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Anjum, M., Khan, M. A., Hassan, S. A., Mahmood, A. & Gidlund, M. (2019). Analysis of RSSI Fingerprinting in LoRa Networks. In: 15th International Wireless Communications & Mobile Computing Conference: . Paper presented at 15th International Wireless Communications & Mobile Computing Conference. IEEE
Open this publication in new window or tab >>Analysis of RSSI Fingerprinting in LoRa Networks
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2019 (English)In: 15th International Wireless Communications & Mobile Computing Conference, IEEE, 2019Conference paper, Published paper (Refereed)
Abstract [en]

Localization has gained great attention in recent years, where different technologies have been utilized to achieve high positioning accuracy. Fingerprinting is a common technique for indoor positioning using short-range radio frequency (RF) technologies such as Bluetooth Low Energy (BLE). In this paper, we investigate the suitability of LoRa (Long Range) technology to implement a positioning system using received signal strength indicator (RSSI) fingerprinting. We test in real line-of-sight (LOS) and non-LOS (NLOS) environments to determine appropriate LoRa packet specifications for an accurate RSSI-to-distance mapping function. To further improve the positioning accuracy, we consider the environmental context. Extensive experiments are conducted to examine the performance of LoRa at different spreading factors. We analyze the path loss exponent and the standard deviation of shadowing in each environment

Place, publisher, year, edition, pages
IEEE, 2019
Keywords
Curve fitting, LoRa, path loss, positioning, RSSI fingerprinting, spreading factor
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:miun:diva-37131 (URN)10.1109/IWCMC.2019.8766468 (DOI)
Conference
15th International Wireless Communications & Mobile Computing Conference
Funder
Knowledge Foundation
Available from: 2019-09-06 Created: 2019-09-06 Last updated: 2019-09-06
Ansari, R. I., Pervaiz, H., Chrysostomou, C., Hassan, S. A., Mahmood, A. & Gidlund, M. (2019). Control-Data Separation Architecture for Dual-Band mmWave Networks: A New Dimension to Spectrum Management. IEEE Access, 7, 34925-34937, Article ID 8663278.
Open this publication in new window or tab >>Control-Data Separation Architecture for Dual-Band mmWave Networks: A New Dimension to Spectrum Management
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2019 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 34925-34937, article id 8663278Article in journal (Refereed) Published
Abstract [en]

The exponential growth in global mobile data traffic, especially with regards to the massive deployment of devices envisioned for the fifth generation (5G) mobile networks, has given impetus to exploring new spectrum opportunities to support the new traffic demands. The millimeter wave (mmWave) frequency band is considered as a potential candidate for alleviating the spectrum scarcity. Moreover, the concept of multi-tier networks has gained popularity, especially for dense network environments. In this article, we deviate from the conventional multi-tier networks and employ the concept of control-data separation architecture (CDSA), which comprises of a control base station (CBS) overlaying the data base station (DBS). We assume that the CBS operates on the sub-6 GHz single band, while the DBS possesses a dual-band mmWave capability, i.e., 26 GHz unlicensed band and 60 GHz licensed band. We formulate a multi-objective optimization (MOO) problem, which jointly optimizes conflicting objectives: the spectral efficiency (SE) and the energy efficiency (EE). The unique aspect of this work includes the analysis of a joint radio resource allocation algorithm based on Lagrangian Dual Decomposition (LDD) and we compare the proposed algorithm with the maximal-rate (maxRx), dynamic sub-carrier allocation (DSA) and joint power and rate adaptation (JPRA) algorithms to show the performance gains achieved by the proposed algorithm.

