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Publications (10 of 37) Show all publications
Hofmann, S., Megas, V., Özger, M., Schupke, D., Fitzek, F. H. & Cavdar, C. (2019). Combined Optimal Topology Formation and Rate Allocation for Aircraft to Aircraft Communications. In: IEEE International Conference on Communications: . Paper presented at 2019 IEEE International Conference on Communications, ICC 2019; Shanghai International Convention Center, Shanghai; China; 20-24 May 2019. Institute of Electrical and Electronics Engineers (IEEE), Article ID 8761882.
Open this publication in new window or tab >>Combined Optimal Topology Formation and Rate Allocation for Aircraft to Aircraft Communications
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2019 (English)In: IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8761882Conference paper, Published paper (Refereed)
Abstract [en]

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

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Series
IEEE International Conference on Communications, ISSN 1550-3607
Keywords
air-to-air communication, direct air-to-ground communication, mixed integer linear programming, rate allocation, topology formation
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-257939 (URN)10.1109/ICC.2019.8761882 (DOI)000492038805008 ()2-s2.0-85070206236 (Scopus ID)9781538680889 (ISBN)
Conference
2019 IEEE International Conference on Communications, ICC 2019; Shanghai International Convention Center, Shanghai; China; 20-24 May 2019
Note

QC 20190909

Available from: 2019-09-09 Created: 2019-09-09 Last updated: 2020-01-07Bibliographically approved
Garcia, A. E., Ozger, M., Baltaci, A., Hofmann, S., Gera, D., Nilsson, M., . . . Schupke, D. (2019). Direct air to ground communications for flying vehicles: Measurement and scaling study for 5g. In: Proceedings of the IEEE 5G World Forum, 5GWF 2019 -: . Paper presented at IEEE 5G World Forum, 5GWF 2019 - Sep 30-Oct 2, 2019 (pp. 310-315).
Open this publication in new window or tab >>Direct air to ground communications for flying vehicles: Measurement and scaling study for 5g
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2019 (English)In: Proceedings of the IEEE 5G World Forum, 5GWF 2019 -, 2019, p. 310-315Conference paper, Published paper (Refereed)
Abstract [en]

Broadband connectivity in the sky for unmanned aerial vehicles (UAVs) and commercial aircraft is the next step toward the ambitious goal of connectivity anywhere. To achieve it, direct air-to-ground communications (DA2GC) is a more promising solution than satellite communications due to its lower latency and higher throughput capabilities. In this paper, we develop a DA2GC system with tilted up directional antennas at ground base station and perform a measurement campaign using a UAV at low altitudes to study the DA2GC link at a carrier frequency of 3.7 GHz in terms of signal-to-noise ratio and throughput. Our designed DA2GC system is a general setup that can enable new frequency spectrum and new applications for 5G implementation. We also scale the obtained results from the measurements to a scenario of an aircraft flying at an altitude of 13 km. We study the physical limits of current cellular networks and analyze link budget for the scaling. A maximum of 14 Mbps is achieved during the measurement campaign. By scaling the measurement results with existing communications techniques such as carrier aggregation and techniques toward 5G such as higher antenna gains due to beamforming, extrapolated throughput could reach up to 257 Mbps with a maximum inter-site distance of 200 km due to limitations of current cellular networks. These results show that cellular networks with communication techniques toward 5G can be utilized for providing high-capacity connectivity for current aircraft at high altitudes as well as next-generation flying vehicles at low altitudes.

National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-268231 (URN)10.1109/5GWF.2019.8911712 (DOI)2-s2.0-85076799289 (Scopus ID)
Conference
IEEE 5G World Forum, 5GWF 2019 - Sep 30-Oct 2, 2019
Note

