umts ran planning by uday raktale

UMTS Radio Access Network Planning

School of Engineering Design & Technology 1

Universal Mobile Telecommunication System

Radio Access Network Planning

Uday Raktale

Project Report submitted in partial fulfillment of the requirements for the

Degree of Masters by advanced study in Personal, Mobile and Satellite Communication.

Supervisor: Professor Y. F. Hu

School of Engineering Design & Technology

University of Bradford

23th May 2005



ABSTRACT Today telecommunication is one of the fastest growing sectors of the world economy. One in

every six people owns a cellular/mobile phone operating on cellular radio technology, one of the

most successful mobile communication system adapted worldwide. We are presently on Second

Generation of wireless communication (2.5G) and at the verge of moving towards third

generation (3G) i.e. Universal Mobile Telecommunication System (UMTS), which is based on

Wideband Coded Division Multiple Access (WCDMA) technology as its access scheme.

By 2006, some 2 billion people will be using mobile phones and devices, in many cases to

access advanced data services. Against this backdrop, the need for efficient and effective

network design will be critical to the success of increasingly complex mobile networks.

Network Planning of a UMTS network poses a much greater challenge then planning a non

CDMA Network as the relationship between coverage and capacity differs from that of a 2.5G

system. One of the basic differences between 3G and previous systems is that there will be

different services, requiring the power level received at the base station from a given subscriber

to be dependent on the service in use at the time. This in turn will create a situation in which the

‘coverage map’ will also depend on the service in use.

The project report encompasses the concept of radio network planning for UMTS networks

and addresses the various issues concerning capacity, coverage, quality of service and

interference. The report concludes the key parameters of Radio network desigining and the

methodes to design a 3G state of art network by establishing a balance between the parameters,

followed by suggested future work.

Key Words: UMTS, WCDMA, URTAN, Link Budget



ACKNOWLEDGEMENT Ruskin says, “Many men fail to achieve success not through insufficiency of means or

impatience of labor but because of confused ideas of the things to be done” and as a matter of

fact it is through Professor Yim Fun Hu’s constructive suggestions which helped me in dragging

out the very route of the confused ideas and thus the project has been brought to a competitive

form. I am grateful to Professor Yim Fun Hu for her kind guidance throughout the project.

I would like to thank Dr. R.A.A. Alhameed, Research Head, for his guidance and moral

support, which helped me, focus on my project.

I would like to thank my parents and my friend Sudhir Aggarwal, in special, for their support

and pushing me to complete my project quickly. I would also like to thank all my friends and

colleagues who believed in me and supported me throughout, giving me the confidence whilst I

was working on my project.



TABLE OF CONTENTS

ABSTRACT……………………………………………………………………………..….……..i

ACKNOWLEDGEMENT………..………………………………………………………….……ii

1 INTRODUCTION..……..………………………………………………….………………….1

2 UNIVERSL MOBILE TELECOMMUNICATIONS SYSTEM- UMTS ……………….....…2

2.1 Radio Access Network Overview……………………………………………….….….3

2.1.1 UTRAN Network Elements..………….………………………………………3

2.2 WCDMA (Wideband Direct-Sequence Code Division Multiple Access) .……………8

2.3 Frequency Bands in WCDMA ………….……………………………………………..9

2.3.1 UTRAN Modes .……………………………….………………….…………..9

3 CELLULAR CONCEPT ……..……………………………………………………………...10

4 RADIO NETWORK PLANNING PROCESS ………….…………………..……………….12

4.1 Planning Process Overview ………………….………………………………….12

4.1.1 Radio Network Design Requirements ………………………………………13

4.1.2 Model Tuning..…..…………………………………………………………...15

4.1.3 Nominal Cell Planning……………………………………………………….15

4.2 CCQ Model (Coverage, Capacity and Quality of Service Model)…………………...16

4.3 Basic Traffic Dimensioning Input……..…………………………………………..…18

4.3.1. Traffic Classes…………………………..………………………………..….18

4.3.2 Input Analysis…………………………………………………………..……19

4.3.3 Determining the Average User Profile..……..………………………………21

4.4 Basic Traffic Dimensioning………………………………………………………….22



5 COVERAGE AND CAPACITY DIMENSIONING……………………………..…………..25

5.1 Capacity……………………………………………………………………..………..25

5.1.1 Effects of Loading………………………………………………………..…..27

5.1.2 Effects of Sectorization………………………………………………………29

6 LINK BUDGET OVERVIEW………………………………………………………………..30

6.1 WCDMA Technology Review ………………………………………………………32

6.2 Link Budget ………………………………………………………………………….33

6.3 Uplink Dimensioning………………………………………………………………....36

6.3.1 Uplink Capacity……………………………………………………………...36

6.3.2 Uplink Coverage……………………………………………………………..38

6.3.3 Uplink budget ...……………………………………………………………...38

6.4 Cell size……………………………………………………………………………...41

6.5 Downlink Dimensioning…………………………………………………………….43

6.5.1 Downlink Curves………………………………………………………….....43

6.5.2 Downlink Link Budget………………………………………………………44

6.6 Link Budget Margins…………………………………………………………..…...47

6.6.1 Log –Normal Fading…………………………………………………………47

6.6.2 Handover gain………………………………………………………………..48

6.6.3 Power Control Margin………………………………………………………..48

6.6.4 Slant Loss…………………………………………………………………….49

6.6.5 Body Loss.……………………………………………………………………49

6.6.6 Car Penetration Loss…………………………………………………………50

6.6.7 Indoor Margins……………………………………………………………….50

6.6.8 Interference Margin ....……...………………………………………………..51



7 LINK BUDGET –Examples………………………………………………………………….52

7.1 Maximum allowed Path Loss for – 12.2 kbps ...………..………………………….52

7.2 Maximum allowed Path Loss for – 144 kbps……………………….……………...53

7.3 Maximum allowed Path Loss for – 384 kbps ….……………………….…………...54

7.4 Cell Size Calculation………………………………………………………………..55

7.5 Calculation of number of sites required in a region ………………………………..56

8 EXPANDING CAPACITY BY CONFIGURATION MODIFICATION………………...…57

8.1 Adding new frequency carriers……………………………………………...………57

8.2 Increase number of sectors………………………………………..…………………57

8.3 Using repeater solutions…………………………………………….…………….…58

8.4 Adding distributed antennas………………………...……………………………….58

8.5 Sites Addition…………………………………………………….………….………58

8.6 Cell split…………………………………………………………….……….………59

8.7 Layered Network…………………………………………………………………….59

9 PRODUCT EVOLUTION………………………………………………….………………...60

9.1 Adaptive Antenna.………………………………………………….……………….60

9.2 Interference Cancellation.....……………………………………….….…………….60

9.3 Transmit Diversity.……………………………………………….….…………..….60

10 CONCLUSION & FUTURE WORK……………………………………………….………61

REFERENCES.………………………………………………………….……………………….63

GLOSSARY..…..……………………………………………………….…………….………….67



Table of Figures

Figure 2.1 UMTS Network Architecture ……………………………………………………..…2

Figure 2.2 Radio network overview…..…………………………………………………….…....3

Figure 2.3 Node B block diagram….…………………………………………………………….4

Figure 2.4 OTSR (Omni Transmit Sector Receiver) Node B…………..……………….……….6

Figure 2.5 STSR (Sectorial Transmit Sector Receive) Node B ..………………………..………6

Figure 2.6 V800 3G handset..………………..…………………………………………………..7

Figure 3.1 Mobile Telephone System Using a Cellular Architecture…………………………..10

Figure 3.2 Cell Distribution in a Network……………………………………………………...11

Figure 4.1 CCQ (Capacity, coverage &Quality of Service) model ……………..……….…….16

Figure 4.2 Erlang-B blocking probability..……………………………………………….….....22

Figure 4.3 Example of multi-rate blocking probability calculations (%)………..………..……23

Figure 4.4 Channel utilization example…..………………………………………………..…...24

Figure 5.1 SNR (Signal to noise) experienced by a user ..……………..…………………..…..26

Figure 5.2 Interference introduced by users in the neighboring cell. ……………....…..……....28