Keywords
Control-data separation architecture, resource allocation, dual-band millimeter wave, energy efficiency, spectral efficiency, multi-objective optimization
National Category
Telecommunications Communication Systems
Identifiers
urn:nbn:se:miun:diva-35739 (URN)10.1109/ACCESS.2019.2903901 (DOI)000463262800001 ()2-s2.0-85063890617 (Scopus ID)
Projects
TIMELINESS
Funder
Knowledge Foundation
Available from: 2019-03-08 Created: 2019-03-08 Last updated: 2019-05-24Bibliographically approved
Mahmood, A., Hossain, M. M., Cavdar, C. & Gidlund, M. (2019). Energy-Reliability Aware Link Optimization for Battery-Powered IoT Devices with Non-Ideal Power Amplifiers. IEEE Internet of Things Journal, 6(3), 5058-5067, Article ID 8625460.
Open this publication in new window or tab >>Energy-Reliability Aware Link Optimization for Battery-Powered IoT Devices with Non-Ideal Power Amplifiers
2019 (English)In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 6, no 3, p. 5058-5067, article id 8625460Article in journal (Refereed) Published
Abstract [en]

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

Keywords
Energy-efficiency, reliability, short-range communication, cross-layer design, IoT, non-linear power amplifiers
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:miun:diva-35507 (URN)10.1109/JIOT.2019.2895228 (DOI)000472596200092 ()2-s2.0-85067841416 (Scopus ID)
Projects
TIMELINESS
Funder
Knowledge Foundation
Available from: 2019-01-23 Created: 2019-01-23 Last updated: 2019-08-09Bibliographically approved
Aslam, M. S., Khan, A., Atif, A., Hassan, S. A., Mahmood, A., Qureshi, H. K. & Gidlund, M. (2019). Exploring Multi-Hop LoRa for Green Smart Cities. IEEE Network Magazine
Open this publication in new window or tab >>Exploring Multi-Hop LoRa for Green Smart Cities
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2019 (English)In: IEEE Network MagazineArticle in journal (Refereed) Accepted
Abstract [en]

With the growing popularity of Internet-of-Things (IoT)-based smart city applications, various long-range and low-power wireless connectivity solutions are under rigorous research. LoRa is one such solution that works in the sub-GHz unlicensed spectrum and promises to provide long-range communication with minimal energy consumption. However, the conventional LoRa networks are single-hop, with the end devices connected to a central gateway through a direct link, which may be subject to large path loss and hence render low connectivity and coverage. This article motivates the use of multi-hop LoRa topologies to enable energy-efficient connectivity in smart city applications. We present a case study that experimentally evaluates and compares single-hop and multi-hop LoRa topologies in terms of range extension and energy efficiency by evaluating packet reception ratio (PRR) for various source to destination distances, spreading factors (SFs), and transmission powers. The results highlight that a multi-hop LoRa network configuration can save significant energy and enhance coverage. For instance, it is shown that to achieve a 90% PRR, a two-hop network provides 50% energy savings as compared to a single-hop network while increasing 35% coverage at a particular SF. In the end, we discuss open challenges in multi-hop LoRa deployment and optimization.

Place, publisher, year, edition, pages
IEEE Communications Society, 2019
Keywords
IoT, Green Communications, Smart Cities, LoRa Technology, Multi-hop Networks
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:miun:diva-37129 (URN)
Funder
Knowledge Foundation
Available from: 2019-09-06 Created: 2019-09-06 Last updated: 2019-09-06
Nikonowicz, J., Mahmood, A., Sisinni, E. & Gidlund, M. (2019). Noise Power Estimators in ISM Radio Environments: Performance Comparison and Enhancement Using a Novel Samples Separation Technique. IEEE Transactions on Instrumentation and Measurement, 68(1), 105-115
Open this publication in new window or tab >>Noise Power Estimators in ISM Radio Environments: Performance Comparison and Enhancement Using a Novel Samples Separation Technique
2019 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 68, no 1, p. 105-115Article in journal (Refereed) Published
Abstract [en]

