to analyse the energy consumption ofthe proposed mechanism and of IEEE 802.11ah. The results show that for a monitoring scenario, the proposed contention reservation mechanism reduces the energy consumption for a successful uplink data transmission by up to 55%.
|
|
| 4. |
- Beltramelli, Luca, et al.
(author)
-
Interference Modelling in a Multi-Cell LoRa System
- 2018
-
In: 2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). - : IEEE. - 9781538668764
-
Conference paper (peer-reviewed)abstract
- As the market for low-power wide-area network (LPWAN) technologies expands and the number of connected devices increases, it is becoming important to investigate the performance of LPWAN candidate technologies in dense deployment scenarios. In dense deployments, where the networks usually exhibit the traits of an interference-limited system, a detailed intra- and inter-cell interference analysis of LPWANs is required. In this paper, we model and analyze the performance of uplink communication of a LoRa link in a multi-cell LoRa system. To such end, we use mathematical tools from stochastic geometry and geometric probability to model the spatial distribution of LoRa devices. The model captures the effects of the density of LoRa cells and the allocation of quasi-orthogonal spreading factors (SF) on the success probability of the LoRa transmissions. To account for practical deployment of LoRa gateways, we model the spatial distribution of the gateways with a Poisson point process (PPP) and Matèrn hard-core point process (MHC). Using our analytical formulation, we find the uplink performance in terms of success probability and potential throughput for each of the available SF in LoRa’s physical layer. Our results show that in dense multi-cell LoRa deployment with uplink traffic, the intercell interference noticeably degrades the system performance.
|
|
| 5. |
- Beltramelli, Luca, et al.
(author)
-
LoRa beyond ALOHA : An Investigation of Alternative Random Access Protocols
- 2021
-
In: IEEE Transactions on Industrial Informatics. - 1551-3203 .- 1941-0050. ; 17:5, s. 3544-3554
-
Journal article (peer-reviewed)abstract
- We present a stochastic geometry-based model to investigate alternative medium access choices for LoRaWAN a widely adopted low-power wide-area networking (LPWAN) technology for the Internet-of-things (IoT). LoRaWAN adoption is driven by its simplified network architecture, air interface, and medium access. The physical layer, known as LoRa, provides quasi-orthogonal virtual channels through spreading factors (SFs) and time-power capture gains. However, the adopted pure ALOHA access mechanism suffers, in terms of scalability, under the same-channel same-SF transmissions from a large number of devices. In this paper, our objective is to explore access mechanisms beyond-ALOHA for LoRaWAN. Using recent results on time- and power-capture effects of LoRa, we develop a unified model for the comparative study of other choices, i.e., slotted ALOHA and carrier-sense multiple access (CSMA). The model includes the necessary design parameters of these access mechanisms, such as guard time and synchronization accuracy for slotted ALOHA, carrier sensing threshold for CSMA. It also accounts for the spatial interaction of devices in annular shaped regions, characteristic of LoRa, for CSMA. The performance derived from the model in terms of coverage probability, throughput, and energy efficiency are validated using Monte-Carlo simulations. Our analysis shows that slotted ALOHA indeed has higher reliability than pure ALOHA but at the cost of lower energy efficiency for low device densities. Whereas, CSMA outperforms slotted ALOHA at smaller SFs in terms of reliability and energy efficiency, with its performance degrading to pure ALOHA at higher SFs.
|
|
| 6. |
- Beltramelli, Luca, et al.
(author)
-
Modeling of Enhanced Distributed Channel Access with Station Grouping: A Throughput Analysis
- 2018
-
In: Proc. IEEE 88th Vehicular Technology Conference (VTC'18-fall), Chicago, USA, Aug. 2018.. - : IEEE conference proceedings.
-
Conference paper (peer-reviewed)abstract
- Machine to Machine (M2M) communication networksare expected to connect a large number of power constrained devices in long range applications with differentquality of service (QoS) requirements. Medium access control with QoS support such as the Enhanced Distributed Channel Access (EDCA) defined by IEEE 802.11e provides traffic differentiation and corresponding priority classes, which guarantees QoSaccording to the needs of applications. In this paper, we employa station grouping mechanism for enhancing the scalability of EDCA to handle the massive number of access attempts expected in large M2M networks. Furthermore, we develop a discrete time Markov chain (DTMC) model to analyze the performance of EDCA with station grouping. Using the developed DTMC model, we calculate throughput for each access category as well as for different combinations of grouping and EDCA parameters. Thenumerical results show that the model can precisely reveal the behavior of EDCA mechanism. Moreover, it is demonstrated that employing the proposed grouping mechanism for EDCA increasesthe normalized throughput significantly for all classes of priority.
|
|
| 7. |
- Beltramelli, Luca, et al.
(author)
-
Modelling of EnergyConsumption in IEEE 802.11.ah Networks for M2M Traffic
- 2016
-
In: Proceedings of SNCNW 2016. ; , s. 38-41
-
Conference paper (peer-reviewed)abstract
- IEEE 802.11ah is a sub-1 GHz standard designed to meet the requirements of future machine-to-machine (M2M) communications. The standard should be able to support use cases for the M2M communications with thousands of stations capable of generating both periodic and aperiodic traffic for a single access point. In some cases, like environmental and agricultural monitoring. the nodes are typically powered by battery or through energy harvesting. For this application it is important for the communication to be energy efficient. IEEE 802.11ah introduces new energy saving mechanisms and a novel channel access mechanism to achieve this objective even for networks with a large nodes number. This work proposes a mathematical model to compute the energy consumption of an IEEE 802.11ah network.
