University POLITEHNICA of Bucharest [627809]

University POLITEHNICA of Bucharest
Faculty of Electronics, Telecommunications and Information Technology
Uplink Interference Cancellation
Diploma thesis
submitted in partial fulllment of the requirements for
the Degree of Engineer
in the domain Electronics, Telecommunications and Information Technology
study program Technologies and Systems of Telecommunications
Thesis Advisors Student: [anonimizat]. Conf. Ing. Simona Halunga
Petrisor IlieDedinoiu Maria-Diana
Year 2019

Statement of Academic Honesty
I hereby declare that the thesis Uplink Interference Cancellation , submitted to the Faculty
of Electronics, Telecommunications and Information Technology in partial fulllment of the
requirements for the degree of Engineer in the domain Electronics and Telecommunications,
study program Technologies and Systems of Telecommunications , is written by myself and was
never before submitted to any other faculty or higher learning institution in Romania or any
other country.
I hereby declare that all information sources sources I used, including the ones I found on
the Internet, are properly cited in the thesis as bibliographical references. Text fragments cited
\as is" or translated from other languages are written between quotes and are referenced to
the source. Reformulation using dierent words of a certain text is also properly referenced. I
understand plagiarism constitutes an oence punishable by law.
I declare that all the results I present as coming from simulations or measurements I per-
formed, together with the procedures used to obtain them, are real and indeed come from the
respective simulations or measurements. I understand that data faking is an oence punishable
according to the University regulations.
Bucharest, July 2019.
Student: [anonimizat] : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : iii
List of tables : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : v
List of abbreviations : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : vi
1. GENERAL ASPECTS : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3
1.1. Mobile communication evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1. First Generation of Mobile Communications(1G) . . . . . . . . . . . . . 3
1.1.2. Global Systems for Mobile Communications(GSM) . . . . . . . . . . . . 3
1.1.3. Third Generation of Mobile Telecommunications Technology(3G) . . . . 7
1.1.4. Fourth Generation of Mobile Telecommunications Technology (4G) . . . 8
1.1.4.1. Fifth Generation of Mobile Communications . . . . . . . . . . . 11
1.2. Antenna and Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.1. Generalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.2. Antenna Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.3. Basic Models of propagation . . . . . . . . . . . . . . . . . . . . . . . . . 16
2. Interference Analysis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 21
2.1. General aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.1.1. Multipath and fading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.1.2. Inter-Symbol Interference . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.1.3. Frequency selective fading . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2. Uplink Interference Analysis in LTE networks . . . . . . . . . . . . . . . . . . . 24
2.2.1. Full duplex procedures used in LTE network . . . . . . . . . . . . . . . . 24
2.2.2. Digital Modulation techniques used in LTE . . . . . . . . . . . . . . . . . 25
3. Uplink Interference Cancellation : : : : : : : : : : : : : : : : : : : : : : : : : : : 28
3.1. General aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2. Macro-Macro and Micro-Micro UL IC . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.1. Event A3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.2. Entering and exiting UL IC . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.3. Macro-Micro UL IC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.3.1. Entering and exiting UL IC . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.4. SFN-Related UL IC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.4.1. Entering and exiting UL IC . . . . . . . . . . . . . . . . . . . . . . . . . 33
4. Uplink Interference Cancellation in a Macro-Macro scenario : : : : : : : : : 35
4.1. Implementing the algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1.1. The map of the Bucharest sites where the algorithm was run . . . . . . . 35
4.1.2. The commands used for algorithm activation . . . . . . . . . . . . . . . . 36
4.2. Monitoring the network performance . . . . . . . . . . . . . . . . . . . . . . . . 37

4.2.1. Overall network indicators . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.2.1.1. Call Setup Succes Rate – CSSR . . . . . . . . . . . . . . . . . . 38
4.2.1.2. Drop Call Rate – DCR . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.1.3. Downlink(DL) Throughput and Uplink(UL) Throughput . . . . 41
4.2.2. Specic UL IC indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.2.2.1. Results before UL IC . . . . . . . . . . . . . . . . . . . . . . . 43
4.2.2.2. Results after UL IC . . . . . . . . . . . . . . . . . . . . . . . . 46
Bibliography : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 51
ii

List of gures
1.1. Evolution of Mobile Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. GSM Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. GPRS Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4. UMTS Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5. LTE Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.6. Adding 5G to the existing 4G/LTE sites . . . . . . . . . . . . . . . . . . . . . . 12
1.7. Coordinate system for antenna analysis [9] . . . . . . . . . . . . . . . . . . . . . 13
1.8. Two dimensional directivity pattern. [9] . . . . . . . . . . . . . . . . . . . . . . 14
1.9. Three dimensional directivity pattern[9] . . . . . . . . . . . . . . . . . . . . . . . 14
1.10. Field regions of an antenna. [9] . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.11. Re
ection, diraction, Scattering [11] . . . . . . . . . . . . . . . . . . . . . . . . 16
1.12. The variation of the propagation loss as a function of distance having frequency
as a parameter [12] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.13. Two-ray ground re
ected model . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.1. Generation of contructive interference, destructive interference and fading – mul-
tipah environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.2. Inter-symbol Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3. Frequency selective fading channel characteristics. [ ?] . . . . . . . . . . . . . . . 23
2.4. Multiple Access Techniques in LTE . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.5. BPSK constellation diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.6. Quadrature phase shift keying. (a) transmitted radio wave. (b) QPSK constel-
lation diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.7. 16-QAM(4 bits per symbol) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.8. 64-QAM(6 bits per symbol) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.1. Dierent cell zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2. Relationship of roles in UL IC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.1. The map of the Bucharest sites where the algorithm was run . . . . . . . . . . . 35
4.2. The distance between BI0120 and BI1757 . . . . . . . . . . . . . . . . . . . . . 36
4.3. CSSR and DCR network indicators . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.4. 4G/LTE CSSR(%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.5. 4G/LTE CSSR(%), excepting ocial non-working days . . . . . . . . . . . . . . 39
4.6. DCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.7. 4G/LTE DCR(%), excepting ocial non-working days . . . . . . . . . . . . . . 40
4.8. Downlink Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.9. Uplink Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.10. 4G/LTE UE Modulation Usage before UL IC . . . . . . . . . . . . . . . . . . . 43
4.11. 4G/LTE UL Throughput Before UL IC . . . . . . . . . . . . . . . . . . . . . . . 44
4.12. 4G/LTE UE Modulation Usage before UL IC . . . . . . . . . . . . . . . . . . . 44
4.13. 4G/LTE UL Throughput Before UL IC . . . . . . . . . . . . . . . . . . . . . . . 45
4.14. 4G/LTE UE Modulation Usage before UL IC . . . . . . . . . . . . . . . . . . . 45
4.15. 4G/LTE UL Throughput Before UL IC . . . . . . . . . . . . . . . . . . . . . . . 46
iii

4.16. 4G/LTE UE Modulation Usage after UL IC . . . . . . . . . . . . . . . . . . . . 47
4.17. 4G/LTE UL Throughput After UL IC . . . . . . . . . . . . . . . . . . . . . . . 47
4.18. 4G/LTE UE Modulation Usage after UL IC . . . . . . . . . . . . . . . . . . . . 48
4.19. 4G/LTE UL Throughput After UL IC . . . . . . . . . . . . . . . . . . . . . . . 48
4.20. 4G/LTE UE Modulation Usage after UL IC . . . . . . . . . . . . . . . . . . . . 49
4.21. 4G/LTE UL Throughput After UL IC . . . . . . . . . . . . . . . . . . . . . . . 49
iv

List of tables
2.1. Modulation and Coding Schemes Table . . . . . . . . . . . . . . . . . . . . . . 27
3.1. Increase in cell throughput after UL IC is enabled . . . . . . . . . . . . . . . . . 29
3.2. Increase in UE throughput after UL IC is enabled . . . . . . . . . . . . . . . . . 30
3.3. RSRP measurement report mapping . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1. Parameters in SRSCFG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2. Parameter that must be set in a CellUlICAlgo . . . . . . . . . . . . . . . . . . . 37
4.3. Parameters that must be set in an NCellSrsMeasPara . . . . . . . . . . . . . . . 37
4.4. General KPI comparison before and after UL IC . . . . . . . . . . . . . . . . . . 41
v

List of abbreviations
ACRONYM DEFINITION
1G First Generation of Mobile Communications
2G Second Generation of Mobile Communications
3G Third Generation of Mobile Communications
3GPP Third Generation Partnership Project
4G Fourth Generation of Mobile Communications
AuC Authentication Center(AuC)
BER Bit Error Rate
BPSK Binary Phase Shift Keying
BSC Base Station Controller
BSS Base Station Subsystem
BTS Base Transceiver Station
CDMA Code Division Multiple Access
CEU Cell Edge Users
CN Core Network
CRS Cell-Specic Reference Signal
CS Circuit Switched
CSSR Call Setup Success Rate
DFT Discrete Fourier Transform
DL Downlink
EDGE Enhanced Data rates for Global Evolution
EIR Equipment Identity Register
EPC Evolved Packet Core
ETSI European Telecommunications Standard Institute
E-UTRAN Evolved UMTS Radio Access Network
FDMA Frequency Division Multiple Access
FFT Fast Fourier Transform
FNBW First-Null Beamwidth
GGSN Gateway GPRS Support Node
GMSC Gateway Mobile Switching Center
GMSK Gaussian Minimum Shift Keying
GPRS General Packet Radio Service
GSM Global System of Mobile Communications
Het-Net Heterogeneous Network
HLR Home Location Register
HPBW The Half Power Beamwidth
HSS Home Subscriber Server
IMEI International Mobile Equipment Identity
IMS IP Multimedia Subsystem
IP Internet Protocol
ISI Inter-Symbol Interference
vi