Noise power estimation is central to efficient radio resource allocation in modern wireless communication systems. In the literature, there exist many noise power estimation methods that can be classified based on underlying theoretical principle; the most common are spectral averaging, eigenvalues of sample covariance matrix, information theory, and statistical signal analysis. However, how these estimation methods compare against each other in terms of accuracy, stability, and complexity is not well studied, and the focus instead remains on the enhancement of individual methods. In this paper, we adopt a common simulation methodology to perform a detailed performance evaluation of the prominent estimation techniques. The basis of our comparison is the signal-to-noise ratio estimation in the simulated industrial, scientific and medical band transmission, while the reference noise signal is acquired from an industrial production plant using a software-defined radio platform, USRP-2932. In addition, we analyze the impact of different techniques for noise-samples' separation on the estimation process. As a response to defects in the existing techniques, we propose a novel noise-samples' separation algorithm based on the adaptation of rank-order filtering. Our analysis shows that the proposed solution, apart from its low complexity, has a very good root-mean-squared error of 0.5 dB and smaller than 0.1-dB resolution, thus  achieving a performance comparable with the methods exploiting information theory concepts.

Keywords
Blind noise separation, noise power estimation, rank-order filtering (ROF), signal-to-noise ratio (SNR) estimation.
National Category
Communication Systems Computer Engineering
Identifiers
urn:nbn:se:miun:diva-33731 (URN)10.1109/TIM.2018.2833998 (DOI)000452611600009 ()
Projects
TIMELINESS
Funder
Knowledge Foundation
Available from: 2018-06-08 Created: 2018-06-08 Last updated: 2019-01-17Bibliographically approved
Zeb, S., Abbas, Q., Hassan, S. A., Mahmood, A., Mumtaz, R., Zaidi, S. M., . . . Gidlund, M. (2019). NOMA Enhanced Backscatter Communication for Green IoT Networks. In: 16th International Symposium on Wireless Communication Systems (ISWCS): . Paper presented at 16th International Symposium on Wireless Communication Systems (ISWCS).
Open this publication in new window or tab >>NOMA Enhanced Backscatter Communication for Green IoT Networks
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2019 (English)In: 16th International Symposium on Wireless Communication Systems (ISWCS), 2019Conference paper, Published paper (Refereed)
Abstract [en]

Backscatter communication has recently emerged as a promising technology to enable passive sensing-based Internet-of-things (IoT) applications. In a backscatter communication network, uplink transmissions of multiple nodes are usually multiplexed in time- or frequency-domain to avoid collisions, yet it is desirable to improve the uplink capacity further. In this paper, we study a wireless-powered backscatter communication system, where the sensors use a hybrid channel access scheme by combining time division multiplexing access(TDMA) with power-domain non-orthogonal multiple access(PD-NOMA) to enhance the system performance in terms of outage probability and throughput. Our analysis shows that the proposed PD-NOMA increases both the spectrum efficiency and the throughput of the system.

Keywords
Backscatter communication, Internet-of-things (IoT), non-orthogonal multiple access (NOMA), wireless-powered communication
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:miun:diva-37133 (URN)
Conference
16th International Symposium on Wireless Communication Systems (ISWCS)
Funder
Knowledge Foundation
Available from: 2019-09-06 Created: 2019-09-06 Last updated: 2019-09-06
Shehzad, M. K., Hassan, S. A., Mahmood, A. & Gidlund, M. (2019). On the Association of Small Cell Base Stations with UAVs using Unsupervised Learning. In: IEEE 89th Vehicular Technology Conference, VTC2019-Spring: . Paper presented at IEEE 89th Vehicular Technology Conference, VTC2019-Spring, 5th International Workshop of CorNer: Communication for Networked Smart Cities, Kuala Lumpur, Malaysia, 28 April – 1 May 2019. Institute of Electrical and Electronics Engineers (IEEE), Article ID 8746456.
Open this publication in new window or tab >>On the Association of Small Cell Base Stations with UAVs using Unsupervised Learning
2019 (English)In: IEEE 89th Vehicular Technology Conference, VTC2019-Spring, Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8746456Conference paper, Published paper (Refereed)
Abstract [en]

