Analysis of the antenna settings, overlapping zones, interferences and data throughput in order to improve the quality of the Vodafone LTE mobile
network by optimising the electrical tilts of the antennas.
CRISTIAN CAMILO MART´INEZ CUELLAR
SAINT THOMAS UNIVERSITY ENGINEERING DIVISION.
TELECOMMUNICATIONS ENGINEERING. MUNICH - GERMANY
Analysis of the antenna settings, overlapping zones, interferences and data throughput in order to improve the quality of the Vodafone LTE mobile
network by optimising the electrical tilts of the antennas.
CRISTIAN CAMILO MART´INEZ CUELLAR
Dissertation performed to obtain the title of telecommunications engineer, considering the work placement at the firm Vodafone GmbH
(Munich - Germany).
Directors
Ing. Victor Manuel Castro Ram´ırez, USTA Dipl.-Ing. Jose Huam´an, Vodafone GmbH
SAINT THOMAS UNIVERSITY ENGINEERING DIVISION.
TELECOMMUNICATIONS ENGINEERING. MUNICH - GERMANY
Munich - Germany, June 18, 2016
Acceptance note
Signature
Name:
Foreman
Signature
Name:
Jury
Signature
Name:
Confidentiality Note:
This document includes internal and confidential information of Vodafone GmbH,
therefore, the student, the thesis tutors and juries shall not take advantage of or
reveal or trade information that have been entrusted to them or they have come to
DEDICATION
This dissertation is dedicated to my father. For his endless love, support and
encouragement.
ACKNOWLEDGEMENTS
Foremost, I would like to express my special thanks to Vodafone GmbH and all of the
people I have met there: thank you for providing me with all the necessary facilities and tools for this project; for your unending patience while listening to my poor German
skills and all the things you have taught me. Thanks to the student interns, who on
several occasions drove me to the city to perform measurements.
There might be not enough space to list all the professors I have met at the Santo
Thomas University, who have taught me not only academic knowledge but also valuable
lessons for my personal life. I would like to sincerely thank you all for the confidence
you exuded to me and the motivation you gave me.
To the DAAD (Deutscher Akademischer Austauschdienst1) and my university itself,
who granted me the “Young Engineers” scholarship, I have nothing but immense grat-itude; you gave me the biggest opportunity of my life and I will not waste it.
Last but not least, I have to thank my father for his love, pride, support and most
impor-tantly for his patience throughout my whole life. Thank you for giving me the strength
to reach my goals and chase my dreams. To Alexandra Thompson, for her funny sense
of humour and support while I was working on this thesis and for proofreading it.
ABSTRACT
This dissertation sets out to improve the quality of the Vodafone LTE network in the
south-Germany by examining and correcting different parameters of antennas within a
cluster and optimising their electrical tilts. It also aims to strengthen the student’s
knowledge, acquired during the telecommunications engineering bachelor at Santo
Thomas University Colombia.
The cellular network business has become more competitive and complex since the
introduction of 4G. LTE has surpassed its predecessors, dominating data services and it is only matter of time before it fully extends to voice services, until we reach a point
where the days of planning GSM, GPRS, WCDMA and UMTS are behind us. Human
behaviour on social networks and the internet requires the best of network capacity
now, which is why engineers must keep optimising processes constantly.
In order to carry out this work, a city in Germany was assigned as the main dissertation
target and its network was enhanced by following the two main phases of an
optimisa-tion process: site verificaoptimisa-tion and RF optimisaoptimisa-tion. Using informaoptimisa-tion from Vodafone
databases and simulation tools, a deep analysis of the state of the cluster was carried
out, apart from LTE parameters such as, RSRP, SINR and DL/UL Throughput. As expected, RSRP coverage was pretty good but throughput and SINR did not reach
maximum values.
Throughout the project, several inconsistencies and network problems were identified
and mostly fixed. The main findings of each phase are presented throughout this
docu-ment. Network performance after optimisation proves that there is no linear relationship
between power and quality.
KEYWORDS:
LTE800 mobile network, Overlapping zones, Interferences, RSRP coverage, SINR,
Throughput (Downlink and Uplink), Electrical Tilt, Measurement, Vodafone,
CONTENTS
Page.
Glossary . . . 16
INTRODUCTION . . . 21
1. Problem Formulation . . . 23
1.1. Approach to the problem . . . 23
1.2. Justification . . . 24
2. Objectives of the project . . . 25
2.1. General Objective . . . 25
2.2. Specific Objectives . . . 25
3. Theoretical framework . . . 26
3.1. Firm overview . . . 26
3.1.1. Vodafone Group . . . 26
3.1.2. Vodafone GmbH - Germany . . . 26
3.1.3. TFL Department, TFLO Group . . . 29
3.2. LTE Fundamentals . . . 30
3.2.1. Basic Parameters . . . 32
3.2.3. The base station - eNB . . . 36
3.2.4. OFDM (Downlink) and SC-FDMA (Uplink) . . . 37
3.2.5. PCI . . . 40
3.2.6. RSRP (Reference Signal Received Power) . . . 41
3.2.7. RSRQ (Reference Signal Received Quality) . . . 41
3.2.8. SINR (Signal to Interference & Noise Ratio) . . . 42
3.2.9. Throughput . . . 42
3.2.10. Bearer Types . . . 42
3.2.11. Radio Resource Control states . . . 43
3.2.12. RRC connection establishment procedure . . . 44
3.2.13. RRC connection re-establishment procedure . . . 45
3.3. Optimisation fundamentals . . . 45
3.4. Vodafone Tools . . . 47
3.4.1. Measurement Hardware . . . 47
3.4.2. Measurement Software . . . 49
3.4.3. Tools for analysis and optimisation . . . 50
3.5. Other tools . . . 55
4. Methodology . . . 57
4.1. Timescale . . . 59
5. Development of the Project . . . 60
5.1.1. Cluster definition . . . 60
5.1.2. Database Validation . . . 62
5.2. Phase 2: RF Optimisation . . . 63
5.2.1. Path-loss calculation . . . 63
5.2.2. Optimisation by simulation . . . 64
5.2.3. Tilts implementation . . . 67
5.2.4. Second optimisation and final stage . . . 68
5.3. Measurement design . . . 68
6. Results . . . 70
6.1. Site verification . . . 70
6.1.1. Inconsistencies . . . 70
6.1.2. Technical errors . . . 71
6.2. RF Optimisation . . . 75
6.3. Measurements . . . 75
6.3.1. Before optimisation . . . 76
6.3.2. After first optimisation . . . 76
6.3.3. After second optimisation . . . 77
6.4. Final statistics . . . 83
6.4.1. Motorways . . . 84
6.4.2. City . . . 85
6.5.1. RRC re-establishment connection failure . . . 87
6.5.2. E-RABs from the QCIs . . . 88
6.5.3. Throughput and Volumes . . . 89
7. Conclusions . . . 90
8. Future Work . . . 92
REFERENCES . . . 93
APPENDIX . . . 96
A. Vodafone base station . . . 97
B. Plots Radioplan . . . 101
C. Datasheet kathrein 80010675 . . . 104
D. Complete measurement results . . . 106
D.1. Motorways . . . 106
LIST OF FIGURES
Page.
