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| 2. |
- Aaboen, Lise, 1978, et al.
(författare)
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Exploring the roles of university spin-offs in business networks
- 2016
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Ingår i: Industrial Marketing Management. - : Elsevier BV. - 0019-8501 .- 1873-2062. ; 59, s. 157-166
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Tidskriftsartikel (refereegranskat)abstract
- This paper identifies different university spin-off (USO) roles related to resource interaction among business parties. It does so by mapping how USOs become part of business networks in terms of their roles relative to other parties. The theoretical frame of reference focuses on roles and resource interaction based on an industrial network approach to business markets. The empirical research is based on five cases of USOs representing a variety in terms of technology, degree of newness, sector, and area of application. As a result of the analysis, three different roles are identified: the USO as resource mediator, resource re-combiner and resource renewer. These roles reflect how USOs adapt resources to, or require changes among, business parties' resources. The paper also discusses the main resource interfaces associated with the three roles and related challenges. The paper contributes to previous research through illustrating USOs' roles relative to business parties from a resource interaction point of view, and by pointing to the establishment of new companies in business networks as a way of implementing innovation. Finally, the paper discusses the managerial implications of the research in terms of the USO's need to understand which role to take and how to develop it.
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| 3. |
- Abas, Naeem, et al.
(författare)
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Dynamic simulation of solar water heating system using supercritical CO2 as mediating fluid under sub-zero temperature conditions
- 2019
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Ingår i: Applied Thermal Engineering. - Oxford, UK : Pergamon Press. - 1359-4311 .- 1873-5606. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- CO2 is becoming increasingly important as a mediating fluid, and simulation studies are indispensable for corresponding developments. In this study, a simulation-based performance investigation of a solar water heating system using CO2 as a mediating fluid under sub-zero temperature condition is performed using the TRNSYS (R) software. The maximum performance is achieved at a solar savings fraction of 0.83 during July. The as lowest solar savingss fraction of 0.41 is obtained during December. The annual heat production of the proposed system under Fargo climate is estimated to be about 2545 kWh. An evacuated glass tube solar collector is designed, fabricated and tested for various climate conditions. Moreover, a detailed comparison of the system's performance at sub/supercritical and supercritical pressures shows that the annual heat transfer efficiency of the modeled system is 10% higher at supercritical pressure than at sub/supercritical pressures. This result can be attributd to the strong convection flow of CO2 caused by density inhomogeneities, especially in the near critical region. This condition resuls in high heat transfer rates.
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| 4. |
- Abbas, Muhammad Tahir, et al.
(författare)
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Energy-Saving Solutions for Cellular Internet of Things - A Survey
- 2022
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Ingår i: IEEE Access. - IEEE : IEEE. - 2169-3536. ; 10, s. 62096-62096
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Tidskriftsartikel (refereegranskat)abstract
- The Cellular Internet of Things (CIoT), a new paradigm, paves the way for a large-scale deployment of IoT devices. CIoT promises enhanced coverage and massive deployment of low-cost IoT devices with an expected battery life of up to 10 years. However, such a long battery life can only be achieved provided the CIoT device is configured with energy efficiency in mind. This paper conducts a comprehensive survey on energy-saving solutions in 3GPP-based CIoT networks. In comparison to current studies, the contribution of this paper is the classification and an extensive analysis of existing energy-saving solutions for CIoT, e.g., the configuration of particular parameter values and software modifications of transport- or radio-layer protocols, while also stressing key parameters impacting the energy consumption such as the frequency of data reporting, discontinuous reception cycles (DRX), and Radio Resource Control (RRC) timers. In addition, we discuss shortcomings, limitations, and possible opportunities which can be investigated in the future to reduce the energy consumption of CIoT devices.
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| 5. |
- Abbas, Muhammad Tahir, et al.
