| 1. |
- Baswade, Anand M., et al.
(author)
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Modelling and Analysis of Wi-Fi and LAA Coexistence with Priority Classes
- 2018
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In: 2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). - : IEEE. - 9781538668764
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Conference paper (peer-reviewed)abstract
- The Licensed Assisted Access (LAA) is shown asa required technology to avoid overcrowding of the licensedbands by the increasing cellular traffic. Proposed by 3GPP,LAA uses a Listen Before Talk (LBT) and backoff mechanismsimilar to Wi-Fi. While many mathematical models have beenproposed to study the problem of the coexistence of LAAand Wi-Fi systems, few have tackled the problem of QoSprovisioning, and in particular analysed the behaviour of thevarious classes of priority available in Wi-Fi and LAA. Thispaper presents a new mathematical model to investigate theperformance of different priority classes in coexisting Wi-Fi andLAA networks. Using Discrete Time Markov Chains, we modelthe saturation throughput of all eight priority classes used byWi-Fi and LAA. The numerical results show that with the 3GPPproposed parameters, a fair coexistence between Wi-Fi and LAAcannot be achieved. Wi-Fi users in particular suffer a significantdegradation of their performance caused by the collision withLAA transmissions which has a longer duration compared toWi-Fi transmissions.
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| 2. |
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| 3. |
- Beltramelli, Luca, et al.
(author)
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Energy efficiency of slotted LoRaWANcommunication with out-of-band synchronization
- 2021
-
In: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662.
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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.
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| 4. |
- Beltramelli, Luca, et al.
(author)
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Hybrid MAC Mechanism for Energy Efficient Communication in IEEE 802.11ah
- 2017
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In: Proceedings of the 2017 IEEE International Conference on Industrial Technology (ICIT). - : IEEE. - 9781509053209 ; , s. 1295-1300
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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%.
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| 5. |
- Beltramelli, Luca, et al.
(author)
-
Interference Modelling in a Multi-Cell LoRa System
- 2018
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In: 2018 14th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). - : IEEE. - 9781538668764
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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.
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| 6. |
- Beltramelli, Luca, et al.
(author)
-
LoRa beyond ALOHA : An Investigation of Alternative Random Access Protocols
- 2021
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In: IEEE Transactions on Industrial Informatics. - 1551-3203 .- 1941-0050. ; 17:5, s. 3544-3554
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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.
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| 7. |
- Beltramelli, Luca, et al.
(author)
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Modeling of Enhanced Distributed Channel Access with Station Grouping: A Throughput Analysis
- 2018
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In: Proc. IEEE 88th Vehicular Technology Conference (VTC'18-fall), Chicago, USA, Aug. 2018.. - : IEEE conference proceedings.
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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.
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| 8. |
- Beltramelli, Luca, et al.
(author)
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Modelling of EnergyConsumption in IEEE 802.11.ah Networks for M2M Traffic
- 2016
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In: Proceedings of SNCNW 2016. ; , s. 38-41
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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.
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| 9. |
- Beltramelli, Luca
(author)
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Random and Hybrid Medium Access for M2M Communication : Scalability and Energy Analysis
- 2020
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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.
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| 10. |
- 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.
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| 11. |
- Forsström, Stefan, 1984-, et al.
(author)
-
Anpassad vidareutbildning för yrkesverksamma ingenjörer och stödja ett livslångt lärande
- 2021
-
In: 8:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar.
-
Conference paper (other academic/artistic)abstract
- Vi har under de senaste två åren arbetat med att gespecialanpassade kurser på avancerad nivå för yrkesverksammaingenjörer, specifikt inom områdena datateknik ochelektronik/elektroteknik. Tanken med denna artikel är att berättaom våra utmaningar, lärdomar, vårt upplägg, och våra framtidasatsningar inom vidareutbildning för yrkesverksamma. Dettaprojekt blev extra viktigt nu under COVID-19 pandemin då detblev en våg av permittering, varsel, och svårare arbetsmarknadför ingenjörer och data/elektro-tekniker.