|
|
| 8. |
- Beltramelli, Luca
(author)
-
Random and Hybrid Medium Access for M2M Communication : Scalability and Energy Analysis
- 2020
-
Doctoral thesis (other academic/artistic)abstract
- The term machine-to-machine (M2M) communication identifies any fully automated communication between intelligent devices, autonomous from human intervention. M2M communication is a key enabling technology for the Internet of Things (IoT), where it is used to provide ubiquitous connectivity between a large number of intelligent devices. M2M technologies find applications in numerous emerging use cases, such as smart metering, smart cities, intelligent transportation systems, eHealth monitoring, and surveillance/security. The service requirements placed onM2M communication can vary greatly depending on the intended area of application. In general, M2M applications are characterized by the high number of devices communicating with one another through sporadic and short transmissions. The devices are generally distributed over wide areas without easy access to the power grid, relying for their energy supply on batteries and energy harvesting. Therefore, the design of M2M communication technologies should meet the goal of supporting a large number of connected devices while retaining low energy consumption. One of the obstacles to achieving this goal is the high level of interference that can be present on the channel if a large number of M2M devices decide to transmit within a short period of time. To understand how to overcome this obstacle, it is necessary to explore new and old design options available in the channel access of M2M communication. The aim of this work is to study the performance and propose improvements to the channel access mechanisms of M2M communication technologies operating in the unlicensed frequency spectrum. The two technologies discussed in this thesis are IEEE 802.11ah and LoRaWAN. The performance metrics that have been considered consistently throughout this work are the scalability and energy efficiency of the investigated channel access mechanisms, which are especially critical to massive M2M.The first part of the thesis focuses on the IEEE 802.11ah standard and its medium access mechanism with station grouping. An analytical model of the grouping mechanism of IEEE 802.11ah combined with enhanced distributed channel access (EDCA) is presented to assess the quality of service (QoS) differentiation available in IEEE 802.11ah. The throughput and delay of the access categories of EDCA are investigated for different group size and composition. The results reveal that grouping is effective at increasing the throughput of both high and low priority access categories up to 40% compared to the case without groups. A redesign of the access mechanism of IEEE 802.11ah is proposed to realize a hybrid channel access for energy efficient uplink data transmission. The numerical results show that fora wide range of contending M2M devices and even for the relatively small frame size of 256 bytes, the use of an hybrid channel access can help reducing the average energy consumption of the devices per successful uplink frame transmission. In the considered scenarios, the proposed MAC mechanism was able to reduce the average energy consumption per successful transmission up to 55% compared to standard approach. The second part of the thesis focuses on LoRa, with an investigation on the performance of alternative random channel access mechanisms in LoRaWAN. The connection between the channel access mechanism and the intensity of interference in LoRa networks is characterized for pure Aloha, slotted Aloha, and CSMA channel access. The results reveal several assisting guidelines on the design and selection of a medium access solution within LoRa’s parameter space: device density, service area, and spreading factor allocation. An out-of-band synchronization mechanism based on FM-Radio Data System (FM-RDS) is proposed to achieve synchronous channel access in LoRa. The throughput and fairness results for the proposed communication show the clear advantages of synchronous communication in LoRa, meanwhile, the use of out-of-band synchronization reduces the usage of LoRa channels, improving the scalability. The timing errors of FM-RDS are evaluated combining experimental approach and analytical methods. The observations reveal that despite the poor absolute synchronization, FM-RDS can effectively be used to realize time-slotted communication in LoRa, with performance similar to those obtained by more accurate but expensive time-dissemination technologies. Finally, a comprehensive model of the interference in neighboring clusters of LoRa devices is proposed, highlights the disruptive effects of the inter-cluster interference on the transmissions success probability, particularly for the devices using the largest spreading factors.
|
|
| 9. |
- Beltramelli, Luca, et al.
(author)
-
Synchronous LoRa Communication by Exploiting Large-Area out-of-band Synchronization
- 2021
-
In: IEEE Internet of Things Journal. - 2327-4662. ; 8:10, s. 7912-7924
-
Journal article (peer-reviewed)abstract
- Many new narrowband low-power wide-area networks (LPWANs) (e.g., LoRaWAN, Sigfox) have opted to use pure ALOHA-like access for its reduced control overhead and asynchronous transmissions. Although asynchronous access reduces the energy consumption of IoT devices, the network performance suffers from high intra-network interference in dense deployments. Contrarily, adopting synchronous access can improve throughput and fairness, however, it requires time synchronization. Unfortunately, maintaining synchronization over the narrowband LPWANs wastes channel time and transmission opportunities. In this paper, we propose the use of out-of-band time-dissemination to relatively synchronize the LoRa devices and thereby facilitate resource-efficient slotted uplink communication. In this respect, we conceptualize and analyze a co-designed synchronization and random access communication mechanism that can effectively exploit technologies providing limited time accuracy, such as FM radio data system (FM-RDS). While considering the LoRa-specific parameters, we derive the throughput of the proposed mechanism, compare it to a generic synchronous random access using in-band synchronization, and design the communication parameters under time uncertainty. We scrutinize the transmission time uncertainty of a device by introducing a clock error model that accounts for the errors in the synchronization source, local clock, propagation delay, and transceiver’s transmission time uncertainty. We characterize the time uncertainty of FM-RDS with hardware measurements and perform simulations to evaluate the proposed solution. The results, presented in terms of success probability, throughput, and fairness for a single-cell scenario, suggest that FM-RDS, despite its poor absolute synchronization, can be used effectively to realize time-slotted communication in LoRa with performance similar to that of more accurate time-dissemination technologies.
|
|
| 10. |
- Butun, Ismail, 1981, et al.
(author)
-
A Review of Distributed Access Control for Blockchain Systems towards Securing the Internet of Things
- 2021
-
In: IEEE Access. - 2169-3536 .- 2169-3536. ; 9, s. 5428-5441
-
Research review (peer-reviewed)abstract
- As the Internet of Things (IoT) paradigm gets more attention from academia and industry, implementation tools of IoT will be explored more and more. One example is the applicability of blockchain systems to provide security and privacy of IoT networks, which is the topic of this article. Blockchain systems are on the rise, as crypto-currency payment systems (such as Bitcoin, Litecoin, etc.) boomed in the last few years due to their attractive de-centralized and anonymous features. As in every transaction, access of the users to IoT systems needs to be controlled. However, these systems are peer-to-peer systems and do not have centralized control, which means that traditional access control techniques will not be optimal. As a result, distributed access control schemes are needed and this paper aims at providing the state of the art in the literature. Thereby, we introduce and discuss the details and applicability of centralized (rolebased) and distributed (threshold-signature, reputation, trusted-computing, identity, capability, ACL, groupsignature, and hybrid) access control schemes to blockchain systems under the IoT ecosystems. Moreover, permissioned vs. permissionless blockchain systems are also discussed. Finally, challenges and research directions related to the application of all those presented blockchain systems to IoT are discussed.
|
|
| 11. |
- Butun, Ismail, et al.
(author)
-
Detecting Intrusions in Cyber-Physical Systems of Smart Cities : Challenges and Directions
- 2019
-
In: Secure Cyber-Physical Systems for Smart Cities. - Hershey, USA : IGI Global. - 9781522571896 ; , s. 74-102
-
Book chapter (peer-reviewed)abstract
- Interfacing the smart cities with cyber-physical systems (CPSs) improves cyber infrastructures while introducing security vulnerabilities that may lead to severe problems such as system failure, privacy violation, and/or issues related to data integrity if security and privacy are not addressed properly. In order for the CPSs of smart cities to be designed with proactive intelligence against such vulnerabilities, anomaly detection approaches need to be employed. This chapter will provide a brief overview of the security vulnerabilities in CPSs of smart cities. Following a thorough discussion on the applicability of conventional anomaly detection schemes in CPSs of smart cities, possible adoption of distributed anomaly detection systems by CPSs of smart cities will be discussed along with a comprehensive survey of the state of the art. The chapter will discuss challenges in tailoring appropriate anomaly detection schemes for CPSs of smart cities and provide insights into future directions for the researchers working in this field.
|
|
| 12. |
- Butun, Ismail, 1981, et al.