1 Vodafone GmbH, branch south (beginning of the bachelor thesis). . . 27
2 Market share of German mobile operators. . . 27
3 Vodafone GmbH, branch south (end of the bachelor thesis). . . 29
4 1Q 2015: LTE Subscribers and Market Shares by World Region. . . 31
5 LTE overall Architecture. . . 33
6 E-UTRAN Architecture. . . 34
7 Distributed Base Station from Huawei (DBS3900). . . 36
8 OFDM frequency and time domain. . . 38
9 Downlink resource grid. . . 39
10 PCI: Deployment Illustration. . . 40
11 Bearers for LTE. . . 43
12 Signalling for RRC connection establishment. . . 44
13 Optimisation methods. . . 46
14 R&S TSMW Network Scanner. . . 47
15 Measurement smartphones. . . 48
17 Software interface of the ROMES 4 drive test tool. . . 49
18 Interface of the SwissQual QualiPoc Android. . . 50
19 D2-RAIT Cellfile-Layer example. . . 51
20 D2-RAIT Measurement-Layer example. . . 52
21 D2-RAIT Background-Layer example. . . 52
22 Example of coverage by signal level in Atoll. . . 54
23 Radioplan LTE System Simulator Architecture. . . 54
24 LTE position-based throughput analysis in Radioplan. . . 55
25 Optimisation flowchart. . . 57
26 RF optimisation flowchart. . . 58
27 Project-workflow timescale. . . 59
28 Terrain Profile of Neuenkirchen. . . 60
29 Satellite view of Neuenkirchen. . . 61
30 Filtering and focus zones. . . 64
31 Simulation and analysis areas. . . 65
32 Motorways of Neuenkirchen. . . 69
33 State of final cluster in matter of antenna types. . . 71
34 MXL773A. . . 73
35 MXL773 sectors A and B. . . 73
36 MXL773A coverage signal with tilt 7o. . . . 74
38 SINR after the first optimisation. . . 76
39 SINR in the city (before and after). . . 78
40 FTP Downloads in the city (before and after). . . 78
41 Special areas with low SINR. . . 79
42 PCI around the MXLV02. . . 80
43 Area 2 →RSRP (with PCI) and SINR. . . 81
44 Area 3 →RSRP with PCI. . . 81
45 RSRP and PCI for the first best server around the MXL773. . . 82
46 RSRP and PCI for the second best server around the MXL773. . . 83
47 CD plots for RSRP and SINR values on the motorways. . . 84
48 CD plots for throughput values on the motorways. . . 85
49 CD plots for RSRP and SINR values in the city. . . 86
50 CD plots for throughput values in the city. . . 86
51 RRC re-establishment connection failure after the optimisation. . . 87
52 QCI 5 (Signalling) after the optimisation. . . 88
53 QCI 9 (Data) after the optimisation. . . 88
54 DL and UL Throughput after the optimisation. . . 89
LIST OF TABLES
Page.
1 Regions of Vodafone Germany GmbH [5]. . . 28
2 Basic parameters of LTE. . . 32
3 Frequency distribution of LTE networks in Germany and Colombia. . . 33
4 Radioplan: general and optimiser Settings. . . 66
5 Measurement design. . . 69
6 Inconsistencies after database validation. . . 70
7 Configuration ports of the site MXL773. . . 72
8 Absolute tilt changes during the project. . . 75
9 Final statistics for the motorways. . . 84
GLOSSARY
3
3GPP Third Generation Partnership Project, p. 30.
A
APM30H Advanced Power Module from Huawei, it supplies DC power and backup power to the distributed or separated base station in outdoor scenarios, p. 37.
B
BCCH Broadcast Control Channel is a point to multipoint, unidirectional
(down-link) channel used in the Um interface of the GSM cellular standard, p. 40.
BTS Base Transceiver Station, is a piece of equipment that facilitates wireless
communication between user equipment (UE) and a network, p. 36.
C
Clutter Clutter refers to a Land Use/Land Cover classification of surface features which impact on radio wave propagation. These features are classed
D
DTM Digital Terrain Model, is a continuous model of ground-level land surface,
represented by a digital raster grid with each grid cell holding an elevation
value, p. 63.
E
Eb/No Bit Energy on the Spectral Noise Density in [dB], p. 47.
EPRE Energy Per Resource Element, is the power of one resource element, p. 62.
ETSI European Telecommunications Standards Institute, p. 32.
F
FDD Frequency Division Duplexing, p. 32.
FDE Frequency Domain Equalisation, used in OFDM systems to gain high
trans-mission efficiency, p. 33.
G
GERAN GSM EDGE Radio Access Network, p. 35.
GmbH German abridging of Gesellschaft mit beschraenkter Haftung which means
limited liability company, p. 4.
GPRS General Packet Radio Service, is a packet oriented mobile data service on
the 2G and 3G cellular communication system’s GSM, p. 7.
GSM Global System for Mobile Communications, standard that describes
L
LTE Long Term Evolution, is a standard for wireless communication of high-speed
data for mobile phones and data terminals, p. 7.
M
MapInfo MapInfo is a desktop geographic information system (GIS) software product produced by Pitney Bowes Software (formerly MapInfo Corporation) and
used for mapping and location analytics, p. 51.
MIMO Multiple Input Multiple Output, p. 32.
O
OFDM Orthogonal Frequency-Division Multiplexing, is a technique for transmitting
large amounts of digital data over a radio wave, p. 37.
OFDMA Orthogonal Frequency Division Multiple Access, is a modulation scheme that supports 100Mbps+ of Download speed in LTE standards with 20Mhz
spectrum, p. 32.
P
Path-loss is the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space, p. 53.
Q
QAM Quadrature Amplitude Modulation, is an analogue and/or a digital
modu-lation scheme that conveys two signals or bit streams by changing
(modu-lating) the amplitudes of two carrier waves, p. 32.
QCI QoS Class Identifier, is a mechanism used in LTE networks to ensure bearer
traffic allocates an appropriate quality of service (QoS), p. 42.
QoS Quality of Service, p. 35.
QPSK Quadrature Phase-Shift Keying, is a digital modulation scheme that conveys
data by changing (modulating) the phase of a reference signal (carrier wave),
using four point on the constellation diagram, p. 32.
R
RAN Radio Access Network, p. 36.
RET Remote Electrical Tilt, it is the engine that adjusts the tilt of an antenna
remotely, p. 37.
RSCP Received Signal Code Power, denotes the power measured in mobile radio
systems of the UMTS standard, p. 47.
RSRP Reference Symbol Received Power, is the linear average of the downlink
reference signals across the channel bandwidth, p. 48.
RSRQ Reference Signal Received Quality, represents the total received wide-band
power by UE, p. 48.
RSSI Received Signal Strength Indicator, indicates quality of received reference
signal, p. 48.
S
SC Scrambling Code, used to separate different cells or Mobility Entities in one
carrier depending on the direction of the communication, p. 40.
SC-FDMA Single Carrier Frequency Division Multiple Access, is a modulation scheme that supports 50Mbps+ of Upload speed in LTE standards with 20Mhz spectrum, p. 32.
SGSN Serving GPRS Support Node, it allows 2G, 3G and WCDMA mobile neworks
to transmit IP packets to external networks such as internet, p. 35.
T
TDD Time Division Duplexing, p. 32.
TMC11H Transmission Cabinet from Huawei, provides DC power and space for user equipment, p. 37.
TTI Transmission Time Interval, parameter that refers to the duration of a
trans-mission on the radio link, p. 32.
U
UMTS Universal Mobile Telecommunications System, is a third generation (3G)
mobile cellular system for networks based on the GSM standard, p. 7.
USIM Universal Subscriber Identity Module, p. 34.
UTRAN UMTS Terrestrial Radio Access Network, p. 33.
W
INTRODUCTION
It may be difficult to believe that it has been six years since the first 4G/LTE
net-work went live in Stockholm. From that date, operators worldwide have been pushing
themselves to their limits to deploy more LTE stations and expand their coverage,
pro-viding better quality and higher speeds to their users. Germany did not lag behind and
launched its first LTE network one year later through Vodafone GmbH.