QC 20200417

Available from: 2020-04-17 Created: 2020-04-17 Last updated: 2020-04-17Bibliographically approved
Mahmood, A., Hossain, A. M., Cavdar, C. & Gidlund, M. (2019). Energy-Reliability Aware Link Optimization for Battery-Powered IoT Devices With Nonideal Power Amplifiers. IEEE Internet of Things Journal, 6(3), 5058-5067
Open this publication in new window or tab >>Energy-Reliability Aware Link Optimization for Battery-Powered IoT Devices With Nonideal Power Amplifiers
2019 (English)In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 6, no 3, p. 5058-5067Article 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 nonideal characteristics of the hardware in Internet-of-Things (IoT) devices. Specifically, we define an energy consumption (EC) model that captures the energy cost-of transceiver circuitry, power amplifier (PA), packet error statistics, packet overhead, etc.-in delivering a useful data bit. We derive the EC models for an ideal and two realistic nonlinear PA models. To incorporate packet error statistics, we develop a simple, in the form of elementary functions, and accurate closed-form packet error rate approximation in Rayleigh block-fading. Using the EC models, we derive energy-optimal yet reliability and hardware compliant conditions for limiting unconstrained optimal signal-to-noise ratio (SNR), and payload size. Together with these conditions, we develop a semianalytic algorithm for resource-constrained IoT devices to jointly optimize parameters on physical (modulation size, SNR) and medium access control (payload size and the number of retransmissions) layers in relation to link distance. Our results show that despite reliability constraints, the common notion-higherorder M-ary modulations are energy optimal for short-range communication-prevails, and can provide up to 180% lifetime extension as compared to often used OQPSK modulation in IoT devices. However, the reliability constraints reduce both their range and the energy efficiency, while nonideal traditional PA reduces the range further by 50% and diminishes the energy gains unless a better PA is used.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
Cross-layer design, energy-efficiency, Internet-of-Things (IoT), nonlinear power amplifiers (PAs), reliability, short-range communication
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-255450 (URN)10.1109/JIOT.2019.2895228 (DOI)000472596200092 ()2-s2.0-85067841416 (Scopus ID)
Note

QC 20190820

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-08-20Bibliographically approved
Masoudi, M., Khafagy, M. G., Conte, A., El-Amine, A., Francoise, B., Nadjahi, C., . . . Cavdar, C. (2019). Green Mobile Networks for 5G and Beyond. IEEE Access, 7, 107270-107299
Open this publication in new window or tab >>Green Mobile Networks for 5G and Beyond
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2019 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 107270-107299Article in journal (Refereed) Published
Abstract [en]

The heated 5G network deployment race has already begun with the rapid progress in standardization efforts, backed by the current market availability of 5G-enabled network equipment, ongoing 5G spectrum auctions, early launching of non-standalone 5G network services in a few countries, among others. In this paper, we study current and future wireless networks from the viewpoint of energy efficiency (EE) and sustainability to meet the planned network and service evolution toward, along, and beyond 5G, as also inspired by the findings of the EU Celtic-Plus SooGREEN Project. We highlight the opportunities seized by the project efforts to enable and enrich this green nature of the network as compared to existing technologies. In specific, we present innovative means proposed in SooGREEN to monitor and evaluate EE in 5G networks and beyond. Further solutions are presented to reduce energy consumption and carbon footprint in the different network segments. The latter spans proposed virtualized/cloud architectures, efficient polar coding for fronthauling, mobile network powering via renewable energy and smart grid integration, passive cooling, smart sleeping modes in indoor systems, among others. Finally, we shed light on the open opportunities yet to be investigated and leveraged in future developments.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
CRAN, DAS, energy efficiency, monitoring, storage, green mobile networks, passive cooling, renewable energy, sleep modes, smart grid, virtualization, Wi-Fi
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-262835 (URN)10.1109/ACCESS.2019.2932777 (DOI)000481972100164 ()2-s2.0-85071088503 (Scopus ID)
Note

QC 20191021

Available from: 2019-10-21 Created: 2019-10-21 Last updated: 2019-10-21Bibliographically approved
Meer, I. A., Ozger, M., Lundmark, M., Sung, K. W. & Cavdar, C. (2019). Ground Based Sense and Avoid System for Air Traffic Management. In: Proceedings of the 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC): . Paper presented at 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 8-11 Sept. 2019.
Open this publication in new window or tab >>Ground Based Sense and Avoid System for Air Traffic Management
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2019 (English)In: Proceedings of the 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2019Conference paper, Published paper (Refereed)
Abstract [en]

Unmanned aerial vehicles (UAVs) need to "see and be seen" by manned aircraft for their safe operation. For this purpose, using available Automatic Dependent Surveillance-Broadcast (ADS-B) for all UAVs will not only saturate the 1090 MHz spectrum but will require an extra hardware. To mitigate these issues, we propose a ground based sense and avoid (GBSAA) system to enable coexistence of low altitude UAVs and ADS-B enabled flying vehicles (FVs), i.e., manned aircraft, for avoiding collisions. UAVs transmit their location information via a cellular technology to cloud, and a GBSAA base station accesses the aggregated information to send it to the ADS-B enabled FVs via ADS-B technology. We performed analytical and simulation studies to investigate the ADS-B message collision probability for different network parameters such as number of UAVs and ADS-B enabled FVs. Our study shows that for a collision probability of 0.1 with the lowest ADS-B update interval, GBSAA system can support approximately 10 times more UAVs than ADS-B only system. The proposed GBSAA approach provides a tremendous potential to integrate UAVs into airspace in a scalable manner.

