Cellular Network Planning and Optimization

ECEG-6222
Lecture 1
Introduction to Cellular/Mobile Systems

May 2022
Contents
 History
 Basics
 Evolution
 Standardization
 Market share
Important events in radio communications
 1855-1870: James Clerk Maxwell
– Developed Maxwell’s equations relating electric
and magnetic fields
– Was laid off from Aberdeen University before
publishing most notable works

 1876: Alexander Graham Bell

– Files the first patent on telephone in the US
– Elisha Gray files his patent for the telephone
just a few hours later than Bell
– Later, Gray challenge Bell’s patent in court
Important events in radio communications
 1888: Heinrich Hertz
– Demonstrate the practical existence of radio
communications, by generating and detecting a radio
wave
– “It's of no use whatsoever […] this is just an experiment
that proves Maestro Maxwell was right”

 "we just have these mysterious electromagnetic

waves that we cannot see with the naked eye. But
they are there“
 Asked about the ramifications of his discoveries,
Hertz replied,
– "Nothing, I guess."
Important events in radio communications
 Guglielmo Marconi
– March, 1897: Transmitted Morse code signals
over a distance of about 6 km
– 13th May, 1897: Sent the first ever wireless
communication over open sea
– 17th December, 1902: A transmission from the
Marconi station in Glace Bay, Nova Scotia,
Canada, became the first radio message to cross
the Atlantic

 Marconi was also an effective business

person. The last lawsuit regarding
Marconi's numerous radio patents was
resolved in the US in 1943 (six years
after his death)
Important events in radio
communications
 1900s: Reginald Fessendon demonstrates first wireless
voice communication
 1907: Commercial transatlantic connections
 1915: Wireless voice transmission NYC – SFO
 1920: Westinghouse company starts the first
commercial radio broadcast station
 1936: First commercial television broadcast
Important events in radio
communications
 1947: The transistor is invented by J. Bardeen, W.
Brattain, and W. Shockley (AT&T Bell Labs)
 1948: Shannon presents the famous channel
capacity expression
 1948: Radio relay system between New York and
Boston, 4 GHz, 350 km, 7 hops
 1957: Russians launched the first satellite, Sputnik

 1981: 1G cellular: NMT 450 in Scandinavia

 1982: Start of GSM-specification. Aim: Create “pan-
European digital mobile phone system with roaming”
 1983: Start of the American AMPS (Advanced Mobile
Phone System, analog)
 1983: AT&T introduces analog AMPS in Chicago and
Washington D.C. (early cellular system)
Important events in radio communications
 1991: 2G cellular: GSM, digital cellular phone
 1993: DECT, digital cordless phone
 1995: First CDMA (code-division multiple-access)
based wireless system available in Hong Kong
 1997: Wireless LAN – IEEE 802.11
 1998: Specification of UMTS (Universal Mobile
Telecommunication System)

 1998: Iridium: portable satellite telephony (Low

Earth Orbit satellite constellation)
 1999: WLAN standard IEEE 802.11b (WiFi). RF
band: 2.4 GHz (ISM). Rate: 11 Mbps
 1999: Bluetooth standard version 1.0 (WPAN). RF
band: 2.4 GHz (ISM). Rate: 1 Mbps
Important events in radio
communications
 2001: 3G cellular: First WCDMA
system available in Japan
 2002: 1 billion mobile subscribers
 2005: 3.5G cellular:
HSDPA specifications
 2007: 3 billion mobile subscribers
 2008: LTE Release 8 specifications
 2009: 4G cellular: First LTE networks deployed
 2010: 5 billion mobile subscribers
 2010: LTE-Advanced Release 10 specifications completed
 2012: 6 billion mobile subscribers
 2014: 7 billion mobile subscribers
Teaser: Future of mobile communication
See the following references for the predictions on the future of mobile
communications:
Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update,
2015–2020.