Among other technical features, LTE offers increased peak data rates, improved
spec-trum efficiency, lower latency and flexible channel bandwidth that offers far better performance in comparison to its predecessors. Social networks influence the behaviour
of users with increasing demands for greater capacity, higher speeds, mobility and
bet-ter quality. Therefore, it is essential for mobile operators to keep constantly growing
their network, deploying more stations everyday, which involves RF planning and RF
optimisation processes.
Sometimes, when a new site goes on air its signal covers an area that other sites were
previously responsible for, altering the propagation conditions and changing the traffic.
This could lead to interferences and the deterioration of the network. To avoid this,
the overlapping zones must be reduced by optimising the cluster; a task that must be carried out constantly. A self-depended department for optimisation (TFLO) within
Vodafone accomplishes this task when needed, taking into account the network changes
performed by the planning and deployment departments.
“Neuenkirchen”1 is a German city with over 140,000 inhabitants and 80 km2 of area,
where the LTE network has not been optimised in the last couple of years. For the
development of the bachelor thesis, this responsibility was assigned to me for the last 6
1The real name of the city was changed due to confidentiality agreements. Neuenkirchenis a common place-name in
months. This project seeks to improve the LTE network quality of the city by optimising
the electrical tilts of antennas.
In order to do this, the project was divided in to two big phases embracing the most
important aspects of an optimisation process. The first phase involved a verification
of the sites from the cluster, including a first drive test to collect relevant information for optimisation. At that point, some inconsistencies and technical errors needed to
be corrected. In the second phase, a simulation and analysis of possible scenarios was
completed, aiming to define an ideal group of adjustments that were later implemented
and measured through a second drive test. Since the results were not as expected, some
1. PROBLEM FORMULATION
1.1. APPROACH TO THE PROBLEM
There are two main issues influencing this project: mistakes and/or inconsistencies on
Vodafone databases on one side and the importance and necessity of optimisation on the
other. The whole dissertation revolves around the following question: how to improve
performance of a LTE cellular network so it offers better quality and coverage to its
users?
When Vodafone switched its radio access network from Nokia Siemens to Huawei1,
sev-eral companies were hired to swap technical devices inside the core and radio networks.
This lead to an inevitable loss of control that lead to differences between what had
been planned and what was deployed in term of antennas, tilts, azimuths etc. There
was also the problem that supervision tools such as M2000 and the databases STOV2
or Saperion2 were not updated. This had impacts not only on network performance
but also on optimisation processes, as the information used for analysis and decision
making was sometimes incorrect.
There are always aspects that influence network performance such as areas with no
coverage, lower throughput, terrain profile and actual orientation of antennas; some
of them can be improved with optimisation. Neuenkirchen was especially important
because its LTE network had been expanded but had not been optimised over the last
couple of years.
1The swap started back in 2012 and it was finished at the end of 2015.
1.2. JUSTIFICATION
As stated before, optimisation is a process that must be carried out constantly. It is
essential as it allows operators to use the deployed network to its full potential. It
avoids wasting energy and can lead to higher capacity, which translates to supporting more users, generating more income for the company.
Neuenkirchen is one of the main tourist cities in Germany because of its river, beautiful
scenery, old town and interesting history during the middle ages and World War II.
Thousands of tourists visit the area every year, especially in summer, to enjoy its
beauty and its beer. Therefore, it is important that the Vodafone network offers the
2. OBJECTIVES OF THE PROJECT
2.1. GENERAL OBJECTIVE
To analyse different signals and configuration settings of the Vodafone LTE800 mobile
network of the city “Neuenkirchen”, in order to improve its quality by optimising the
electrical tilt of the antennas.
2.2. SPECIFIC OBJECTIVES
• To look into the hardware and software configuration of the built antennas in order
to find possible inconsistencies on Vodafone databases and/or technical errors on the network.
• To analyse and to reduce the overlapping zones and interferences on the network,
taking into account the RSRP coverage.
• To measure the most important streets of the city before and after the optimisation
3. THEORETICAL FRAMEWORK
3.1. FIRM OVERVIEW
3.1.1. Vodafone Group
Vodafone Group Plc is one of the world’s largest telecommunications companies
pro-viding a wide range of services, including: voice, messaging and data across mobile and
fixed networks [2]. The headquarters of the international company with the acronym
Voice-Data-Fone, as firm name, are located in Newbury, UK, near London. With
more than 438 million customers worldwide it is, in terms of the number of subscribers, the second largest mobile operator of the world behind China Mobile [3].
Vodafone operates one of the largest and most powerful mobile networks in the world.
With the current CEO Vittorio Colao, the Vodafone Group maintains in addition to its
26 subsidiaries, many other investments and Joint Ventures in numerous mobile phone
companies spread across the entire globe [2].
The biggest and most recent achievements of the group are the acquisition of Kabel
Deutschland in 2013, the largest cable television operator in Germany and the
acqui-sition of Ono in Spain, a broadband communication and entertainment company that
delivers integrated telephone, television and internet services [2].
3.1.2. Vodafone GmbH - Germany
Since the introduction of the digital mobile radio standards GSM 900 in 1992, four
mobile network operators in Germany have been established. One of these four network
operators is the Vodafone GmbH, also known as Vodafone Germany, a subsidiary of
Figure 1: Vodafone GmbH, branch south (beginning of the bachelor thesis).
Source: self-made.
Vodafone Germany has more than 32 million customers, making it the fourth largest
subsidiary in the Vodafone group, behind Vodafone India, USA and South Africa,
operating one of the most advanced and capable mobile networks. Despite the large
number of subscribers, Vodafone GmbH is currently the smallest operator in Germany
due to the recent merger of O2 and E-Plus in 2014 (fig. 2).
Figure 2: Market share of German mobile operators.
Vodafone Germany gained full control of Arcor AG & Co KG in May 2008, the second
largest fixed provider in Germany. This acquisition was accomplished to gain a foothold
in the market as an integrated telecommunications operator and also offer consumers
new technologies related to NGN (Next Generation Network) and FMC (Fixed Mobile
Convergence). Currently they have more than 5.3 million fixed line customers [2].
The headquarters of Vodafone Germany are located in D¨usseldorf. In addition, there
are nine other regional offices, which are responsible for the operation of mobile phone
networks in the assigned region, plus the representative office in Berlin and the former
regional offices from Kabel Deutschland in Munich, Hannover, Berlin, Leipzig, Mainz
and N¨urnberg, which are in charge of other services. The locations of the different
branches are presented in table 1.
City Branch
D¨usseldorf Campus (Headquarters)
Berlin Representative office
Radebeul, near Dresden East
Langenhagen, near Hannover North (H)
Hamburg North (HH)
Berlin North-East
Dortmund North-West
Eschborn, near Frankfurt Rhine-Main
Munich South
Stuttgart South West
Ratingen, near D¨usseldorf West
Table 1: Regions of Vodafone Germany GmbH [5].
The Vodafone South or Vodafone Munich1 is responsible for the whole of Bavaria,
geographically the largest catchment area in the Vodafone network and also one of the
most difficult to deal with, because network planners and engineers must overcome
special challenges on account of the topographical peculiarities in the mountains to the
south (Alps) and many other hilly terrains.
1Two locations during this project: Kastenbauerstraße2, Munich at the beginning andBeta-Straße6-8,Unterf¨ohring
Figure 3: Vodafone GmbH, branch south (end of the bachelor thesis).
Source: self-made.