LTE Long Term Evolution
LTE-FDD LTE Frequency Division Duplexing
LTE-TDD LTE Time Division Duplexing
MCS Modulation and Coding Schemes
ME Mobile Equipment
MIMO Multiple-Input Multiple-Output
MME Mobility Management Unit
MS Mobile Station
MSC Mobile Switching Center
NSS Network and Switching Sybsystem
OFDMA Ortogonal Frequency Division Multiple Access
P-GW Paket Data Network Gateway
PAPR Peak to Average Ratio
PCEF Policy Control Enforcement Function
PCell Primary Cell
PCRF Policy Control and Charging Rules Function
PCU Packet Control Unit
PRB Physical Resource Blocks
PS Packet Switched
PSTN Public Switched Telephone Network
PSK Phase Shift Keying
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
QoS Quality of Service
RAN Radio Access Network
RE Resource Element
RNC Radio Network Controller
RS Reference Signal
RSRP Reference Signal Received Power
RX Received
S-GW Serving Gateway
SAE System Architecture Evolution
SC-FDMA Single Carrier Frequency Division Multiple Access
SFN Single Frequency Network
SGSN Serving GPRS Support Node
SIM Subscriber Identity Module
SMS Short Message Service
SRS Sounding Reference Signal
TCP/IP Transmission Control Protocol/Internet Protocol
TDMA Time Division Multiple Access
TX Transmit
UE User Equipment
UL Uplink
UL-IC Uplink Interference Cancellation
UMTS Universal Mobile Telecommunications System
USIM UMTS Subscriber Identication Module
UTRAN UMTS Terrestrial Radio Access Network
VLR Visitor Location Register
vii

VOIP Voice Over Internet Protocol
WCDMA Wide Code Division Multiple Access
viii

1
INTRODUCTION
Mobile communication systems
People communicate for a variety of reasons, from sharing information, expressing wants
and needs or just socialization. It is a truth universelly acknowledged that human beings have
always had the need to communicate and the way they evolved in this direction has changed
incredibly over the years. Considering these needs, they had to gure out some methods in
order to create opportunities to communicate and telecommunications represented the best
choice. The term telecommunications generally refers to the process by which information gets
transferred electronically across distances without any changes taking place to the initial mes-
sage. Mobile communication allows information exchange(transmission of voice and multimedia
data) via a mobile device or a computer regardless of any physical link.
Over the last half decade, telecommunication technologies have changed signicantly. One
important transition was the one from analog to digital signals that had revolutionized commu-
nication because digital signals typically use less bandwidth and transport more information
with greater noise immunity. Also, digital techniques have facilitated the development of mobile
networks making them aordable and easy to use. [2]
Four mobile telecommunication technologies have been developed up to now and a fth one
is carefully planned to be developed as a non stand-alone version for its rst phase. These
evolutions will continue at an even more rapid pace in the next years. Technological politics
plays a fundamental role in the evolution of new technologies, since spectrum usage is controlled
by governments and not by service providers or equipment manufacturers. [2]
Studies show that since 2005 the total mobile usage on the market has more than doubled
in all regions of the world. These signicant penetration increases have really transformed the
social-economic life, making mobile services available to billions of people across all levels of
income. For this reason, there is a strong connection between the usage of mobile data and
the economic growth: increasing the use of mobile data leads to an important increase of the
Gross Domestic Product(GDP). In other words, mobile phones have improved communication,
scocial and economic activities, productivity in sectors such as agriculture, health, education
and nance [3].
The importance of monitoring and optimizing radio networks and the
introduction of interference cancellation algorithms
Large telecommunication networks can be assessed through various parameters concerning
network coverage and the quality of the services. These parameters are strongly in
uenced
by dierent types of interferences. With this in mind, specialists have searched and identied
interferences causes, then they tried to nd various methods and algorithms in order to minimize
or eliminate these problems.
This paper aims to increase the network performance. It contains 4 chapters that comple-
ment each other as follows:
Chapter 1 – constitute the foundation stone of this paper, since it provides information
about the evolution of mobile communication networks, as well as some important facts
about antenna and propagation.

2
Chapter 2 – aims to highlight an interference analysis and presents general aspects about
interferece causes and the manner in which they are dealt with in LTE.
Chapter 3 – provides a solution for interference cancellation in some scenarios in the
uplink.
Chapter 4 – is treating uplink interference cancellation in a specic scenario, describing
all implementation, analysis and interpretation steps.
The chosen scenario is a macro-macro one located in the area of Politehnica University
of Bucharest. The intended results are:
1. Increasing the Modulation and Coding Schemes(MCS) index of UL IC beneted UEs
2. Decreasing the Uplink Initial Block Error Rate
3. Increasing the uplink cell coverage
4. Increasing the average cell throughput and the average uplink CEU throughput
Specic Key Performance Indicators (KPI) were used in order to monitor the eective-
ness of these results: CSSR (Call Setup Success Rate), DCR(Drop Call Rate), UL (Uplink)
Throughput, DL(Downlink) Throughput, UE (User Equipment) Modulation Usage.

3
Chapter 1
GENERAL ASPECTS
1.1 Mobile communication evolution
Mobile communication technology has evolved over the past half decade, bringing with each
phase new capabilities and advantages to the end user. The interval between each technology
platform is approximately 10 years, as showed in Figure 1.1. However, there is a constant
innovation process within each platform which leads to the next one.
Figure 1.1: Evolution of Mobile Technology
1.1.1 First Generation of Mobile Communications(1G)
First generation of mobile communications was developed in the early 1980s and was based
on analog transmissions. The voice calls transmitted through the network are modulated to a
higher frequency of about 150MHz as it is transmitted between the radio towers.
For this generation, each country had developed their own set of standards for communica-
tions resulting many incompatibilities between technologies from dierent regions. Therefore,
there were no concepts of international roaming. In addition, analog signals can be damaged
by the interference phenomenon and the call quality is substantially decreased. Another prob-
lem was that the usage of analog signals allowed listening to the phone conversation easily by
simple techniques. First generation of mobile communication does not allow advanced encrip-
tion methods, consequenctly there is no security of data. Moreover, the mobile phones were
relatively heavy, most initial models having around 3-4 kg.
On the positive side, the rst generation of mobile communications has meant a totally new
era for the users because it allowed voice transmission without the constraint of a xed telephone
line. In terms of accessibility, the 1G mobile devices were very expensive and represented a
symbol of auence and social status.
1.1.2 Global Systems for Mobile Communications(GSM)
At the beginning of 1990s, GSM, the Global System of Mobile Communications provoked
extraordinary changes for facilitating the communication between users. While 1G analog

4
wireless systems were used only by high-end consumers such as executives and very wealthy
because of the phones costs, 2G, the Second Generation of Mobile Communications, is used by
over 3 billion subscribers worldwide in 2010. GSM was initially designed as a circuit-switched
network where all voice or data resources are set up at the beginning of the call and are kept
for the user until the end of the call.[1]
The second generation of mobile communications introduces the concept of digital modu-
lation in contrast to the rst generation where the modulation was analog. Hence, 2G highly
improves the transmission quality because digital signals are easier to process and more resis-
tant to perturbations. In Europe, GSM was intially specied for operation in the 900-MHz
band, but the number of available channels was not sucient to deal with the growing demand.
Therefore, the additional 1800-MHz band was assigned. At the same time, in The United
States and Canada, the frequency bands were 850-MHz and 1900-MHz. The drawback of this
approach is that not all american GSM mobile phones can be used in Europe and vice versa.
[1]
The development of the second generation brought in addition to voice telephony: Short
Messaging Service(SMS), roaming, conferencing, call waiting, call hold, call forwarding, call
baring, number identication, advice of charge(AoC). Moreover, bearer services(data services)
are used through a GSM phone with a data transfer rate of maximum 9.6 Kb/s.
Figure 1.2: GSM Architecture
The architecture of the GSM network is pictured in Figure 1.2 and comprises the fallowing
systems[6]:
1. Mobile Station(MS) or Mobile Equipment(ME): its two main elements are the main hard-
ware and the SIM(Subscriber Identity Module).The SIM have information that provides
the identity of the user to the network.
2. Base Station Subsystem(BSS): connects all subscribers to the core network and it consists
of two elements:
(a) Base Transceiver Station(BTS): it is the dening elements for each cell and commu-
nicates with the MS throungh Um or air interface with its associated protocols.
(b) Base Station Controller(BSC): it controls a group of BTSs and it communicates with
the BTSs over the Abis interface.

5
3. Network and Switching Subsystem(NSS): it is often named as the core network and
it provides the main control and interfacing for the whole network. NSS contains the
fallowing entities:
(a) The Mobile Switching Center(MSC): is the central elements of a mobile telecommuni-
cation network and is generally responsible for registration of mobile subscribers, call
establishment and call routing between two subscribers, forwarding of SMS(Short
Message Service) messages.
(b) Gateway MSC(GMSC): is responsible of routing the call to the correct visited MSC,
being the point to which a ME terminating call is initially routed, without any
knowledge of the MS's location.
(c) Home Location Register(HLR): the database that contains all administrative infor-
mation about its network subscribers, as well as their last known location, having
one HLR per network.
(d) Visitor Location Register(VLR): contains information from the HLR regarding the
subscribers that are temporary in the network location.
(e) Authentication Center(AuC): contains an individual key per subscriber, which is a
copy of the key on the SIM card of the subscriber. The AuC is a protected database
used for authentication and for ciphering on the radio channel.
(f) Equipment Identity Register (EIR): based on the IMEI(International Mobile Equip-
ment Identity) decides whether a given mobile equipment may be allowed in the
network or not.
To allow the base station to communicate with several subscribers concurrently, two metods
are used:
Frequency Division Multiple Access(FDMA): users communicate with the base station
on dierent frequencies
Time division multiple access (TDMA): uses carrier frequencies with a bandwidth of
200-KHz over which up to eight subscribers can communicate with the base station si-
multaneously.
Extended versions of GSM
Int the mid-1990s, the importance of the data services has been constantly increasing and
it became evident that the circuit switched bearer services were no longer suited for the user
demand. The new technologies implemented the packet switching method of sending data:
General Packet Radio Service – GPRS(2.5G)
General Packet Radio Service is a wireless communication based on packet switching method
and promises data rates from 56 Kb/s to 114 Kb/s and uninterrupted internet connection for
mobile phones and computer users. In contrast to circuit-switched network, where charging is
done per minute, in GPRS it is done per number of transferred MB [4].