http://www.cisco.com/c/en/us/
solutions/collateral/service-
provider/visual-networking-
index-vni/mobile-white-paper-
c11-520862.html
Characteristics of mobile (cellular)
systems
 From the perspective of a mobile user, the cellular systems are
characterized by:
– Two-way communication between users and the network
– Wide area coverage, where users can connect to the network anywhere at
any time
– Ubiquitous mobility: User services continue smoothly when users move from
one cell to another
 Thus, cellular systems are by nature wireless Wide Area Networks (WANs),
while wireless Local Area Networks (LANs) provide connectivity in a
limited geographical area
 Note that in recent terminology, ”cellular system” has been replaced by
terms like ”mobile networks” or ”mobile systems”
The reasoning behind mobile
communication systems
 Global connectivity and seamless mobility
– User should be able to connect to the network everywhere (i.e., the user should have
service continuity).
– This aspect is very well handled for speech connection, but may sometimes fail in
case of data services (e.g., when user is moving from a 3G coverage area to a 2G
coverage area)

 Global roaming
– User expect to have mobile connectivity (almost) anywhere in
world
– Of course, recent technologies like 3G (or 4G) may provide
coverage only in major cities, but GSM is a truly global system
• 3G is rapidly becoming global as well
– Obstacles for global roaming: lack of a roaming agreement
between operators (usually not an issue) and costs (this is an
issue)
The reasoning behind mobile
communication systems
 Trustworthy authentication and secure connection
– Nowadays, WLANs may also provide secure connectivity but manual
authentication is usually needed.
– However, centralized authentication is employed in mobile networks
– Thus, secure connection and authentication service is available basically
everywhere, without additional manual actions
 Global standards
– Open global standards, designed jointly by industry community, have lead to
global markets for both terminals and networks
– Large production volumes and tight competition have lead to low
equipment prices
The reasoning behind mobile
communication systems
 To sum up,
– Wide area connectivity,
– Mobility,
– Roaming, and
– Centralized authentication
are the main differences between mobile systems and other
communication technologies
 Although WLANs standards are also global in nature, security and
connectivity are usually handled locally by network administrator.
Wide area connectivity and mobility
 Wide area connectivity basically means
that all areas where users may move needs
to be covered by the system
– Thus, numerous equipment providing
connectivity (in practice, a lot of base
stations) are needed
 Wide area connectivity requirement leads
to the so-called cellular structure of the
network, where geographical area is
divided into cells served by different base
stations
 Limitation: Radio spectrum availability is limited
– All users in the network should share the same set of channels
– So, radio resource reuse principle between cells needs to be applied
Cellular network structure
1

 Wide area coverage

(connectivity everywhere) 1 2 3 1
 Cellular structure like honeycomb
2 3 1 2 3

1 2 3 1

 Radio resource reuse

– Reuse = 1/3 in the figure 2 3 1 2 3
 Cells can be split into sectors
– Three sectors per site in the fig. 2 3
 Wide area mobility (handover points marked with blue dots)
Network architecture
 Mobility and global authentication require
the presence of centralized network
elements, connected to other network
elements that provide wireless
connectivity (i.e., BSs)
– Those centralized elements form the Core
Network (CN), while
– Elements handling wireless connectivity
form the Radio Access Network (RAN)

 Global standards ensure compatibility of radio devices produced by

different manufacturers
 However, a legal contract called “roaming agreement” is needed to
ensure reliable authentication & billing
General system architecture
CN-External
Radio interface RAN-CN interface Network interface

RAN CN
Handles all radio Switching, routing,
related functions. security and mobility
User May also handle related functions. External
Terminal some mobility Includes switches, networks
issues. gateways, registers,
Include at least and other controlling
base stations elements