3.1.3. TFL Department, TFLO Group
The TFL department is divided into three groups: Radio Planning, Network
Improve-ment and Transmissions Planning. These groups are mainly tasked with the planning,
dimensioning, parametrisation, optimisation and implementation of all components of
the Vodafone network. The current focus of the department is the optimisation and
extension of UMTS and LTE networks and the expansion of high-speed Internet access
in areas where there is no DSL connection.
As a bachelor thesis student I belong to the group Local Network Performance and
Optimisation (TFLO). The group TFLO-S is responsible for the ongoing radio network
optimisation in the south region. Our goal is to offer the mobile customers the best
quality network and performance, focusing on voice and data in 2G, 3G and 4G. For that, a continuous monitoring of the network is carried out, aimed at verifying network
elements that are in operation with regards to network coverage, voice quality,
han-dover relations, newly-established features and parameter settings. Later, comes the
optimisation of identified network problems in relation to the above mentioned points,
Amongst other things, the group is responsible for: problem analysis, selection and
configuration of appropriate measuring systems; performing measurements as well as
the evaluation of them and the simulation of new settings, from which the corresponding
configurations or changes are defined. This includes change of parameters, changes of
antennas on the base stations, modification of tilts: downtilts or uptilts, configuration
changes of network elements and replacement or expansion of technology.
In addition, TFLO gives recommendations and proposals for new network elements.
However, these are mostly the construction of a repeater and not new base stations.
Other responsibilities of the department include the analysis of performance and
ca-pacity planning.
It is important to mention that, due to the acquisition of Kabel Deutschland, Vodafone
is currently restructuring the whole company, merging and/or renaming some
depart-ments. As a consequence of this, it is possible that at the end of this project the
information presented about the TFLO group may be out of date.
3.2. LTE FUNDAMENTALS
The user demand for higher data rates and service quality and the need for a less
complex system combined with the continued demand for cost reduction brought about
the introduction of the Long Term Evolution (LTE) systems, but what is LTE? It is the
forth and current generation in cellular technology, based on an international standard
defined by the 3GPP which all mobile networks operators are deploying [6].
Open Signal is a source of insight into the coverage and performance of Mobile
Oper-ators worldwide. Its latest: state of LTE in February 2016 [7], collected some relevant
information about the global LTE coverage as well as global LTE speed, both by country
and by network.
This report shows that, after five straight years of 4G rollouts, the maturity of LTE is
still below that of 3G. Only in South Korea and Japan the availability of 4G actually
exceeds that of 3G. The rest of the world has a long way to go before 4G and 3G reach
It is satisfying to see that Colombia is in 41th place with regards to LTE coverage, with
59% coverage (especially considering that 49% of the country is jungle) and 28th in LTE
download speed with an average of 15 Mbps. This makes its LTE network the fifth most
expanded and the third fastest of Latin America. On the other hand, Germany ranks
49th in LTE coverage, with 56% coverage and 34th in LTE download speed, with an
average of 14 Mbps.
According to the economic times [8], LTE reached 635 million subscribers at the end of
the first quarter from 2015. (fig. 4). A very good share but of course not comparable
with that of GSM and UMTS.
Figure 4: 1Q 2015: LTE Subscribers and Market Shares by World Region.
Source: http://www.4gamericas.org/files/cache/
d1bc3e7c4a64a95fa15955b6223a8515_f777.PNG
The most relevant concepts used during the development of this project are summarised
in the following sections. Given that LTE can be extremely extensive, only the
top-ics relevant to the understanding of the project are described, others sometimes just
mentioned. References are provided with hyper-links throughout to offer easy access to
3.2.1. Basic Parameters
Table 2 sums the basic parameters of LTE up.
Parameter Description
Frequency Range
FDD and TDD bands defined by ETSI and 3GPP1
Duplexing FDD, TDD & Half-Duplexing FDD
Channel Coding Turbo code
Channel Bandwidth [Mhz] 1.4 / 3 / 5 / 10 / 15 / 20 2
Transmission Bandwidth
ConfigurationNRB
6 / 15 / 25 / 50 / 75 / 1003
Modulation Schemes UL: QPSK, 16QAM, 64QAM (Optional)
DL: QPSK, 16QAM, 64QAM
Modulation Access Schemes UL: SC-FDMA
DL: OFDMA
MIMO UL: 1x2 and 1x4
DL: 2x2, 4x2 and 4x4
Coverage 5 - 100km with slight degradation after 30km4
Latency End-user<10ms
Pick data rate UL: 75Mbps (20Mhz bandwidth)
DL: 150 Mbps (UE Cat. 4, 2x2 MIMO, 20Mhz BW)
DL: 300 Mbps (UE Cat. 5, 4x4 MIMO, 20Mhz BW)
Table 2: Basic parameters of LTE.
Table 3 shows the distribution of frequencies for LTE networks used by mobile operators
in Colombia and Germany. As you can see, Vodafone works on the 800 Mhz and 2600
Mhz but the optimisation of the city was done only on the 800 Mhz Band because the
amount of 2600 Mhz stations was too small to be considered.
1Technical Specification (TS) 136.101 V12.9.0, Release 12 3GPP, Table 5.5-1: E-UTRA Operating bands. Available:
http://www.etsi.org/deliver/etsi_ts/136100_136199/136101/12.09.00_60/ts_136101v120900p.pdf
2Technical Specification (TS) 136.101 V12.9.0, Release 12 3GPP, Table 5.6-1: Transmission bandwidth configuration
NRBin E-UTRA channel Bandwidths. Available:http://www.etsi.org/deliver/etsi_ts/136100_136199/136101/12. 09.00_60/ts_136101v120900p.pdf
3One Resource Block = 180 Khz = 12 Subcarriers (each 15 Khz) in 1msTTI.
Country Frequency Band Mobile Operator
Germany
800 Mhz 20 Vodafone, Telekom and O2
2600 Mhz 7 Vodafone, Telekom and O2
1800 Mhz 3 Telekom and O2
Colombia 2600 Mhz 7 Claro and Tigo
2600 Mhz 38 DirecTv
1700 Mhz & 2100 Mhz 4 Avantel, ETB, Movistar and Tigo
Table 3: Frequency distribution of LTE networks in Germany and Colombia.
3.2.2. Architecture
The 3GPP Release 8 from 2008 [6], is the first LTE release and it embraces among
others things, network architecture and interfaces; information about all-IP Networks
(SAE), OFDMA, FDE and MIMO based radio interfaces.
The general architecture of a mobile network comprises four main components: the
terminals; the access network; the core network and the external networks. Their
respective concepts in LTE according to the 3GPP are: User Equipments (UE),
E-UTRAN (Enhanced-E-UTRAN), EPC (Evolved Packet Core) and PDNs (Packet Data
Network); represented by the colours yellow, green, blue and red respectively in figure 5,
where the overall network architecture can be seen, including the standardised interfaces
and network elements inside these four components.
Figure 5: LTE overall Architecture.
While the term “LTE” encompasses the evolution of the UMTS radio access through the
E-UTRAN, it is accompanied by an evolution of the non-radio aspects under the term
“System Architecture Evolution” (SAE), which includes the EPC network. Together
LTE and SAE comprise the Evolved Packet System (EPS) [9].
• The User Equipment (UE):
Previously called Mobile Equipment (ME) in the GSM standards, comprises the
following modules:
– Mobile Termination (MT): handles all the communication functions.
– Terminal Equipment (TE): terminates de data streams.
– Universal Integrated Circuit Card (UICC): also known as SIM card, runs
the USIM where information about the user’s phone number, home network
identity and security keys is stored, among others.