6
Figure 1.3: GPRS Architecture
GPRS overlaps the GSM network, having software updates and tree new additional entities
into the mobile network that allow packet data transmission. Those tree network components
are:
The Packet Control Unit(PCU): hardware router added to the BSC which handles packet-
switched GPRS trac.
The Serving GPRS Support Node(SGSN): packet-switched counterpart to the MSC in
the circuit-switched network, being responsible for the user plane management and the
signaling plane management. It lies between the radio access newtork and the core net-
work.
Gateway GPRS Support Node(GGSN): connects the GPRS network to the external data
network – Internet or, for business applications, a company intranet. It updates its routing
table when a subscriber moves to a new location(a new SGSN might become responsible
and data packets are sent to the new SGSN).
Enhanced Data rates for Global Evolution – EDGE(2.75G) EGPRS(Enhanced
Datarates for GSM Evolution) or EDGE is built on top of GPRS(the packet-switched data
service of GSM) to further increase data transmission speeds up to 473.6 kb/s(maximum theo-
retical data transmission speed) . It has been introduced into the standards a new modulation
and coding scheme, which uses 8 PSK(8 Phase Shift Keying). The remarkable results of using
8 PSK are that EDGE transmits three bits in a single transmission step compared to GSM
and GPRS, both using GMSK(Gaussing Minimum Shift Keying) modulation, that transmits a
single bit per transmission step. For this reason, data transmission in EDGE can be up to three
times faster compared to GSM and GPRS. It has to be noted that faster data transmission
means higher data errors, so superior correction error codes are necessary. [4]
GPRS and EDGE work in parallel and a user can automatically connect to one of them
depending on the coverage area, but also on the mobile equipment's type. To improve the
quality and the eciency, a combination of GMSK and 8PSK is used: when the radio signal
is favorable, 8PSK modulation is used because it oers high data transmission rates, when the

7
radio signal is not satisfactory, GMSK modulation is used because it maintains the connection
even though there are low data transmission rates.
1.1.3 Third Generation of Mobile Telecommunications Technology(3G)
The need for releasing the 3G technology was supported by requests for higher data rates and
greater voice services at low-cost and the necessity of a standard or a set of global standards.
3G technology enhances the features available in the second generation (2G) by adding ad-
vanced applications as: multimedia services(videoconferencing, teleconferencing), localization
services for accessing trac and weather updates, TV channels over phones, games and song
downloading at high speed. The transmission rates of 4 Mbit/s(sometimes up to 12 Mbit/s)
guarantees these services.
The principal feature brought by 3G is the dynamic allocation of the system's resources
for the users. Compared to 2G, where the user had a frequency band and a time slot at the
beginning of the communication and mantained them until the communication is over, in 3G
resources are assigned proportional to the communication necessities by sending a data stream
at a very high speed over a single carrier.
The technologies for 3G mobile communications are splitted into two big families [1]:
CDMA2000(Code Division Multiple Access): developed by Qualcomm company and used
in America and South Korea.
UMTS(Universal Mobile Telecommunications System): initially developed by ETSI(European
Telecommunications Standard Institute), then taken under subordination by 3GPP group(Third
Generation Partnership Project) and used in Europe. This standard will be presented
hereinafter:
Figure 1.4: UMTS Architecture
The UMTS architecture is represented in Figure 1.4 and it comprises the fallowing systems:
1. User Equipement(UE): It is called UE rather than simply mobile because it has a far
greater number of applications and facilities that it can perform comparing to the 2G
mobile phone. The user equipement is composed of:

8
(a) UMTS Subscriber Identication Module(USIM)
(b) Mobile Equipment(ME)
2. UMTS Terrestrial Radio Access Network(UTRAN): The principal UTRAN functions are
radio resource management and mobility management functions, data encryption/decryp-
tion, access control into the system. Its components are:
(a) Node B: It is a base station that communicates with the user equipement with
WCDMA(Wide Code Division Multiple Access)technology – users are no longer sep-
arated from each other by timeslots and frequencies but are assigned a unique code.
Node Bs are responsible for covering one or more cells.
(b) Radio Network Controller(RNC): Controls the Node Bs that are connected to it,
which implies that it controls the radio resources in its domanin.
3. Core Network(CN): Comparing to a GSM/GPRS core network(presented in chapter
2.1.3), no major changes were necessary. The MCSs and SGSNs only required a soft-
ware update and new interface cards to support the Iu(cs) and Iu(ps) interfaces. The CN
connects UTRAN to external networks(PSTN and Internet), its principal function being
to provide switching, routing and transit for user trac.
The main goal of the new radio access technology was the introduction of the fast packet
data services. The fact that the core network of UMTS is essentially the same core
network as is used for GSM/GPRS means there is a signicat opportunity to reuse the
components of the existing network to the greatest extent possible.
1.1.4 Fourth Generation of Mobile Telecommunications Technology
(4G)
There was a constant evolution in UMTS, but the number of inherent design limitations deter-
mined The Third Generation Partnership Project(3GPP) to redesign both the radio network
and the core network. Their result is commonly called Long Term Evolution(LTE).
LTE is a mobile communication technology which by optimizing the frequency spectrum
allows a fast and ecient transfer. As a result, 4G systems support a wide range of new
applications like virtual navigation, tele-medicine(remote health monitoring of patients), tele-
geo-processing applications(the user will get location querying), on-line courses for a cost-
eective learning manner, gaming networks. All of these applicatons are successfully working,
even though the user is in motion.
Compared to previous systems, LTE is the adoption of an all-IP core network[1]. SMS
is the single exception which is transported over signaling messages. The design and imple-
mentation of the LTE air interface, the radio network and the core are greatly simplied by
and all-IP network architecture. In the foundation, LTE is based on TCP/IP(Transmission
Control Protocol/Internet Protocol) [7] which gives full information about the way in which
data is sent and received through network adapters, hubs, switches, routers and other network
communications hardware.
Theoretically, 4G LTE oers download speeds of 150Mb/s and is boosts upload speeds to
50Mb/s. There are faster versions of 4G (4G LTE-Advanced) with typical download speeds od
42Mb/s and theoretical limits of 300 Mb/s. It should be noted that those speeds are reached
only under ideal conditions, but even the average 4G speeds are four times faster than UMTS.
In EUTRAN (Evolved UMTS Radio Access Network) radio interface three technologies are
integrated in order to achieve the presented results:

9
Ortogonal Frequency Division Multiple Access (OFDMA) for downlink(DL) transmission:
The data stream is splitted into many slower data streams that are transported simulta-
neously over many carriers and the users are scheduled in the frequency domain and in
the time domain. LTE uses a verry narrow subcarrier spacing of 15kHz which remains
the same regardless the overall channel bandwidth.
Single Carrier Frequency Division Multiple Access(SC-FDMA) for uplink(UL) transmis-
sion: When the signals from multiple subcarriers are combined, the use of OFDMA is
not an optimal choice because of its high Peak to Average Power Ratio(PAPR).For a
base station, a high PAPR can be accepted as power is abundant. At the same time,
mobile devices are battery driven, so a low PAPR would be benecial to balance power
requirements of the transmitter with the achievable datarates. SC-FDMA is similar to
OFDMA, but it has an extra DFT(Discrete Fourier Transform) pre-coding prior to OFDM
modulation.
Multiple-Input Multiple-Output (MIMO) technology: It is a multistream data transmis-
sion method in which several data streams are transmitted on the same carrier frequency
from multiple antennas from the base station to multiple antennas in the user equipment.
The number of data streams that can be sent in parallel is given by the number of trans-
mit and receive antennas. MIMO enhances link performance while maintaining a good
BER(Bit Error Rate) of the system.
The architecture of 3G network undergoes some signicant evolutionary changes. Its circuit
switched part is removed, since circuit-switched capabilities are redundant in 4G. Therefore,
the number of logical network nodes has been reduced to simplify the overall architecture and
reduce the latency and costs in the network. A new hardware which had to be universal was
introduced, because LTE-capable devices must also support GSM, GPRS, EDGE and UMTS.
Let us give an overview of the tasks of dierent nodes and how they interract with each other:
Figure 1.5: LTE Architecture

10
The 4G network architecture(Figure 1.5) is composed of:
1. User Equipment(UE)
2. Evolved UMTS Radio Access Network(E-UTRAN)
3. Core Network EPC – Evolved Packet Core(CN)
The most complex device in the LTE network is the base station, called eNode-B(evolved
Node-B). It was decided to integrate most of the functionality that in UMTS was part of
the radio network controller(RNC) into the base station itself. Therefore, besides being re-
sponsible scheduling air interface resources, eNode-B is also responsible for ensuring quality of
service(QoS), mobility management, interference management(reduce the impact of downlink
transmissions on neighboring base stations in cell edge scenarios). These eNode-Bs are directly
connected to the core network through S1 interface. Moreover, LTE base stations communicate
directly with each other over the X2 interface which, on the one hand, means that handovers
are now controlled by the base stations themselves. Cells communicate directly with each other
if the target cell is known and reachable over the X2 interface. Otherwise, the handover is
performed by the S1 interface and a core network. On the other hand, X2 interface is used
for interference coordination. Mobile devices can report the noise level at their current loca-
tion and the perceived source to their serving base station to contact the neighboring base
station and agree on methods to diminish the problem. LTE base stations, eNodeBs, handle
users and their radio bearers once they are established by themselves, but the overall user
control is centralized in the core network. The LTE core network(called EPC(Evolved Packet
Core) or SAE(System Architecture Evolution)) is formed of ve principal nodes: Mobility
Management Entity(MME), PDN Gateway(P-GW – Packet Data Network Gateway), Serving
Gateway(S-GW), Home Subscriber Server(HSS), Policy and Charging Rules Function(PCRF),
each performing specic functions as follows:
The Mobility Management Entity(MME): The node responsible for all signaling exchanges
between the users and the core network and between the base stations and the core
network. Usually, in large networks there are many MMEs in order to deal with the
amount of signaling and for redundancy reasons. In particular, MME is responsibe for
two cathegories of tasks:
{Related to bearer management: it comprises establishment, maintenance and release
of bearers.
{Related to connection management: it covers creating the connection while assuring
security between user equipment and network.
Packet Data Network Gateway(PDN Gateway): This node connects the EPC(Evolved
Packet Core) network to the external networks called PDN(Packet Data network). The
PDN GW routes packets to and from the external networks It is also responsible for
performing functions as assigning IP addresses to mobile devices or policy control and
charging.
Serving Gateway(S-GW): This node is the connection between the radio-side and the
EPC, being logically connected to the other gateway, PDN GW. S-GW routes the in-
coming and outgoing IP packets for the user equipment. In case of handover between
eNodeBs, it is the anchor point for the intra-LTE mobility.