(author)
-
Hardware security of fog end-devices for the internet of things
- 2020
-
In: Sensors. - : MDPI AG. - 1424-8220. ; 20:20, s. 1-28
-
Research review (peer-reviewed)abstract
- The proliferation of the Internet of Things (IoT) caused new application needs to emerge as rapid response ability is missing in the current IoT end-devices. Therefore, Fog Computing has been proposed to be an edge component for the IoT networks as a remedy to this problem. In recent times, cyber-attacks are on the rise, especially towards infrastructure-less networks, such as IoT. Many botnet attack variants (Mirai, Torii, etc.) have shown that the tiny microdevices at the lower spectrum of the network are becoming a valued participant of a botnet, for further executing more sophisticated attacks against infrastructural networks. As such, the fog devices also need to be secured against cyber-attacks, not only software-wise, but also from hardware alterations and manipulations. Hence, this article first highlights the importance and benefits of fog computing for IoT networks, then investigates the means of providing hardware security to these devices with an enriched literature review, including but not limited to Hardware Security Module, Physically Unclonable Function, System on a Chip, and Tamper Resistant Memory.
|
|
| 13. |
- Butun, Ismail, et al.
(author)
-
Preserving location privacy in cyber-physical systems
- 2019
-
In: 2019 IEEE Conference on Communications and Network Security (CNS). - : IEEE. ; , s. 1-6
-
Conference paper (peer-reviewed)abstract
- The trending technological research platform is Internet of Things (IoT)and most probably it will stay that way for a while. One of the main application areas of IoT is Cyber-Physical Systems (CPSs), in which IoT devices can be leveraged as actuators and sensors in accordance with the system needs. The public acceptance and adoption of CPS services and applications will create a huge amount of privacy issues related to the processing, storage and disclosure of the user location information. As a remedy, our paper proposes a methodology to provide location privacy for the users of CPSs. Our proposal takes advantage of concepts such as mix-zone, context-awareness, and location-obfuscation. According to our best knowledge, the proposed methodology is the first privacy-preserving location service for CPSs that offers adaptable privacy levels related to the current context of the user.
|
|
| 14. |
- Butun, Ismail, et al.
(author)
-
Security Implications of Fog Computing on the Internet of Things
- 2019
-
In: International Conference on Consumer Electronics (ICCE). - : IEEE. - 9781538679104
-
Conference paper (peer-reviewed)abstract
- Recently, the use of IoT devices and sensors has been rapidly increased which also caused data generation (information and logs), bandwidth usage, and related phenomena to be increased. To our best knowledge, a standard definition for the integration of fog computing with IoT is emerging now. This integration will bring many opportunities for the researchers, especially while building cyber-security related solutions. In this study, we surveyed about the integration of fog computing with IoT and its implications. Our goal was to find out and emphasize problems, specifically security related problems that arise with the employment of fog computing by IoT. According to our findings, although this integration seems to be non-trivial and complicated, it has more benefits than the implications. Index Terms—IoT, IIoT, vulnerabilities, trust, end-device, confidentiality, integrity, availability.
|
|
| 15. |
- Butun, Ismail, et al.
(author)
-
Security of the Internet of Things : Vulnerabilities, Attacks, and Countermeasures
- 2020
-
In: IEEE Communications Surveys and Tutorials. - 1553-877X. ; 22:1, s. 616-644
-
Journal article (peer-reviewed)abstract
- Wireless Sensor Networks (WSNs) constitute one of the most promising third-millennium technologies and have wide range of applications in our surrounding environment. The reason behind the vast adoption of WSNs in various applications is that they have tremendously appealing features, e.g., low production cost, low installation cost, unattended network operation, autonomous and longtime operation. WSNs have started to merge with the Internet of Things (IoT) through the introduction of Internet access capability in sensor nodes and sensing ability in Internet-connected devices. Thereby, the IoT is providing access to huge amount of data, collected by the WSNs, over the Internet. Hence, the security of IoT should start with foremost securing WSNs ahead of the other components. However, owing to the absence of a physical line-of-defense, i.e., there is no dedicated infrastructure such as gateways to watch and observe the flowing information in the network, security of WSNs along with IoT is of a big concern to the scientific community. More specifically, for the application areas in which CIA (confidentiality, integrity, availability) has prime importance, WSNs and emerging IoT technology might constitute an open avenue for the attackers. Besides, recent integration and collaboration of WSNs with IoT will open new challenges and problems in terms of security. Hence, this would be a nightmare for the individuals using these systems as well as the security administrators who are managing those networks. Therefore, a detailed review of security attacks towards WSNs and IoT, along with the techniques for prevention, detection, and mitigation of those attacks are provided in this paper. In this text, attacks are categorized and treated into mainly two parts, most or all types of attacks towards WSNs and IoT are investigated under that umbrella: 'Passive Attacks' and 'Active Attacks'. Understanding these attacks and their associated defense mechanisms will help paving a secure path towards the proliferation and public acceptance of IoT technology.
|
|
| 16. |
- Farag, Hossam, et al.
(author)
-
A Delay-Bounded MAC Protocol for Mission- and Time-Critical Applications in Industrial Wireless Sensor Networks
- 2018
-
In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 18:6, s. 2607-2616
-
Journal article (peer-reviewed)abstract
- Industrial Wireless Sensor Networks (IWSNs) designedfor mission- and time-critical applications require timelyand deterministic data delivery within stringent deadline bounds.Exceeding delay limits for such applications can lead to system malfunction or ultimately dangerous situations that can threaten human safety. In this paper, we propose SS-MAC, an efficient slot stealing MAC protocol to guarantee predictable and timely channel access for time-critical data in IWSNs. In the proposed SS-MAC, aperiodic time-critical traffic opportunistically steals time slots assigned to periodic non-critical traffic. Additionally, a dynamic deadline-based scheduling is introduced to provide guaranteed channel access in emergency and event-based situations where multiple sensor nodes are triggered simultaneously to transmit time-critical data to the controller. The proposed protocol is evaluated mathematically to provide the worst-case delay bound for the time-critical traffic. Performance comparisons are carried out between the proposed SS-MAC and WirelessHARTstandard and they show that, for the time-critical traffic, theproposed SS-MAC can achieve, at least, a reduction of almost 30% in the worst-case delay with a significant channel utilization efficiency.
|
|
| 17. |
- Farag, Hossam, et al.
