IMPACT OF FEMTOCELL BACKHAUL LIMITATION ON PERFORMANCE OF MACRO-FEMTO HetNet

103 Pages·2015·5.88 MB·English

WAQAS UL HASAN ANSARI
IMPACT OF FEMTOCELL BACKHAUL LIMITATION ON
PERFORMANCE OF MACRO-FEMTO HETNET
Master of Science thesis
Examiner: Prof. Mikko Valkama
Supervisor: MSc. Syed Fahad Yunas
Examiner and topic approved by the
Faculty Council of the Faculty of
Computing and Electrical Engineering
on 8th April 2015
i
ABSTRACT
TAMPERE UNIVERSITY OF TECHNOLOGY
Degree Programme in Electrical Engineering
ANSARI, WAQAS UL HASAN: Impact of Femtocell backhaul limitation on
performance of Macro-Femto HetNet
Master of Science Thesis, 84 pages
November 2015
Major Subject:Wireless Communication Circuits and Systems
Examiner: Professor Mikko Valkama
Keywords: Het-Nets, Macrocells, Femtocells, Ultra-dense Networks, 5G local area
This thesis is a techno-economical study which focuses on addressing the expo-
nentially rising data capacity demand through network densification. The study
is based on the two popular deployment strategies; Macrocellular networks and
Macro-Femto heterogeneous networks, deployed in a suburban type environment
with modern houses. The main aim of the dissertation is to investigate the impact
ofnetworkdensificationoncapacity,energy-andcost-efficiency ofthenetwork,while
considering different femtocell backhaul connectivity limitations.
The network performance is evaluated for both indoor and outdoor scenarios. A
comparative analysis between the macrocellular and macro-femto network is done
by increasing the density of the macrocells, femtocells and the operating frequency
spectrum. The capacity is enhanced by increasing the density of the cell sites in the
network but operators want to generate profit and want to adopt a cost effective
solution to cater the problems. The results show that increasing the density of
low-cost, low-powered femtocell access points (FAPs) in the network can solve the
problemof1000xfuturedatacapacitydemandwhilekeepingtheCAPEXandOPEX
of the network relatively lower than legacy pure macrocellular deployments. The
deployment of the FAPs both in indoor and outdoor environments enhances the
network capacity.
This study helped in providing results, understanding and insight of both technical
and techno-economical aspects of different mobile network deployment and densifi-
cation solutions. Furthermore, the outcome of the thesis will give some guidelines
for network vendors and mobile operators in evolving their network in future.
ii
PREFACE
This Master of Science thesis has been written for the completion of my M.Sc degree
in Electrical Engineering from Tampere University of Technology. The research was
carried out during the year 2015 at the Department of Electronics and Communi-
cations Engineering, Tampere University of Technology, Tampere, Finland.
I would like to thank my supervisor M.Sc Syed Fahad Yunas for guiding me to carry
out and complete this research. I learned a lot from his academic and technical
expertise in the field of wireless communications. His valuable experience helped me
a lot in learning and exploring new things.
I extend my gratitude and pay warmest regards to my parents and sisters. Their
support and encouragement is continuous source of motivation.
In the end, I would like to thank every person who helped me in this study especially
my friends; Salman, Hamza Ehtisham, Adnan, Ali, Qutab and others. I thank all
of them for their encouragement and motivation.