• The E-UTRAN:
The E-UTRAN handles the radio communications between the UEs and the
EPC through the interfaces Uu and S1. Its unique elements are the evolved base
stations: eNodeB or eNB, communicated over theX2interfaces as shown in figure 6.
Figure 6: E-UTRAN Architecture.
Source: LTE Overview 3GPP [6]
Some of the functions supported by eNB are: communication with UEs:
user & control plane, radio resources management (RRM) (including handover
scheme, to brand packages with QoS, IP header compression and user data
encryption, to route user data towards SGW through bearer path, to route control
data towards MME, as well as to measure and to report terminal mobility [9].
The following subsection (3.2.3) describes the elements inside the eNB, the
hardware main hardware component of this dissertation.
• The EPC:
The EPC is responsible for the overall control of the UE and establishment of the
bearers. There are five main elements inside the EPC displayed in figure 5.
– Policy Control and Charging Rules (PCRF): responsible for policy control
decision-making, apart from controlling the flow-based charging functionalities
in the Policy Control Enforcement Function (PCEF), which resides in the
P-GW [9].
– Packet Data Network (PDN) - Gateway (P-GW): communicates with the
out-side world (others PDNs). It is responsible for IP address allocation for the
UEs, in addition to QoS enforcement and flow-based charging, according to
rules from the PCRF [9].
– Home Subscriber Server (HSS): central database that contains information
about all the network operator’s subscribers and their hired services [9].
– Serving Gateway (S-GW): acts as a router and forwards data between the eNB
and the P-GW. It manages the user plane.
– Mobility Management Entity (MME): control node that processes the
sig-nalling between the UEs and the core network. It manages the control plane.
Its functions are related to bearer managment and connection management [9].
Other elements mentioned on figure 5, such as the GERAN, UTRAN and the SGSN
are not defined inside the E-UTRAN or EPC networks, because they do not belong to
LTE standards, but they are necessary to guarantee inter-mobility with the previous
3.2.3. The base station - eNB
Base stations are composed of various elements, depending on the cellular network
standard, the mobile operator and the scenario. Since Vodafone’s RAN currently holds
Huawei technologies, the following information is based on the3900 Series Base Station
Product Description1 from Huawei [11].
According to [11], the main modules inside a base station are:
• Cabinets: depending on the scenario they are classified as indoor macro base
tions (BTS3900), outdoor macro base stations (BTS3900A), distributed base
sta-tions (DBS3900) or mini base stasta-tions (BTS3900C).
• BBU (Baseband Unit): centrally manages the entire base station.
• RF module: modulates and demodulates baseband and RF signals, processes data,
amplifies power for signals and conducts voltage standing wave ratio (VSWR) tests.
Figure 7: Distributed Base Station from Huawei (DBS3900).
Source: 3900 Series Base Station Product Description [11].
Figure 7 shows the structure scenario of a DBS from Huawei which is important
be-cause it illustrates the structure of most of the LTE sites insideNeuenkirchen’s cluster.
Its main elements can be observed: antennas, the RRU (Remote Radio Unit), the
tower/building, a APM30H or TMC11H and not displayed a RET.
The RRU performs the same functions as an RF module, there are several RRUs that support different standards e.g. GSM only, UMTS only or UMTS+LTE FFD+UL.
Appendix A shows pictures of some Vodafone’s base stations in order to demonstrate
what these components look like. Remaining concepts are defined in the glossary as
well as linked to it.
3.2.4. OFDM (Downlink) and SC-FDMA (Uplink)
Orthogonal Frecuency Division Multiple Access (OFDMA) is a form of OFDM, which
is the underlying technology. A modulation format designed to carry high data rates
in both FDD and TDD formats, OFDM works by splitting the single radio signal
into multiple smaller sub-signals, subchannels or subcarriers that are then transmitted
simultaneously at different frequencies to the receiver. On the other hand, OFDMA is
a multi-user version of the popular OFDM digital modulation scheme. Multiple access
is achieved in OFDMA by assigning subsets of subcarriers to individual users; meaning
that they are based on the same principle but work differently.
The concept of OFDM is to optimise access, as it’s subcarriers transmit data without being affected by a high intensity of multipath distortion faced in single carrier
trans-mission schemes which makes it possible to manage data for more users simultaneously.
This is accomplished by making the signals orthogonal to each other, avoiding mutual
interference.
“The difference between OFDM and OFDMA is that OFDMA has the ability to
dynam-ically assign a subset of those subcarriers to individual users, making this the multi-user
version of OFDM, using either Time Division Multiple Access (TDMA) (separate time
frames) or Frequency Division Multiple Access (FDMA) (separate channels) for
multi-ple users. OFDMA simultaneously supports multimulti-ple users by assigning them specific
Figure 8: OFDM frequency and time domain.
Source: LTE Standards Pag. 114 [12]
In LTE, subcarriers are spaced at 15 Khz and then modulated individually using QPSK,
16QAM or 64QAM. OFDMA assigns each user the bandwidth needed for their
trans-mission. Unassigned subcarriers are turned off, thus reducing power consumption and
interference.
Previous access mechanisms of cellular networks used just a unidimensional resource,
OFDMA can be difficult to understand, as its resource: Resource Block is defined in
two dimensions: frequency and time. A resource block has dimensions of subcarriers
by symbols: twelve consecutive subcarriers in the frequency domain and six or seven
symbols in the time domain. Users get a number of resource elements in the resource
grid (fig. 9), in which data is allocated. The more resource blocks a user gets, and the
higher the modulation used in the resource elements, the higher the bit-rate.
Further information about the system description, key technical characteristics,
fea-tures, protocols and advantages of OFDM as an access mechanism can be found in
[14].
OFDMA solution leads to high Peak-to-Average Power Ratio (PAPR) demanding
ex-pensive power amplifiers with high requirements on linearity, increasing the power
con-sumption for the sender and creating a huge problem for mobile devices [6]. Hence,
Single Carrier FDMA (SC-FDMA) was selected for the uplink, a pre-coded version of
Figure 9: Downlink resource grid.
Source: 3GPP Technical Specification 136.211 V8.7.0 Release 8 [13]
SC-FDMA combines the properties of single carrier transmission with an OFDMA-like multiple access, taking advantage of the strengths of both techniques: low PAPR
and flexible dynamic frequency allocation. In this way it reduces battery power
consumption and uses a simpler amplifier design. In SC- FDMA, data spreads across
3.2.5. PCI
Originally defined as Physical-layer Cell Identity in the Technical Specification 136.2111
from the ETSI and then defined as Physical Cell Identity (Phy ID) in the Technical Report 36.902 [15], is an essential configuration parameter of a radio cell, it corresponds
to a unique combination of one orthogonal sequence and one pseudo-random sequence.
“There are 168 unique physical-layer cell-identity groups, each one with three unique
identities, thus, 504 unique physical-layer cell identities, leading to unavoidable reuse
of PCI in different cells. When the eNodeB is brought into the field, a PCI needs to be
selected for each of its supported cells, avoiding collision with respective neighbouring
cells” [15], as shown in figure 10 .
Figure 10: PCI: Deployment Illustration.
Source: Self-configuring and self-optimising network (SON) use cases and solutions (3GPP TR 36.902 version 9.3.1 Release 9) [15]
All cellular networks use something to distinguish the cells transmitters from their
neighbours. In GSM these are the BCCHs, in UMTS the SCs and in LTE the PCIs.
This does not help to minimise interferences, as it is just a number, but it determines
the sequence to be used in the Primary and Secondary Synchronization Signals (P-SS
& S-SS). It is also important during optimisation processes as its analysis helps to decrease interference at the cell borders.
1Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation. Online: http://www.