(author)
-
Congestion control and traffic differentiation for heterogeneous 6tisch networks in IIoT
- 2020
-
In: Sensors. - : MDPI AG. - 1424-8220. ; 20:12, s. 1-25
-
Journal article (peer-reviewed)abstract
- The Routing Protocol for Low power and lossy networks (RPL) has been introduced as the de-facto routing protocol for the Industrial Internet of Things (IIoT). In heavy load scenarios, particular parent nodes are likely prone to congestion, which in turn degrades the network performance, in terms of packet delivery and delay. Moreover, there is no explicit strategy in RPL to prioritize the transmission of different traffic types in heterogeneous 6TiSCH networks, each according to its criticality. In this paper, we address the aforementioned issues by introducing a congestion control and service differentiation strategies to support heterogeneous 6TiSCH networks in IIoT applications. First, we introduce a congestion control mechanism to achieve load balancing under heavy traffic scenarios. The congestion is detected through monitoring and sharing the status of the queue backlog among neighbor nodes. We define a new routing metric that considers the queue occupancy when selecting the new parent node in congestion situations. In addition, we design a multi-queue model to provide prioritized data transmission for critical data over the non-critical ones. Each traffic type is placed in a separate queue and scheduled for transmission based on the assigned queue priority, where critical data are always transmitted first. The performance of the proposed work is evaluated through extensive simulations and compared with existing work to demonstrate its effectiveness. The results show that our proposal achieves improved packet delivery and low queue losses under heavy load scenarios, as well as improved delay performance of critical traffic.
|
|
| 18. |
- Farag, Hossam, et al.
(author)
-
Congestion Detection and Control for 6TiSCH Networks in IIoT Applications
- 2020
-
In: ICC 2020 - 2020 IEEE International Conference on Communications (ICC). - : IEEE. - 9781728150895
-
Conference paper (peer-reviewed)abstract
- In the context of Industrial Internet of Things (IIoT), the 6TiSCH working group has been created with the aim to enable IPv6 over the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) mode. The Routing Protocol for Low power and lossy networks (RPL) is introduced as the de-facto routing protocol for 6TiSCH networks. However, RPL is primarily designed to handle moderate traffic loads, whereas, during specific events in industrial applications, high traffic rates cause congestion problems at particular intermediate nodes while other nodes are underutilized. Accordingly, packets are dropped due to buffer overflow, which in turn degrades the network performance in terms of packet loss and delay. In this paper, we introduce a congestion detection and control mechanism to reliably handle high traffic load in 6TiSCH networks. The proposed method comprises two parent selection mechanisms to adapt to dynamic traffic load in the network. Congestion is detected through monitoring of the queue backlog level of each node and new parent nodes are selected accordingly to balance the load in the network. Moreover, a new routing metric is defined that considers the queue occupancy while selecting the new parent node. Performance evaluations are carried out to prove the effectiveness of the proposed method and the results show that with a marginal increase in the average delay, our proposal improves the performance of the standard RPL under heavy traffic load conditions by at least 60% and 74% in terms of the packet delivery and queue loss, respectively.
|
|
| 19. |
- Farag, Hossam, et al.
(author)
-
DeP-D : A Decentralized Primal-Dual Optimization Algorithm for Industrial Wireless Sensor Networks
- 2019
-
In: 2019 15th IEEE International Workshop on Factory Communication Systems (WFCS). - : IEEE. - 9781728112688
-
Conference paper (peer-reviewed)abstract
- Industrial Wireless Sensor Networks (IWSNs) are emerged as flexible and cost-efficient alternatives to the traditional wired networks in various monitoring and control applications within the industrial domain. Low delay is a key feature of delay-sensitive applications as the data is typically valid for a short interval of time. If data arrives too late it is of limited use which may lead to performance drops or even system outages which can create significant economical losses. In this paper, we propose a decentralized optimization algorithm to minimize the End-to-End (E2E) delay of multi-hop IWSNs. Firstly, we formulate the optimization problem by considering the objective function as the network delay where the constraint is the stability criteria based on the total arrival rate and the total service rate. The objective function is proved to be strictly convex for the entire network, then a Decentralized Primal-Dual (DeP-D) algorithm is proposed based on the sub-gradient method to solve the formulated optimization problem. The performance of the proposed DeP-D is evaluated through simulations and compared with WirelessHART network and the results show that the proposed DeP-D can achieve at least 40% reduction in the average E2E delay.
|
|
| 20. |
- Farag, Hossam
(author)
-
Enabling Industrial IoT Applications : Supporting Reliable and Real-Time Data Delivery
- 2020
-
Doctoral thesis (other academic/artistic)abstract
- The Industrial Internet of Things (IIoT) has become a promising technology for the improvement of the productivity, efficiency, and intelligence of the manufacturing process. Industrial Wireless Sensor Networks (IWSNs) represent a main pillar of IIoT to support communications within the field network level. For several IIoT applications, IWSNs are defined by strict communication requirements in terms of latency and reliability to support the proper functioning of the industrial system and avoid production loss. However, there are many challenges in efficiently satisfying these requirements. The key challenges investigated in this thesis are related to the shortcomings of the existing IWSN standards to enable timely delivery of aperiodic critical data, support traffic differentiation, and maintain reliable end-to-end communications. The overall objective of this work is to improve the reliability and real-time communication at the field network level in IIoT applications, particularly in process automation scenarios. Specifically, the proposed solutions represent improvements within the data-link and network layers of the IWSN protocol stack. The work in this thesis introduces the following contributions. The first part of the thesis focuses on improving real-time delivery for critical traffic and enabling traffic differentiation for mixed-criticality systems. The contribution in this part comprises three approaches. The first approach introduces a deterministic priority-based channel access mechanism for emergency data in time- and mission-critical applications. The approach is based on a dynamic deadline-aware schedule to provide a delay-bounded performance for the unpredictable emergency traffic along with efficient channel utilization. In the second approach, a priority-based wireless fieldbus protocol is proposed to enable traffic differentiation in mixed-criticality systems, where each traffic flow is given a transmission priority according to its corresponding criticality level. The third approach presents an optimized retransmission scheme to maximize the probability that an emergency packet is successfully delivered within its deadline bound. The results of the proposed schemes prove their effectiveness in providing real-time delivery for critical traffic and efficient service differentiation for mixed-criticality systems. The second part of the thesis introduces a routing framework to improve the connectivity and the end-to-end communication reliability of 6TiSCH networks. The proposed solutions in this part are mainly designed on the basis of the standard Routing Protocol for Low-Power and Lossy Networks (RPL). The proposed framework comprises the following approaches: 1) a reliable mobility-aware routing scheme to support node connectivity and reliable routing in mobile 6TiSCH networks, 2) a congestion control and detection strategies to enhance packet delivery performance under imbalanced network and heavy load scenarios, 3) a hybrid multi-cast method to maintain downlink connectivity and mitigate routing memory limitations in large-scale 6TiSCH networks. The conducted performance evaluations prove the effectiveness of the proposed approaches to enhance network performance in terms of reliability and delay metrics. The proposed approaches manage to improve routing performance of 6TiSCH networks in terms of connectivity and end-to-end data delivery, which in turn improves the real-time communication in IIoT.