Figure 5.3 Loading factor as perceived by cell………………………………………..…..……28

Figure 6.1 Link Budget Process flow block diagram ..………………………………………....30

Figure 6.2 Link Budget Flow Chart..……..…………………………………………….……....31

Figure 6-3 Schematics of components included in the link budget….……………………….….39

Figure 6.4 Example of capacity versus cell range in an urban environment…..………….……43

Figure 6.5 Lognormal fading margins. Handover gain is included in these curves. …………...48

Figure 7.1 Cell coverage comparision….……………………………………………………….63



List of Tables

Table 2.1 Frequency Band in WCDMA …………..……………………………….……………9

Table 4.1 Cell type classification……………………………………………..…...……..……..13

Table 4.2 Area type classification …………..……………………………………………….…13

Table 4.3 Examples of input data………………………………………………….…..…….….19

Table 4.4 Example of mapping of services to Radio Access Bearers..……………….…….…..20

Table 4.5 Example of an average user profile………………………………………….…...…..21

Table 6.1 Uplink values of Eb/I0..……..……………………………………………….………..37

Table 6.2 Uplink values of Mpole ….…………..………………………………………..………37

Table 6.3 Uplink link budget for voice 12.2 kbps and 95% probability of coverage….…….…42

Table 6.4 Downlink values of Mpole (three-sector site) ………..……………………..…….…..44

Table 6.5 Typical values of building penetration loss ….………………………………..…….50

Table 7.1 Link budget example 12.2 kbps voice ....…...……………………………..…………52

Table 7.2 Link budget example 144 kbps …………..………………………………………….53

Table 7.3 Link budget example 384 kbps …………...…………………………………………54



1. INTRODUCTION

After the explosion in the mobile telecommunication back in the late 1990s with second

generation (2G) networks springing up all over the world, the race was on for the next generation

of wireless communication. The Universal Mobile Telephony System (UMTS), or 3G as it is

known, is the next big thing in the world of mobile telecommunications. It provides convergence

between mobile telephony broadband access and Internet Protocol (IP) backbones [1].

The success of the technology lies in optimum utilisation of resources by efficient planning of

the network for maximum coverage, capacity and quality of service. The report aims to detail

method of UMTS Radio Network (UTRAN) Planning.

The new technologies and services have brought vast changes within the network planning; the

planning of a 3G network is now a complex balancing act between all the variables in order to

achieve the optimal coverage, capacity and Quality of Service simultaneously.

The layout of this report is as follows. In Section 1 we shall talk about the telecommunication

in general followed by section 2 which provides an understanding of UMTS technology, then in

section 3 we shall talk about the Cellular Network Principal followed by section 4 detailing

Network planning process and various parameters to be considered. Section 5 encompasses

coverage and capacity dimensioning, section 6 gives a comprehensive review of WCDMA

technology and Link budget calculation, followed by examples in section 7. Section 8 comprises

of various metholodology for capacity expansion followed by section 9 giving a brief description

on the product evolution. Section 10 presents an overall summary and conclusions from the

project work, suggestions for further work are also included.

In present telecommunication scenario, it is a must for a telecommunication engineer to have

good understanding of cellular network. Keeping in view the topic of the report was chosen. It

provides a clear understanding of basic fundamentals of 3G cellular network designing, and

describes a method of designing a modern 3G Radio Access Network.



2. UNIVERSL MOBILE TELECOMMUNICATIONS SYSTEM- UMTS

Figure 2.1. UMTS Network Architecture [2]

Qualcomm developed the world's first commercially available, fully integrated WCDMA

network, also known as UMTS [3]. The UMTS network architecture is depicted in figure 2.1.

The core network (CN) handles call control and mobility management functionalities, while the

UTRAN (UMTS terrestrial radio access network) manages the radio packet transmission and

resource management. CN consists of two domains Circuit Switched (CS) and Packet Switched

(PS). CS handles the real time traffic & PS handles the other traffic. CS connects to other

communication network (e.g PSTN & PLMN) and PS connects to IP backbone. The major

elements of CN are MSC/VLR, HLR, GMSC and SGSN, GGSN on PS side [2].

In the core network logical network nodes GGSN (Gateway GPRS [General Packet Radio

System] Support Node) and SGSN (Serving GPRS Support Node) support packet routing and

transfer. The GGSN is basically a packet router and acts as a physical interface to the external

packet data networks. The SGSN handles packet delivery to and from mobile terminals. GGSN

and SGSN are capable of supporting terminal data rates up to 2 Mbps. [4]

A UTRAN consists of one or more RNSs (radio network subsystems), which in turn consist of

base stations (Node Bs) and RNCs (radio network controllers). The RNS performs all of the

radio resource and air interface management functionalities. [4]

Node B

Node B

Node B

RNC

Node B

Node B

Node B

RNC

MSC

SGSN

GMSC

GGSN

AuC

VLR

EIR

PSTN, PLMN

PSPDN

RAN CN

UE

UE

lub

lub

Uu

Uu

luCS

luCS

luPS

luPS

HLR

CS

PS



2.1 Radio Access Network Overview

Figure 2-2 Radio network overview [5]

The figure 2.2 depicts various network elements and the interface. The RNC manages Radio

Access Bearers (RABs) for user data, the radio network and mobility. The RBS provides the

radio resources.

The key external interfaces are the Iu interface between RNC and core network and the Uu

between User Equipment (UE) and NodeB, RBS. Within the RAN, the RNCs communicates

with each other over Iur and with RBSs over Iub See Figure 2.2.

2.1.1 UTRAN Network Elements

• RNC (Radio Network Controller)

• Node B (Radio Base Station)

• UE (User Equipment, Mobile terminal)

2.1.1.1 RNC (Radio Network Controller) Radio Network Controller is responsible for RRC (Radio Resource Control), RRM, QoS, Call

Admission Control, Channel Allocation, Power Control Settings, Handover Control, Ciphering,

Broadcast Signalling, Open Loop Power Control. Some of them are described in brief under this

section. [6]



• RRC (Radio Resource Control)

1 Management of radio resources (establishment, release and termination of connection)

2 Management of RRC connection between the UE and network (establishment, release)

• RRM (Radio Resource Management)

1 The RRM is the most critical resource in wireless systems.

2 It is in charge of allocating and managing radio resources in the most effective way.

• QoS (Quality of Service)

1 High QoS (ensuring subscribers satisfaction)

2 High spectrum efficiency (maximum operator revenue)

3 Easy (re) configuration (lowering operational cost)

2.1.1.2 Node B

Node B functions as a RBS (Radio Base Station) and provides radio coverage to a

geographical area, by providing physical radio link between the UE (User Equipment) and the

network. Along with the transmission and reception of data across the radio interface the Node B

also applies the codes that are necessary to describe channels in a WCDMA system. [7]

It contains the RF transceiver, combiner, network interface and system controller, timing card,

channel card and backplane. A typical Node B is shown in figure 2.3 below.

Figure 2.3 Node B block diagram. [8]

RF Modules (DDMs, Pas, Tx Splitters)

RF Feeders

Interconnect Module

Digital Shelf

CCM CEMs GPSAM TRM(s)

GPS Receiver (Optional)

Functions : •Tx amplification •Coupling

External Alarms

RNC lub

Functions: •Network Interface •Call processing •Signal Processing •Frequency up/down conversion

Power Supply - 48 V DC nominal

UMTS Mark – II BTS

Sector à Sector ß Sector ý



• The Functions of Node B are: [6]

• Air interface Transmission /Reception

• Modulation /Demodulation

• CDMA Physical Channel coding

• Micro Diversity

• Error Handing

• Closed loop power control

Depending on sectoring (omni/sector cells), one or more cells may be served by a Node B. A

Single node B can support both FDD and TDD modes, and it can be co-located with a GSM BTS

to reduce implementation costs. Nmode B connects with the UE via the WCDMA Uu radio

interface and with the RNC via the lub asynchronous transfer mode (ATM) – based interface.[9]

The main task of the Node B is the conversion of data to and from the Uu radio interface,

including Forward Error Correction (FEC) , rate adaption , WCDMA spreading /dispreading ,

and quadrature phase shift keying (QPSK) modularion on the air interface. It measures quality

and strength of the connection and determines the Frame Error Rate (FER), transmitting these

data to the RNC as a measurement report for handover and macro diversity combining . The

Node B is also responsible for the FDD softer hadover. This micro diversity combining is carried

out independently , eliminating the need for additional transmission capacity in the lub. [9]

The Node B also participates in power control, as it enables the UE to adjust its power using

downlink (DL) Transmission Power Control(TPC) commands via the inner –loop power control

on the basis of uplink (UL) TPC information. The predefined values for inner –loop power

control are derived from the RNC via outer –loop power control. [9]



On the baisis of coverage, capacity and antenna arrangement node B can be catageorises as

Omnidirectional and Sectorial. Later can further be categorised as OTSR (Omni Transmitter

Sector Receiver) and STSR (Sector Transmitter Sector Receiver).