3.2.6. RSRP (Reference Signal Received Power)
In all wireless systems there are two main measurements constantly being performed:
the first one relating to signal strength and the second one to signal quality. In the case of cellular networks, these are measured by mobiles in the neighbour cells as well
because they are needed for cell selection or reselection and handovers. They also give
an idea of the network status which is why they are used during optimisation analysis.
In LTE they are called: RSRP and RSRQ respectively.
According to the Technical Specification 136.214 from the 3GPP, the Reference Signal
Received Power (RSRP) “is defined as the linear average over the power contributions
of the resource elements that carry cell-specific reference signals within the considered
measurement frequency bandwidth” [16], which means, that RSRP is only measured in
the symbols (resource elements) carrying reference signals.
Unlike RSSI (Receive Strength Signal Indicator), which is the more traditional metric
that has long been used to display signal strength for previous cellular standards, RSRP
does not include all interference and thermal noise. For this reason RSRP is used instead
of RSSI, as it provides better information about signal strength, while RSSI includes
interference and noise information.
3.2.7. RSRQ (Reference Signal Received Quality)
As its name indicates, RSRQ is a measure of signal quality of the reference signals. It
can be used by the UE to perform cell reselection or handover if RSRQ is configured for
the cell. According to the Technical Specification 136.214 from the 3GPP, the Reference
Signal Received Quality (RSRQ) “is defined as the ratioN× RSRP / (E-UTRA carrier
RSSI), where N is the number of Resource Blocks (RBs) of the E-UTRA carrier RSSI
measurement bandwidth” [16]. Which means that, RSRQ is calculated as a relation
between RSRP and RSSI.
RSRQ=N ∗ RSRP
3.2.8. SINR (Signal to Interference & Noise Ratio)
SINR is also a measure of signal quality. Unlike RSRQ, it is not defined in the 3GPP
specifications but defined by the UE vendor. It is not reported to the network but it is extremely important as it better quantifies the relationship between RF conditions
such as quality and it has repercussions for throughput. The UE uses SINR to calculate
the CQI (Channel Quality Indicator), depending on that value (from 0 up to 15), the
eNB determines the modulation and coding scheme (MCS): QPSK, 16QAM or 64QAM
[17]. The higher the CQI, the higher the MCS and the higher the throughput.
SIN R = S
I+N, (2)
Where S indicates the power of measured usable signals, mainly: reference signals
and Physical Downlink Shared Channels (PDSCHs),I indicates the power of measured
signals or channel interference signals from other cells in the current system and N
indicates background noise, which is related to measurement bandwidths and receiver noise coefficients [17].
3.2.9. Throughput
Throughput is defined as the number of payload bits successfully received per second for
a reference measurement channel in a specified reference condition, in cellular networks
this is associated with the speed of transmission. It is measured in bits per second [bps] and as mentioned before, it reaches peak data rates of 75 Mbps in UL and 300 Mbps in
DL in LTE, depending on bandwidth and MIMO scheme and under ideal conditions.
3.2.10. Bearer Types
A bearer is a virtual concept usually associated with apipe between the UE and another
network element. Considering the QCI (different to the CQI), it defines how the UE data is treated when it travels across the network. LTE provides an end-to-end service
from the UE to the different PDNs using the hierarchy of bearers presented in figure 11.
Some of those concepts exist in UMTS standards as well but under UMTS terminology
do not include an E before the concept, which stands for E-UTRAN, to differentiate
Figure 11: Bearers for LTE.
Source: Long Term Evolution in Bullets, Page 25 [18]
An EPS-Bearer provides user plane connectivity between the UE and a PDN and all
user data transferred within it has the same QoS. It is generated from a combination
of E-RAB (E-Radio Access Bearer) and S5/S8 Bearer. The E-RAB is an essential
concept that will be needed later to analyse network performance and is generated from a combination of Radio Bearer and S1 Bearer. The first one provides the connection
across the air-interface, whereas the second one provides the connection across the
transport network [18].
The E-RAB QoS parameters include: QoS Class Identifier (QCI), Allocation and
Re-tention Priority (ARP), Guaranteed Bit Rates (GBR) and Maximum Bit Rates (MBR)
[18].
3.2.11. Radio Resource Control states
Unlike GSM and UMTS standards, the state machine for LTE includes only two states:
RRC Idle and RRC Connected. RRC stands for Radio Resource Control. The RRC
• acquiring system information from the Broadcast Control Channel (BCCH).
• UE controlled mobility based upon cell reselection.
• monitoring paging messages for incoming calls, system information changes,
Earth-quake and Tsunami Warning System (ETWS) notifications, etc. [18].
The RRC Connected mode is mainly characterised by:
• the ability to transfer data to and from the UE.
• using control channels to signal resource allocations.
• network controlled mobility based upon handovers and cell change orders [18].
The transition from RRC Idle mode to the RRC Connected mode is done using theRRC
connection establishment procedure, a 3-Way handshake process from layer 3, which will
be explained in the following subsection.
3.2.12. RRC connection establishment procedure
The UE needs resources from the E-UTRAN when it wants to establish either
Cir-cuit Switched Call (CS Call, Voice) or Packet Switched Call (PS Call, Data). Before
transferring any kind of data or completing any signalling procedures, it must make the
transition from RRC Idle mode to RRC Connected mode by following the steps shown
in figure 12: RRC Connection Request, RRC Connection Setup and RRC Connection
Setup complete. It is also used for tracking area update and attach/detach.
Figure 12: Signalling for RRC connection establishment.
“The RRC connection establishment configures Signalling Radio Bearer (SRB) 1 and
allows subsequent signalling to use the Dedicated Control Channel (DCCH) rather
than the Common Control Channel (CCCH) used by SRB 0. The entire procedure is
completed using only RRC signalling [18]”. The RRC connection procedure ends when
all UE dedicated resources, such as E-RABs, tied to the RRC connection are released
and the UE goes back to the RRC Idle mode.
It is important to mention that RRC is used for signalling transfer while E-RAB is
used for user data transfer. They are comparable to SDCCH (Standalone Dedicated
Control Channel) and TCH (Traffic Channel) respectively in GSM standard, although
GSM also has RRC.
3.2.13. RRC connection re-establishment procedure
The RRC connection re-establishment procedure is needed when the UE loses the radio
connection due to a radio link failure. After a new cell has been selected, the UE sends a
RRC connection re-establishment request message to the eNodeB in order to re-establish
the resources. The network acknowledges later the connection re-establishment with a
RRC connection re-establishment message [18].
The processes previously described include extra signalling steps embracing further
technical concepts, signals and channels that are not necessary for the understanding
of this dissertation but can be found in [18], chapter 26: Signalling Procedures.
3.3. OPTIMISATION FUNDAMENTALS
Every communication system requires a permanent planning and optimisation of its
network equipment to achieve a suitable performance as traffic patterns are constantly
changing. Radio Frequency (RF) context, is a mayor requirement in mobile networks, as
it embraces the behaviour of electromagnetic waves and every pattern that could affect
Between the four components of a mobile network, the operator answers for the
admin-istration of the access network and the core network. Considering that, transmission
mediums of the core network e.g. optical fiber and ethernet are rarely affected because
they are controlled environments (point to point connections), the core network uses
configuration standards that are modified very rarely. On the other hand, the access
network uses the air-interface as a transmission medium, where there are many uncon-trolled variables that lead engineers to readjust network elements, confronting problems
and improving the quality of service offered to the users on a daily basis.
Network Optimization
Azimuth Adjustment Tilt Adjustment
Feature Configuration Reselection and Handover
Parameter Adjustment Power Adjustment
Antenna Height
Figure 13: Optimisation methods.