|
|
| 21. |
- Farag, Hossam
(author)
-
Enabling Time- and Mission-Critical Applications in Industrial Wireless Sensor Networks
- 2019
-
Licentiate thesis (other academic/artistic)abstract
- Nowadays, Wireless Sensor Networks (WSNs) have gained importance as aflexible, easier deployment/maintenance and cost-effective alternative to wired networks,e.g., Fieldbus and Wired-HART, in a wide-range of applications. Initially,WSNs were mostly designed for military and environmental monitoringapplications where energy efficiency is the main design goal. The nodes in the network were expected to have a long lifetime with minimum maintenance while providing best-effort data delivery which is acceptable in such scenarios. With recent advances in the industrial domain, WSNs have been subsequently extended to support industrial automation applications such as process automation and control scenarios. However, these emerging applications are characterized by stringent requirements regarding reliability and real-time communications that impose challenges in the design of Industrial Wireless Sensor Networks (IWSNs) to effectively support time- and mission-critical applications.Typically, time- and mission-critical applications support different traffic categories ranging from relaxed requirements, such as monitoring traffic to firm requirements, such as critical safety and emergency traffic. The critical traffic is mostly acyclic in nature and occasionally occurs at unpredictable time instants. Once it is generated, it must be delivered within strict deadlines. Exceeding the delay bound could lead to system instability, economic loss, or even endanger human life in the working area. The situation becomes even more challenging when an emergency event triggers multiple sensor nodes to transmit critical traffic to the controller simultaneously. The unpredictability of the arrival of such a type of traffic introduces difficulties with regard to making a suitable scheduling that guarantees data delivery within deadline bounds. Existing industrial standards and related research work have thus far not presented a satisfactory solution to the issue. Therefore, providing deterministic and timely delivery for critical traffic and its prioritization over regular traffic is a vital research topic.Motivated by the aforementioned challenges, this work aims to enable real-timecommunication for time- and mission-critical applications in IWSNs. In this context, improved Medium Access Control (MAC) protocols are proposed to enablea priority-based channel access that provides a timely delivery for acyclic critical traffic. The proposed framework starts with a stochastic modelling of the network delay performance under a priority-oriented transmission scheme, followed by two MAC approaches. The first approach proposes a random Clear Channel Assessment (CCA) mechanism to improve the transmission efficiency of acyclic control traffic that is generated occasionally as a result of observations of an established tendency, such as closed-loop supervisory traffic. A Discrete-Time Markov Chain (DTMC) model is provided to evaluate the performance of the proposed protocol analytically in terms of the expected delay and throughput. Numerical results show that the proposed random CCA mechanism improves the shared slots approach in WirelessHART in terms of delay and throughput along with better transmission reliability.The second approach introduces a slot-stealing MAC protocol based on a dynamic deadline-aware scheduling to provide deterministic channel access in emergency and event-based situations, where multiple sensor nodes are triggered simultaneously to transmit time-critical data to the controller. The proposed protocol is evaluated mathematically to provide the worst-case delay bound for the time-critical traffic and the numerical results show that the proposed approach outperforms TDMA-based WSNs in terms of delay and channel utilization.
|
|
| 22. |
- Farag, Hossam, et al.
(author)
-
HyS-R: A Hybrid Subscription-Recovery Method for Downlink Connectivity in 6TiSCH Networks
- 2020
-
In: 2020 25th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA). - : IEEE. - 9781728189567
-
Conference paper (peer-reviewed)abstract
- The Routing Protocol for Low power and lossy network (RPL) is designed to support communication requirements in 6TiSCH networks in Industrial Internet of Things (IIoT) applications. RPL is mostly optimized for uplink communication, however, less attention is given to maintain connectivity for downlink communications. Supporting downlink communications is non-trivial task in process automation and control scenarios within the IIoT. RPL in its current definition is inefficient to support reliable downlink communications in terms of scalability and memory requirements leading to significant degradation in network performance. This paper introduces HyS-R, a Hybrid Subscription-Recovery method to maintain downlink connectivity and mitigate memory limitations in large-scale 6TiSCH networks. The proposed method is based on a relief group that is used as alternative route to unreachable destinations in the network. An intermediate node subscribes to the relief group when it fails to advertise a destination to its next-hop node. In addition, members of the relief group keep searching for alternative forwarders to keep the communication traffic to a minimum. Performance evaluations are carried out and the results demonstrate that the proposed HyS-R attains significant improvements in downlink communications compared to RPL storing and non-storing modes with a margin of energy cost.
|
|
| 23. |
- Farag, Hossam, et al.
(author)
-
PR-CCA MAC : A Prioritized Random CCA MAC Protocol for Mission-Critical IoT Applications
- 2018
-
In: 2018 IEEE International Conference on Communications (ICC). - : IEEE. - 9781538631805 - 9781538631812
-
Conference paper (peer-reviewed)abstract
- A fundamental challenge in Mission-Critical Internetof Things (MC-IoT) is to provide reliable and timely deliveryof the unpredictable critical traffic. In this paper, we propose an efficient prioritized Medium Access Control (MAC) protocol for Wireless Sensor Networks (WSNs) in MC-IoT control applications. The proposed protocol utilizes a random Clear Channel Assessment (CCA)-based channel access mechanism to handlethe simultaneous transmissions of critical data and to reduce thecollision probability between the contending nodes, which in turn decreases the transmission latency. We develop a Discrete-Time Markov Chain (DTMC) model to evaluate the performance of the proposed protocol analytically in terms of the expected delay and throughput. The obtained results show that the proposed protocolcan enhance the performance of the WirelessHART standard by 80% and 190% in terms of latency and throughput, respectively along with better transmission reliability.
|
|
| 24. |
- Farag, Hossam, et al.
(author)
-
Priority-Aware Wireless Fieldbus Protocol for Mixed-Criticality Industrial Wireless Sensor Networks
- 2019
-
In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 19:7, s. 2767-2780
-
Journal article (peer-reviewed)abstract
- Industrial wireless sensor networks are becoming popular for critical monitoring and control applications in industrial automation systems. For such type of applications, providing reliable real-time performance regarding data delivery is considered as a fundamental challenge. The problem becomes more prominent with mixed-criticality systems, where different data flow with different levels of criticality (importance) coexist and characterized by different requirements regarding delay and reliability. In this paper, we propose a wireless fieldbus protocol to enable real-time communication and service differentiation for cluster-based mixed-criticality networks. A process monitoring scenario of plastic extrusion is used to define the protocol requirements and elaborate the working principle of the proposed work. In our proposed protocol, each data flow is scheduled for channel access based on its criticality level using a distributed prioritized medium access mechanism that ensures a guaranteed channel access for the most critical traffic over other traffic types. The performance of the proposed protocol is analyzed analytically using a discrete-time Markov chain model to evaluate the performance in terms of delay and throughput. Moreover, the extensive simulations are conducted to prove the analytical claims and different performance assessments are provided, which also demonstrate the effectiveness of the proposed approach compared with the related existing work.
|
|
| 25. |
- Farag, Hossam, et al.
