Wireless Communications and Networking with Unmanned Aerial Vehicles

259 Pages·2017·19.63 MB·English

Wireless Communications and Networking with
Unmanned Aerial Vehicles: Fundamentals,
Deployment, and Optimization
MohammadMozaffari
DissertationsubmittedtotheFacultyofthe
VirginiaPolytechnicInstituteandStateUniversity
inpartialfulfillmentoftherequirementsforthedegreeof
DoctorofPhilosophy
in
ElectricalEngineering
WalidSaad,Chair
JeffreyH.Reed
HarpreetDhillon
MantuK.Hudait
AnilKumarS.Vullikanti
May16,2018
Blacksburg,Virginia
Keywords: UnmannedAerialVehicle(UAV),3DWirelessNetworks,Drone,Optimization,
OptimalTransportTheory,PerformanceAnalysis
Copyright2018,MohammadMozaffari
Wireless Communications and Networking with Unmanned Aerial Vehicles:
Fundamentals, Deployment, and Optimization
MohammadMozaffari
ABSTRACT
Theuseofaerialplatformssuchasunmannedaerialvehicles(UAVs),popularlyknownasdrones,
hasemergedasapromisingsolutionforprovidingreliableandcost-effectivewirelesscommunica-
tions. Inparticular,UAVscanbequicklyandefficientlydeployedtosupportcellularnetworksand
enhance their quality-of-service (QoS) by establishing line-of-sight communication links. With
theirinherentattributessuchasmobility,flexibility,andadaptivealtitude,UAVsadmitseveralkey
potentialapplicationsinwirelesssystems. Remarkably,despitetheseinherentadvantagesofUAV-
based communications, little work has analyzed the performance tradeoffs associated with using
UAVs as aerial wireless platforms. The key goal of this dissertation is to develop the analytical
foundationsfordeployment,performanceanalysis,andoptimizationofUAV-enabledwirelessnet-
works. This dissertation makes a number of fundamental contributions to various areas of UAV
communicationsthatinclude: 1)EfficientdeploymentofUAVs,2)Performanceevaluationandop-
timization,and3)Designofnewflying,three-dimensional(3D)wirelesssystems. Fordeployment,
usingtoolsfromoptimizationtheory,holisticframeworksaredevelopedfortheoptimal3Dplace-
ment of UAV base stations in uplink and downlink scenarios. The results show that the proposed
deployment approaches significantly improve the downlink coverage for ground users, and enable
ultra-reliableandenergy-efficientuplinkcommunicationsinInternetofThings(IoT)applications.
For performance optimization, a novel framework is developed for maximizing the performance
of a UAV-based wireless system, in terms of data service, under UAVs’ flight time constraints.
To this end, using the mathematical framework of optimal transport theory, the optimal cell as-
sociations, that lead to a maximum data service to ground users within the limited UAVs’ hover
duration, are analytically derived. The results shed light on the tradeoff between hover time and
quality-of-service in UAV-based wireless networks. For performance evaluation, this dissertation
provides a comprehensive analysis on the performance of a UAV-based communication system in
coexistence with a terrestrial network. In particular, a tractable analytical framework is proposed
foranalyzingthecoverageandrateperformanceofanetworkwithaUAVbasestationanddevice-
to-device (D2D) users. The results reveal the fundamental tradeoffs in such a UAV-D2D network
that allow adopting appropriate system design parameters. Then, this dissertation sheds light on
thedesignofthreenewdrone-enabledwirelesssystems. First,anovelframeworkforeffectiveuse
ofcache-enabledUAVsinwirelessnetworksisdeveloped. Theresultsdemonstratehowtheusers’
quality of experience substantially improves by exploiting UAVs’ mobility and user-centric infor-
mation. Second, a new framework is proposed for deploying and operating a drone-based antenna
array system that delivers wireless service to ground users within a minimum time. The results
show significant enhancement in QoS, spectral and energy efficiency while levering the proposed
droneantennaarraysystem. Finally,toeffectivelyincorporatevarioususecasesofdronesranging
from aerial users to base stations, the new concept of a fully-fledged 3D cellular network is intro-
duced. For this new type of 3D wireless network, a unified framework for deployment, network
planning, and performance optimization is developed that yields a maximum coverage and mini-
mumlatencyinthenetwork. Inanutshell,theanalyticalfoundationsandframeworkspresentedin
this dissertation provide key guidelines for effective design and operation of UAV-based wireless
communicationsystems.