Figure 2.4 OTSR (Omni Transmit Sector Receiver) Node B. [10] The OTSR configuration uses a single (PA)Power Amplifier (figure2.4), whose output is fed

to a transmit splitter. The power of the RF signal is divided by three and fed to the duplexers of

the three sectors, which are connected to sectorized antennas. [10]

Figure 2.5 STSR (Sectorial Transmit Sector Receive) Node B. [10]

The STSR configuration uses three (PA) Power Amplifier (figure 2.5), whose output is fed

directly to the duplexers of the three sectors, which are connected to sectorized antennas.

Transmit path : 3 cells, 3 antennas

1 Watt

1 Watt

1 Watt

Transmit path : 1 cell, 3 antennas DDM – Dual Duplexer module (for Main and Diversity)

Receive path : continuous softer handover

TRM

Tx Splitter

PA

DDM DDM DDM

DDM DDM DDM

PA PA PA

Receive path : Possible softer handover

TRM



• OTSR vs STSR

OTSR uses only one PA, so compared to an STSR configuration, two power amplifiers are

saved, with the associated cost savings, which means the OTSR configuration is up to 30%

cheaper than the STSR configuration hence at the initial phase of network deployment** OTSR

is preffered over STSR. When the traffic demands grow and thus the interference created by the

users, there may be a need to provide more capacity, upgrading to STSR, which multiplies

between 2.4 and 3.3 times the capacity. This can be done simply by adding two more power

amplifiers, and removing the transmit splitters from the OTSR configuration. The cell planning

does not need to be changed and no site alterations of antenna, cabling, or other hardware is

necessary. [10]

This “pay as you grow” method is consequently a good use of resources, both in terms of

initial expenditure and engineering Opex. So by starting with an OTSR configuration an operator

may in fact end up spending less money in the long term than it would with an STSR

configuration that might never be used to its full potential. [10]

2.1.1.3 User Equipment

The radio terminal that a subscriber uses to receive service from the UTRAN is

known as the UE. The UMTS Subscriber or UE (User Equipment) is a combination

of ME (Mobile Equipment) and SIM /USIM (Subscriber Identity Module / UMTS

Subscriber Identity Module).[7]

It is in the form of PDA terminals or a handset similar to GSM mobiles. The UE

supports multimode GSM, GPRS and UMTS services and support multi-band

GSM900, DCS1800 and PCS1900 systems. Figure 2.6 shows the best 3G handset of

year 2004 manufactured by Sony Ericsson. [9]

Figure 2.6. V800 3G handset

** For UMTS, O2 has chosen OTSR for the launch of their networks in Germany and UK.



2.2. WCDMA (Wideband Direct-Sequence Code Division Multiple Access)

In UMTS access scheme is DS-CDMA (The name “direct sequence CDMA” means that a

code sequence is directly used to modulate the transmitted radio signal) with information spread

over approximately 5 MHz bandwidth.[11].

Each information bit is coded with a pseudo random sequence or code. Each information bit is

thus represented by a sequence of “chips”. This gives a considerable bandwidth expansion, as the

chip rate is much higher than the information rate. The number of chips per data symbol is called

the Spreading Factor (SF). In WCDMA the basic chip rate is set to 3.84 Mcps which leads to a

carrier spacing of around 5 MHz. [11]

In WCDMA all users share the same band. Their signals are spectrally much wider than the

information data rate. The reason for that is the use of a spreading sequence of much higher data

(chip rate) than the information data rate. Ideally the sequences of different users do not interfere

with each other because they are mutually orthogonal. Thus taking advantage of this property,

though the correlation of the received signal generated by many users with the spreading

sequence uniquely assigned to a particular user, we extract the interesting signal, zeroing the

remaining signals due to the orthogonality of applied spreading sequences.[12].

Every user is assigned a separate code/s depending upon the transaction, thus separation is not

based on frequency or time but on the basis of codes. The major advantage of using WCDMA is

that there is no plan for frequency re-use [13]. (WCDMA technology is explained in detail in

section 6.1).

WCDMA is intended for wideband multimedia services and support for bit-rates of at-least 384

kbit/s with good coverage and full mobility. Up to 2 Mb/s can be supported with one 5 MHz

carrier with local coverage.[14]



2.3 Frequency Bands in WCDMA The air interface transmission direction are separated at different frequencies with a duplex

distance of 190 MHz (Table 2.3.1) the uplink frequency band is 1920-1980MHz and the

downlink is 2110-2170 MHz. 5 MHZ bandwidth is currently being used in network

development.[2].

Table 2.1 Frequency Band in WCDMA [15]

* The center frequency must be an integer multiple of 200 kHz.

** The TDD mode is viewed to be a complement to WCDMA to boost the capacity.

In WCDMA networks there is no frequency planning, because all cells use the same frequency.

A typical WCDMA operator may be given, for example 35 MHZ slice, which is enough for 7*5

MHz WCDMA frequency channels.

2.3.1 UTRAN Modes

• FDD (Frequency Division Duplex): A duplex method whereby uplink and downlink

transmissions use two separated radio frequencies. In the FDD, each uplink and downlink

uses the different frequency band. [16]

• TDD (Time Division Duplex): A duplex method whereby uplink and downlink

transmissions are carried over same radio frequency by using synchronized time

intervals. In the TDD, time slots in a physical channel are divided into transmission and

reception part. Information on uplink and downlink are transmitted reciprocally. [16]

MODE UP-LINK DOWN-LINK NOMINAL CHANNEL CHANNELWCDMA MHz MHz SPACING RASTER

FDD 1920-1980 2110-2170 5MHz 200kHz*

1900-1920 1900-19202010-2025 2010-2025

5 MHz 200kHzTDD**



3. CELLULAR CONCEPT The UMTS network is third generation of cellular radio network which operate on the principle

of dividing the coverage area into zones or cells (node B in this case), each of which has its own

set of resources or transceivers (transmitters /receivers) to provide communication channels,

which can be accessed by the users of the network [17].

A cellular mobile communications system uses a large number of low-power wireless

transmitters to create cells as shown in figure 3.1. Variable power levels allow cells to be sized

according to the subscriber density and demand within a particular region. As mobile users travel

from cell to cell, their conversations are handed off between cells to maintain seamless service.

Cells can be added to accommodate growth. [18]

Communication in a cellular network is full duplex, which is attained by sending and receiving

messages on two different frequencies. The cellular topology of the network enables frequency

re-use (cells at a certain distance apart can reuse the same frequencies), which ensures the

efficient usage of limited radio resources.[2]

Figure 3.1 Mobile Telephone System Using a Cellular Architecture [17]



In order to increase the frequency reuse capability to promote spectrum efficiency of a

system, it is desirable to reuse the same channel set in two cells which are close to each other as

possible, however this increases the probability of co-channel interference .[19]

The performance of cellular mobile radio is affected by co channel interference (due to the

interference caused by the other radio users). Co-channel interference, when not minimized,

decreases the ratio of carrier to interference powers (C/I) at the periphery of cells, causing

diminished system capacity, more frequent handoffs, and dropped calls.

Usually cells are represented by a hexagonal cell structure (Figure. 3.2), to demonstrate the

concept, however, in practice the shape of cell is determined by the local topography [17].

Figure 3.2 Cell Distribution in a Network [20]

Fading is another major constraint in wireless communication. All signals regardless of the

medium used, lose strength this is known as attenuation/fading. There are three types of fading

• Pathloss : Occours as the power of the signal steadily decreases over distance from the

transmitter.

• Shadowing : or Log normal Fading is causes by the presence of building , hills or even

tree foilage.