(author)
-
REA-6TiSCH : Reliable Emergency-Aware Communication Scheme for 6TiSCH Networks
- 2021
-
In: IEEE Internet of Things Journal. - 2327-4662. ; 8:3, s. 1871-1882
-
Journal article (peer-reviewed)abstract
- In the perspective of the emerging Industrial Internet of things (IIoT), the 6TiSCH working group has been created with the main goal to integrate the capabilities of the IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) with the IPv6 protocol stack. In order to support time-critical applications in IIoT, reliable real-time communication is a key requirement. Specifically, aperiodic critical traffic, such as emergency alarms, must be reliably delivered to the DODAG root within strict deadline bounds to avoid system failure or safety-critical situations. Currently, there is no mechanism defined in the 6TiSCH architecture for timely and reliably handling of such traffic and its prioritization over the non-critical one. In this paper, we introduce REA-6TiSCH, a reliable emergency-aware communication scheme to support real-time communications of emergency alarms in 6TiSCH networks. In REA-6TiSCH, the aperiodic emergency traffic is opportunistically enabled to hijack transmission cells pre-assigned for the regular periodic traffic in the TSCH schedule. Moreover, we introduce a distributed optimization scheme to improve the probability that an emergency flow is delivered successfully within its deadline bound. To the best of our knowledge, this is the first approach to incorporate emergency alarms in 6TiSCH networks. We evaluate the performance of REA-6TiSCH through extensive simulations and the results show the effectiveness of our proposed method in handling emergency traffic compared to Orchestra scheme. Additionally, we discuss the applicability of REA-6TiSCH and provide guidelines for real implementation in 6TiSCH networks.
|
|
| 26. |
- Farag, Hossam, et al.
(author)
-
RMA-RP: A Reliable Mobility-Aware Routing Protocol for Industrial IoT Networks
- 2019
-
In: 2019 IEEE Global Conference on Internet of Things (GCIoT). - : IEEE. - 9781728148731
-
Conference paper (peer-reviewed)abstract
- Many emerging Industrial Internet of Things (IIoT) applications involve the use of mobile devices, such as sensors and robots in industrial automation scenarios. Movement of mobile sensor nodes causes intermittent connectivity which in turn deteriorates the network performance in terms of packet loss and delay. The Routing Protocol for Low Power and Lossy Networks (RPL) is introduced as the standard routing protocol for IIoT networks. Although RPL constitutes a reliable and energy-efficient solution for static networks, there is no mechanism defined in the RPL standard of how to support routing in mobile IIoT networks. This paper introduces RMA-RP, a reliable mobility-aware routing protocol to support mobile IIoT networks. RMA-RP utilizes a dynamic motion detection mechanism based on the link quality to cope with topology changes by updating next-hop nodes. Moreover, an adaptive timer is introduced to manage the transmission rate of control messages in order to decrease the network overhead and in turn the energy consumption. We evaluate the performance of RMA-RP through extensive simulations in comparison to existing works and the results demonstrate that RMA-RP has at least 17% higher packet delivery ratio and achieves a reduction of 34% and 51% in terms of delay and network overhead, respectively.
|
|
| 27. |
- Forsström, Stefan, 1984-, et al.
(author)
-
Surveying and identifying the communication platforms of the internet of things
- 2018
-
In: 2018 Global Internet of Things Summit, GIoTS 2018. - : IEEE. - 9781538664513
-
Conference paper (peer-reviewed)abstract
- Research and industry invest time and resources in producing Internet of Things-based services, and the concept of Internet of Things platforms is climbing in the hype cycle for emerging technologies. Consequently, there is a vast number of enabling technologies, making it difficult to find the most suitable platform. The aim and goal of this article is to list and identify the currently available communication platforms for the Internet of Things. In this workwe surveyed the area and found over 128 different platforms for communication of data between things and services, out of which 42 fulfilled our listed basic requirements for being an IoT communication platform.
|
|
| 28. |
- Kanter, Theo, 1954-, et al.
(author)
-
Distributed Context Support for Ubiquitous Mobile Awareness Services
- 2009
-
In: 2009 Fourth International ICST Conference on Communications and Networking in China. ChinaCom'09.. - : IEEE conference proceedings. - 9781424443376 ; , s. 869-873
-
Conference paper (peer-reviewed)abstract
- Context-aware applications and services require ubiquitous access to context information about the users or sensors such as preferences, spatial & environmental data, available connectivity, and device capabilities. Systems for the brokering or the provisioning of context data via wireless networks do so with centralized servers or by employing protocols that do not scale well with real-time distribution capabilities. In other cases, such as the extending of presence systems, the data models are limited in expressive capabilities and consequently incur unnecessary signaling overhead. This paper presents a distributed protocol, the Distributed Context eXchange Protocol (DCXP), and an architecture for the real-time distribution of context information to ubiquitous mobile services: We present the architecture and its principle operation in a sample ubiquitous mobile awareness service. Preliminary results indicate that our approach scales well for the ubiquitous provision of context data in real-time to clients on the Internet via 3G wireless systems. Performed measurements show that DCXP can reduce the time to process context data with a factor of 20 compared to similar approaches.
|
|
| 29. |
- Kanter, Theo, 1954-, et al.
(author)
-
The MediaSense Framework
- 2009
-
In: Proceedings - 2009 4th International Conference on Digital Telecommunications, ICDT 2009. - New York : IEEE conference proceedings. - 9780769536958 ; , s. 144-147
-
Conference paper (peer-reviewed)abstract
- Mobile telecommunication is evolving rapidly. People no longer only communicate with each other regardless of time and place, but also share other information that is important for tasks with which they are involved. In response to this growing trend the MediaSense framework addresses the intelligent delivery of any information to any host, anywhere, based on context-aware information regarding personal preferences, presence information, and sensor values. This includes another challenge to achieve seamless delivery, especially of multimedia content, and multimodal services via heterogeneous connections.
|
|
| 30. |
- Khodakhah, Farnaz, et al.
(author)
-
Design and Resource Allocation of NOMA-based Transmission Scheme for Industrial Collaborative AR
- 2022
-
In: 2022 IEEE GLOBECOM Workshops, GC Wkshps 2022 - Proceedings. - : IEEE conference proceedings. - 9781665459754 ; , s. 1604-1609
-
Conference paper (peer-reviewed)abstract
- Collaborative augmented reality (AR), which enables interaction and consistency in multi-user AR scenarios, is a promising technology for AR-guided remote monitoring, optimization, and troubleshooting of complex manufacturing processes. However, for uplink high data rate demands in collaborative-AR, the design of an efficient transmission and resource allocation scheme is demanding in resource-constrained wireless systems. To address this challenge, we propose a collaborative non-orthogonal multiple access (C-NOMA)-enabled transmission scheme by exploiting the fact that multi-user interaction often leads to common and individual views of the scenario (e.g., the region of interest). C-NOMA is designed as a two-step transmission scheme by treating these views separately and allowing users to offload the common views partially. Further, we define an optimization problem to jointly optimize the time and power allocation for AR users, with an objective of minimizing the maximum rate-distortion of the individual views for all users while guaranteeing a target distortion of their common view for its mutual significance. For its inherent non-linearity and non-convexity, we solve the defined problem using a primal-dual interior-point algorithm with a filter line search as well as by developing a successive convex approximation (SCA) method. The simulation results demonstrate that the optimized C-NOMA outperforms the non-collaborative baseline scheme by 23.94% and 77.28% in terms of energy consumption and achievable distortion on the common information, respectively.
|
|
| 31. |
- Khodakhah, Farnaz, et al.