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| 12. |
- Mahmood, Aamir, et al.
(author)
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Industrial IoT in 5G-and-Beyond Networks : Vision, Architecture, and Design Trends
- 2022
-
In: IEEE Transactions on Industrial Informatics. - : IEEE Computer Society. - 1551-3203 .- 1941-0050. ; 18:6, s. 4122-4137
-
Journal article (peer-reviewed)abstract
- Cellular networks are envisioned to be a cornerstone in future industrial Internet of Things (IIoT) wireless connectivity in terms of fulfilling the industrial-grade coverage, capacity, robustness, and timeliness requirements. This vision has led to the design of vertical-centric service-based architecture of 5G radio access and core networks. The design incorporates the capabilities to include 5G-AI-Edge ecosystem for computing, intelligence, and flexible deployment and integration options (e.g., centralized and distributed, physical, and virtual) while eliminating the privacy/security concerns of mission-critical systems. In this article, driven by the industrial interest in enabling large-scale wireless IIoT deployments for operational agility, flexible, and cost-efficient production, we present the state-of-the-art 5G architecture, transformative technologies, and recent design trends, which we also selectively supplemented with new results. We also identify several research challenges in these promising design trends that beyond-5G systems must overcome to support rapidly unfolding transition in creating value-centric industrial wireless networks.
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| 13. |
- Mahmood, Aamir, 1980-, et al.
(author)
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Industrial IoT in 5G-and-Beyond Networks: Vision, Architecture, and Design Trends
- 2022
-
In: IEEE Transactions on Industrial Informatics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1551-3203 .- 1941-0050. ; 18:6, s. 4122-4137
-
Journal article (peer-reviewed)abstract
- Cellular networks are envisioned to be a cornerstone in future industrial IoT (IIoT) wireless connectivity in terms of fulfilling the industrial-grade coverage, capacity, robustness, and ultra-responsiveness requirements. This vision has led to verticals-centric service-based architecture in 5G radio access and core networks, with the capabilities to include 5G-AI-Edge ecosystem for computing, intelligence, and flexible deployment and integration options (e.g., centralized and distributed, physical and virtual) while eliminating the privacy/security concerns of mission-critical systems. In this paper, driven by the industrial interest in enabling large-scale wireless IIoT deployments for operational agility, flexible, and cost-efficient production, we present the state-of-the-art 5G architecture, transformative technologies, and recent design trends, which we also selectively supplemented with new results. We also identify several research challenges in these promising design trends that beyond-5G systems must overcome to support the rapidly unfolding transition in creating value-centric industrial wireless networks.
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| 14. |
- Mugisha, Richard, et al.
(author)
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Joint Power and Blocklength Allocation for Energy-Efficient Ultra- Reliable and Low- Latency Communications
- 2021
-
In: International Symposium on Wireless Communication Systems (ISWCS).
-
Conference paper (peer-reviewed)abstract
- In this work, we address the problem of jointly optimizing the transmit power and blocklength of a two-users scenario for orthogonal multiple access (OMA) and non-orthogonal (NOMA) access schemes. We formulate an optimization problem to obtain the energy-optimal blocklength and transmit power under ultra-reliable and low-latency communications (URLLC) reliability and latency constraints. The aim is to minimize the energy consumption at short-blocklength regime. Due to the problem's complexity, we decompose it into two sub-problems for the OMA case, where the base station (BS) employs a 2D search for strong user, and the bisection method for the weak user. On the contrary, we find the sufficient transmit power conditions for NOMA to obtain the feasible solution. Our results show that the minimum required energy increases with the reliability requirement for both the OMA and NOMA, while NOMA consumes more energy than OMA for the same reliability target. Moreover, the results indicate that NOMA reduces latency due to better blocklength utilization compared to OMA when the channel gain disparity between the users is small.
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