• Rayleigh Fading : or multipath fading is a sudden decrease in signal strength as a result

of interference between direct and reflected signal reaching the mobile station. [8]

Highway Town Suburb

Rural



4. RADIO NETWORK PLANNING PROCESS The aim of Network Planning is to provide a cost effective solution for the radio network in

terms of coverage, capacity and quality of service. The network planning process and design

criteria vary from region to region depending upon the dominating factor, could be capacity or

coverage [2].

4.1. Planning Process Overview In the following figure, the workflow of the planning process is illustrated

1. Definition of the Requirements: At the beginning, it is necessary to define the

performance requirements of the WCDMA network to be implemented.

2. Radio Propagation Model tuning Activity: In order to obtain more reliable radio

propagation predictions, it is suitable to tune the models implemented in WCDMA

planner for the most important and critical areas to be covered.

3. Nominal Cell Planning: The requirements, defined in the first phase, are the input to

dimensioning of the network in terms of nominal number of sites, using dimensioning

and/or design tools.

4. Site Search and Survey: The cell planner, with the support of the site hunters, finds the

most appropriate sites to achieve the radio coverage, according to the general criteria.

5. Radio Network Design: Different network design aspects are analyzed, in particular

-downlink common channel power allocation

-frequency planning in the case of cells with more than one carrier for capacity

requirement

-code planning

-parameters involved in the handover algorithms

6. Initial Tuning: The default setting of the cell data parameters and the site configuration

are optimized using measurements in the field.

DEFINITION OF THE REQUIREMENTS

RADIO PROPAGATION MODEL TUNING ACTIVITY

NOMINAL CELL PLANNING

SITE SEARCH AND SURVEY

RADIO NETWORK DESIGN

INITIAL TUNING



The work flow of the planning process is described in brief in the following part of this chapter.

The table 4.1 provides the typical cell range for various types and can be considered for use,

based on the coverage and capacity requirement. [8]

Table 4.1 Cell type classification [21] 4.1.1. Radio Network Design Requirements The radio network design requirements are related to coverage, capacity and services and they

are specified for each area type: dense urban, urban, suburban and rural (see Table 4.2 ).

Table 4.2 Area type classification [8]

C ell typ e T yp ica l ce ll ra d iu s T y p ica l p osition o f b ase sta tio n an ten n a

M acro C ell .. . .(L arge ce ll)

1 k m to 30 k mO utdo o r , m o unted abo u ve m ed iu m ro o fto pleve l heights o f a ll su rro u nd ing bu ild ing s arebelo w bare sta t io n an tenna height .

S m all m acro - ce ll 0 .5 km to 3 k mO utdo o r , m o unted abo u ve m ed iu m ro o fto pleve l heights o f a ll su rro u nd ing bu ild ing s arebelo w bare sta t io n an tenna height .

M icro ce ll U p to 1 k m O utdo o r , m o u nted abo uve m ed iu m ro o fto p

P ico -cell/indo o r U p to 5 00 mIndo o r o r o u tdo o r (m o unted be lo w m ed iumro o f - to p level)

DENSE

Areas within the urban perimeter. This includers densely developed areas wherebuilt up features do not appear distinct from each other. The typical street is notparallel.

URBANThe average building height is below 40 m. the average building density is >35%.

Built up areas with buildings blocks, where features do appear more distinct fromeach other in comparision to Dense Urban. The street pattern could be parallel ornot.The Average building height is below 40 m. the average building density is from 8%to 35%.Suburban density typically involves laid out street patterns in which streets arevisible. Building blocks may be as small as 30 by 30 m, but are typically larger andinclude vegetation cover. Individual houses are frequently visible.The Average building height is below 20 m. the average building density is from 3%to 8%.

Small and scattered built up areas in the outskirts of larger built up environments.

The Average building height is below 20 m. the average building density is <3%.RURAL

URBAN

SUBURBAN



4.1.1.1. Coverage Requirements

• For each area, the extension in km2 of coverage area is defined. The value of required

coverage area may increase through several phases in the evolution of the network.

• The coverage priority is normally identified according to land usage, population

distribution and/or vehicular distribution. The high traffic areas (the highest priority

coverage) where a continuous coverage has to be guaranteed, are, for example, highways

or roads with high vehicular traffic, business areas and other hot spots like Airport, train

station, Interchange etc. [8]

4.1.1.2. Capacity Requirements

• For each area, the number of subscribers and their “profile” (business, conventional, data

or/and speech user) is defined. This value can be obtained considering census data. An

annual subscriber forecast is required in order to plan the network growth.

• The traffic volume per subscriber and service type is determined on average during the

busy hour. Typically, this amount is given in Erlang for speech service and in kbyte/h for

data services. [8]

4.1.1.3. Service Requirements

• The types of service offered must be given for each area, the estimated usage of each

service should also be given. The services are characterized by the QoS (Quality of

Service) parameter related to different radio access bearer attributes. The main attributes

to define a service are, Bit Error Rate (BER) and Block Error Rate (BLER).

• The areas with different coverage reliability should be distinguished to determine which

service could be guaranteed. [8]



4.1.2. Model Tuning In the cell planning process, the WCDMA planner tool is used to predict the radio coverage by

means of propagation models, for a particular site configuration.

Different propagation models are considered according to the different environments and site

configurations. The Okumura-Hata model, is recommended for macrocell configuration, in

urban, suburban and rural environments. [22]

The model tuning (model calibration) is performed in order to obtain more reliable radio

propagation predictions. Measured and predicted signal strength samples are compared, and the

mean error between them minimized.

4.1.3. Nominal Cell Planning A nominal cell plan shows the mast sites of the base stations, the coverage of each antenna and

the distribution of frequencies among the cells. These factors and others are based on the forecast

of traffic demand. The nominal cell plan often takes the form of a hexagonal pattern.[23]

While preparing the nominal cell plan, not only current traffic demand but also the possibility of

future traffic growth and cell splitting is considered and accordingly, mast sites are planned to

permit use in future network configurations.[23]

The scope of a nominal cell planning activity depends usually on requirements according to the

particular phase of the network planning process e.g. license application or radio network design.

In the case of a license application activity, the site count needed to achieve the required

coverage/capacity. [24]

Radio network design is an activity based on predictions by the design tool and knowledge of the

actual local environment. The result of this activity is a complete radio network plan with a

realistic number of sites and RBS (Radio Base Station/ Node B) configurations.[24]



4.2. CCQ Model (Coverage, Capacity and Quality of Service Model) Designing a UMTS network is a multi-dimensional process due to the large number of

different design requirements and system parameters. In addition, when the number of users

increases, the interference in the coverage area also increases, thus causing the cell size to shrink.

Thus 3G planning is a complex and challenging task. The three factors affecting the 3G network

performance are coverage, capacity and Quality of Service, Figure 4.1 shows the CCQ model.

This is the basis of quality 3G planning [1].

Figure 4.1 CCQ (Capacity, coverage &Quality of Service) model [A]

Firstly, it is necessary to estimate the number of cell sites, the type of base stations and their

configurations (including the number of network elements, and antenna configurations). In order

to attain the number of cell sites and their configurations we need to assess the coverage capacity

and Quality of Service (QoS) requirements together with the type of area to be covered, such as a

dense urban area. With this information available it will be possible to start the dimensioning,

coverage and capacity planning [1].

Optimisation

Capacity

Quality of Service

Coverage

Infrastruct

Number of Users



The radio network planning starts with collection of the input parameters such as the network

requirements of capacity, coverage and quality.

The definition of coverage would include defining the coverage area ( e.g. 1000 km2), service

probability (e.g. 75 % voice, 25 % data subscribers etc), related signal strength (e.g. 106 db for

voice, 90dBm for data) etc.

The definition of capacity would include subscriber and traffic profile in the region of whole

area, availability of frequency band e.g. (35MHZ = 7 *5 MHz WCDMA frequency channels),

and frequency planning methods.

The penetration of the UMTS at the introduction will not necessarily include all populated

environments. Thus, starting in the main cities, and suburban areas, 3G network coverage can

progress in phases, i.e. 50 %, 75%, 99% for business strategic reasons within a region. With the

above data, a theoretical coverage and capacity plan is determined [25].