(author)
-
Multiple Access-Enabled Relaying with Piece-Wise and Forward NOMA : Rate Optimization under Reliability Constraints
- 2021
-
In: Sensors. - : MDPI AG. - 1424-8220. ; 21:14
-
Journal article (peer-reviewed)abstract
- The increasing proliferation of Internet-of-things (IoT) networks in a given space requires exploring various communication solutions (e.g., cooperative relaying, non-orthogonal multiple access, spectrum sharing) jointly to increase the performance of coexisting IoT systems. However, the design complexity of such a system increases, especially under the constraints of performance targets. In this respect, this paper studies multiple-access enabled relaying by a lower-priority secondary system, which cooperatively relays the incoming information to the primary users and simultaneously transmits its own data. We consider that the direct link between the primary transmitter-receiver pair uses orthogonal multiple access in the first phase. In the second phase, a secondary transmitter adopts a relaying strategy to support the direct link while it uses non-orthogonal multiple access (NOMA) to serve the secondary receiver. As a relaying scheme, we propose a piece-wise and forward (PF) relay protocol, which, depending on the absolute value of the received primary signal, acts similar to decode-and-forward (DF) and amplify-and-forward (AF) schemes in high and low signal-to-noise ratio (SNR), respectively. By doing so, PF achieves the best of these two relaying protocols using the adaptive threshold according to the transmitter-relay channel condition. Under PF-NOMA, first, we find the achievable rate region for primary and secondary receivers, and then we formulate an optimization problem to derive the optimal PF-NOMA time and power fraction that maximize the secondary rate subject to reliability constraints on both the primary and the secondary links. Our simulation results and analysis show that the PF-NOMA outperforms DF-NOMA and AF-NOMA-based relaying techniques in terms of achievable rate regions and rate-guaranteed relay locations.
|
|
| 32. |
- Khodakhah, Farnaz, et al.
(author)
-
NOMA or Puncturing for Uplink eMBB-URLLC Coexistence from an AoI Perspective?
- 2023
-
In: GLOBECOM 2023 - 2023 IEEE Global Communications Conference. - : IEEE. - 9798350310900 ; , s. 4301-4306
-
Conference paper (peer-reviewed)abstract
- Through the lens of the age-of-information (AoI) metric, this paper takes a fresh look into the performance of coexisting enhanced mobile broadband (eMBB) and ultra-reliable low-latency (URLLC) services in the uplink scenario. To reduce AoI, a URLLC user with stochastic packet arrivals has two options: orthogonal multiple access (OMA) with the preemption of the eMBB user (labeled as puncturing) or non-orthogonal multiple access (NOMA) with the ongoing eMBB transmission. Puncturing leads to lower average AoI at the expense of the decrease in the eMBB user's rate, as well as in signaling complexity. On the other hand, NOMA can provide a higher eMBB rate at the expense of URLLC packet loss due to interference and, thus, the degradation in AoI performance. We study under which conditions NOMA could provide an average AoI performance that is close to the one of the puncturing, while maintaining the gain in the data rate. To this end, we derive a closed-form expression for the average AoI and investigate conditions on the eMBB and URLLC distances from the base station at which the difference between the average AoI in NOMA and in puncturing is within some small gap β. Our results show that with β as small as 0.1 minislot, the eMBB rate in NOMA can be roughly 5 times higher than that of puncturing. Thus, by choosing an appropriate access scheme, both the favorable average AoI for URLLC users and the high data rate for eMBB users can be achieved.
|
|
| 33. |
- Lindén, Johannes, 1993-
(author)
-
Extracting Text into Meta-Data : Improving machine text-understanding of news-media articles
- 2021
-
Licentiate thesis (other academic/artistic)abstract
- Society is constantly in need of information. It is important to consume event-based information of what is happening around us as well as facts and knowledge. As society grows, the amount of information to consume grows with it. This thesis demonstrates one way to extract and represent knowledge from text in a machine-readable way for news media articles. Three objectives are considered when developing a machine learning system to retrieve categories, entities, relations and other meta-data from text paragraphs. The first is to sort the terminology by topic; this makes it easier for machine learning algorithms to understand the text and the unique words used. The second objective is to construct a service for use in production, where scalability and performance are evaluated. Features are implemented to iteratively improve the model predictions, and several versions are run at the same time to, for example, compare them in an A/B test. The third objective is to further extract the gist of what is expressed in the text. The gist is extracted in the form of triples by connecting two related entities using a combination of natural language processing algorithms. The research presents a comparison between five different auto categorization algorithms, and an evaluation of their hyperparameters and how they would perform under the pressure of thousands of big, concurrent predictions. The aim is to build an auto-categorization system that can be used in the news media industry to help writers and journalists focus more on the story rather than filling in meta-data for each article. The best-performing algorithm is a Bidirectional Long-Short-Term-Memory neural network. Three different information extraction algorithms for extracting the gist of paragraphs are also compared. The proposed information extraction algorithm supports extracting information from texts in multiple languages with competitive accuracy compared with the state-of-the-art OpenIE and MinIE algorithms that can extract information in a single language. The use of the multi-linguistic models helps local-news media to write articles in different languages as a help to integrate immigrants into the society.
|
|
| 34. |
- Lindén, Johannes, 1993-, et al.
(author)
-
Multi-language Information Extraction with Text Pattern Recognition
- 2021
-
In: Computer Science & Information Technology (CS & IT). - 9781925953541 ; , s. 1-17
-
Conference paper (peer-reviewed)abstract
- Information extraction is a task that can extract meta-data information from text. The research in this article proposes a new information extraction algorithm called GenerateIE. The proposed algorithm identifies pairs of entities and relations described in a piece of text. The extracted meta-data is useful in many areas, but within this research the focus is to use them in news-media contexts to provide the gist of the written articles for analytics and paraphrasing of news information. GenerateIE algorithm is compared with existing state of the art algorithms with two benefits. Firstly, the GenerateIE provides the co-referenced word as the entity instead of using he, she, it, etc. which is more beneficial for knowledge graphs. Secondly GenerateIE can be applied on multiple languages without changing the algorithm itself apart from the underlying natural language text-parsing. Furthermore, the performance of GenerateIE compared with state-of-the-art algorithms is not significantly better, but it offers competitive results.
|
|
| 35. |
- Wanjura, Viktor, 1975-, et al.