Source: LTE RF Optimisation Guide [19]
Regardless of the cellular network standard (GSM, UMTS, WCDMA or LTE) an
op-timisation process includes the six methods displayed in figure 13. Vodafone has the
same power settings for almost 90% of its antennas in the across network, excluding
some particular cases like indoor scenarios and/or locations with special regulations or
exemptions. The reselection and handover parameter adjustment was studied and im-plemented by the optimisers of the TFLO group between February and March of 2016.
That is why these aspects where not considered inside the development of the current
project. The unique criteria authorised by Vodafone to optimise the network was the
3.4. VODAFONE TOOLS
This section is aimed at presenting the tools used during the development of the project
at the different stages.
3.4.1. Measurement Hardware
Drive tests are an important component of the optimisation process because they
pro-vide useful information for analysis and decision-making. In order to carry them out,
the measuring equipment described below was needed.
• TSMW from Rhode & Schwarz:
The most important device is the TSMW scanner from Rohde & Schwarz (fig 14), a universal radio network analyser used for optimising all conventional wireless
communications networks.
Figure 14: R&S TSMW Network Scanner.
Source:
http://www.rohde-schwarz.de/de/Produkte/messtechnik-testsysteme/aerospace-and-defense/messtechnik/Drive_Test_L\unhbox\ voidb@x\bgroup\accent127o\penalty\@M\hskip\z@skip\egroupsungen/TSMW-|-Frontansicht-|-30-|-4287.html
The scanner is used by Vodafone to perform all kinds of outside measurements including network scanning, duration calls and FTP Downloads/Uploads over all
cellular networks. Some examples of the most frequently measured signals on
mobile networks are:
– BCCH and RxLev in GSM networks.
– RSRP, RSRQ,RSSI, SINR and PCI in LTE networks.
– Location/tracking (LTE) area, country and network code in all networks.
• Smartphones:
Figure 15: Measurement smartphones.
Source: self-made.
There are different types of test smartphones and tablets used for indoor and
outdoor measurements at Vodafone. Two samsung galaxy S5 were needed during
the drive tests performed in this project.
• Bus:
All measurement and power devices are assembled inside the cabin of the
measure-ment vehicles, fig 16 shows one of them.
Figure 16: Measurement vehicle.
3.4.2. Measurement Software
• Measurement and Replay System ROMES 4 from Rhode & Schwarz:
ROMES4 is the drive test software needed to perform, analyse and replay
mea-surements. It “is the universal software platform for network optimisation systems
from Rohde & Schwarz. In combination with other test and measurement equip-ment such as wireless communications scanners (TSMW or TSME) and test mobile
phones, it provides solutions for all essential tasks involved in coverage
measure-ments, interference identification, performance measurements and quality analysis
in mobile networks. In addition to measuring and displaying test parameters, data
is processed instantly and statistics are calculated in realtime” [20].
Figure 17: Software interface of the ROMES 4 drive test tool.
Source: R&S ROMES4 Drive Test Software [20]
There are two different versions: the measurement version and the replay
version. While using the measurement version, a dongle is needed to access the
application. It contains licences that expire every two days for each required
• QualiPoc Android from Rhoede & Schwarz:
“SwissQual QualiPoc Android is a high-performance, smartphone-based
optimi-sation product for mobile radio networks. The product is based on commercial
smartphones, supports all mobile radio technologies used worldwide and covers
multiple protocol layers as well as the IP stack in real time. When installed on
a smartphone, the QualiPoc Android application can be used for taking measure-ments anywhere and at any time. A wide range of test scenarios help users detect
possible weak points or interference sources in a mobile radio network.
Straight-forward displays and graphics provide a clear overview of test results and network
parameters in real time during the entire test sequence” [21].
Figure 18: Interface of the SwissQual QualiPoc Android.
Source: SwissQual QualiPoc Android [21]
The QualiPoc Android is installed on the test smartphones and generally used
to perform indoor measurements, as it is suitable and portable. The recorded
information is saved in a test file and subsequently replayed on the smartphone
or analysed in detail with the ROMES 4. During the project it was used to link
the cellphone together with the ROMES 4 measurement version and perform FTP
downloads and uploads.
3.4.3. Tools for analysis and optimisation
• D2-RAIT (Radio Analysis Information Tool):
measure-ments. It is an extension to the standard GIS (Geographical Information System)
ArcGIS developed by the company con terra GmbH for the Vodafone-D2 GmbH.
It allows the graphical visualisation, analysis and interpretation of several data
and it is similar to MapInfo. As a basis, there are different maps with different
resolutions. Obtained RSRP [dBm] or PCI values from LTE measurements can
be then visualised on these maps.
D2-RAIT works by representing graphic elements with multiple layers. Here,
each recorded signal has been assigned its own layer. This can be displayed, hidden,
edited or corrected. The most important layers are described below:
– Cellfile-Layer: displays the location of all base stations (fig. 19). This layer is
converted almost weekly from the Cellfile created by the planning department.
Among other things, it contains information about coordinates, antenna types
(omni or directional), height of the towers, azimuths, technologies,
neighbour-hood relationships, BCCHs, SCs and PCIs.
Figure 19: D2-RAIT Cellfile-Layer example.
Source: self-made.
– Measurement-Layer: Measurement files are exported from ROMES 4 replay
and then converted to a .mfi file. The measurement-Layer contains the values
of the measured signals and can later plot its results in a more understandable
Figure 20: D2-RAIT Measurement-Layer example.
Source: self-made.
– Background-Layer: This layer can be covered with raster data1, map services
(fig. 21) or vector data. Vodafone raster data is stored on the central server
and is available in the form of height profile or landscape maps in different
resolutions.
Figure 21: D2-RAIT Background-Layer example.
Source: self-made.
• Huawei M2000:
The Vodafone branch south has deployed Huawei technologies for its radio
architecture during the past few years, hence, inside the O&M (Operation and
Maintenance) platform the administration tool used by the network is the Huawei
iManager M2000, also know as U2000.
M2000 offers a cluster solution based on an ATAE platform to ensure
smooth network expansion and cost-efficient hardware reuse. In addition, it
supports long-term network evolution and convergent network technologies. It
provides network quality improvements via network management, functions for
configurations, performance, security, daily reports, and systems administration
[22].
Through U2000 it was possible to look into the settings of the antennas and
find technical errors. It was also used to implement changes on the network during
the optimisation process.
• Atoll (Wireless Network Engineering Software):
Developed by Forsk, is a multi-technology GSM/UMTS/CDMA/LTE wireless
network design and optimisation platform that supports wireless operators
throughout the network lifecycle, from initial design to densification and
optimi-sation. Among other things, it includes traffic models, Monte Carlo simulators,
ACP (Automatic Cell Planning) module, GIS features, software development and
automation tools, propagation modelling engine, data management services and
interfaces. Atoll is able to use both predictions and live network data throughout
the network planning and optimisation process [23].
The application is mainly used by the planning department. During
optimisa-tion processes it is used to carry out two main funcoptimisa-tions: calculaoptimisa-tion of Path-loss
matrices and different types of predictions, such as: coverage by transmitters,
coverage by signal level, overlapping zones, coverage by throughput in
Figure 22: Example of coverage by signal level in Atoll.
Source: self-made.
• Radioplan:
Developed by Actix GmbH, is a comprehensive system for planning, deployment
and operation support of mobile radio networks, it is also the main optimisation
tool for the TFLO group. Several modules are embedded into the platform for
different, partly interacting tasks. The one that interests us is the Dynamic
LTE Radio Access Network System Simulator, which can be used for analysis,
planning and optimisation of network performance in the LTE radio access network.