11
Home Subscriber Server(HSS): It is a database which holds user-related and subscriber-
related information. An IP-based protocol called DIAMETER is used to exchange in-
formation with the database. HSS provides support functions in call and session setup,
mobility managemnt, user authentication and access authorization.
Policy Control and Charging Rules Function(PCRF): This server manages the policy
control decision making, along with controlling the
ow-based charging functionalities in
the Policy Control Enforcement Function (PCEF). It provides QoS authorization that
determine how data
ow will be treated in the PCEF in accordance with the user's
subscription prole.
In theory, MME, S-GW and PDC-GW could all be physically implemented in a single
device. However, in practice the functionality is generally decoupled because of the dierent
evolution of trac and signaling load.
As it turns out from Figure 1.4, the circuit switched domain from the legacy networks
has been removed. However, there are some alternatives to have voice services in LTE. CS
fallback(Circuit Switched Fallback) is a method for delivering voice services where the mobile
device has to fall back to a GSM or UMTS network. Next, a circuit-switched connection is
established for the call. A further step towards handling voice calls over IP(VoIP – Voice Over
Internet Protocol) in LTE is using an all IP wireless network: Ip Multimedia Subsystem(IMS).
VoIP delivers voice and multimedia content over the internet by using codecs(that compresses
and decompresses large amounts of data) to encapsulate audio into data packets, then transmit
the packects across an IP network and encapsulate them back into audio at the end of the
connection.
1.1.4.1 Fifth Generation of Mobile Communications
The Fifth Generation of Mobile Communications (5G) is expected to connect everything:
people, data, applications(for smart homes, smart cities, remote medical services, machine to
machine communication in smart networked communication evironments), Consequently, it
should transport a huge amount of data in order to support all these services
These days, many of the largest telecommunication companies are making a transition to
5G by enabling in the existing 4G/LTE infrastructure support for 5G bearers. [8]
The architecture of the 5G network is represented in Figure 1.6. In the rst instance, 5G
mobile services will be available to the end users in a 4G network via mobile equipments that
support a dual connectivity to 4G/LTE and 5G base stations simultaneously.
In order to have dual connectivity, the 4G network infrastructure has to support a connection
to a 5G base station (gNodeB). As it can be observed in Figure 1.6 the 5G base station
(gNodeB) is connected to the 4G Evolved Packet Core (EPC) at the data plane level, but it is
not connected to the Mobility Management Entity(MME). At the same time, gNodeB connects
to the LTE eNodeB to receive requests for 5G bearers activation and deactivation.
In 5G, the user equipment announces the 4G network that it supports dual connectivity
and while maintaining the link with the 4G eNodeB, it switches to the 5G bearer. The Evolved
Packet Core(EPC) veries if the user equipment is authorized for dual connectivity access
during the attach procedure. Therefore, the 4G EPC has to support switching of bearers
between eNodeBs and gNodeBs.

12
Figure 1.6: Adding 5G to the existing 4G/LTE sites
1.2 Antenna and Propagation
1.2.1 Generalities
Antennas and propagation are of great importance to the coverage, capacity and quality of
wireless communication systems. The reason is that an antenna is the interface between the
electronic systems and the propagation medium. Physically, it is a metallic device for radiating
or receiving radio waves by converting electromagnetic radiation in space into electrical currents
in conductors or vice-versa.
Statistics plays an important role in the behavioral study of many success communication
system because of the wave propagation through non-ideal mediums. In communication engi-
neering exists several instances where statistic modelling is used for system planning, design,
then operation, management and estimation of network parameters.
An ideal device called isotropic antenna is frequently used to simplify estimation analysis
along with providing a reference point in comparing dierent types of antennas. This represen-
tative case has the same radiation pattern in all directions and a power gain of 1.
1.2.2 Antenna Parameters
In reality, antennas are dierent from the isotropic one. The signal strength at a distance
d from the antenna in some directions is stronger than in others for a real case directional
antenna. To give details about the performance of an antenna, various parameters have to be
dened.

13
Radiation Pattern
A radiation patern is a graphical representation of the radiation properties of the antenna
as a function of space coordinates. Most of the time, the radiation pattern is determined in the
far-eld region and a set of convenient coordinates is shown in Figure 1.7.
A radiation lobe is that part of the radiation pattern bounded by regions of relatively low values
of radiation intensity. Some are of greater radiation than others. They are classied in the
fallowing way:
1. Main lobe: it is designed to have the highest eld strength, containing the higher power.
2. Minor lobe(s): all lobes, excepting the main lobe. Usually represent unwanted radiation
in undesired directions.
(a) Side lobe(s): are normally the largest of the minor lobes
(b) Back lobe(s): situated in the opposite direction from the main lobe ( 180)
Some common angles are dened as follows:
The Half Power Beamwidth(HPBW): the angle subtended by the half-power points of the
main lobe.
The First-Null Beamwidth(FNBW): the angular sepparation between the rst nulls of
the pattern.
Figure 1.7: Coordinate system for antenna analysis [9]
Directivity
The directivity D of an antenna, a function of direction, is dened as the ratio of the radiation
intensity in a given direction from the antenna and the radiation intensity averaged over all
directions. In a mathematical form:
D=U
U0=4U
Prad(1.1)

14
When the direction is not specied, it suggests the direction of maximum radiation intensity
– maximum directivity [9]. It can be expressed as:
Dmax=D0=Umax
U0=4Umax
Prad(1.2)
For an isotropic antenna, the transmitted signal power is the same in all directions, which
implies that the directivity is unity because U, UmaxandU0are all equal to each other. It is
common to express the directivity in decibels-isotropic. The usage of an isotropic antenna as a
reference is indicated by giving the directivity units of dBi:
D[dBi] = 10logD (1.3)
Figure 1.8: Two dimensional directivity pat-
tern. [9]
Figure 1.9: Three dimensional directivity
pattern[9]
Power gain
The power gain of antenna is closely related to directivity. While directivity is a measure
that describes only the directional properties of the antenna and is controlled only by the
pattern, the gain is a measure that takes into consideration the eciency of the antenna as well
as its directional capabilities. For lossless antennas, the power gain is equal to directivity.
The power gain of an antenna, denoted with G, is a dimensionless, supraunitary parameter
and is dened as the ratio of its radiation intensity in a given direction to the radiation intensity
that would be obtained if the power accepted by the antenna were radiated isotropically.[10]
The radiation intensity corresponding to the isotropically radiated power can be expressed as:
I=totalacceptedpower
4(1.4)
Consequently, the gain can be written as:
G= 4radiationintensity
totalacceptedpower(1.5)
In most cases we deal with relative gain which is the ratio between the power gain in a given
direction and the power gain of a reference antenna in its referenced direction. Usually, the
refence antenna is a lossless isotropic source. If In general, if the direction is not mentioned,
the gain is taken in the direction of maximum radiation.
The gain is an important parameter which gives us an estimation about the coverage area
of an antenna.

15
Field regions
The space surrounding the antenna has dierent radiating properties, depending on the distance
R from the antenna surface. It is usually subdivided into three regions [9]:
1. Reactive near-eld region: that portion in the immediate vicinity of the antenna where
the reactive eld predominates. The boundary of this region is generally described by:
R< 0:62r
D3
(1.6)
where,is the wavelength and D is the largest dimension of the antenna.
2. Radiating near-eld(Fresnel) region: that portion where the radiation elds also predom-
inate and wherein the angular eld distribution is dependent upon the distance R from
the antenna. The boundaries are taken to be:
0:62r
D3
<R< 2D2
(1.7)
where D is the largest dimension of the antenna(D must be large compared cu - the
wavelength). Note that if the antenna has a maximum overall dimension which is very
small compared to the wavelength, the Fresnel region may not exist.
3. Far-eld(Fraunhofer) region: the region where the angular led distribution is indepen-
dent of the distance from the antenna. The boundaries are:
R>2D2
(1.8)
The amplitude pattern of an antenna changes in shape because of the eld variations. In the
reactive near-eld region, the pattern is nearly uniform, with small variations. While in the
Fresnel region the pattern begins to form lobes, in the Fraunhofer region, the pattern is formed
and usually has a few minor lobes and one, or more, major lobes.
Figure 1.10: Field regions of an antenna. [9]