National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-268236 (URN)10.1109/PIMRC.2019.8904324 (DOI)2-s2.0-85075882343 (Scopus ID)
Conference
2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 8-11 Sept. 2019
Note

QC 20200415

Available from: 2020-04-15 Created: 2020-04-15 Last updated: 2020-04-15Bibliographically approved
Sriram, A., Masoudi, M., Alabbasi, A. & Cavdar, C. (2019). Joint functional splitting and content placement for green hybrid CRAN. In: 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC): . Paper presented at 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 8-11 September 2019 Istanbul, Turkey.
Open this publication in new window or tab >>Joint functional splitting and content placement for green hybrid CRAN
2019 (English)In: 2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2019Conference paper, Published paper (Refereed)
Abstract [en]

A hybrid cloud radio access network (H-CRAN) architecture has been proposed to alleviate the midhaul capacity limitation in C-RAN. In this architecture, functional splitting is utilized to distribute the processing functions between a central cloud and edge clouds. The flexibility of selecting specific split point enables the H-CRAN designer to reduce midhaul bandwidth, reduce latency, save energy, or distribute the computation task depending on equipment availability. Meanwhile, techniques for caching are proposed to reduce content delivery latency and the required bandwidth. However, caching imposes new constraints on functional splitting. In this study, considering H-CRAN, a constraint programming problem is formulated to minimize the overall power consumption by selecting the optimal functional split point and content placement, taking into account the content access delay constraint. We also investigate the trade-off between the overall power consumption and occupied midhaul bandwidth in the network. Our results demonstrate that functional splitting together with enabling caching at edge clouds reduces not only content access delays but also fronthaul bandwidth consumption and saves energy finding a compromise between these performance metrics.

National Category
Communication Systems
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-271326 (URN)10.1109/PIMRC.2019.8903627 (DOI)
Conference
2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 8-11 September 2019 Istanbul, Turkey
Note

QC 20200327

Available from: 2020-03-25 Created: 2020-03-25 Last updated: 2020-03-27Bibliographically approved
Azari, A., Stefanovic, C., Popovski, P. & Cavdar, C. (2019). On the Latency-Energy Performance of NB-IoT Systems in Providing Wide-Area IoT Connectivity. IEEE Transactions on Green Communications and Networking
Open this publication in new window or tab >>On the Latency-Energy Performance of NB-IoT Systems in Providing Wide-Area IoT Connectivity
2019 (English)In: IEEE Transactions on Green Communications and NetworkingArticle in journal (Refereed) Published
Abstract [en]

Narrowband Internet-of-Things (NB-IoT) offers a significant link budget improvement in comparison with the legacy networks by introducing different coverage classes, allowing repeated transmissions, and tuning the repetition order based on the path-loss in communications. However, those repetitions necessarily increase energy consumption and latency in the whole NB-IoT system. The extent to which the whole system is affected depends on the scheduling of the uplink and downlink channels. We address this question, not treated previously, by developing a tractable model of NB-IoT connectivity, comprising message exchanges in random-access, control, and data channels. The model is then used to analyze the impact of channel scheduling and interaction of coverage classes on the performance of IoT devices through the derivation of the expected latency and battery lifetime. These results are subsequently employed in determining the optimized operation points, i.e., (i) scheduling of data and control channels for a given set of users and respective coverage classes, or (ii) determining the optimal set of coverage classes and served users per coverage class for a given scheduling strategy. Simulations results show the validity of the analysis and confirm that channel scheduling and coexistence of coverage classes significantly affect latency and battery lifetime performance of NB-IoT devices.

National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-268315 (URN)10.1109/TGCN.2019.2948591 (DOI)2-s2.0-85074140777 (Scopus ID)
Note

QC 20200310

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2020-03-10Bibliographically approved
Vondra, M., Dinc, E. & Cavdar, C. (2018). Coordinated resource allocation scheme for 5G direct air-to-ground communication. In: 24th European Wireless 2018 "Wireless Futures in the Era of Network Programmability", EW 2018: . Paper presented at 24th European Wireless Conference 2018: Wireless Futures in the Era of Network Programmability, EW 2018, 2 May 2018 through 4 May 2018 (pp. 137-143). VDE Verlag GmbH
Open this publication in new window or tab >>Coordinated resource allocation scheme for 5G direct air-to-ground communication
2018 (English)In: 24th European Wireless 2018 "Wireless Futures in the Era of Network Programmability", EW 2018, VDE Verlag GmbH, 2018, p. 137-143Conference paper, Published paper (Refereed)
Abstract [en]