4.3. Basic Traffic Dimensioning Input 4.3.1. Traffic Classes From end-user and application point of view four major traffic classes can be identified:

• Real time applications

o Conversational class (e.g. voice), where the fundamental characteristics for QoS

are to preserve time relation (variation) between information entities of the stream

and to have a low delay [26] [27]

o Streaming class (e.g. streaming video), where the fundamental characteristics for

QoS are to preserve time relation (variation) between information entities of the

stream. [26] [27]

• Non-real time applications

o Interactive class (e.g. web browsing), where a request/response pattern is of

importance and the payload content must be preserved. [26] [27]

o Background class (e.g. background download of emails), where the destination is

not expecting the data within a certain time but with preserved payload content.

Conversational and streaming classes are intended to carry real-time traffic flows, like speech

and video streaming.

Interactive class and background class are mainly meant to be used by traditional Internet

applications like WWW, e-mail and by a number of vertical applications like Telemetry and E-

Commerce. [26] [27]



4.3.2 Input Analysis One of the most important steps in any dimensioning process is defining the input data

thoroughly. This can be difficult in some circumstances due to limited or vague input

requirements. It is up to the dimensioning engineer to interpret the input data so that it reflects

reasonable values. Table 4.3 depicts a typical example of the input data needed for network

dimensioning.

Table 4.3 Examples of input data [8]

4.3.2.1 Required Services

The required services are then mapped onto the existing Radio Access Bearers. The number of

required individual bearers (RABs) are kept to a minimum. Up to five-six bearer types is

reasonable for a typical dimensioning case; one RAB can handle several different services.

Table-4.4 depicts a typical example of various RABs required for different services.

The following items can be useful to consider when selecting RAB:

Service Traffic during BH Speech - AMR 12000 Erl Video service 38.4 Mbps

UL : 19.2 Mbps DL : 38.4 Mbps UL : 16 Mbps DL : 64 Mbps

Total Environment Service City area Indoor- all services

In car for web service and voice

Subscriber distributionSpectrum

2 x 10 MHz50 % city area50 % suburban

Coverage70 km sq

1600 km sq

600k

50k

130k

400k Subscribers

20kTraffic Loadand Capacity

Environment and services

Miscellaneous

Ftp service

Suburban /outskirts

Internet web service



• Delay Criteria

Delay criteria indicate whether to use a conversational/streaming or interactive/background

type RAB. As a rule of thumb use conversational if the delay requirement is less than 0.5

seconds. In case the delay is greater than 1 second an interactive/background RAB can be used.

• Maximum User Data Rate/Throughput

This gives some indication as to which type of bearer to use. It is not necessary to have a RAB

that conforms exactly to the maximum user data rate. The given service may be specified with a

lower data rate than the RAB rate.

• Other Service Requirements

Some of the information given may not be expressed as hard numbers specifying delay criteria

and throughput. Often the service is described from the end user perspective. Then the service

has to be interpreted based on those criteria.

Table 4.4. Example of mapping of services to Radio Access Bearers [8]

Service RAB MotivationSpeech - AMR Speech

Video serviceCircuit 128. . .(conversational )

A video service requires data transfer at lowdelay. A high data rate is required for the qualityaspect of the video link.

Ftp serviceCircuit 64 ..(Conversational)

A conversational class bearer is used since it isexpected that the user does not send burstytraffic but long constant streams of data. Themedium data rate is a design choice; norequirements for the maximum data rate havebeen given.

Internet Web . .service

Packet 64/384(interactive)

This service does not require low delay data andtherefore an interactive (packet) RAB can beused. The medium /high data rate in the UL/DLis a design choice chosen due to the strongasymmetry of the traffic volume.



4.3.3. Determining the Average User Profile It is often convenient to define an “average user” to obtain a good feeling for the traffic

distribution generated by the service provider. The “average user” defines the traffic for all

services during the busy hour. Besides defining the average traffic during the busy hour several

other parameters must be defined that describes quality parameters for the users: [8]

• Activity factor

This has an impact on the air interface dimensioning as well as the hardware dimensioning. A

low activity factor allows more users to share the same spectrum. This however, requires more

allocation of hardware resources. The activity factor for speech cannot be used directly to obtain

a capacity gain since there is no activity factor to the signaling overhead. Instead, the capacity is

modeled through the pole capacity. For higher data rates however the signaling overhead is

negligible and for dimensioning purposes it is possible to utilize the gain fully.

• Retransmission rate

In the radio interface there are always retransmissions due to frame errors. This reduces the

total throughput of the channel and must be compensated for in the dimensioning. (Estimated

10%)

• Grade of service (GoS)

Used for circuit switched traffic, GoS defines how many calls that are allowed to be blocked.

Table 4.5 shows acceptable GOS for various services and an average user profile.

BH Traffic Average bit Retrans - (UL/DL) rate/user mission

Speech AMR 20 mErl 0.5 2% Video service C128 0.5 mErl 1 2% Ftp service C64 0.5 / 1m Erl 1 2%

Best effort, maxsystem throughput

10kbps 10% Web service P64/384 27/ 107 bps

Service RAB Activity factor GOS

Table 4.5 Example of an average user profile [8]



4.4. Basic Traffic Dimensioning The purpose of the basic traffic dimensioning is to find the maximum number of users

supported by the actual cell under investigations. In a WCDMA network this process becomes

quite complex. Three types of services can be supported in a cell; voice, circuit switched data

and packet switched data services. The different service types must be treated differently as they

are carrying different applications. Voice and circuit switched data services require allocation of

fixed rate resources to provide the actual service while packet switched traffic can utilize the

remaining resources efficiently due to its elastic nature.

• Speech Only Networks

In traditional speech only services traffic dimensioning is based on the Erlang-B calculations.

This method calculates the number of users in a cell (with a predefined offered traffic per user of

e.g. 30 mErlang) based on the actual network resources for a given call blocking probability (e.g.

2%). Generally, Erlang tables are used for this purpose. Figure 4.2 indicates dimensioning of a

cell with only one speech service. The blocking probability increases as the number of user

increases. The input data used in this example corresponds to the existence of 59 channels for

voice. Then the cell can support at most 1623 users if the blocking probability is restricted to 2%.

Figure 4.2. Erlang-B blocking probability [8]

Number of speech users

1623 speech users

3

2

1

0

6

5

4

Parameters: 3 Sector cell 1 RF carrier Max 59 voice Channel available 30 m Erlang

10 0 0 10 50 110 0 1150 12 0 0 12 5013 0 0 13 50 14 0 0 14 50150 0 1550 16 0 0 16 50 170 0 1750 18 0 0



• Multi Service Networks

In multi service networks several services with different parameters share the same resource.

Therefore, the inputs of multi-service cell dimensioning are the offered load, the required

resource (effective bandwidth), the requirements on blocking for each service and the total

resource available in the cell. Figure 4-3 shows an example of multi-rate blocking probability

calculations using five different circuit switched services.

For a given number of subscribers the blocking probabilities are different for different services

because they share the same pool of resources. The more resources a service needs for one user

the higher is the blocking probability, e.g. CS 384 is assumed to need 23 times the resources of

voice in this example. If 2% blocking probability for each service is taken as the criteria of the

dimensioning 133 users can be supported with the given in data. [8]

Figure 4-3 Example of multi-rate blocking probability calculations (%)

The actual channel utilization for the example above is shown in figure 4-4, It illustrates that

handling large bandwidth circuit switched services may result in very low utilization of the

available channel resource.

Number of users 133 users

Parameters: 3 Sector cell 59 voice Channel available 30 m Erlang for voice 1mErlang for all other services

Blocking Probability (%)

50 100 150 200 250 300 350 400 450

Circuit 384 Circuit 144

Circuit 64

Circuit 32

Voice

87

6

5

4

3

2

1

0



Figure 4-4 Channel utilization example

Packet Data Services

Voice and circuit switched services should be handled in the way described above but for

packet switched services this leads to over dimensioning.

In packet switched applications the minimum average throughput can be taken as dimensioning

criteria. The part of the resource which is not used for circuit switched services can be utilized by

packet services. This part of the total resource is clearly visible in Figure 4-3. For example if the

number of users are 133 the channel utilization becomes 16%. That means that on average 84%

of the resources are available for best effort services.