16
Bandwidth
The bandwidth of an antenna can be considered to be the range of frequencies where
the antenna characteristics(such as gain, pattern, side lobe level, radiation eciency) have
acceptable values. It is often refered as the rande over which the power gain is kept to within
3dB of its maximum value.[10]
For broadband antennas, the bandwidth represents the ratio of the upper and the lower
frequencies of acceptable operation.
For narrowband antennas, the bandwidth is expressed as a percentage of the frequency
dierence over the center frequency of the bandwidth.
1.2.3 Basic Models of propagation
There are diverse mechanisms behind electromagnetic wave propagation, but can generally
be attributed to diraction, re
ection, and scattering. These three mechanisms are explained
brie
y in the fallowing:
Figure 1.11: Re
ection, diraction, Scattering [11]
Re
ection
It occurs when a propagationg electromagnetic wave trespasses on an object which has very
large dimensions when compared to the wavelength of the propagating wave. Re
ections occur
from building, walls or from the surface of the earth and the wave is partially re
ected, partially
transmitted, depending on the electrical properties of the two media.
Diraction
It occurs when the radio path between the receiver and the transmitter is obstructed by a
surface that has sharp edges.There are some secondary waves resulting from the obstructing
surface which are present throughout the space and even behind the obstacle, giving rise to a
bending of waves around the obstacle, even when a line-of-sight path does not exist between
transmitter and receiver.
At high frequencies, diraction and re
ection depends on the geometry of the object, as
well as the amplitude, phase, and polarization of the incident wave at the point of diraction.
Scattering
It occurs when the medium through which the wave travels consists of objects with dimensions
that are small compared to the wavelength and where there is a large number of obstacles per
unit volume. Rough surfaces, small objects, or other irregularities in the channel produces

17
scattered waves. In practice, in a mobile communiction system, foliage, street signs and lamp
posts induce scattering.
Propagation models are focused on predicting the average signal strength at a given distance
from the transmitter, as well as the variability of the signal strength near a particular location.
Received power is generally the most important parameter predicted by large-scale propagation
models based on the physics of re
ection, scattering, and diraction.
1. Deterministic Models: These kind of models require a complete 3D map of the propagation
environment. Deterministic models are mainly used for the determination of received
signal power at a particular location using the laws of electromagnetic wave propagation
[12].
(a) Free Space propagation Model: When the transmitter and receiver have a clear,
unobstructed line-of-sight path between them, the free space propagation model is
used to predict received signal strength. The free space power received by a receiver
antenna which is found at the distance d from the radiating transmitter, is give by
the Friis free space equation, where the antenna parameters have been previousely
described in section 1.2.2:
PR
PT=GT
GR

4d2
=GT
GR
c
4fd2
[12] (1.9)
The losses are found by expressing equation 1.9 in dB:
LF[dB] = 10 lgPR
PT= 10 lgGT+10 lgGR20 lgf20 lgd+20 lgc
42
[12] (1.10)
where:
PTis the power delivered to the transmit antenna
PRis the power received by the receive antenna
GTis the gain of the transmit antenna in the direction of the receive antenna
GRis the gain of the receive antenna
d is the distance between transmitter and receiver
is the wavelength: the ration between the speed of light and the working
frequency
LFare the losses in free space
The free space equation shows that the received power decreases as the square of the
distance between the transmitter and the receiver increases. Or, that more power is
lost at higher frequencies. This implies that the received power decays with distance
at a rate of 20dB/decade.
For an isotropic antenna, the gain is unitary. Consequently, from equation 1.10,
losses in the baseband, LB, can be expressed as:
LB[dB] =32:44[dB]20 lgf[MHz ]20 lgd[km] (1.11)

18
Figure 1.12: The variation of the propagation loss as a function of distance having frequency
as a parameter [12]
(b) Wave propagation above curved re
ective surfaces. For a mobile radio channel, a
single direct path between the base station and a mobile is rarely the only physical
means for propagation. Hence, the free space propagation model is in most of the
cases imprecise when used alone. This useful propagation model is based on geo-
metric optics and considers both the direct path and a ground re
ected propagation
path between transmitter and receiver. This model is very accurate for predicting
the large scale signal strength over distances of several kilometers for mobile radio
systems that use tall towers(heights which exceed 50 m), as well as for line-of-sight
microcell channels in urban environments.
Figure 1.13: Two-ray ground re
ected model
In gure 1.12, the fallowing notations are used:
ht- the height of the transmitter
hr- the height of the receiver
R1- the direct line-of-sight component
R2- the ground re
ected component
d1- the distance between the transmitter and the incidence point

19
d2- the distance between the incidence point and the receiver
d is the total distance between the transmitter and the receiver, d=d2+d2
ht- the height of the transmitter
hr- the height of the receiver
 – the angle used for determining the re
ection coecient for ground.
The received power is proportional to the square of the electric eld intensity, so the
equation of free space propagation is modied as follows:
PR= 4

PT
GT
GR
c
4fd2
sin22hThRf
cd
(1.12)
A simplied version of the equation 1.12 can be obtained if d >>h Tand d>>h R:
PR
PT=GT
GR
hThR
d22
(1.13)
Using equation 1.13, the propagation losses can be expressed in decibels as follows:
LF[dB] = 10 lgPR
PT= 10 lgGT+ 10 lgGR+ 20 lghT+ 20 lghR40 lgd (1.14)
There are two main dierences between the equation associated to the two-ray
ground re
ected model and the free space propagation equation:
frequency independence in contrast to frequency dependence
the distance dependence with d4in contrast to d2
The height of an antenna has a major impact on its performance. Generally,the
higher the antenna, the lower the losses, the better the performance.
2. Statistical Models
These models are used to predict the propagation losses when designing a mobile radio
system, allowing us to nd the optimal parameters of the radio communication system,
in order to obtain an ecient link in the interest area [12]. The propagation of the signal
is also in
uenced by:
The eect of buildings and other obstacles in urban areas.
Shadowing, absorbtion and dispersion due to trees and water surfaces.
(a) Egli Model: it is used to predict medium propagation losses(meaning the losses
that do not surpass more that 50% of the locations and/or 50% of the time). This
prediction model is suitable for areas with irregularities. The basic equation of
this model is the one for the propagation above plane surfaces. The expression for
medium propagation losses is:
L50=GRGThThR
d22
 (1.15)
whereis a correction coecient that takes into account supplementary losses and
the frequency variations:
=40
f[MHz ]2
(1.16)

20
For urban areas, the fallowing models for the prediction of propagation losses are
used:
(b) Okumura-Hata model: it is used for the prediction of propagation losses in case of
quasi-smooth lands in urban areas.
(c) Walsh-Ikegami model: it us a model suitable for urban areas with dense construc-
tions.
(d) Ibrahim-Parsons model: it is a model that uses the land usage factor(the percentage
from the test area covered with buildings, no matter the height) and the urbanization
degree(percentage from the buildings that are higher than 4 or more
oors)

21
Chapter 2
Interference Analysis
2.1 General aspects
Interference is the eect of unwanted signals or noise at the reception of a wanted signal. It may
aect the quality of the signal, it may cause a temporary loss of a signal or, in the worst case,
it may prevent reception altogether. Mobility and conectivity at the global level was achieved
by the introduction of wireless communications, but here are several problems assiciated with
wireless channels.
2.1.1 Multipath and fading
Rays can take several dierent paths from the transmitter to the receiver because of the re-

ections. When arriving at the receiver, the incoming rays can add together in the fallowing
ways:
If the peaks of the incoming rays coincide they are building up together. This is known
as constructive interference
If the peaks of one ray coincide with the troughts of another, they are cancelling each
other. The result is known as destructive interference and it can make the received signal
power drop to a very low level(fading). The error rate increases signicantly, which makes
fading a serious problem for any mobile communication system.
As the mobile moves from one place to another, the ray geometry changes. It results a
changing interference pattern between constructive and destructive. Therefore, fading is a
function of time and the amplitude and phase of the received signal vary over a period of time
called coherence time, Tc, which can be appoximated with:
Tc=1
fD(2.1)
where,fDis the mobile's Dopler frequency:
fD=v
cfc (2.2)
where,fcis the carrier frequency, v is the speed of the mobile and c is the speed of light.
The radio signal changes with the carrier frequency, too. This causes the interference pattern
change between contructive and destructive. Consequently, fading is a function of frequency.
The amplitude an phase of the received signal vary over a frequency scale named coherence
bandwidth, Bc, which can be estimated as fallows:
Bc=1
(2.3)

22
Figure 2.1: Generation of contructive interference, destructive interference and fading – multi-
pah environment
Here,is the delay spread of the radio channel and it can be calculated as follows:
=
L
c(2.4)
where,
Lrepresents the dierence between the path lengths of the longest and the shortest
rays. For a macrocell, a normal path dierence might be around 300 meters, resulting a delay
spread of 1 sand a coherence bandwidth of aproximatively 1MHz. Smaller cells introduces
smaller delay spread, thus, a larger coherence bandwidth.
The impact of the multipath propagation phenomena is Inter-Symbol Interference(ISI):
2.1.2 Inter-Symbol Interference
The existance of re
ecting objects and scatterers in the radio propagation channel produces
an environment who changes constantly and dissipates the signal energy in amplitude, phase
and time. At the receiving antenna will arrive multiple versions of the transmitted signal
displaced with respect to one another in time and spatial orientation.For example, while still
receiving the previous symbol from a long re
ected way, the receiver can start to receive the
current one from a stort direct way.
The random amplitudes and phases of the dierent multipath components can cause
uctua-
tions in signal strength, inducing fading and/or signal distortion.Consequently, the inter-symbol
interference(ISI) or cross talk takes place and because of this the error rate at the receiver is
greatly increased. Thereby, inter-symbol interference is a huge problem for all communications
systems using high data rates.
In order to avoid it, guard periods were introduced.

23
Figure 2.2: Inter-symbol Interference
2.1.3 Frequency selective fading
A signal propagation through a mobile radio channel experiences fading which depends on
the nature of the transmitted signal with respect to the characteristics of the channel.
When a transmission channel has a constant gain and a linear phase response over a band-
width that is smaller than the bandwidth of the transmitted signal, the channel creates fre-
quency selective fading on the received signal [ ?]. In this case, dierent frequency components
experience dierent fading. Thus, in the frequency domain certain frequency components in
the received signal spectrum have greater gains than the others, as it can be observed in Figure
2.3.
Comparing to
at fading channels, frequency selective fading channels are much more dif-
cult to model because each multipath signal must be modeled and the channel must be con-
sidered to be a linear lter. Frequency selective fading channels are also known as wideband
channels because the bandwidth of the signal is wider than the bandwidth of the channel
impulse response.
Complex channel equalization techniques are employed in order to reduce frequency selective
fading.
Figure 2.3: Frequency selective fading channel characteristics. [ ?]

