Efficient Resource Allocation for 5G Hybrid Wireless Networks

146 Pages·2017·3.55 MB·English

Efficient Resource Allocation for 5G
Hybrid Wireless Networks
Yongxu Zhu
Adissertationsubmittedinpartialfulfillment
oftherequirementsforthedegreeof
DoctorofPhilosophy
of
UniversityCollegeLondon.
DepartmentofElectronicandElectricalEngineering
UniversityCollegeLondon
September5,2017
2
I,YongxuZhu,confirmthattheworkpresentedinthisthesisismyown. Where
information has been derived from other sources, I confirm that this has been indi-
catedinthework.
Abstract
This thesis explores three directions of energy-efficiency(EE) and spectral-
efficiency(SE) under 5G wireless networks. Firstly, we study the optimization
of power control for the small (two-user) interference channel in which the ter-
minals are time-switched between the signal-processing and energy-harvesting
phases. Both energy harvesting and signal-processing processes are during the
downlink. The objective is to maximize the sum-rate, subject to the minimum data
and harvested energy constraints at the receivers, assuming a fixed time-switching
coefficient. The key contribution is using a geometric approach that analyzes the
feasible region governed by the constraints, which gives rise to the optimal power
controlsolution.
Another topic focuses on the performance analysis of two user association
schemes for wireless power transfer (WPT) in heterogeneous networks (HetNets)
massive multiple-input multiple-output (MIMO) antennas, downlink for the WPT
in the first phase and uplink for wireless information transfer (WIT) in the second
phase. The two user association schemes considered in the analysis are the Down-
link received signal power (DRSP) based approach for maximizing the harvested
energy; and the uplink received signal power (URSP) based approach for minimiz-
ing the uplink path loss. In the downlink, we adopt a low-complexity approach for
massiveMIMOpowertransfertorechargeusers. Thenwederivetheaverageuplink
achievableratewiththeharvestedenergy.
Thelasttopicanalysesalarge-scalemmWaveadhocnetworkintherandomly
locatedeavesdroppersarea,whereeavesdropperscanstillintercepttheconfidential
messages, since they may reside in the signal beam. This chapter explores the
Abstract 4
potential of physical layer security in mmWave ad hoc networks. Specifically, we
characterizetheimpactofmmWavechannelcharacteristics,randomblockages,and
antennagainsonthesecrecyperformance. Forthespecialcaseoftheuniformlinear
array (ULA), a tractable approach is proposed to evaluate the average achievable
secrecyrate.
Acknowledgements
Theworkpresentedinthisthesiswouldnothavebeenpossiblewithoutthesupport
andadvicereceivedfromamultitudeofpeopletowhomIwouldliketoexpressmy
mostsinceregratitude.
First and foremost, I would like to thank my supervisor, Professor Kai-Kit
Wong, for constantly providing me advices, encouragements and graveness which
I will benefit for the rest of my life. I will always be in his debt for his help and
instruction.
Iamalsoverygratefultoallmyseniors,DrLifengWangforhissincerelyhelp
and countless discussions in academic; Prof. Shi Jin for his encouragement and
generousassistance;Prof. CaijunZhong,DrArmanShojaeifardandDrMuhammad
RAKhandakerfortheirinsightsandconstantsupportsinresearch. Especiallythank
DrGanZhengwhosupportedmyfirstpostdoctoraljobinlife.
Iwouldalsoliketothankmygroup,loveandwarmfamily’UCLWireless’,Mr
Raoul,forhishonestandkindlyhelpbeforegroupeverymeeting. MrAlex,always
tookmyphotoswhenIampresentingintheconference. Also,Iwouldliketothank
MissJialing,MissXiaoyanandMrEmanueleforsharetheresearchexperience.
Lastbutnotleast,Iamdeeplygratefultomyfamily. Inparticular,myhusband,
my faithful companions, Mr Jie Deng for his encouragement and positive attitude
during my growth in academic and daily life. Thanks to my mother, father and
parentsinlaw,fortheirsupportsandconcernseveryday,theyarethefoundationof
allmyachievements.