Tampere, November 2015
Waqas ul Hasan Ansari
iii
TABLE OF CONTENTS
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . v
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
LIST OF ACRONYMS . . . . . . . . . . . . . . . . . . . . . . . . . . x
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Background and Motivation . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Scope of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Previous studies on network densification . . . . . . . . . . . . . . . . 4
1.4 Outline of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. CELLULAR CONCEPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Brief History of Cellular Systems . . . . . . . . . . . . . . . . . . . . 6
2.2 Fundamentals of Cellular Communications . . . . . . . . . . . . . . . 10
2.2.1 Frequency Reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.2 Multiple Access Techniques . . . . . . . . . . . . . . . . . . . . . 12
2.2.3 Duplex Communication . . . . . . . . . . . . . . . . . . . . . . 19
2.3 Interference and Capacity . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.1 Co-Channel Interference and Capacity . . . . . . . . . . . . . . . 23
2.3.2 Adjacent Channel Interference . . . . . . . . . . . . . . . . . . . 24
2.4 Classification of Base Station Types . . . . . . . . . . . . . . . . . . . 25
2.4.1 Macrocellular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.4.2 Microcellular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.4.3 Femtocells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.5 Backhaul Limitation in Femtocell Networks . . . . . . . . . . . . . . 29
2.6 Capacity Enhancing Techniques . . . . . . . . . . . . . . . . . . . . . 31
2.6.1 Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.6.2 Signal to Interference-plus-Noise Ratio . . . . . . . . . . . . . . . 32
iv
2.6.3 Interference Cancellation . . . . . . . . . . . . . . . . . . . . . . 33
2.6.4 Multiple Antenna Systems . . . . . . . . . . . . . . . . . . . . . . 33
2.6.5 Network Densification . . . . . . . . . . . . . . . . . . . . . . . . 34
3. RADIO PROPAGATION IN CELLULAR SYSTEM . . . . . . . . . . . . 37
3.1 Propagation Environment . . . . . . . . . . . . . . . . . . . . . . . . 38
3.1.1 Macrocellular Environment . . . . . . . . . . . . . . . . . . . . . 39
3.1.2 Microcellular Environment . . . . . . . . . . . . . . . . . . . . . 39
3.1.3 Indoor Environment . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.2 Propagation Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2.1 Empirical models . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2.2 Semi-empirical models . . . . . . . . . . . . . . . . . . . . . . . 43
3.2.3 Deterministic Models . . . . . . . . . . . . . . . . . . . . . . . . 46
4. SYSTEM MODEL AND ANALYSIS METHODOLOGY . . . . . . . . . . 47
4.1 Scenario Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.2 Propagation Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.3 Antenna Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.4 Deployment Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.4.1 Pure Macrocell network . . . . . . . . . . . . . . . . . . . . . . . 51
4.4.2 Pure Femtocell deployment . . . . . . . . . . . . . . . . . . . . . 51
4.4.3 Heterogeneous Macro-Femto Network . . . . . . . . . . . . . . . 51
4.5 Analysis Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.6 Cell and Network Area capacity . . . . . . . . . . . . . . . . . . . . . 54
4.7 Energy Efficiency Analysis . . . . . . . . . . . . . . . . . . . . . . . . 56
4.7.1 Power Consumption Model for Macrocell Base stations . . . . . . 57
4.7.2 Power consumption model for Femtocell Access Points . . . . . . 58
4.8 Cost Efficiency Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 59
5. RESULTS AND ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . 62
v
5.1 RSSI, SINR and Average Spectral Efficiency . . . . . . . . . . . . . . 62
5.2 Indoor capacity, cost- and energy- efficiency analysis . . . . . . . . . . 68
5.2.1 Pure macrocellular densification indoor analysis . . . . . . . . . . 69
5.2.2 Macro-Femto cell densification indoor analysis . . . . . . . . . . 70
5.3 Outdoor capacity, cost- and energy-efficiency analysis . . . . . . . . . 76
5.3.1 Pure macrocell densification outdoor analysis . . . . . . . . . . . 77
5.4 Macro-Femto cell densification outdoor analysis . . . . . . . . . . . . 78
6. CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
vi
LIST OF FIGURES
2.1 Illustration of frequency reuse concept . . . . . . . . . . . . . . . . . 11