Small cell networks (SCNs) offer a cost-effective coverage solution to wireless applications demanding high data rates. However in SCNs, a challenging problem is the proper management of backhaul links to small cell base stations(SCBSs). To make a good backhaul link, perfect line-of-sight (LoS) communication between the SCBSs and the core network plays a vital role. In this study, we use the idea of employing unmanned aerial vehicles (UAVs) to provide connectivity betweenSCBSs and the core network. We focus on the association of SCBSs with UAVs by considering multiple communication-related factors including data rate limit and available bandwidth resources of the backhaul. In particular, we address the optimum placement of UAVs to serve a maximum number of SCBSswhile considering available resources using the unsupervised k-means algorithm. Numerical results show that the proposed approach outperforms the conventional approach in terms of associatedSCBSs, bandwidth consumption, available link utilization, and sum-rate maximization.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
Drones, unmanned aerial vehicles (UAVs), small cell base stations, fronthaul/backhaul network, unsupervised learning
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:miun:diva-35732 (URN)10.1109/VTCSpring.2019.8746456 (DOI)2-s2.0-85068960845 (Scopus ID)
Conference
IEEE 89th Vehicular Technology Conference, VTC2019-Spring, 5th International Workshop of CorNer: Communication for Networked Smart Cities, Kuala Lumpur, Malaysia, 28 April – 1 May 2019
Funder
Knowledge Foundation
Available from: 2019-03-05 Created: 2019-03-05 Last updated: 2019-08-13Bibliographically approved
Grimaldi, S., Mahmood, A. & Gidlund, M. (2019). Real-time Interference Identification via Supervised Learning: Embedding Coexistence Awareness in IoT Devices. IEEE Access, 7, 835-850
Open this publication in new window or tab >>Real-time Interference Identification via Supervised Learning: Embedding Coexistence Awareness in IoT Devices
2019 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 835-850Article in journal (Refereed) Published
Abstract [en]

Energy sampling-based interference detection and identification (IDI) methods collide with the limitations of commercial off-the-shelf (COTS) IoT hardware. Moreover, long sensing times, complexity and inability to track concurrent interference strongly inhibit their applicability in most IoT deployments. Motivated by the increasing need for on-device IDI for wireless coexistence, we develop a lightweight and efficient method targeting interference identification already at the level of single interference bursts. Our method exploits real-time extraction of envelope and model-aided spectral features, specifically designed considering the physical properties of signals captured with COTS hardware. We adopt manifold supervised-learning (SL) classifiers ensuring suitable performance and complexity trade-off for IoT platforms with different computational capabilities. The proposed IDI method is capable of real-time identification of IEEE 802.11b/g/n, 802.15.4, 802.15.1 and Bluetooth Low Energy wireless standards, enabling isolation and extraction of standard-specific traffic statistics even in the case of heavy concurrent interference. We perform an experimental study in real environments with heterogeneous interference scenarios, showing 90%–97% burst identification accuracy. Meanwhile, the lightweight SL methods, running online on wireless sensor networks-COTS hardware, ensure sub-ms identification time and limited performance gap from machine-learning approaches.

Keywords
Bluetooth; interference detection and identification, IoT, machine learning, wireless coexistence, wireless sensor networks, WLAN
National Category
Communication Systems
Identifiers
urn:nbn:se:miun:diva-35184 (URN)10.1109/ACCESS.2018.2885893 (DOI)000455177700001 ()
Projects
SMART (Smarta system och tjänster för ett effektivt och innovativt samhälle)
Available from: 2018-12-12 Created: 2018-12-12 Last updated: 2019-09-09Bibliographically approved
Mahmood, A., Sisinni, E., Guntupalli, L., Rondón, R., Hassan, S. A. & Gidlund, M. (2019). Scalability Analysis of a LoRa Network under Imperfect Orthogonality. IEEE Transactions on Industrial Informatics, 15(3), 1425-1436
Open this publication in new window or tab >>Scalability Analysis of a LoRa Network under Imperfect Orthogonality
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2019 (English)In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 15, no 3, p. 1425-1436Article in journal (Refereed) Published
Abstract [en]