RAN = Radio Access Network; CN = Core Network

Radio spectrum
 Conventionally two types of radio frequency bands have been available for
commercial radio systems:
– Licensed and unlicensed frequency bands
 License for certain frequency band can be granted by national regulator,
which administrates the usage of radio frequencies
– E.g., FCC in the US
 In case of mobile communication systems, license is usually granted for a
certain operator
– Operator then owns the right for exclusive use of the freq. band
 There are also global agreements and guidelines, regarding to the use of
the applied frequencies
– National regulators usually follow these guidelines quite well, to make radio
devices compatible in different countries
Radio spectrum
 The most important unlicensed spectrum covers Industrial, Scientific and Medical
(ISM) radio bands
– These bands were originally reserved internationally for the use by industrial,
scientific and medical purposes
 Currently, one of the most important radio systems (i.e., IEEE 802.11) operates in
this band and provides local connectivity
– Unlicensed freq. bands have also been granted for experimental use
 From a radio system perspective, the important difference between licensed and
unlicensed frequency bands is that licensed spectrum provides resources which
are free from external interference
– Thus, all interference in the network is created by the own system
– So, it is feasible for implementing a radio communication system that
guarantees Quality of Service (QoS) to the served users
Mobility
 As discussed earlier, the user mobility is one of the basic characteristics of a mobile
network
– To ensure a smooth switch of a user connection between neighboring base stations, a
handover operation is needed
– Handover operation is also called hand-off
 The main phases of the handover include:
1) Signal quality measurements by mobile station,
2) Handover decision, usually made at the base station (i.e., from the network side), and
3) Exchange of signaling required to inform to the target base station the control
information regarding the new mobile user
 Handover protocol details are system specific
Mobility

Three phases for mobile assisted handover:

1) Signal quality measurements (@ MS),
2) Handover decision (@ BS/NTW)
3) Exchange of control information (@ NTW)

MS = Mobile Station, BS = Base Station, NTW = Network

Radio Resource Management (RRM)
 The radio resource management (RRM) functions are responsible for efficient
usage of the air interface (physical layer) resources
 In general, RRM is needed to:
– Guarantee QoS for users,
– Maintain the coverage according to network plan, and
– Provide as high system efficiency as possible
 The RRM concept covers usually the following functions:
– Handover control
– Power control
– Admission control, load control, and congestion
control
– Packet scheduling
Radio Resource Management (RRM)
Radio Resource Management Concepts:
 Handover control is used to guarantee the mobility in a
communication in a transparent way (from user’s
perspective)
 Power control is used to keep proper power levels at
the receiver side, to guarantee target QoS
• Power control is also important from interference perspective
 Admission, load and congestion control:
• Aim of these functions is to keep the cell load on feasible level
• In addition, the goal is to resolve overload situations effectively
 Packet scheduling is used to serve mobile users
according to their QoS requirement, so that system
efficiency is maximized
Procedures
 In connection with e.g. 3GPP technologies, an important part of the
system is formed by the so-called Procedures that may cover
– System specific power control,
– Paging procedure,
– Random access procedure,
– Cell search procedure, and other
– Measurement and multi-antenna algorithms
 Procedures are system specific
Network planning
 “Radio network planning” as such could be a course topic itself
 In this presentation, we consider network planning only very briefly, and
focus mostly on link budgets
 Conventionally, network planning is divided into three phases:
(1) Initial planning phase, known as dimensioning
(2) Detailed planning (and implementation)
(3) Network optimization

Phase 1: Dimensioning
 Includes the rough evaluation of the amount of network elements that
are needed to provide coverage in the target service area
 Network element count is obtained through link budget calculations
Network planning
Phase 2: Detailed Planning (and implementation)
 Site locations are selected, system coverage and capacity planning is
carried out in details
 More sophisticated planning and simulation tools are used for this
purpose
Phase 3: Network Optimization
 Not all parameters can be optimally defined during planning phase
 After network implementation, performance measurements are done
− System parameters should can be then optimized, based on
measurement results
 Optimization may be also needed when traffic conditions change, or new
features (like advanced antennas) are introduced
Network planning
Dimensioning Note: We omit core network
150

140

+
Path Loss [dB]
130
EIRP 58dB
120
Margins 23dB
110 Sensitivity -100dB 1000 x 5000 x
100
Allowed PL 135 dB
90
0 0.2 0.4 0.6 0.8 1 1.2 1.4
Distance from BS [km]

Area and propagation information Link budget # Network elements

Detailed planning
TX power 43dBi
Antennas 2
Input from Antenna tilt 5o
Parameter x, y, z
dimensioning