(author)
-
Gastrointestinal quality-of-life after cholecystectomy : indication predicts gastrointestinal symptoms and abdominal pain
- 2014
-
In: World Journal of Surgery. - New York, USA : Springer-Verlag New York. - 0364-2313 .- 1432-2323. ; 38:12, s. 3075-3081
-
Journal article (peer-reviewed)abstract
- Background: Despite the fact that cholecystectomy is a common surgical procedure, the impact on long-term gastrointestinal quality of life is not fully known.Methods: All surgical procedures for gallstone disease performed at Mora County Hospital, Sweden, between 2 January 2002 and 2 January 2005, were registered on a standard database form. In 2007, all patients under the age of 80 years at follow-up were requested to fill in a form containing the Gastrointestinal Quality-of-Life Index (GIQLI) questionnaire and a number of additional questions. The outcome was analysed with respect to age, gender, smoking, surgical technique, and original indication for cholecystectomy.Results: A total of 627 patients (447 women, 180 men) underwent cholecystectomy, including laparoscopic cholecystectomy (N = 524), laparoscopic cholecystectomy converted to open cholecystectomy (N = 43), and open cholecystectomy (N = 60). The mean time between cholecystectomy and follow-up with the questionnaire was 49 months. The participation rate was 79 %. Using multivariate analysis in the form of generalised linear modelling, the original indication for cholecystectomy in combination with gender (p = 0.0042) was found to predict the GIQLI score. Female gender in combination with biliary colic as indication for cholecystectomy correlated with low GIQLI scores. Female gender also correlated with a higher risk for pain in the right upper abdominal quadrant after cholecystectomy (p = 0.028).Conclusions: We found the original indication for cholecystectomy, together with gender, to predict gastrointestinal symptoms and abdominal pain after cholecystectomy. Careful evaluation of symptoms is important before planning elective cholecystectomy.
|
|
| 36. |
- Österberg, Patrik, 1975-, et al.
(author)
-
Fair Allocation of Multicast Transmission Costs
- 2008
-
In: International Journal on Advances in Telecommunications. - : IARIA. - 1942-2601. ; 1:1, s. 1-13
-
Journal article (peer-reviewed)abstract
- In scenarios where many receivers simultaneously are interested in the same data, multicast transmission is more bandwidth efficient than unicast. The reason is that the receivers of a multicast session share the resources through a common transmission tree. Since the resources are shared between the receivers, it is reasonable that the costs corresponding to these resources should be shared as well.This paper deals with fair cost sharing among multicast receivers, and the work is based upon the assumption that costs should be shared according to the resource usage. However, it is not for certain that an optimally fair cost allocation is most beneficial for the receivers; receivers that cannot cover their fair share of the costs may nevertheless be able to contribute to the cost sharing to some extent. We propose a cost-allocation mechanism that strives to allocate the costs fairly, but gives discount to poor receivers who at least manage to cover the additional cost of providing them with the service.
|
|
| 37. |
- Österberg, Patrik, 1975-
(author)
-
Fair Treatment of Multicast Sessions and Their Receivers : Incentives for more efficient bandwidth utilization
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Tjänster för strömmad media stiger kraftigt i popularitet, samtidigt som utbudet av denna typ av tjänster ökar. Internet protocol television (IPTV) med standardupplösning levereras redan till många hem, och högupplöst IPTV kommer att bli vanligt inom en relativt snar framtid. Mer avancerade tjänster, som tredimensionell TV och TV med fritt valbara vyer, står sedan på tur. Strömmad video är av naturen väldigt bandbreddskrävande, och denna utveckling kommer därför att sätta den befintliga nätverksinfrastrukturen på prov. Multicast är mer bandbreddseffektivt än unicast för scenarion där många mottagare samtidigt är intresserade av samma data, vilket är fallet med populärt direktsänt material. Anledningen är att mottagarna av multicast-sessioner delar på resurserna via ett gemensamt transmissionsträd, där ingen data sänds mer än en gång över någon gren. Användningen av multicast kan därför generera stora besparingar av bandbredd. Internetleverantörerna har dock inga riktigt starka skäl för att stödja multicast, vilket medfört att spridningen varit långsam. Vi föreslår att multicast-sessioner tilldelas mer bandbredd när det uppstår trafikstockningar i näten. Fördelningen baseras på antalet mottagare och datatakten som de erhåller, eftersom det är det som avgör graden av resursdelning. Vi anser att det är rättvist att ta hänsyn till detta, och kallar därför den föreslagna bandbreddsfördelningen multicast-favorable max-min fair. Vidare så presenteras två bandbreddstilldelningspolicyer som använder sig av olika mängd återkoppling för att uppnå fördelningar som ligger förhållandevis nära den föreslagna. Vi föreslår även två mekanismer för kostnadsallokering, vilka bygger på antagandet att kostnaden för dataöverföring ska täckas av mottagarna. De föreslagna mekanismerna fördelar kostnaderna mellan mottagarna baserat på deras andel av resursutnyttjandet, vilket generellt är fördelaktigt för multicast-mottagare. De två mekanismerna för kostnadsallokering skiljer sig åt genom att den ena eftersträvar optimalt rättvis fördelning av kostnaderna, medan den andra kan ge rabatt till vissa mottagare. Rabatten möjliggör större grupper med mottagare, vilket även kan reducera kostnaderna för icke rabatterade mottagare. Förslagen gör multicast mer attraktivt för användarna av strömmad media. Om förslagen implementerades i nätverk med multicast-stöd så skulle övriga Internetleverantörer bli tvungna att stödja multicast för att vara konkurrenskraftiga.
|
|
| 38. |
- Österberg, Patrik, 1975-, et al.
(author)
-
Multicast-Favourable Max-Min Fairness : The Definition and How to Comply
- 2011
-
In: International Journal of Computers and Applications. - Calgary, Canada : ACTA Press. - 1206-212X .- 1925-7074. ; 33:1, s. 1-8
-
Journal article (peer-reviewed)abstract
- In scenarios where many receivers simultaneously are interested in the same data, multicast transmission is more bandwidth efficient than unicast. Consequently, the benefit of multicast transmission is growing with the rising interest in video-streaming services. To prioritize multicast flows and thereby create an incentive for the use of multicast transmission might therefore make sense. Research in this area is usually denoted multicast fairness. In this paper, we present a general definition of multicast fairness, named multicastfavourable max-min fairness (MFMF), which specifies the properties a global bandwidth allocation should possess to be considered fair to both unicast and multicast flows. A description of how the definition can be used to evaluate the fairness of other bandwidth allocations is also included. Further, two bandwidth-allocation policies that aim at producing allocations close to fulfilling the MFMF definition are presented.
|
|