24
2.2 Uplink Interference Analysis in LTE networks
LTE's uplink(UL) eciency strongly depends on the way the interference is controlled across
dierent cells. All these network limitations, compound with the scarcity of bandwidth gave rise
to a new multiple access technique: Orthogonal Frequency Division Multiple Access(OFDMA).
OFDMA is a special case of Frequency Division Multiple Access(FDMA) where users are
provided a set of subcarriers overlapping in frequncy domain. LTE supports variable bandwidth,
and, as the bandwidth increases, so does the number of subcarriers. To use bandwidth in an
ecient way, the subcarriers are spaced in such a way that the side lobes of each subcarrier
wave are zero at the center of the neighboring subcarrier. This property is referred to as
`orthogonality'.
Figure 2.4: Multiple Access Techniques in LTE
SC-FDMA for Uplink Transmission
For uplink data transmissions, the use of OFDMA is not recommended because of its high
PAPR (Peak to Average Power Ratio) when the signals from multiple subcarriers are combined.
Because handled devices have limited power capacity, the transmitter should be as ecient
as possible. For this purpose, a dierent transmission scheme, reered to as Single-Carrier
Frequency Division Multiple Access (SC-FDMA) was proposed.
SC-FDMA is similar to OFDMA, but instead of dividing the data stream and putting the
resulting streams directly on the individual subcarriers, the time based signal is converted to
a frequency based signal with an FFT function. In this way, the information of each bit is
distributed onto all subcarriers that will be used for the transmission and thus reduces the
power dierences between the subcarriers. The number of subarriers used depends on the
signal conditions, the transmission power of the device and the number of users simultaneously
in the uplink.
2.2.1 Full duplex procedures used in LTE network
Mobile-phone trac is divided into two parts: uplink and downlink. LTE has two natural
strategies for separating resources between the uplink and the downlink: LTE-FDD(Frequency
Division Duplexing) and LTE-TDD(Time Division Duplexing).

25
1. Frequency Division Duplexing: data is transmitted and received simultaneously on two
separate channels. There are two carrier frequencies – one for uplink transmission, one
for downlink transmission. LTE-FDD implies that downlink and uplink transmission
take place in dierent, suciently separated frequency bands, so there is no interference.
The transmission is continuous. It is not possible to make dynamic changes in UL/DL
capacity. Normally, regulatory changes would be required and capacity is allocated so
that it is the same in either direction. Most parts of the world, including Europe and
America uses FDD.
2. Time Division Duplexing: uplink and downlink transmissions use the same carrier and
are saparated in time. Consequently, a transmission gap is required when switching
from transmission mode to reception mode. This is also called the guard period. The
more distant a mobile device is from the center of the cell, the earlier it has to start its
transmissions so that there is a synchronization with the transmissions of devices that
are closer to the center of the cell. To allow both uplink and downlink transmissions,
discontinuous transmission is required. Base staions must be synchronised with respecr
to the uplink and downlink transmission times. If neighbouring base stations use dierent
uplink and downlink time values and share the same channel, then interference may occur
between cells. LTE-TDD is used, for example, in China.
2.2.2 Digital Modulation techniques used in LTE
In order to transmit data on this subcarriers, they are loaded with modulation symbols that
represent the constellation points of digital modulation schemes. To reach the highest pos-
sible datarate during favorable transmission conditions, in adition to the already existing
BPSK(Binary Phase Shift Keying) modulation that transmits 1 bit per symbol and QPSK(Quadrature
Phase Shift Keying) modulation that transfer 2 bits per transmission step, several new modu-
lation schemes have been introduced:
16-QAM: 4 bits per transmission step. The name comes from the 16 values that can be
encoded in 4 bits(24).
64-QAM: 6 bits per transmission step.
A closer examination of each modulation scheme is given in the fallowing:
BPSK
BPSK, also refered to as 2-PSK, uses two phases which are separated by 180. This is the
simplest form of phase shift keying and it handles the highest noise level or distortion before
the demodulator takes a wrong decision. Although it is the most robust of all PSKs, it is able
to modulate at 1bit/symbol. Thus, it is not suitable for high data-rate applications.
Figure 2.5: BPSK constellation diagram

26
QPSK
A QPSK modulator takes the incoming bits two at a time and transmits them using a radio
wave that can have four dierent states. Phase and amplitude assignment in done according to
the QPSK Constellation. In the diagram, the distance of each state from the origin represents
the amplitude of the transmitted wave and the angle, measuread anti-clockwise from the x-axis,
represents its phase.
The advantage of QPSK over BPSK is straight forward: QPSK transmits twice the data
rate in a given bandwidth compared to BPSK, while the bit error rate remains the same with
the cost of using twice the power used for BPSK(since two bits are transmitted at the same
time) The drawback is that QPSK transmitters are more expensive than the onef for BPSK.
Figure 2.6: Quadrature phase shift keying. (a) transmitted radio wave. (b) QPSK constellation
diagram.
Moving to a higher order QAM constellation, which means higher data rates, multipath
interference typically increases.
16-QAM
This modulation scheme sends four bits at a time, using 16 states that have dierent amplitudes
and phases.
64-QAM
Similarly, 64-QAM sends six bits at a time using 64 dierent states, so it has a data rate six
times greater than that of BPSK.
Figure 2.7: 16-QAM(4 bits per symbol)
Figure 2.8: 64-QAM(6 bits per symbol)
Modulation and Coding Schemes(MCS) are used in LTE to determine the data rate. Based
on the channel conditions, LTE systems determine the proper MCS to use. The MCS is
negotiated during communication and it is keeping a balance between the maximum possible
data rate and maximum acceptable error rate. The more complex the modulation, the higher
the data rate. Better conditions such as less interference and a good line of sight are required
for more complex modulations.

27
MCX index Spatial Streams Modulation type Coding rate
0 1 BPSK 1/2
1 1 QPSK 1/2
2 1 QPSK 3/4
3 1 16-QAM 1/2
4 1 16-QAM 3/4
5 1 64-QAM 2/3
6 1 64-QAM 3/4
7 1 64-QAM 5/6
8 2 BPSK 1/2
9 2 QPSK 1/2
10 2 QPSK 3/4
11 2 16-QAM 1/2
12 2 16-QAM 3/4
13 2 64-QAM 2/3
14 2 64-QAM 3/4
15 2 64-QAM 5/6
Table 2.1: Modulation and Coding Schemes Table

28
Chapter 3
Uplink Interference Cancellation
3.1 General aspects
Generally, macrocells and microcells are used to provide mobile network. Both of them assures
radio coverage, but have dierent approaches each one being eective in distinctive situations.
Microcells are generally equipped with a single transceiver that covers a small area, for
example, several hundred meters of a street. The necessary transmission power for such a small
coverage area is very low and most network vendors have micro Node-Bs with very compact
dimensions.
Macrocells can provide cellular network coverage for a large area which can extend across
an entire city. The antennas can be positioned in the ground, rooftops other structures as long
as there is a clear view of the surroundings so that the signal is not obstructed. In contrast to
microcells, they need high transmit power.
What dierentiates macrocells and microcells is that microcells are for capacity and macro-
cells are for coverage. There are still some shortcomings since macrocells can overpower micro-
cells because they are more dominant. This causes interference, which means that the power
needs to be carefully set in such a way that neighbouring microcells are not overpowered.
Figure 3.1: Dierent cell zones
In an intra-frequency LTE network, cell edge users(CEU) could get interfered by intra-
frequency neighboring cells. Uplink Interference cancellation(UL IC) reduces the interference
and increases cell an CEU throughputs in the uplink. It does this by reconstructing the uplink
interfering signals of the neighboring cells and eliminating the interfering signals from the uplink
received(RX) signals, improving uplink RX signal quality.
Uplink interference cancellation works for the fallowing scenarios:
Networking between macro cells
A macro cell has a large coverage area and a high transmit power.
Networking between micro cells
A micro cell has a small coverage area and a low transmit power.

29
Networking between a macro and a micro cell
Networking between a single frequency network(SFN) cell and another cell.
For the IC beneted UE the spectral eciency increases after UL IC is enabled for the IC
beneted cell, while the IC interfering UE is the one that causes interference to an IC beneted
cell.
Figure 3.2: Relationship of roles in UL IC
Benets
When the UL PRB usage exceeds 15 %, the cell throughput can be increased. The increase
gains vary with the proportion of UL IC beneted UEs and the quantity of physical resource
blocks(PRBs) used by such UEs. The cell throughput increase gains also vary with networking
schemes and the number of receive (RX) antennas.
FeatureBenets in Macro-Macro and
Micro-Micro ScenariosBenets in Macro-Micro Scenarios
LOFD-120202
Intra-eNodeB and
Inter-eNodeB Uplink
Interference CancellationThe average cell throughput
increases by up to 5%- In IP RAN scenarios with two receive
antennas, the average cell throughput
increases by up to 15%.
– In other scenarios, the average cell
throughput increases by up to 5%.
Table 3.1: Increase in cell throughput after UL IC is enabled
On the user equipment side, when the UL PRB exceeds 15 %, the UE throughput can be
increased. The strength of interference from neighboring cells and the signal quality of beneted
UEs strongly in
unces the throughput gains.