(författare)
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Evaluating the Impact of Pre-Configured Uplink Resources in Narrowband IoT
- 2024
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Ingår i: Sensors. - Switzerland. - 1424-8220. ; 24:17
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Tidskriftsartikel (refereegranskat)abstract
- Deploying Cellular Internet of Things (CIoT) devices in urban and remote areas faces significant energy efficiency challenges. This is especially true for Narrowband IoT (NB-IoT) devices, which are expected to function on a single charge for up to 10 years while transmitting small amounts of data daily. The 3rd Generation Partnership Project (3GPP) has introduced energy-saving mechanisms in Releases 13 to 16, including Early Data Transmission (EDT) and Preconfigured Uplink Resources (PURs). These mechanisms extend battery life and reduce latency by enabling data transmission without an active Radio Resource Control (RRC) connection or Random Access Procedure (RAP). This paper examines these mechanisms using the LENA-NB simulator in the ns-3 environment, which is a comprehensive framework for studying various aspects of NB-IoT. The LENA-NB has been extended with PURs, and our analysis shows that PURs significantly enhance battery life and latency efficiency, particularly in high-density environments. Compared to the default RAP method, PURs reduce energy consumption by more than 2.5 times and increases battery life by 1.6 times. Additionally, PURs achieve latency reductions of 2.5 - 3.5 times. The improvements with PURs are most notable for packets up to 125 bytes. Our findings highlight PURs' potential to enable more efficient and effective CIoT deployments across various scenarios. This study represents a detailed analysis of latency and energy consumption in a simulated environment, advancing the understanding of PURs' benefits.
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| 6. |
- Abbas, Muhammad Tahir, et al.
(författare)
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Guidelines for an Energy Efficient Tuning of the NB-IoT Stack
- 2020
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Ingår i: 45th IEEE Conference on Local Computer Networks (LCN). - : IEEE Communications Society. ; , s. 60-69
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Konferensbidrag (refereegranskat)abstract
- In this paper, we study the energy consumptionof Narrowband IoT devices. The paper suggests that key tosaving energy for NB-IoT devices is the usage of full Discontinuous Reception (DRX), including the use of connected-mode DRX (cDRX): In some cases, cDRX reduced the energy consumption over a 10-year period with as much as 50%. However, the paper also suggests that tunable parameters, such as the inactivity timer, do have a significant impact. On the basis of our findings, guidelines are provided on how to tune the NB-IoT device so that it meets the target of the 3GPP, i.e., a 5-Wh battery should last for at least 10 years. It is further evident from our results that the energy consumption is largely dependent on the intensity and burstiness of the traffic, and thus could be significantly reduced if data is sent in bursts with less intensity,irrespective of cDRX support.
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| 7. |
- Abbas, Muhammad Tahir, et al.
(författare)
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Impact of Tunable Parameters in NB-IoT Stack onthe Energy Consumption
- 2019
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Ingår i: Proceedings of Fifteenth Swedish National Computer Networking Workshop (SNCNW).
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Konferensbidrag (refereegranskat)abstract
- This paper studies the impact of tunable parametersin the NB-IoT stack on the energy consumption of a user equipment(UE), e.g., a wireless sensor. NB-IoT is designed to enablemassive machine-type communications for UE while providing abattery lifetime of up to 10 years. To save battery power, most oftime the UE is in dormant state and unreachable. Still, duringthe CONNECTED and IDLE state, correct tuning of criticalparameters, like Discontinuous reception (DRX), and extendedDiscontinuous reception (eDRX), respectively, are essential to savebattery power. Moreover, the DRX and eDRX actions relate tovarious parameters which are needed to be tuned in order toachieve a required UE battery lifetime. The objective of thispaper is to observe the influence of an appropriate tuning ofthese parameters to reduce the risk of an early battery drainage
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| 8. |
- Abbas, Muhammad Tahir
(författare)
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Improving the Energy Efficiency of Cellular IoT Device
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cellular Internet of Things (CIoT) has emerged as a promising technology to support applications that generate infrequent data. One requirement on these applications, often battery-powered devices, is low energy consumption to enable extended battery life. Narrowband IoT (NB-IoT) is a promising technology for IoT due to its low power consumption, which is essential for devices that need to run on battery power for extended periods. However, the current battery life of NB-IoT devices is only a few years, which is insufficient for many applications. This thesis investigates the impact of energy-saving mechanisms standardized by 3GPP on battery life of NB-IoT devices. The main research objective is to classify and analyze existing energy-saving solutions for CIoT and examine their limitations, to study the impact of standardized energy-saving mechanisms on the battery life of NB-IoT devices, both in isolation and combined, and to provide guidelines on how to configure NB-IoT devices to reduce energy consumption efficiently. The research aims to provide a deeper understanding of the effect of energy-saving mechanisms and best practices to balance energy efficiency and performance of NB-IoT devices. Applying the proposed solutions makes it possible to achieve a battery life of 10~years or more for CIoT devices.