Contents
1 Introduction 14
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2 PromisingKey5GWirelessTechnologies . . . . . . . . . . . . . . 16
1.2.1 WPTandEH . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.2.2 Heterogeneousnetworks . . . . . . . . . . . . . . . . . . . 18
1.2.3 MassiveMIMO . . . . . . . . . . . . . . . . . . . . . . . . 20
1.2.4 MillimeterWave . . . . . . . . . . . . . . . . . . . . . . . 21
1.3 FundamentalConcepts . . . . . . . . . . . . . . . . . . . . . . . . 22
1.3.1 ResourceAllocation . . . . . . . . . . . . . . . . . . . . . 22
1.3.2 PhysicallayerSecurityinadhocnetworks . . . . . . . . . 24
1.4 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1.5 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1.6 ThesisOrganization . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2 GeometricPowerControlforTime-SwitchingEnergy-HarvestingTwo-
UserInterferenceChannel 29
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.2 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.3 Two-UserTime-SwitchingSWIPT . . . . . . . . . . . . . . . . . . 31
2.4 OptimalPowerControl . . . . . . . . . . . . . . . . . . . . . . . . 34
2.4.1 Lemmas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.4.2 WithData/RateConstraintsOnly . . . . . . . . . . . . . . 42
2.4.3 WithEnergyHarvestingConstraintsOnly . . . . . . . . . . 44
Contents 7
2.4.4 WithBothDataandEnergyHarvestingConstraints . . . . . 46
2.5 SimulationResults . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3 Wireless Power Transfer in Massive MIMO Aided HetNets with User
Association 61
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.2 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.3 NetworkDescription . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.3.1 UserAssociation . . . . . . . . . . . . . . . . . . . . . . . 64
3.3.2 DownlinkWPTModel . . . . . . . . . . . . . . . . . . . . 66
3.3.3 UplinkWITModel . . . . . . . . . . . . . . . . . . . . . . 68
3.4 EnergyAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.4.1 NewStatisticalProperties . . . . . . . . . . . . . . . . . . 70
3.4.2 AverageHarvestedEnergy . . . . . . . . . . . . . . . . . . 72
3.5 UplinkPerformanceEvaluation . . . . . . . . . . . . . . . . . . . . 75
3.5.1 AverageUplinkAchievableRate . . . . . . . . . . . . . . . 76
3.6 NumericalResults . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.6.1 UserAssociation . . . . . . . . . . . . . . . . . . . . . . . 78
3.6.2 DownlinkEnergyHarvesting . . . . . . . . . . . . . . . . . 79
3.6.3 AverageUplinkAchievableRate . . . . . . . . . . . . . . . 83
3.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4 SecureCommunicationsinMillimeterWaveAdHocNetworks 88
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
4.2 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.3 SystemDescription . . . . . . . . . . . . . . . . . . . . . . . . . . 90
4.4 SecrecyEvaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4.4.1 SimplifiedLoSMmWaveModel . . . . . . . . . . . . . . . 96
4.4.2 UniformLinearArray . . . . . . . . . . . . . . . . . . . . 97
4.5 ArtificialNoiseAidedTransmission . . . . . . . . . . . . . . . . . 100
4.6 NumericalResults . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Contents 8
4.6.1 AverageAchievableSecrecyRate . . . . . . . . . . . . . . 104
4.6.2 averageachievablesecrecyratewithULA . . . . . . . . . . 107
4.6.3 averageachievablesecrecyratewithArtificialNoise . . . . 108
4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
5 ConclusionsandFutureWork 113
5.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
5.2 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.2.1 FutureWork1: GeometricProgrammingPowerControlfor
3-pairCells . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.2.2 FutureWorks2: Multi-hoppingforTwo-tierHeterogeneous-
UserinWearableDevicesNetworks . . . . . . . . . . . . . 116
Appendices 118