There is an increasing demand for in-flight broadband connectivity. Some airlines are already deployed satellite-based solutions, which have low data rate and high latency. In order to tackle these problems, direct air-to-ground communication (DA2GC), where a direct link between a ground station and an airplane is established, is a promising solution. The resource utilization in DA2GC systems can be enhanced with the introduction of multi-user beamforming techniques, where each airplane has its dedicated beam and exploits a larger portion of the spectrum available to DA2GC. Even with multiuser beamforming technique, some airplanes may experience low data rates due to interference caused by beams aimed at airplanes in the mutual vicinity. The probability that two or more beams will interfere is higher with longer inter-site distance or wider beamwidth, which is often the case for DA2GC systems. To address significant research problem, we propose a coordinated resource allocation scheme with beam selection and spectrum allocation. The proposed beam selection scheme coordinates the neighboring base stations such that the number of airplanes sharing the same beam is minimized. In addition, the proposed coordinated spectrum allocation scheme maximizes the minimum amount of spectrum dedicated for each airplane. According to our results, the proposed coordinated beam selection with efficient spectrum allocation improves average capacity available per airplane by 60% in comparison with the uncoordinated scheme.

Place, publisher, year, edition, pages
VDE Verlag GmbH, 2018
Keywords
5G networks, DA2GC, Multi-user beamforming, SDMA, Space division multiple access, 5G mobile communication systems, Aircraft, Beamforming, Resource allocation, Satellite communication systems, Air-to-ground communications, Beamforming technique, Broadband connectivity, Multi-user, Resource allocation schemes, Spectrum-allocation scheme
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-236377 (URN)2-s2.0-85050010079 (Scopus ID)9783800745609 (ISBN)
Conference
24th European Wireless Conference 2018: Wireless Futures in the Era of Network Programmability, EW 2018, 2 May 2018 through 4 May 2018
Note

QC 20181105

Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2018-11-05Bibliographically approved
Cavdar, C., Gera, D., Ghosh, A., Hofmann, S., Nordlow, A. & Schupke, D. (2018). Demonstration of an Integrated 5G Network in an Aircraft Cabin Environment. In: 2018 IEEE/AIAA 37TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC): . Paper presented at IEEE/AIAA 37th Digital Avionics Systems Conference (DASC), SEP 23-27, 2018, London, ENGLAND (pp. 334-343). IEEE
Open this publication in new window or tab >>Demonstration of an Integrated 5G Network in an Aircraft Cabin Environment
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2018 (English)In: 2018 IEEE/AIAA 37TH DIGITAL AVIONICS SYSTEMS CONFERENCE (DASC), IEEE , 2018, p. 334-343Conference paper, Published paper (Refereed)
Abstract [en]

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

Place, publisher, year, edition, pages
IEEE, 2018
Series
IEEE-AIAA Digital Avionics Systems Conference, ISSN 2155-7195
Keywords
Aircraft Connectivity, Direct Air-to-Ground Communications, LAA, LTE, Machine Type Communications
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-242203 (URN)10.1109/DASC.2018.8569540 (DOI)000455217900049 ()2-s2.0-85060661069 (Scopus ID)978-1-5386-4112-5 (ISBN)
Conference
IEEE/AIAA 37th Digital Avionics Systems Conference (DASC), SEP 23-27, 2018, London, ENGLAND
Note

QC 20190128

Available from: 2019-01-28 Created: 2019-01-28 Last updated: 2019-06-26Bibliographically approved
Hossain, M. M., Cavdar, C., Bjornson, E. & Jantti, R. (2018). Energy Saving Game for Massive MIMO: Coping With Daily Load Variation. IEEE Transactions on Vehicular Technology, 67(3), 2301-2313
Open this publication in new window or tab >>Energy Saving Game for Massive MIMO: Coping With Daily Load Variation
2018 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, no 3, p. 2301-2313Article in journal (Refereed) Published
Abstract [en]

Massive MIMO (MM) is one of the leading technologies that can cater for very high capacity demand. However, energy consumption of MM systems needs to be load adaptive in order to cope with the significant temporal load variations (TLV) over a day. In this paper, we propose a game-theoretic model for studying load adaptive multicell massive MIMO system where each base station (BS) adapts the number of antennas to the TLV in order to maximize the downlink energy efficiency (EE). The utility function considered here is defined as the number of bits transferred per Joule of energy. In order to incorporate the TLV, the load at each BS is modeled as an M/G/m/m state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through the best response iteration. This load adaptive system achieves around 24% higher EE and saves around 40% energy compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at the peak load and that can be switched OFF when there is no traffic.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Massive MIMO, energy efficiency, M/G/m/m queue, game theory
National Category
Communication Systems Telecommunications
Identifiers
urn:nbn:se:kth:diva-226226 (URN)10.1109/TVT.2017.2769163 (DOI)000427863000038 ()2-s2.0-85032734158 (Scopus ID)
Note

QC 20180531

Available from: 2018-05-31 Created: 2018-05-31 Last updated: 2018-05-31Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0525-4491

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