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| 9. |
- Abbas, Muhammad Tahir, et al.
(författare)
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On the Energy-efficient Use of Discontinuous Reception and Release Assistance in NB-IoT
- 2022
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Konferensbidrag (refereegranskat)abstract
- Cellular Internet of Things (CIoT) is a Low-Power Wide-Area Network (LPWAN) technology. It aims for cheap, lowcomplexity IoT devices that enable large-scale deployments and wide-area coverage. Moreover, to make large-scale deployments of CIoT devices in remote and hard-to-access locations possible, a long device battery life is one of the main objectives of these devices. To this end, 3GPP has defined several energysaving mechanisms for CIoT technologies, not least for the Narrow-Band Internet of Things (NB-IoT) technology, one of the major CIoT technologies. Examples of mechanisms defined include CONNECTED-mode DRX (cDRX), Release Assistance Indicator (RAI), and Power Saving Mode (PSM). This paper considers the impact of the essential energy-saving mechanisms on minimizing the energy consumption of NB-IoT devices, especially the cDRX and RAI mechanisms. The paper uses a purpose-built NB-IoT simulator that has been tested in terms of its built-in energy-saving mechanisms and validated with realworld NB-IoT measurements. The simulated results show that it is possible to save 70%-90% in energy consumption by enabling the cDRX and RAI. In fact, the results suggest that a battery life of 10 years is only achievable provided the cDRX, RAI, and PSM energy-saving mechanisms are correctly configured and used
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| 10. |
- Abbas, Muhammad Tahir, et al.
(författare)
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SD-IoV : SDN enabled routing for internet of vehicles in road-aware approach
- 2019
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Ingår i: Journal of Ambient Intelligence and Humanized Computing. - : Springer. - 1868-5137 .- 1868-5145. ; 11:3, s. 1265-1280
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Tidskriftsartikel (refereegranskat)abstract
- Proposing an optimal routing protocol for internet of vehicles with reduced overhead has endured to be a challenge owing to the incompetence of the current architecture to manage flexibility and scalability. The proposed architecture, therefore, consolidates an evolving network standard named as software defined networking in internet of vehicles. Which enables it to handle highly dynamic networks in an abstract way by dividing the data plane from the control plane. Firstly, road-aware routing strategy is introduced: a performance-enhanced routing protocol designed specifically for infrastructure-assisted vehicular networks. In which roads are divided into road segments, with road side units for multi-hop communication. A unique property of the proposed protocol is that it explores the cellular network to relay control messages to and from the controller with low latency. The concept of edge controller is introduced as an operational backbone of the vehicle grid in internet of vehicles, to have a real-time vehicle topology. Last but not least, a novel mathematical model is estimated which assists primary controller in a way to find not only a shortest but a durable path. The results illustrate the significant performance of the proposed protocol in terms of availability with limited routing overhead. In addition, we also found that edge controller contributes mainly to minimizes the path failure in the network.
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