A AppendixA:ProofofLemma1 118
B AppendixB:AproofofLemma2 119
C AppendixD:AproofofCorollary3 124
D AppendixE:AproofofTheorem2 125
E AppendixF:AproofofTheorem3 127
F AppendixG:AdetailedderivationofTheorem4 129
G AppendixH:AdetailedderivationofEq. (4.10) 131
H AppendixI:AdetailedderivationofTheorem6 133
Bibliography 135
List of Figures
1.1 CellularNetworkTopology. . . . . . . . . . . . . . . . . . . . . . 19
2.1 Atime-switchingSWIPTnetworkmodel. . . . . . . . . . . . . . . 31
2.2 Illustrationofthetimeswitchingoperation. . . . . . . . . . . . . . 31
2.3 Illustration of the possible feasible regions (shaded areas) for PPPi
when considering the rate constraints: (a) The box region Π, with
onlypeakpowerconstraintsandnorateconstraints;(b)–(d)Πwith
peak power constraints and minimum rate constraints, (b) when
D < D◦ and D < D◦, (c) when D > D◦ and D < D◦, and (d)
1 1 2 2 1 1 2 2
when D <D◦ and D >D◦. Note that if D >D◦ and D >D◦,
1 1 2 2 1 1 2 2
the intersection point will appear outside the box region Π and in
this case, no power will be feasible. For the same reason, due to
Corollary2,thisfigureonlyillustratesthecasesiftheslopeoflll >
R
1
the slope of lll ; otherwise, the intersection point will appear in the
R
2
thirdquadrantofthe(Pi,Pi)-planeandnopowerwillbefeasible. . . 38
1 2
2.4 Illustration of the possible feasible regions (shaded areas) for PPPi
when considering both the energy harvesting constraints and the
peak power constraints Π, assuming the slope of lll > that of lll
Y Y
2 1
(thetypicalsituation). In(a),PPPi,× occursinsideΠ,or0≤Pi,×≤P¯
Y 1,Y 1
and 0≤Pi,× ≤P¯ , while in (b), PPPi,× is outside Π on the right, i.e.,
2,Y 2 Y
Pi,× >P¯ and0≤Pi,× ≤P¯ . For(c),PPPi,× isaboveΠor0≤Pi,× ≤
1,Y 1 2,Y 2 Y 1,Y
P¯ and Pi,× >P¯ . The case that the slope of lll < that of lll is also
1 2,Y 2 Y2 Y1
i,×
possible,andtheanalysisissimilar. InthecasethatPPP isfaraway
Y
fromΠ,theproblemisinfeasible. . . . . . . . . . . . . . . . . . . 41
ListofFigures 10
2.5 Illustration of the possible combinations of lines lll , lll , lll and
R R l
1 2 1
i,×
lll for scenario (i) where PPP is inside Π. In (a)–(d), it shows 4
l2 Y
possible ways lll and lll may cut Π to form the region due to the
Y Y
1 2
energy harvesting constraints with numbered edges, while (e)–(h)
provideexamplesforeachofthecaseshowlll andlll maycutthe
R R
1 2
edgestoformthefeasibleregion. . . . . . . . . . . . . . . . . . . . 54
2.6 Illustrationofthepossiblecombinationsoflineslll ,lll ,lll andlll
R R l l
1 2 1 2
i,×
for scenario (ii) where PPP is outside and on the right of Π. In (a)
Y
and(b),itshows2possiblewayslll andlll maycutΠwhilein(c)
Y Y
1 2
and(d),itshowsexamplesofhowlll ,lll cuttheedgestoformthe
R R
1 2
feasibleregion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
2.7 Illustrationofthepossiblecombinationsoflineslll ,lll ,lll andlll
R R l l
1 2 1 2
i,×
for scenario (iii) where PPP is at the top or left side of Π. In (a)
Y
and(b),itshows2possiblewayslll andlll maycutΠwhilein(c)
Y Y
1 2
and(d),itshowsexamplesofhowlll ,lll cuttheedgestoformthe
R R
1 2
feasibleregion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
2.8 Resultsforthetime-switchingSWIPTsystemforagivenG. . . . . 56
2.9 Resultsforthetime-switchingSWIPTsystemforanotherG. . . . . 57
2.10 Feasibleregionversusτ. . . . . . . . . . . . . . . . . . . . . . . . 58
2.11 Thesum-ratesversusthetime-switchingfactorτ. . . . . . . . . . . 59
2.12 The sum rates with both rate and energy harvesting constraints
againstthepowerbudgetP¯ ,withτ =0.5. . . . . . . . . . . . . . 60
1,2
3.1 An illustration of wireless power transfer in the two-tier HetNet
consistingofmassiveMIMOMBSandpicocellbasestation(PBS). 67
3.2 AssociationprobabilityversusthenumberofantennasfortheMBS. 79
3.3 Theaverageharvestedenergyagainstthenumberofantennas. . . . 80
3.4 The average harvested energy against the number of antennas for
theMBS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81