Network planning tools BS Configurations and

System simulations topology plan

Optimization

+
Operating network 30 Optimized system
System performance evaluation
 In addition to network planning, the network performance can be studied
on many levels
 When considering practical networks, sophisticated tools are needed to
model all details of the system.
 Nevertheless, in initial system standardization phases, the mobile system
performances is examined (e.g. 3GPP) using so-called static system
simulators
– In an static simulator, network layout is uniform and physical layer modeling is
kept simple
 Principles for such evaluations are straightforward, and can be understood
based on this course
1st generation (1G)
 AMPS (Advanced Mobile Phone System), in the Americas
 NMT (Nordic Mobile Telephone), in the Nordic countries
• variants for 450 MHz and 900 Mhz bands
 TACS (Total Access Communication System), in Europe

Analog modulation & voice processing

 Almost voice only application
Systems are incompatible each other
Roaming inexistent
Handset were so expensive (more than $1000)
Low penetration
Why Digital Cellular?
 Digitaliza on:
 Digital source code
 Digital air interface
 Digital source coding allows compression
 Narrowing the bandwidth by removing redundancy of speech
 Nyqvist sampled, almost distortion free: ISDN 64 kbps Î GSM voice 13 kbps
 Spectrum efficiency: less resources used per call
 Digital air interface allows
 Error detection and error correction
 Robustness against noise and interference
 QoS can be guaranteed independently of location
 TDMA & CDMA possible
 More flexibility in resource usage, multiplexing of different kinds of data
 Half duplex implementation possible (no duplex filter)
 Adapta on to radio conditions
 Security (digital encryption)
 Drawbacks of digital:
 Processing & delays
 Applica on specific (voice) codecs
2nd generation (2G)
 GSM (Global System for Mobile Communications / Groupe
Special Mobile), almost worldwide
 Variants for 900 MHz, 1800 MHz, 1900 MHz bands
 PDC (Personal Digital Cellular), in Japan
 a.k.a. JDC (Japanese Digital Cellular)
 DAMPS (Digital AMPS), in Americas
 a.k.a. IS-54 (Interim Standard 54), IS-136
 a.k.a. TDMA in the US
 IS-95 (Interim Standard 95), in Americas, South Korea, India,
China
 a.k.a. cdmaOne

 Digital modulation and voice processing

 Voice and some data
 SMS was a phenomenal success
2G evolution (2.5G)
 Higher data rates, packet switched data
 GSM evolution
 HSCSD (High Speed Circuit-Switched Data), extension of
GSM
 GPRS (General Packet Radio Services), extension of GSM
 EDGE (Enhanced Data rates for GSM Evolution),
extension of GSM
IS-95 evolution
 cdma2000 1x uses one 1.25 MHz band, in Americas
Why 3G?
 The success of 2G digital cellular (GSM) lead to capacity exhaustion → need
for systems with higher spectral efficiency
 2G radio interfaces optimized for voice
 only low-rate data services
 Need system supporting high-speed multirate data services with
asymmetric radio links
 The majority of users are pedestrians or indoor nomadic users with handheld
terminals
 3G cellular standard to merge most mobile communications into a single
system
 Cellular, cordless, paging, satellite, private mobile radio
 ITU IMT-2000 recommendations define a common, worldwide framework
for future mobile commun. at 2 GHz
 ITU approved IMT-2000 radio interfaces in 1999 and 2007
3 rd generation (3G)
 CDMA2000 family
 CDMA2000 1xEV-DO (Evolution-Data Optimized), in Americas,
Japan, South Korea
 WCDMA release 99
 UMTS (Universal Mobile Telecommunica on System), almost
worldwide
 TD-SCDMA (Time Division Synchronous CDMA), in China