Wireless Communications and Networking with Unmanned Aerial Vehicles:
Fundamentals, Deployment, and Optimization
MohammadMozaffari
GeneralAudienceAbstract
Unmannedaerialvehicles(UAVs),commonlyknownasdrones,havebeenthesubjectofconcerted
research over the past few years, owing to their autonomy, flexibility, and broad range of applica-
tion domains. Indeed, UAVs have been considered as enablers of various applications that include
military, surveillance and monitoring, telecommunications, delivery of medical supplies, and res-
cue operations. The unprecedented recent advances in drone technology has made it possible
to widely deploy UAVs, such small aircrafts, balloons, and airships for wireless communication
purposes. In particular, if properly deployed and operated, UAVs can provide reliable and cost-
effectivewirelesscommunicationsolutionsforavarietyofreal-worldscenarios. Ontheonehand,
drones can be used as aerial base stations that can deliver reliable, cost-effective, and on-demand
wireless communications to desired areas. On the other hand, drones can function as aerial user
equipments,knownascellular-connectedUAVs,incoexistencewithgroundusers.
Despite such promising opportunities for drones, one must address a number of technical chal-
lengesinordertoeffectivelyusethemforeachspecificnetworkingapplication. Forinstance,while
using drone-BS, the key design considerations include performance characterization, optimal 3D
deployment of drones, wireless and computational resource allocation, flight time and trajectory
optimization, and network planning. Meanwhile, in the drone-UE scenario, handover manage-
ment, channel modeling, low-latency control, 3D localization, and interference management are
amongthemainchallenges.
Therefore, this dissertation addresses the fundamental challenges in UAV-enabled wireless com-
municationsthatallowsprovidingbroadband,wide-scale,cost-effective,andreliablewirelesscon-
nectivity. To this end, various mathematical frameworks and efficient algorithms are proposed to
design,optimize,deploy,andoperateUAV-basedcommunicationsystems. Theresultsshowsthat,
the proposed aerial communication system can deliver ultra-reliable, and cost-effective wireless
services,thusprovidingubiquitoushighspeedInternetconnectivityforthewholeworld.
Tomyparents,mysister,andShaghayegh
iv
Acknowledgments
First and foremost, I owe my deepest gratitude to my advisor, Dr. Walid Saad, for his continuous
support of my Ph.D study, his patience, motivation, and immense knowledge and experience. I
wouldliketothankyoufortheamountoftimeandeffort,ideas,andfundingyouhavegenerously
dedicatedtomakemyPh.D.experienceproductiveandstimulating. Iamalsogratefulforbelieving
in me and giving me the freedom to pursue diverse, yet coherent research directions which has
made my Ph.D. study a joyful and unforgettable journey. I am thankful for your priceless advice
andgreatsupervisionthathavehelpedmetogrowasaresearchscientistandfindtherightpathfor
my future career. I would like to thank the members of my Ph.D. advisory committee, Dr. Jeffrey
H. Reed, Dr. Harpreet Dhillon, Dr. Mantu K. Hudait, and Dr. Anil Kumar S. Vullikanti, for their
valuablecommentswhichhavehelpedmetosubstantiallyimprovethequalityofthisdissertation.
I am grateful for having the opportunity to work with great researchers and scientists during my
Ph.D.studytopublishscholarlypapers. Specialthankstomycollaborators,Dr. MerouaneDebbah,
Dr. Mehdi Bennis, and Dr. Ismail Guvenc for their time and effort to provide me with their
insightfulcommentstoimprovemyworkthroughoutmyPhD.
I would like to thank the folks at Wireless@VT, especially my friends at NetSciWis lab for their
help and support. In particular, thanks to Priyabrata for his great help during my PhD. Additional
gratitude is offered to my amazing friends: Homa, Mehrnoosh, Rashidi, Eragh, Lotfian, Beshkar,
andEskandar.
I am greatly thankful to my family, Zahra, Ali, Saeed, MohammadReza, and Shayan for their
sustainedencouragement,support,andunconditionallove.