30
FeatureBenets in Macro-Macro and
Micro-Micro ScenariosBenets in Macro-Micro Scenarios
LOFD-120202
Intra-eNodeB and
Inter-eNodeB Uplink
Interference Cancellation- In IP RAN scenarios with
two receive antennas, the
average CEU throughput
increases by up to 20%.
– In other scenarios, the
average CEU throughput
increases by up to 5%.- In IP RAN scenarios with two receive
antennas, the average CEU throughput
increases by up to 20%.
– In other scenarios, the average CEU
throughput increases by up to 5%.
Table 3.2: Increase in UE throughput after UL IC is enabled
3.2 Macro-Macro and Micro-Micro UL IC
Both macro-macro and micro-micro UL IC follow the same principles: they select inter-
fering UEs to perform interference cancellation based on downlink reference signal received
power(RSRP) measurement results.
RSRP
As a mobile moves from cell to cell in a celular network and performs handover and cell
selection/reselection, it has to measure the strength of the signal as well as the quality of the
neighboring cells. In LTE, RSRP is one of the parameters measured by the user equipment on
reference signal, giving us the signal strength of the desired signal.
3GPP denes RSRP as the linear average power of Resource Elements(RE) that carry
cell specic Reference Signals(RS) over the entire bandwidth. Consequently, RSRP is only
measured in the symbols carrying RS and the UE measures the power of multiple resource
elements used to transfer the reference signal and takes an average of them.
There is a reporting interval of RSRP dened from -140 dBm to -44 dBm with 1 dB
resolution. These values are mapped as shown in the fallowing table:
Reported Value Measured quantity value Unit
RSRP 00 RSRP<-140 dBm
RSRP 01 -140<= RSRP<-139 dBm
RSRP 02 -139<= RSRP<-138 dBm
… … …
RSRP 95 -46<= RSRP<-45 dBm
RSRP 96 -45<=RSRP<-44 dBm
RSRP 97 -44<= RSRP dBm
Table 3.3: RSRP measurement report mapping
Typically, RSRP levels for usable signal range from about -75 dBm close to an LTE cell site
to -120 dBm at the edge of LTE coverage.
In the fallowing, macro-macro UL IC will be used as an example to describe the principles.
The eNodeB obtains downlink RSRP measurements from event A3 reports for macro-macro
UL IC.

31
3.2.1 Event A3
Event A3 is used in order to trigger an intra LTE mobility. When this event is accomplished,
…..ask petrisor ((Neighbour becomes oset better than PCell(primary cell)??)
The UE shall consider the entering condition for this event to be satised when condition
A3-1 is fullled:
Mn+Ofn +OcnHys>Mp +Ofp +Ocp+Off (3.1)
The leaving condition for this event is satised when condition A3-2 is fullled:
Mn+Ofn +Ocn+Hys<Mp +Ofp +Ocp+Off (3.2)
where:
Mn is the measurement result of the neighbouring cell, not taking into account any
osets.
Ofn is the frequency specic oset of the frequency of the neighbour cell (i.e. osetFreq
as dened within measObjectEUTRA corresponding to the frequency of the neighbour
cell).
Ocn is the cell specic oset of the neighbour cell (i.e. cellIndividualOset as dened
within measObjectEUTRA corresponding to the frequency of the neighbour cell), and set
to zero if not congured for the neighbour cell.
Mpis the measurement result of the PCell, not taking into account any osets.
Ofp is the frequency specic oset of the primary frequency (i.e. osetFreq as dened
within measObjectEUTRA corresponding to the primary frequency).
Ocpis the cell specic oset of the PCell (i.e. cellIndividualOset as dened within
measObjectEUTRA corresponding to the primary frequency), and is set to zero if not
congured for the PCell.
Hys is the hysteresis parameter for this event (i.e. hysteresis as dened within report-
CongEUTRA for this event).
Ois the oset parameter for this event (i.e. a3-Oset as dened within reportCon-
gEUTRA for this event).
Observations:
1. Mn, Mp are expressed in dBm in case of RSRP, or in dB in case of RSRQ.
2. Ofn, Ocn, Ofp, Ocp, Hys, O are expressed in dB.
3.2.2 Entering and exiting UL IC
When the trigger condition for the UL IC event A3 is met in macro-macro networking scenar-
ios with UL IC enabled, a UE reports the A3 measurement result to its PCell(Primary Cell or
Serving cell). In this case, the UE is considered as a UL IC interfering UE and the measured
neighboring cell is a candidate beneted cell and the serving cell is the interfering cell. When
the positions of RBs used by a UE in a candidate beneted cell for performing uplink services

32
coincide partially or wholly with those of RBs used by an interfering UE, UL IC can be per-
formed in the candidate beneted cell for the UE to improve uplink spectral eciency. In this
case, the UE is a UL IC beneted UE.
The beneted cell will remove the interfering cell from the IC interfering cell set if all
interfering UEs in an IC interfering cell corresponding to an IC beneted cell meet the leavng
condition of the UL IC A3 event. If the interfering cell set of and IC beneted cell contains no
cells, the beneted cell exits UL IC.
3.3 Macro-Micro UL IC
A common heterogeneous network (HetNet) uses a combination of legacy systems(such as
GSM and UMTS) and modern radio access technologies such as LTE, sometimes completed
with Wi-Fi. In a HetNet, there are dierences in downlink cell-specic reference signal(CRS)
transmit(TX) power between macro and micro cells.
CRS
In order to deliver the reference point for the downlink power, reference signals are used.
When the user equipment tries to nd out the downlink power, it measures the power of this
reference signal and takes it as downlink cell power. These CRSs are carried by multiples of
specic RE in each slot and the location of the RE is determined by the antenna conguration.
Even though the dierence in uplink RSRP between the cells meets the UL IC A3 reporting
conditions in some areas, the dierence in downlink RSRP between the cells does not. To avoid
this situation, the eNodeB determines the meadurement results to be used depending on the
dierence in CRS TX power between macro and micro cells.
When the dierence in CRS TX power between macro and micro cells is less than 6 dB,
the downlink RSRP measurement results are directly used. The required parameters are
the same as those for macro-macro UL IC.
When the dierence in CRS TX power between macro and micro cells is greater than or
equal to 6 dB, the measurement results to be used are further determined by the setting
of the NCellSrsMeasPara.SrsAutoNCellMeasSwitch parameter.
{When the NCellSrsMeasPara.SrsAutoNCellMeasSwitch parameter is set to ON, the
eNodeB uses the uplink RSRP measurement results of the serving cell and inter-
fering cells that are based on SRS measurement for common use. Neighboring
cells where SRS measurement for common use is to be performed are automati-
cally added. The A3 oset for SRS measurement is specied by the NCellSrsMeas-
Para.NCellSrsMeasA3Oset parameter.
{When the NCellSrsMeasPara.SrsAutoNCellMeasSwitch parameter is set to OFF, the
eNodeB uses the downlink RSRP measurement results
3.3.1 Entering and exiting UL IC
If UL IC is enabled in macro-micro networking scenarios,there are two methods for identifying
interfering UEs, based on the fallowing measurement results:
Downlink RSRP measurement results. In this case, the methods for identifying UEs and
interfering cells are the same as those in macro-macro and micro-micro scenarios UL IC
presented in section 3.2.

33
Uplink RSRP measurement results. The serving cell obtains the uplink RSRP measure-
ment results of the serving and neighboring cells from the UE.If the measurement results
meet the trigger condition of the UL IC event A3, the UE is regarded as a UL IC in-
terfering UE, its neighboring cell is a candidate beneted cell, and its serving cell is the
interfering cell of the candidate beneted cell.
The beneted UE in macro-micro UL IC is identied in the same manner that is done for
macro-macro and micro-micro UL IC.
Here, the leaving condition depends on the used measurement results:
Downlink RSRP measurement results.The leaving condition of macro-micro UL IC is the
same as that of macro-macro or micro-micro UL IC.
Uplink RSRP measurement results. The uplink RSRP measurement results of the serving
cell and a neighboring cell based on SRS measurement for common use determine whether
an interfering UE exits the UL IC A3 measurement. When all interfering UEs in an
interfering cell corresponding to a beneted cell meet the condition of exiting the UL IC
A3 measurement, the beneted cell removes the interfering cell from the IC interfering
cell list. If all interfering cells are removed from the list, UL IC does not take eect on
the beneted cell.
SRS
Sounding Reference Signal(SRS) it is used to estimate the uplink channel quality. SRS
reports the channel quality of over all bandwidth and using this information the eNodeB
assigns the resources to the UEs for the uplink transmission.
3.4 SFN-Related UL IC
A SFN(Single Frequency Network), particularly interesting for brpadcasting, is a network of
transmitting stations that use the same frequency to transmit the same information. In SFN
networking scenarios, an interfering cell determines whether a neighboring cell is a beneted
cell according to the following rules:
If a neighboring cell is a common physical cell, the interfering cell determines whether the
neighboring cell is a beneted cell based on the downlink RSRP measured in event A3.
If a neighboring cell is an SFN cell, the interfering cell determines whether a specic phys-
ical cell is a beneted cell based on the uplink RSRP obtained through SRS measurement
for common use.
In SRS measurement for common use, SRS resources in SFN cells are preferentially allo-
cated to UEs for SFN-related measurement so that the eNodeB can select target RRUs
and determine UE attributes. If many UEs exist in SFN cells, SRS resources may be in-
sucient and the number of identied UL IC interfering UEs in SFN cells may decrease,
compared with that in common cells performing UL IC.
3.4.1 Entering and exiting UL IC
An interfering UE in an interfering cell will report information about neighboring cells when
the RSRP measurement results of the interfering UE meet the trigger condition of the UL IC
event A3. This occurs regardless of whether the interfering cell is a common cell or an SFN
cell. The principle for entering UL IC in SFN scenarios is the same as that for entering UL IC
in macro-micro scenarios.