Circuit switched voice and packet switched data

 Increased data rate and network capacity
3G evolution (3.5G/3.75G)
HSDPA = High Speed Downlink Packet Access. Release 5 was
the first HSDPA release (2005)
HSUPA = High Speed Uplink Packet Access. Release 6 was the
first HSUPA release (2007)
HSPA = High Speed Packet Access = HSDPA + HSUPA
HSPA Evolution (HSPA+)=Since Release 7
Driving forces for 4G
Wireline capability evolution
Need for additional wireless capacity
Need for lower cost wireless data delivery
Competition of other wireless technologies (WiMax)
4th generation
 Long term evolution (LTE), first version in Release 8, enhancement in
Release 9
 Approaching 4G
 Packet switched only
 Increased network capacity, data rate
 Decreased latency
 Different access principle for DL and UL
 LTE-Advanced, first version in Release 10
 Real 4G
 Backward compatible with LTE Release 8
 Efficient utilization of spectrum
 Homogeneous distribution of capacity provisioning and user
experience
 LTE-Advanced pro, further enhancement since Release 12
 D2D, M2M, …
5th generation
Key drivers:
1. Massive growth in traffic
volume
5G under
2. Massive growth in connected development
devices/things
3. Wide range of requirements
and characteristics
 2G: Voice: Analog to digital
– New radio
 3G: Voice + Broadband data
– New radio
 4G: Broadband data
– New radio
 5G: All data – lots of it
– 3G+4G+new technology components
– New radio
Mobile network evolution paths

Simplified picture of most important evolution paths from 2G

technologies (e.g., GSM) to 4G technologies (e.g., LTE-Advanced)
Mobility and data rate evolution
User mobility
1985 1995 2000 2005 2010 2015 Time

Large
LTE-A
LTE
3G 3.5G
2G
1G

802.16 (WiMAX)

Small
802.11 (WLAN)
Information rate
<10 kbps <200 kbps <2 Mbps <10 Mbps <50 Mbps <1 Gbps
3GPP family of technologies
 The 3rd Generation Partnership Project (3GPP) unites different standard
development organizations in the field of telecommunications:
– Association of Radio Industries and Businesses (ARIB), Japan
– Alliance for Telecommunications Industry Solutions (ATIS), USA
– China Communications Standards Association (CCSA), China
– European Telecommunications Standards Institute (ETSI), Europe
– Telecommunications Technology Association (TTA), Korea
– Telecommunication Technology Committee (TTC), Japan
 The 3GPP provides their members a stable environment to produce
Reports and Specifications that define 3GPP technologies
3GPP family of technologies
 3GPP has four Technical Specification Groups (TSG)
 Each TSG has a set of Working Groups (WG) which
– Meet regularly few times a year (from four to six times), and
– Are responsible for development of Reports and Specifications that
belong to their area of competence
3GPP family of technologies
 The 3GPP technologies from these groups are constantly evolving
through Generations of commercial cellular/mobile systems
 Although these Generations have become an adequate descriptor for
the type of network under discussion, real progress on 3GPP standards
is measured by the milestones achieved in particular Releases
 New features are ’functionality frozen’ and are ready for
implementation when a Release is completed
 Although this adds some complexity to the work of WGs, such a way of
working ensures that progress is continuous and stable
3GPP family of technologies
3GPP works on a number of Releases in parallel, starting future work well
in advance of the completion of the current Release

2000 2004 2008 2012

Time schedule of 3GPP standards

3GPP Standardization process
 The 3GPP process is such that more topics are started than eventually
end up in the specifications.
 Within the study, only a small set of features is usually entering to
specification.
 Sometimes a study is closed after it is found that there is not enough
gain to justify the added complexity. A change requested in the work
item phase could also be rejected for this same reason.
Mobile network coverage share
Share as of Q1 2016 according to GSA
Mobile subscriptions worldwide - all technologies  7.416
billion  ≥ 100% of the global population

3GPP-family mobile system technologies  6.946 billion

 93.66% market share
 GSM/EDGE3.451 billion subscriptions46.5%
market share
 WCDMA/ HSPA/HSPA+  2.202 billion subscriptions 
29.7% market share
 LTE/LTE-Advanced/LTE-Advanced Pro  1.292 billion
subscriptions 17.4% market share
Mobile connections share
Mobile data traffic growth
Mobile traffic share