2.2 Channels in FDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3 Channels in TDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.4 Near-Far problem in CDMA . . . . . . . . . . . . . . . . . . . . . . . 15
2.5 Cyclic Prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.6 Structure of sub-carriers in OFDMA . . . . . . . . . . . . . . . . . . 17
2.7 Illustration of OFDMA vs SC-FDMA channels . . . . . . . . . . . . . 18
2.8 Illustration of SDMA concept . . . . . . . . . . . . . . . . . . . . . . 19
2.9 Half Duplex Communications . . . . . . . . . . . . . . . . . . . . . . 20
2.10Full Duplex Communication . . . . . . . . . . . . . . . . . . . . . . . 20
2.11Frequency Division Duplexing illustrating guard band . . . . . . . . 21
2.12Time Division Duplexing illustrating guard times . . . . . . . . . . . 22
2.13Cell layout illustrating cell radius R and co-channel distance D. . . . 24
2.14Femtocells Network Architecture . . . . . . . . . . . . . . . . . . . . 27
2.15Femtocell network architecture illustrating backhaul link . . . . . . . 29
2.16Illustration of Carrier Aggregation using FDD in LTE-Advanced . . . 32
2.17Antenna beamforming . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.18Illustration of MIMO system between a base station and UE . . . . . 34
2.19Illustration of omni-directional cell site . . . . . . . . . . . . . . . . . 35
LIST OF FIGURES vii
2.20Illustration of a) 3-sector, b) 6-sector and c) 12-sector cell sites. . . . 35
2.21Illustration of cell splitting technique . . . . . . . . . . . . . . . . . . 36
3.1 Types of propagation environments . . . . . . . . . . . . . . . . . . . 38
3.2 Illustration of Macrocells, Microcells and Femtocells . . . . . . . . . . 41
3.3 Illustration of transmitted wave to the receiver after reflection from
walls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.4 Illustration of a) ray tracing, b) ray launching propagation models . . 46
4.1 Suburban scenario used in the analysis . . . . . . . . . . . . . . . . . 48
4.2 Comparison of traditional ray tracing and Dominant Path Model. . . 49
4.3 Interference experienced by UE in co-channel Macro-Femto network [1]. 55
5.1 10th percentile values of RSSI for Suburban Indoor Environment . . . 63
5.2 10th percentile values of RSSI for Suburban Outdoor Environment . . 63
5.3 10th percentile values of SINR for Suburban Indoor Environment . . . 64
5.4 10th percentile values of SINR for Suburban Outdoor Environment . . 65
5.5 Average Spectral Efficiency values for Suburban Indoor Environment 66
5.6 Average Spectral Efficiency values for Suburban Outdoor Environment 67
5.7 Network Capacity - Suburban Indoor . . . . . . . . . . . . . . . . . . 72
5.8 Cost Efficiency - Suburban Indoor . . . . . . . . . . . . . . . . . . . . 73
5.9 Energy Efficiency - Suburban Indoor . . . . . . . . . . . . . . . . . . 74
5.10Network Capacity - Suburban Outdoor . . . . . . . . . . . . . . . . . 79
5.11Cost Efficiency - Suburban Outdoor . . . . . . . . . . . . . . . . . . . 80
viii
5.12Energy Efficiency - Suburban Outdoor . . . . . . . . . . . . . . . . . 81
ix
LIST OF TABLES
1.1 Global Average Broadband Connection Speeds [2] . . . . . . . . . . . 4
4.1 Cell densities for different ISDs with different femtocell penetration
rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.2 General Simulation Parameters . . . . . . . . . . . . . . . . . . . . . 53
4.3 Input Parameters for the Macro BS Power Consumption Model . . . 58
4.4 Input Parameters for Femtocell BS power consumption model . . . . 59
4.5 CAPEX and OPEX for Macro- and Femto- base stations . . . . . . . 60
5.1 Network Capacity, Cost & Energy efficiency @ 5 MHz spectrum . . . 69
5.2 Macro-Femto Het-Net Capacity, Cost and Energy Efficiency @ Fem-
tocell penetration = 5% . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3 Network Capacity, Cost & Energy efficiency @ 40 and 100 MHz spec-
trum (Macro Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.4 Network Capacity of Macro-Femto Het-Net 5 MHz with 50% FAPs . 76
5.5 Network Capacity, Cost & Energy efficiency @ 5 MHz spectrum . . . 77
5.6 Macro-Femto Het-Net Capacity, Cost and Energy Efficiency @ Fem-
tocell penetration = 5% . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.7 Network Capacity, Cost & Energy efficiency @ 40 and 100 MHz spec-
trum (Macro only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.8 Macro-Femto Het-Net Capacity, Cost and Energy Efficiency @ Fem-
tocell penetration = 50% operating at 5 MHz . . . . . . . . . . . . . 82