Best effort means that the packet service can utilize the resource that is available, but there are

no guarantees on “blocking probabilities”, delays or throughput. [8]

Number of users 133 users

Channel Utilization (%)

5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0 4 5 0

4 03 5

3 0

2 5

2 0

1 5

1 0

5

0



5. COVERAGE AND CAPACITY DIMENSIONING The scope here is to outline how to calculate the capacity and coverage of the radio access

network. The methods described can be used for rough estimates suitable in the dimensioning

process.

5.1 Capacity

Capacity is defined as the total number of simultaneous users the system can support, and

quality is defined as the perceived condition of a radio link assigned to a particular user; this

perceived link quality is directly related to the probability of bit error, or bit error rate (BER).

The actual capacity of a CDMA cell depends on many different factors, such as receiver

demodulation, power-control accuracy, and actual interference power introduced by other users

in the same cell and in neighboring cells. [28]

In digital communication, we are primarily interested in a link metric called Eb /No, or energy

per bit per noise power density.

This quantity can be related to the conventional signal-to-noise ratio (SNR) by recognizing that

energy per bit equates to the average modulating signal power allocated to each bit duration; i.e,

Where S is the average modulating signal power and T is the time duration of each bit. Notice

that (5.1) is consistent with dimensional analysis, which states that energy, is equivalent to power

multiplied by time. We can further manipulate (5.1) by substituting the bit rate R, which is the

inverse of bit duration T:

S R Eb =

Eb S T = …………. (5.1)



Eb / No is thus

We further substitute the noise power density No, which is the total noise power N divided by the

bandwidth W; that is,

Substituting (5.3) into (5.2) yields

Equation (5.4) relates the energy per bit E N b / 0 to two factors: the signal-to noise ratio (S /N)

of the link and the ratio of transmitted bandwidth W to bit rate R. The ratio W /R is also known as

the processing gain of the system. The SNR of one user can be written as

Where M is the total number of users present in the band. This is so because the total

interference power in the band is equal to the sum of powers from individual users. Figure 5.1

illustrates the principle behind (5.5).

Power

Figure 5.1. SNR (Signal to noise) experienced by a user. [28]

Eb S No

= RNo

……….…. (5.2)

N No =

W

……….…. (5.3)

Eb S No

= N

…………... (5.4) W R

S 1 N

= M - 1

………..…. (5.5)

User A7

User A1 User A2

Frequency

S =

N

1

6 A1



In CDMA, the total interference power in the band is equal to the sum of powers from

individual users. Therefore, if there are seven users occupying the band, and each user is power-

controlled to the same power level, then the SNR experienced by any one user is 1/ 6.

We proceed to substitute (5.5) into (5.4), and the result is

Solving for (M − 1) yields

Note that if M is large, then

5.1.1 Effects of Loading

Equation (5.8) is effectively a model that describes the number of users a single CDMA cell

can support. This single cell is omni directional and has no neighboring cells, and the users are

transmitting 100% of the time. In reality, there are many cells in a CDMA cellular or PCS

system. Figure 5.2 shows that a particular cell (cell A) is bordered by other CDMA cells

supporting other users. Although these other users from other cells are power-controlled by their

respective home cells, the signal powers from these other users constitute interference to cell A.

Therefore, cell A is said to be loaded by users from other cells. [28] Equation (5.6) is modified to

account for the effect of loading:

Where η is the loading factor, η is a factor between 0% and 100%. In the example shown in

Figure 5.3, the loading factor is 0.5 resulting in (1 + 0.5), or a 150% increase of interference

W R

Eb 1 No

= M - 1

……….….. (5.6)

(W / R) (Eb / No )

= M - 1 ………… (5.7)

(W / R) (Eb / No )

≈ M ……….….. (5.8)

W R

Eb 1 No

= (M – 1)

……… (5.9) 1

1 + η



above those introduced by home users alone. The inverse of the factor (1+ η) is sometimes

known as the frequency reuse factor F; that is,

The frequency reuse factor is ideally 1 in the single-cell case (η = 0). In the multicell case, as

the loading η increases, the frequency reuse factor correspondingly decreases.

Figure 5.2 Interference introduced by users in the neighboring cell. [28]

Power

Figure 5.3 Loading factor as perceived by cell A. [28]

1 F =

( 1+η ) ……….…. (5.10)

User C2

User A7

Frequency

User C1 User B2 User B1

User A1 User A2

Loading Factor = 0.5



5.1.2 Effects of Sectorization

The interference from other users in other cells can be decreased if the cell in question is

sectorized. Instead of having an omni-directional antenna, which has an antenna pattern over 360

degrees, cell A can be sectorized to three sectors so that each sector is only receiving signals over

120 degrees. In effect, a sectorized antenna rejects interference from users that are not within its

antenna pattern.

This arrangement decreases the effect of loading by a factor of approximately 3. If the cell is

sectorized to six sectors, then the loading effect is decreased by a factor of approximately 6. This

factor is called sectorization gain. [28] [25]



6. LINK BUDGET OVERVIEW

Link budget planning is part of the network planning process, which helps to dimension the

required coverage, capacity and quality of service requirement in the network. UMTS WCDMA

macro cell coverage is uplink limited, because mobiles power level is limited to (voice terminal

125mW). Downlink direction limits the available capacity of the cell, as BTS transmission

power (typically 20-40W) has to be divided to all users. In a network environment both coverage

and capacity are interlinked by interference. So by improving one side of the equation would

decrease the other side. System is loosely balanced by design. [6]

The aim of the link budget design is to calculate maximum cell size under given criteria:

• Type of service (data type and speed)

• Type of environment (terrain, building penetration)

• Behavior and type of mobile (speed, max power level)

• System configuration (Node B antennas, Node B power, cable losses, handover gain)

• Financial and economical factors (use of more expensive and better quality equipment or not)

and to match all of those to the required system coverage, capacity and quality needs with each

area and service. [6]

Figure 6.1 Link Budget Process flow block diagram [29]

�PA Power �Diversity (Tx Rx) �Eb/No �Processing Gain �……

Node B Site �PA Power �Diversity (Tx Rx) �Eb/No �Processing Gain �……

�Cable losses �Antennas �Site Configuration ...(bi, tri sectorial)

� Margins � Propagation

Service

Cell Range Traffic offered per cell

MS



Figure 6.2 Link Budget Flow Chart [29]

Link budget calculations give the loss in the signal strength on the path between the mobile

station antenna and base station antenna. These calculations help in defining the cell ranges

along with the coverage thresholds. Coverage threshold is a downlink power budget that gives

the signal strength at the cell edge (border of the cell) for a given location probability [A].

Link budget calculations are done for both the uplink and downlink . As the power transmitted

by the mobile stating antenna is less than the power transmitted by the base station antenna, the

uplink power budget is more critical than the downlink power budget. Thus the sensitivity of the

base station in the uplink direction becomes one of the critical factors as it is related to receptions

of the power transmitted by the mobile station antenna. In the downlink direction, transmitted

power and the gains if the antennas are important parameters. In terms of losses in the

equipment, the combiner loss and the cable loss are to be considered. Combiner loss comes only

in the downlink calculations while cable losses are incorporated in both directions [A].

Link Budget @ X% load Design assumptions

Cell size Cell Capacity

Sites for Coverage Sites for Traffic

Comparison Decision

Final number of Sites

Adjust Load



6.1 WCDMA Technology Review

Wideband CDMA system occupy a bandwidth of 5 MHZ. Digital information is spread by a

channalization code and then scrambled by a scrambling code. Each of these codes is a digital

sequence at the “chip rate of 3840000 chips per second. Multiplying the message by these high

chip rates has the effect of spreading the signal power over a wider bandwidth. Many channels

can be multiplexed into the same frequency band at the base station by utilizing orthogonal

channalisation codes. The overall effect is the each individual channel contributes only a small

fraction of the total power transmitted by the base station. Because the scrambling code is a

“Pseudo Random Binary Sequence” the transmitted signal will have the appearance of noise.

Each individual message channel will be buried in the noise and will need to be extracted at the

receiver. This is achieved by de-scrambling and de-spreading at the receiver making use of the

processing gain where each channel is de-spread using its own unique channalisation code. On

the uplink each mobile has a unique scrambling code that allows the base station to discriminate

between many users. [29]

On the downlink the base station transmits synchronization and pilot channels along with the

message channel. The pilot channel is simply an un-modulated scrambling code sequence. This

is used to allow the wideband radio channel characteristics to be estimated and the rake receiver

within the mobile station to be automatically programmed. Further it is the pilot signals from

various base stations that the mobile monitors in order to inform handover decisions.