Last, but not least, words cannot express how grateful I am to Mehrnaz. Indeed, without her
support,Icouldhaveneverbeenabletofinishthisdissertation.
v
Contents
1 Motivation,Background,andContributions 1
1.1 BenefitsandApplicationsofUAVCommunications . . . . . . . . . . . . . . . . . 2
1.1.1 UAVsasBaseStationsforCoverageandCapacityEnhancement . . . . . . 2
1.1.2 UAVsinPublicSafetyScenarios . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.3 Energy-EfficientIoTCommunications . . . . . . . . . . . . . . . . . . . . 5
1.1.4 UAVsasFlyingBackhaulforTerrestrialNetworks . . . . . . . . . . . . . 6
1.2 ChallengesandRelatedStudiesinUAVCommunications . . . . . . . . . . . . . . 6
1.2.1 Air-to-GroundPathLossModeling . . . . . . . . . . . . . . . . . . . . . 8
1.2.2 OptimalDeployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2.3 PerformanceAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.4 EnergyEfficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.5 TrajectoryOptimization . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.3 LimitationsofExistingWorks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4 SummaryofContributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.4.1 DeploymentandMobility . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.4.2 PerformanceAnalysisandOptimization . . . . . . . . . . . . . . . . . . . 17
1.4.3 CommunicationsandControlforWirelessDrone-BasedAntennaArray . . 18
1.4.4 CellAssociationinUAV-assistedCellularNetworks . . . . . . . . . . . . 19
1.4.5 ProactiveDeploymentofCache-EnabledUAVs . . . . . . . . . . . . . . . 19
1.4.6 Foundationsofa3DCellularNetworkwithDrones . . . . . . . . . . . . . 20
1.4.7 Sum-RateAnalysisforHAPDroneswithTetheredBalloonRelay . . . . . 20
vi
1.5 ListofPublications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.5.1 JournalPublications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.5.2 ConferencePublications . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2 Efficient Deployment of Multiple Unmanned Aerial Vehicles for Optimal Wireless
Coverage 24
2.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 24
2.2 SystemModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.3 OptimalMulti-UAVdeployment . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3 MobileUnmannedAerialVehiclesforEnergy-EfficientInternetofThingsCommuni-
cations 33
3.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 33
3.2 SystemModelandProblemFormulation . . . . . . . . . . . . . . . . . . . . . . . 35
3.2.1 Ground-to-AirPathLossModel . . . . . . . . . . . . . . . . . . . . . . . 36
3.2.2 IoTDeviceActivationModel . . . . . . . . . . . . . . . . . . . . . . . . 37
3.2.3 ChannelAssignmentStrategy . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3 UAVDeploymentandDeviceAssociationwithPowercontrol . . . . . . . . . . . 40
3.3.1 DeviceAssociationandPowerControl . . . . . . . . . . . . . . . . . . . 40
3.3.2 OptimalLocationsoftheUAVs . . . . . . . . . . . . . . . . . . . . . . . 44
3.4 UpdateTimesandMobilityofUAVs . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.4.1 UpdateTimeAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.4.2 UAVs’Mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.5 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4 HoverTimeOptimizationinUAV-EnabledWirelessNetworks 62
4.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 62
vii
4.2 SystemModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4.2.1 Air-to-groundpathlossmodel . . . . . . . . . . . . . . . . . . . . . . . . 65
4.3 Scenario 1: Optimal Cell Partitioning for Data Service Maximization under Fair-
nessConstraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3.1 OptimalTransportTheory: Preliminaries . . . . . . . . . . . . . . . . . . 69
4.3.2 OptimalCellPartitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.3.3 CellPartitioninginUplinkCase . . . . . . . . . . . . . . . . . . . . . . . 74
4.4 Scenario2: MinimumHoverTimeFormeetingLoadRequirements . . . . . . . . 76
4.5 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.5.1 ResultsforScenario1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.5.2 ResultsforScenario2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.7 AppendixA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5 Fundamental Performance Analysis of Unmanned Aerial Vehicle with Terrestrial
Device-to-DeviceNetwork 90
5.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 90
5.2 SystemModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5.2.1 Air-to-groundchannelmodel . . . . . . . . . . . . . . . . . . . . . . . . . 94
5.3 NetworkwithaStaticUAV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.3.1 CoverageprobabilityforD2Dusers . . . . . . . . . . . . . . . . . . . . . 95