Figure 23: Radioplan LTE System Simulator Architecture.
The LTE system simulator (architecture depicted in figure 23) consists of a
complete 3GPP release 8 conform layer 2 protocol, including PDCP (Packet Data
Convergence Protocol), RLC (Radio Link Control) and MAC (Medium Access
Control) layer implementations. As an example, figure 24 shows a throughput
analysis with radioplan within a cluster.
Figure 24: LTE position-based throughput analysis in Radioplan.
Source: Actix radioplan user guide [24]
Radioplan is used for optimisation rather than Atoll because Atoll does not
have artificial intelligence and cannot propose tilt changes based on an analysed
cluster. Nevertheless, it can plot calculations/predictions about the proposed
changes taking radio waves propagation in to account.
3.5. OTHER TOOLS
• Saperion (El Doku 7.5.):
It is a local database (El Doku 7.5. its access application) where all the
docu-mentation related to the base stations is stored. Among other things, it contains:
commissioning, BnetzA1 approval, specifications, mast building plan, execution
plan, correspondence and acceptance report. Usually, when the site is built the
construction firm attaches pictures of the antennas, electrical connections, cables
and other base stations components.
The research component of this project was accomplished mainly by looking
into the database documentation relating to all the sites inside the defined cluster.
• PPlus (Projekt Planung und Steuerung):
PPlus stands for Project Planing and Controlling/Management, a tool from the
planning department, in which all the appointments and deadlines related to
all processes of the base stations are scheduled. For example, if a site is being
reconstructed or optimised it must have deadlines, like being ready for service and
ready for the customer. Throughout the project, it was necessary to complement
information not found in saperion and to solve questions about stations with
inconsistencies on the network or in the databases.
• STOV:
It is a database from the planning department where all the information
re-lated to the settings of a base station is stored. Its access tool runs over a
virtualised desktop from Citrix Systems. Among other parameters of a site, it
includes: azimuths, antenna types, electrical and mechanical tilts, power settings,
antenna highs, radiation pattern, MIMO configuration (if applicable), diversity
and losses. Such information, is available about all potential sites for a base
station, including site-candidates that were not and will never be built. All the
information that Atoll needs to run it’s calculations is extracted from this database.
• Hyperion Interactive Reporting Studio:
“Oracle Hyperion Interactive Reporting software is a module of Oracle Business Intelligence Suite Enterprise Edition Plus that provides executives, business users
and analysts with intuitive user-directed relational query capabilities. Interactive
Reporting can pull together data from disparate sources to produce easy to use
charts, pivot tables, highly formatted reports and more” [25]. In connection with
the database vedas.oce this interface allows access to the network counters.
Through this application it was possible to analyse the results after the
opti-misation and get an insight into the KPIs (Key Performance Indicators) such as:
4. METHODOLOGY
To meet customer’s requirements for high-quality service, LTE networks must be
opti-mised during and after implementation. According to the flowchart presented in figure 25, there are two main phases inside an optimisation process: site verification and RF
Optimisation.
New site on air
Single site verification
Are clusters ready?
RF optimization
Service test and parameter optimization
Are KPI requirements met?
No Yes Yes
No
End
Figure 25: Optimisation flowchart.
Source: LTE RF Optimisation Guide [19]
Usually, every time a new site comes into service the whole cluster must be newly optimised. Although there were three new base stations within the cluster, this was
not the main reason for carrying out this project. The main reason for the project was
the fact that the LTE network had not been optimised during the last couple of years.
This is why phase one was performed on the whole cluster rather than just the three
The (new) site verification is the first phase of the network optimisation process and
involves function verification at each (new) site. Single site verification aims to ensure
that each site is properly installed and that parameters are correctly configured [19].
RF (or cluster) optimisation starts after all sites in the planned area are installed
and verified. RF optimisation aims to reduce overlapping zones while optimising signal coverage, increase handover success rates and ensure normal distribution of radio signals
before parameter optimisation. RF optimisation involves optimisation and adjustment
of antenna system hardware and neighbour lists. The first RF optimisation test must
traverse all cells in an area to rectify hardware faults [19].
Data collection:
Ø Drive test
Ø Indoor measurement
Ø eNodeB configuration data
Problem analysis:
Ø Coverage problem analysis
Ø Handover problem analysis
Adjustment & implementation:
Ø Engineering parameter
adjustment
Ø Neighboring cell parameter
adjustment
Do the RF KPIs meet the KPI requirements?
Y
End
N Start
Test preparations:
Ø Establish optimization objectives
Ø Partition clusters
Ø Determine test routes
Ø Prepare tools and materials
Figure 26: RF optimisation flowchart.
Source: LTE RF Optimisation Guide [19]
The regular RF optimisation flowchart can be appreciated in figure 26. Given that
the selected method for optimisation was the tilt adjustment, the problem analysis was
the overlapping zones and the adjustment as well as implementation criteria, were just
The methodology of the project has followed the described flowcharts of an optimisation
process and considered the mentioned changes. A more complete explanation of the
tasks carried out in each phase can be found in section 5: development of the project.
4.1. TIMESCALE
The development period was between 16th November 2015 and 13th May 2016. At
the beginning, the scope of the project was discussed and defined with the Vodafone’s
tutor and the team leader Ramona Quiel1. Later, the access accounts for the different
Vodafone tools were requested. Due to internal company processes and also because
of the Christmas season, that took until early 2016. During that time, a phase of
documentation about optimisation, antennas and LTE fundamentals took place, in
addition to an introduction and training on the Vodafone tools.
Taking into account the flowchart optimisation process in fig. 25, the activities of the
timescale displayed in fig. 27 were set and successfully accomplished.
Figure 27: Project-workflow timescale.
Source: self-made.
5. DEVELOPMENT OF THE PROJECT
This section describes the tasks performed throughout the whole project. Sometimes,
situations are mentioned as an example, nonetheless, the results of each stage are pre-sented in section 6.
5.1. PHASE 1: SITES VERIFICATION
5.1.1. Cluster definition
Figure 28: Terrain Profile ofNeuenkirchen.
Source: self-made with D2-RAIT.
Firstly, the geographical conditions of the city were studied. As shown in figures 28 and
![Table 1: Regions of Vodafone Germany GmbH [5].](https://thumb-us.123doks.com/thumbv2/123dok_es/6719535.257125/28.918.282.728.450.781/table-regions-of-vodafone-germany-gmbh.webp)
![Figure 8: OFDM frequency and time domain. Source: LTE Standards Pag. 114 [12]](https://thumb-us.123doks.com/thumbv2/123dok_es/6719535.257125/38.918.210.797.129.389/figure-ofdm-frequency-time-domain-source-lte-standards.webp)
![Figure 11: Bearers for LTE. Source: Long Term Evolution in Bullets, Page 25 [18]](https://thumb-us.123doks.com/thumbv2/123dok_es/6719535.257125/43.918.283.723.122.467/figure-bearers-source-long-term-evolution-bullets-page.webp)
![Figure 12: Signalling for RRC connection establishment. Source: Long Term Evolution in Bullets, Page 414 [18]](https://thumb-us.123doks.com/thumbv2/123dok_es/6719535.257125/44.918.283.713.749.990/figure-signalling-connection-establishment-source-long-evolution-bullets.webp)
![Figure 17: Software interface of the ROMES 4 drive test tool. Source: R&S ROMES4 Drive Test Software [20]](https://thumb-us.123doks.com/thumbv2/123dok_es/6719535.257125/49.918.229.780.446.755/figure-software-interface-romes-source-romes-drive-software.webp)