34
The leaving condition of UL IC in SFN scenarios is the same as that of UL IC in macro-micro
scenarios.

35
Chapter 4
Uplink Interference Cancellation in a Macro-Macro
scenario
4.1 Implementing the algorithm
Bucharest is the most populous city of Romania and because in some scenarios the trac
is really heavy, it is reccomended that some parameter settings to be optimized in order to
have a properly working network. The Intra-eNodeB and Inter-eNodeB Uplink Interference
Cancellation algorithm is suitable in densely populated urban areas or urban areas where the
inter-site distance is less than 1000m.
4.1.1 The map of the Bucharest sites where the algorithm was run
The map of the Bucharest sites is extracted from Asset program and presented in Figure 4.1
where the parameters used for the algorithm application are described in Table
Figure 4.1: The map of the Bucharest sites where the algorithm was run
As can be seen in Figure 4.2, the distance between BI0120 and BI1757 is 337.25m. Also,
this area is a densely populated one which means that UL IC algorithm is best-suited for this
scenario.

36
Figure 4.2: The distance between BI0120 and BI1757
4.1.2 The commands used for algorithm activation
The algorithm was activated in 22.05.2019 at 09:00 PM and the program U2000 was used. The
fallowing MML(Man-Machine Language) commands were introduced:
1. MOD SRSCFG:SRSSUBFRAMECFG=SC3, SRSCFGIND=BOOLEAN TRUE, FDDSRSCFG-
MODE=DEFAULTMODE;
This command is used for setting the parameters for SRS. Those parameters need to be
set because SRS is to be used for uplink RSRP measurement.
Parameter
NameParameter
IDSetting Notes
SRS
Conguration
IndicatorSRSCfg.SrsCfgIndIt is adviced for this parameter to be
set to BOOLEAN TRUE(True).
FDD SRS
Conguration
ModeSRSCfg.FddSrsCfgModeIt is adviced for this parameter to be
set to DEFAULTMODE(Default
Mode).
SRS subframe
congurationSRSCfg.SrsSubframeCfgIt is adviced for this parameter to be
set to the conguration with the index
that is equal to (PCI mod 3) plus 3.
Table 4.1: Parameters in SRSCFG
2. MOD CELLSRSADAPTIVECFG:SRSPERIODADAPTIVE=OFF,USERSRSPERIOD=ms40;
This command is used for setting the transmission SRS parameters:
SRS Period Adaptive Switch is set to OFF
User SRS Period [ms] is set to 40 ms

37
3. MOD CELLULICALGO:ULICA3OFFSET=-20; This command is used for setting the
UL IC A3 oset to the value -10dB (in the Graphical User Interface(GUI) the value is
-20)
Parameter
NameParameter
IDSetting Notes
UL IC A3 Oset CellUlIcAlgo.UlIcA3Oset The default value is recommended.
Table 4.2: Parameter that must be set in a CellUlICAlgo
4. MOD NCELLSRSMEASPARA:SRSAUTONCELLMEASSWITCH=ON,NCELLSRSMEASA3OFFSET=-
20; This command is used for setting the parameters that must be set in the NCellSrsMea-
sPara MO to congure SRS measurement for common use.
Parameter
NameParameter
IDSetting Notes
SRS Auto Neighbour Cell
Measurement SwitchNCellSrsMeasPara.SrsAut
oNCellMeasSwitchBecause we have micro-micro
networking scenario where
the dierence in downlink
CRS TX power between
the cells is
greater than or equal to 6
dB, It is recommended that this
parameter be set to ON(On)
Table 4.3: Parameters that must be set in an NCellSrsMeasPara
5. MOD CELLALGOSWITCH:UPLINKICSWITCH=UlInterSiteIcSwitch-1; This command
is used for algorithm activation
4.2 Monitoring the network performance
The outcomes and performances of the network can be described either through overall
indicators or through specic performance indicators for UL IC.
4.2.1 Overall network indicators
The overall network indicators take into consideration the fallowing issues which contribute to
the netowk performance:
Figure 4.3: CSSR and DCR network indicators
CSSR (Call Setup Success Rate)

38
DCR (Drop Call Rate)
DL Throughput
UL Throughput: the average datarate on uplink
4.2.1.1 Call Setup Succes Rate – CSSR
It represents the percentage of successful call setups of all call attempts made. The
CSSR(Call Setup Success Rate) network performance indicator is illustrated in Figure 4.4
for the period 06.05.2019 – 09.06.2019(it contains approximatively two weeks before and after
algorithm activation). It can be seen that since the time of the UL IC activation, the call setup
success rate increases from 99.943% to 99.956%, which means an improvement of 1.3%.
To better analyze the increase of the call setup success rate, Figure 4.5 is represented. It
also contains approximatively two weeks before and after algorithm activation, excepting ocial
non-working days. In this way, there is a more accurate comparison between similar days(having
approximatively the same number of users and approximatively the same throughput).
Figure 4.4: 4G/LTE CSSR(%)

39
Figure 4.5: 4G/LTE CSSR(%), excepting ocial non-working days
4.2.1.2 Drop Call Rate – DCR
The percentage of all losses connections of the trac channels during a call in connection
with the number of successful Call Setups. Consequently, DCR shoud be extremely low, signif-
icantly less than 0.01%. Network telecommunication operatiors are looking towards values as
low as possible. In case of very bad conditions, it may reach a few percents. The main reasons
for dropped calls are:
Technical Failures (like power failure for a BTS)
Lack of radio coverage(Either in uplink or downlink)
Overloaded network elements(Such as cells)
Monitoring and optimizing this parameter is a very important task for telecommunications
network operators because customer satisfaction strongly depends on it.
In Figure 4.6 it can be observed that after the activation of UL IC the drop call rate is
stabilized and it goes from the average value of 0.059 % before the date 22.05.2019 to 0.055%
after the same date.
Moreover, in Figure 4.7 we can observe that the average value of the DCR Key Performance
Indicator(KPY) from 06.05.2019 to 22.05.2019 is around 0.0563 % and from 23.05.2019 to
07.06.2019 is around 0.553%, where the ocial non-working days were excluded in order to
have a more precise comparation between similar days.

40
Figure 4.6: DCR
Figure 4.7: 4G/LTE DCR(%), excepting ocial non-working days

41
4.2.1.3 Downlink(DL) Throughput and Uplink(UL) Throughput
Downlink throughput is dened as the average datarate on downlink. Normally, through-
put is calculated as symbols per second, and then, depending on how many bits a symbol can
carry, is transformed in bits per second.
From Figure 4.8 it can be easily observed that the throughput increases after UL IC ac-
tivation(22.05.2019). Results show that form the average value of 20172.9258 Kbps before
algorithm activation, the average DL throughput increases to 25423.7000 Kbps after algorithm
activation.
Uplink throughput is dened as the average datarate on uplink. Here, the average value
also increases from 3935.8527 Kbps to 3989.2700 Kbps and the
uctuations can be observed in
Figure 4.9.
CSSR DCR Throughput DL Throughput UL
Average before UL IC 99.9433 0.0593 20172.9258 3934.8527
Average after UL IC 99.95433 0.057194 25423.7000 3989.2700
Table 4.4: General KPI comparison before and after UL IC

42
Figure 4.8: Downlink Throughput
Figure 4.9: Uplink Throughput

43
4.2.2 Specic UL IC indicators
For UL IC beneted UEs, this feature can increase the Modulation and Coding Scheme(MCS)
and can increase the uplink cell coverage. Also, the average uplink cell throughput increases
considerably.
For the fallowing results, there were made some measurements with a qualied LTE user
equipment before and after UL IC activation.
4.2.2.1 Results before UL IC
Figures 4.10, 4.12 and 4.14 are showing the modulation usage before UL IC activation for a
4G/LTE UE. It has to be noted that there is a considerable percent of QPSK modulation
usage for the rst two timeslots (8:42:23 PM – 8:43:40 PM and 8:47:50 PM – 8:49:08 PM). For
the third timeslot(8:58:58 PM – 9:00:16 PM), BPSK modulation usage increases dramatically.
Therefore, in this case there is used the same bandwidth, but the datarate is halved.
At the same time, uplink throughput increases with higher modulation usage. In Figure
4.11 the average 4G LTE UE throughput is 33993.11 Kbps and in Figure 4.13 its value is
25140.69 Kbps. In Figure 4.15, because of the high percent of BPSK modulation usage, the
user equipment throughput has the average value of 12776.53 Kbps in the third timeslot.
Figure 4.10: 4G/LTE UE Modulation Usage before UL IC

44
Figure 4.11: 4G/LTE UL Throughput Before UL IC
Figure 4.12: 4G/LTE UE Modulation Usage before UL IC

45
Figure 4.13: 4G/LTE UL Throughput Before UL IC
Figure 4.14: 4G/LTE UE Modulation Usage before UL IC

46
Figure 4.15: 4G/LTE UL Throughput Before UL IC
4.2.2.2 Results after UL IC
Comparing these results with those before UL IC activation, it can be observed that there
are signicant increases for the superior modulation schemes(16 QAM and 64 QAM). In the
same way as for section 4.2.2.1, 3 sets of measurements were done. In the rst set, Figure
4.16, signicant increases of superior modulation schemes usage can be observed and those
improvements are getting even better for the second(Figure 4.18) and the third(Figure 4.20)
sets of measurements.
Regarding the uplink throughput, higher values are expected. Indeed, for the rst set of
measurements(9:04:23PM – 9:05:42PM, Figure 4.17), the average value of the throughput is
38406.11 Kbps and a few seconds later, for the second set(9:09:50 PM – 9:11:08, Figure 4.19 it
is 53127.61 Kbps). For the third set (09:31:46 PM – 09:32:19 PM, Figure 4.21), the throughput
takes the average value of 52390.46 Kbps.

47
Figure 4.16: 4G/LTE UE Modulation Usage after UL IC
Figure 4.17: 4G/LTE UL Throughput After UL IC

48
Figure 4.18: 4G/LTE UE Modulation Usage after UL IC
Figure 4.19: 4G/LTE UL Throughput After UL IC

49
Figure 4.20: 4G/LTE UE Modulation Usage after UL IC
Figure 4.21: 4G/LTE UL Throughput After UL IC

50
CONCLUSIONS

51
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