5.3.2 CoverageProbabilityforDownlinkUsers . . . . . . . . . . . . . . . . . . 97
5.3.3 Systemsum-rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
5.4 NetworkwithaMobileUAV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
5.5 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
5.5.1 ThestaticUAVscenario . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
5.5.2 ThemobileUAVscenario . . . . . . . . . . . . . . . . . . . . . . . . . . 111
5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.7 AppendixB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
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6 Cache-EnabledUnmannedAerialVehiclesinWirelessNetworks 120
6.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 120
6.2 SystemModelandProblemFormulation . . . . . . . . . . . . . . . . . . . . . . . 123
6.2.1 MobilityModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
6.2.2 TransmissionModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.2.3 Quality-of-ExperienceModel . . . . . . . . . . . . . . . . . . . . . . . . 127
6.2.4 ProblemFormulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
6.3 ConceptorEchoStateNetworksforContentandMobilityPredictions . . . . . . . 131
6.3.1 ConceptorESNComponents . . . . . . . . . . . . . . . . . . . . . . . . . 132
6.3.2 ConceptorESNAlgorithmforContentandMobilityPredictions . . . . . 133
6.4 OptimalLocationandContentCachingforUAVs . . . . . . . . . . . . . . . . . . 136
6.4.1 Users-RRHAssociation . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
6.4.2 OptimalContentCachingforUAVs . . . . . . . . . . . . . . . . . . . . . 137
6.4.3 OptimalLocationsofUAVs . . . . . . . . . . . . . . . . . . . . . . . . . 138
6.4.4 ImplementationandComplexity . . . . . . . . . . . . . . . . . . . . . . . 139
6.5 SimulationResults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
6.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
6.7 AppendixC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
6.7.1 ProofofTheorem10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
7 CommunicationsandControlforWirelessDrone-BasedAntennaArray 149
7.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 149
7.2 SystemModelandGeneralProblemFormulation . . . . . . . . . . . . . . . . . . 151
7.3 OptimalPositionsofDronesinArrayforTransmissionTimeMinimization . . . . 155
7.3.1 PerturbationTechniqueforDroneSpacingOptimization . . . . . . . . . . 155
7.3.2 OptimalLocationsofDrones . . . . . . . . . . . . . . . . . . . . . . . . . 157
7.4 Time-OptimalControlofDrones . . . . . . . . . . . . . . . . . . . . . . . . . . 159
7.4.1 DynamicModelofaQuadrotorDrone . . . . . . . . . . . . . . . . . . . . 160
7.5 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
ix
7.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
7.6.1 D.4 ProofofTheorem15 . . . . . . . . . . . . . . . . . . . . . . . . . . 172
8 OptimalTransportTheoryforCellAssociationinUAV-EnabledCellularNetworks 175
8.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 175
8.2 SystemModelandProblemformulation . . . . . . . . . . . . . . . . . . . . . . . 176
8.2.1 UAV-UserandBS-Userpathlossmodels . . . . . . . . . . . . . . . . . . 176
8.2.2 Problemformulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
8.3 OptimalTransportTheoryforCellAssociation . . . . . . . . . . . . . . . . . . . 178
8.4 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
8.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
9 Beyond5GwithUAVs: Foundationsofa3DWirelessCellularNetwork 184
9.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 184
9.2 SystemModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
9.3 Three-dimensional Network Planning of Drone-BSs: A Truncated Octahedron
Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
9.4 EstimationoftheSpatialDistributionofDrone-UEs . . . . . . . . . . . . . . . . . 195
9.5 Optimal3DCellAssociationforMinimumLatency . . . . . . . . . . . . . . . . . 198
9.6 SimulationResultsandAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
9.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
10 Sum-Rate Analysis for High Altitude Platform (HAP) Drones with Tethered Balloon
Relay 209
10.1 Background,RelatedWorks,andContributions . . . . . . . . . . . . . . . . . . . 209
10.2 SystemModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
10.2.1 ChannelModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
10.3 DFrelayaidedInterferenceAlignmentforsystemswithoutCSIT . . . . . . . . . . 211
10.3.1 FeasibilityofDFintetheredballoonrelay . . . . . . . . . . . . . . . . . . 212
10.3.2 CapacityofRicianXnetwork . . . . . . . . . . . . . . . . . . . . . . . . 213
x