One vital parameter known as Ec/Io (the ratio of the energy perchip in the pilot signal to the

received noise density). In order to use the pilot signal effectively, the value of Ec/Io must be at

least “-15” dB. Setting the transmitted power level of the pilot forms a significant element of

network planning. [29]



Further to the pilot channel being received at an appropriate level, each service requires a certain

signal to noise ratio in order to be effective. This signal to noise ratio is known as the Eb/No ratio.

The relationship between Eb and Ec is defined by the processing gain and can be calculated by

dividing the chip rate by the actual data rate. The necessary value of Eb/No in order to deliver an

acceptable service varies from service to service and depends on the condition prevalent in the

radio channel. Generally, the lower the data rate the greater the overhead imposed by the control

channel and hence the higher the value of Eb/No that should be targeted (because the

transmission of actual user bits occupies a smaller percentage of the total time. Values of Eb/No

have a big impact on the network performance. Typical values vary from 1.5 dB to 10 dB.[29]

Orthogonality between the canalization codes will allow a further processing gain to be

realized in the downlink. In practice, multipath phenomenon reduce the benefits from

orthogonality. This is accounted for by introducing an orthogonality factor that assumes a value

between zero and one. A value of one represents the situation where perfect orthogonality is

maintained and zero represents the situation where there is effectively no orthogonality between

the different codes. In typical practical situation, a value of 0.6 has been found to be

appropriate.Two further key parameters for a UMTS channel are therefore the target Eb/No value

on the uplink and the downlink. Failure to achieve these will result in connection failure. [25]

The fact that each user affects all other users, influences the admission control algorithms within

WCDMA system. Admitting a new user will increase the noise expericenced by all existing user

channels. This phenomenon is referred to as “Noise Rise”. Noise Rise escalates as more users

access the system, It has the effect of reducing the maximum path loss between mobile and user

and hence it reduces the coverage distance. This “cell breathing” phenomenon should be limited

if coverage is to be maintained. This entails setting a limit to Noise Rise as a part of the system

planning procedure. [22]



6.2 Link Budget

The new terms introduced, most notably Noise Rise and Processing Gain, appear in the link

budget for a UMTS radio bearer. Because the mobile (UE) has much less power available to it

than the cell, coverage is normally “uplink limited” and, at least in the initial stages of planning,

it is the uplink budget that is of most interest. These are not dissimilar from the link budget for

GSM. Naturally the transmit power of the UE (typically +21 dBm) and the thermal noise floor of

the cell receiver (typically -104 dBm) play an important part. The noise power quoted is larger

that that for GSM links. This is because the bandwidths is much larger (nominally 3840 kHz or

65.8 dBHz) KTB is equal to -108.1 dBm. A typical noise figure of 4.1 dB results in the value of

-104 dBm quoted above. [30]

The cell must receive sufficient power to deliver the required Eb/No value when the Noise Rise

level is at its limit. The values, combined with the processing gain (which is dependent on bit

rate) allow us to derive a value for the minimum acceptable receiver power at the cell

(effectively the receiver sensitivity).

For example, consider the following parameter values.

Noise Rise limit : 4dB

Cell thermal Noise Floor -104dBm

Target Eb/No 5dB

Processing Gain (full rate Voice) 25dB (Ratio of Chip rate to Bit Rate)

Minimum acceptable receive power = -104 +4+6-25 = -120 dBm

If the UE transmits at 21 dBm then the maximum loss that can be tolerated is 141dB.

This is the overall “link loss”. If we wish to determine the allowable air interface path loss then

we need to consider the antenna gain and “miscellaneous losses” (including feeder loss and body



loss) . Suppose the antenna gain is 17 dBi and the miscellaneous losses amount to 4dB then the

maximum path loss allowed is 154 dB.

It is important to remember that this does not consider any margins (such as “log-normal

fading” (LNF) also known as “shadowing”) or building penetration loss. So, in practice, 130 dB

could be a safer value to consider.

The above link budget has been conducted for voice. It is highly likely that UMTS networks

will provide coverage for higher services such as Video telephony (VT). Video telephony will

utilize 64 kbits/s bearer and, therefore , the processing gain will be reduced to 17.8 dB. If all

other parameters remain the same, the maximum path loss allowed will reduce from 154 dB to

146.8 dB. This difference in allowed path losses immediately shows a problem confronting the

UMTS radio network planning, the coverage will be different for different services. The uplink

coverage range for voice will be typically 60 % larger than for VT. [30]



6. 3. Uplink Dimensioning

6.3.1 Uplink Capacity

The uplink pole capacity, Mpole, is the theoretical limit for the number of UEs that a cell can

support. It is service (RAB) dependent. At this limit the interference level in the system is

infinite and thus the coverage reduced to zero. Mpole is calculated according to: [8]

where γ ,

the C/I target of the RAB in linear units, is calculated as:

where

Rchip is the chip rate (=3.84 Mcps) [cps],

Rinfo is the information bit rate for the RAB [bps],

PG is the processing gain, i.e. the ratio of the system chip rate and the information bit rate [dB],

F is the ratio of the interference from other cells and the interference generated in the own cell

Eb/Io is the target bit energy to interference power ratio [dB].

* γ�=10 (C/I)/10 if C/I is given in [dB]

6.3.1.1 The Eb/I0 value

The Eb/Io values that should be used are those that are needed to reach the quality requirements.

The quality requirements are

- Speech : BER < 10-3

- Circuit switched data : BER < 10-6

- Packed switched data : BLER 10%

1 (1+F) γ

M pole = ……….…. (6.1) 1 +

(Eb / Io) - PG

10 γ = ……….…. (6.2) 10

(Eb / Io) / 10 Rchip/Rinfo

C / I = *………. (6.3)



Eb/Io values depend on the type of environment/channel model assumed. All values in this

chapter (Table 6.1, Table 6.5) are examples taken from the RTT submission to ITU, assuming

the pedestrian A channel model, plus an additional implementation margin of 1 dB.

RAB Pedestrian A

Speech 12.2 kbps 4.2

Circuit 64 kbps 3.9

Packet 128 kbps 1.9

Table 6.1. Uplink values of Eb/I0 [8]

6.3.1.2 The F value

The equation for pole capacity is straightforward except for the F value. F is the ratio between

the interference from other cells and the interference generated in the own cell. This means that F

depends on the characteristics of the cell plan such as numbers of sectors, wave propagation

characteristics, log-normal fading and antenna beam width. A typical F-value for a three-sector

site is 0.93. [8]

6.3.1.3 Table of Mpole

Table 6.2 contains approximate values of Mpole for a three-sector configuration, calculated using

the previous equation

RAB Pedestrian A

Speech 12.2 kbps 95 Circuit 64 kbps 14 Packet 128 kbps 11 Table 6.2. Uplink values of Mpole [8]



6.3.2 Uplink Coverage

6.3.2.1 Loading

In WCDMA analysis, it is customary to define the concept Loading:

where M is the number of simultaneous users in the cell.

For a multi-service system where the services utilize different types of RABs, the expression can

be generalized as:

where

Mn is the number of simultaneous users for the nth RAB

Mpole , n is the uplink pole capacity for the nth RAB.

6.3.2.2 Uplink load limit

A WCDMA system cannot be loaded up to 100%. To secure a well performing network the

uplink load used in the dimensioning process should be of the order of 50-60 % depending on the

implementation of radio network functionalities. [8]

6.3.2.3 Noise Rise

The more loaded the system, the more interference is generated. This has the effect that the

receiver noise floor is higher in a loaded system as compared to an unloaded system. The

increase is often referred to as noise rise and is denoted IUL.

The noise rise can be calculated from the relative uplink system load as follows:

where:

IUL is the noise rise [dB] and the Loading is the uplink system loading [%].

M M pole

Loading = ……….…. (6.4)

M1

M pole,1 Loading = … (6.5) M2

M pole, 2

M3

M pole3 + + +

1 1 - Loading

IUL = ……….…. (6.6) 10 log



6.3.3 Uplink budget

Having determined the noise rise, a conventional link budget for the uplink can be set up (Fig 6-3):

Figure 6-3 Schematics of components included in the link budget. [8]

G=Gain, L=Loss, ant=antenna, f+j=feeder & jumper, UE=User Equipment RBS=Radio Base

Station.