Low-power wide-area network (LPWAN) technologies are gaining momentum for internet-of-things (IoT) applications since they promise wide coverage to a massive number of battery-operated devices using grant-free medium access. LoRaWAN, with its physical (PHY) layer design and regulatory efforts, has emerged as the widely adopted LPWAN solution. By using chirp spread spectrum modulation with qausi-orthogonal spreading factors (SFs), LoRa PHY offers coverage to wide-area applications while supporting high-density of devices. However, thus far its scalability performance has been inadequately modeled and the effect of interference resulting from the imperfect orthogonality of the SFs has not been considered. In this paper, we present an analytical model of a single-cell LoRa system that accounts for the impact of interference among transmissions over the same SF (co-SF) as well as different SFs (inter-SF). By modeling the interference field as Poisson point process under duty-cycled ALOHA, we derive the signal-to-interference ratio (SIR) distributions for several interference conditions. Results show that, for a duty cycle as low as 0.33%, the network performance under co-SF interference alone is considerably optimistic as the inclusion of inter-SF interference unveils a further drop in the success probability and the coverage probability of approximately 10% and 15%, respectively for 1500 devices in a LoRa channel. Finally, we illustrate how our analysis can characterize the critical device density with respect to cell size for a given reliability target.

Keywords
IoT, low-power wide-area networks, LoRaWAN, interference, stochastic geometry
National Category
Communication Systems Telecommunications Computer Engineering
Identifiers
urn:nbn:se:miun:diva-34280 (URN)10.1109/TII.2018.2864681 (DOI)000460580100018 ()
Projects
TIMELINESSSMART (Smarta system och tjänster för ett effektivt och innovativt samhälle)
Funder
European Regional Development Fund (ERDF)Knowledge Foundation
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2019-09-09Bibliographically approved
Mahmood, A., Hossain, M. M. & Gidlund, M. (2018). Cross-Layer Optimization of Wireless Links under Reliability and Energy Constraints. In: IEEE Wireless Communications and Networking Conference, WCNC: . Paper presented at IEEE WCNC'18 IEEE Wireless Communications and Networking Conference, Barcelona, Spain, 15-18 April 2018. New York: IEEE
Open this publication in new window or tab >>Cross-Layer Optimization of Wireless Links under Reliability and Energy Constraints
2018 (English)In: IEEE Wireless Communications and Networking Conference, WCNC, New York: IEEE, 2018Conference paper, Published paper (Refereed)
Abstract [en]

The vision of connecting billions of battery operated devices to be used for diverse emerging applications calls for a wireless communication system that can support stringent reliability and latency requirements. Both reliability and energy efficiency are critical for many of these applications that involve communication with short packets which undermine the coding gain achievable from large packets. In this paper, we study a cross-layer approach to optimize the performance of low-power wireless links. At first, we derive a simple and accurate packet error rate (PER) expression for uncoded schemes in block fading channels based on a new proposition that shows that the waterfall threshold in the PER upper bound in Nakagami-m fading channels is tightly approximated by the m-th moment of an asymptotic distribution of PER in AWGN channel. The proposed PER approximation establishes an explicit connection between the physical and link layers parameters, and the packet error rate. We exploit this connection for cross-layer design and optimization of communication links. To this end, we propose a semi-analytic framework to jointly optimize signal-to-noise ratio (SNR) and modulation order at physical layer, and the packet length and number of retransmissions at link layer with respect to distance under the prescribed delay and reliability constraints.

Place, publisher, year, edition, pages
New York: IEEE, 2018
Series
IEEE Wireless Communications and Networking Conference, ISSN 1525-3511
Keywords
Wireless sensor networks, Packet error rate, Fading channels, Cross-layer optimization, Energy efficient communication
National Category
Communication Systems Telecommunications Computer Engineering
Identifiers
urn:nbn:se:miun:diva-32449 (URN)000435542401068 ()2-s2.0-85049232011 (Scopus ID)978-1-5386-1734-2 (ISBN)
Conference
IEEE WCNC'18 IEEE Wireless Communications and Networking Conference, Barcelona, Spain, 15-18 April 2018
Projects
TimelinessSMART (Smarta system och tjänster för ett effektivt och innovativt samhälle)
Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2019-09-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3717-7793

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