SSRBS = PUE – Lpath +Gant –L f + j � SSdesign …………………………………………………….(6.7)

where the design criterion, SSdesign, is equal to the sensitivity of the radio base station, RBSsens,

plus a number of margins as

SSdesign = RBSsens + BL + CPL + BPL + PCmarg + IUL + LNFmarg………………………….…(6.8)

where:

Lpath is the path loss (on the uplink) [dB].

PUE is the maximum UE output power (= 21 or 24) [dBm].

RBSsens is the RBS sensitivity. It depends on the RAB [dBm].

LNFmarg is the lognormal fading margin (this margin depends on the environment and the

desired degree of coverage) [dB].

IUL is the noise rise [dB].0

PCmarg is the power control margin, dependent on channel model [dB].

BL is the body loss (= 0 or 3)[dB].

CPL is the car penetration loss (= 6) [dB].

BPL is the building penetration loss [dB].

Gant is the sum of the RBS antenna gain and UE antenna gain [dBi].

Lf+j is the loss in feeders and jumpers [dB].



The path loss is the difference (in dB) between the transmitted power and the received power.

The maximum pathloss allowed, Lpathmax, is obtained when SSRBS = SSdesigh so solving for Lpathmax

we obtain

Lpathmax = P UE – RBS sens – I UL - LNF marg – PC marg – BL – CPL – BPL +Gant – L f + j ………(6.9)

The RBS sens depends on the user data rate and the E b/I o target value as

RBS sens = Nt + Nf + 10·log(Ruser) + E b/I o ……………………………………………..……(6.10)

Nt is the thermal noise power density = -174 dBm/Hz

Nf is the noise figure = 3 dB with TMA (Tower mounted Amplifier), 4 dB without it.

Ruser is the user bit rate (information bits per second, excluding retransmission, i.e. the

service rate of the RAB)



6.4 Cell size

Once the maximum path loss is calculated we can calculate the maximum cell rage, based on the

type of the topography and other margins.

When roughly estimating the size of macro cells, without respect to specific terrain features in

the area, a fairly simple Okumura-Hata propagation formula is often used. [31]

L path = A - 13.82logHb +(44.9-6.55logHb)logR - a(Hm) [dB]………………………………..(6.11)

where

A = 155.1 urban areas

A = 147.9 suburban and semi-open areas

A = 135.8 rural areas

A = 125.4 open areas

Hb = base station antenna height [m]

Hm = UE antenna height [m]

R = distance from transmitter [km]

a(Hm) = 3.2(Log(11.75*Hm))2- 4.97

a(1.5) = 0

The cell range at is then given by:

R = 10 α, where α = [Lpath - A + 13.82logHb + a(Hm)]/[44.9 - 6.55logHb]………………..…(6.12)

that is

R pathmax = 10α, where α = [Lpathmax - A + 13.82logHb + a(Hm)]/[44.9 - 6.55logHb]…………(6.13)

The Okumura-Hata formula only can be used for rough estimates. For more precise calculations,

network-planning tools are used.

For small cells in an urban environment the cell range is typically less than 1 km and in that case

the Okumura-Hata formula is not valid. The COST 231-Walfish-Ikegami model, gives a better

approximation for the cell radius in urban environments. The path loss according to Walfish-

Ikegami is: [31]

Lpath = 155.3 + 38logR – 18log(Hb – 17) [dB]

R = 10 α , where α = [Lpath – 155.3 + 18 log(Hb – 17)]/38………………..……...…………..(6.14)



EXAMPLES

Example 1:

Calculation for the capacity and the range of a three-sector site at maximum loading. Assume

urban environment and speech 12.2 kbps

1) For 12.2 kbps speech RAB in urban environment Mpole is 95 simultaneous users (Table 6.2).

2) At 50% loading this is equivalent to 47 simultaneous users, or a site capacity of three-sector

site 3 x 47 = 141 simultaneous users.

3) The noise rise (IUL) is calculated according to 3 dB at 50% loading.

The maximum path loss can be calculated according to the Lpathmax equation. The result depends

on the environment and the desired degree of coverage. In Table 4 the link budget is calculated,

considering a three-sector sites with TMA and 95% probability of coverage. For configurations

with TMA L f+j should be set to zero.

From equation 6.9 we get


Table 6.3. Uplink link budget for voice 12.2 kbps and 95% probability of coverage. [8]

Coverage [%] UrbanPUE 21RBSsens -125.9LNFmarg 4PC marg 2I UL 3BL 3Gant 17.5L f+j 0L pathmax (Outdoor) 152.4CPL 6L pathmax (in-car) 146.4BPL 18L pathmax (indoor) 134.4 dB



6.4 Downlink Dimensioning

6.4.1 Downlink Curves

The downlink equations are more complex than the uplink ones. For the downlink it is not as

easy to separate the coverage and capacity in the way that is done for the uplink. The main

difference as compared to the uplink is that the UEs in the downlink share one common power

source. Thus the cell range is not dependent only on how many UEs there are in the cell but also

on the geographical distribution of the UEs.

Despite orthogonal codes, the downlink channels cannot be perfectly separated due to multi-

path propagation. This means that a fraction of the BS power will be experienced as interference.

Also, the downlink interference, caused by neighboring base stations transmitting channels non-

orthogonal with the serving base station, is user equipment position dependent.

Typical parameter values have been used and 20% of the power has been allocated to control

channels. A homogenous user distribution has been assumed. To account for non-homogenous

distributions and log-normal fading a 5 W headroom has been used. Thus the curves are based on

a total power Ptot,s of 15 W instead of 20 W. This roughly corresponds to 95% coverage

probability.

Figure 6.4 Example of capacity versus cell range in an urban environment. Each curve

corresponds to a certain downlink margin (DLmarg) [8].

Loading %

DLmarg

Cell Range in Km

Urban 3 sector site



6.4.2 Downlink Link Budget

A downlink link budget is obtained by determining DLmarg according to the following equation.

All units are in dB:

DLmarg = BL + CPL + BPL + ∆Gant + Lf+j + Lslant +LTMA + ∆Nf + ∆A0 …………………(6.15)

where:

BL is the body loss, 0 or 3 dB.

CPL is the car penetration loss, 6 dB.

BPL is the building penetration loss.

∆Gant is the difference in antenna gain compared to the value used in the curves: ∆ Gant =

17.5 – Gant where Gant [dBi] is the sum of the BS and the UE antenna gain.

L f+j is the loss in feeders and jumpers.

∆Nf is the difference in UE noise figure compared to the value used in the curves: ∆Nf =

Nf –7 (where Nf is the noise figure of the UE (7 dB recommended).

Lslant is the slant loss (1 dB) associated with cross-polarized antennas.

LTMA is the insertion loss of the TMA (if used).

∆A0 is the difference of the distance independent term, in Okumura Hata, compared to

the value used in the curves:

∆A0 = A0 – A0curves, (A0 = A – 13.82 logHb and A0curves is 134.7, Hb = 30 m in this case .)

Once DLmarg is determined it is possible to check what capacity and coverage that can be

obtained by using the graphs. 6.4.2.1 Tables of Mpole

Some approximate values of Mpole for a three-sector configuration. (Eb/Io value based on the RTT

submission to IUL).

Table 6.4. Downlink values of Mpole (three-sector site). [8]

RAB Pedestrian A Speech 12.2 kbps 110 Circuit 64 kbps 14

Packet 128 kbps 11



6.4.2.2 Downlink load limit

The values in Table 6.4 correspond to 100% system load. To secure a well performing network

the downlink load used in the dimensioning process should be of the order of 65-75% depending

on the implementation of radio network functionalities.

6.4.2.3 EXAMPLES

• Single service

The number of simultaneous voice users in an urban environment at a range of 1.5 Km is

calculated:

1. DLmarg is calculated to 25.7, using the DLmarg equation (6.15), with the following: assumptions:

Service: Speech 12.2 kbps

Body loss BL 3 dB

Car penetration loss CPL 0 dB

Building penetration loss BPL 18 dB

Antenna gain Gant 17.5 dBi

Feeder and jumper loss Lf+j 5 dB

Slant loss Lslant 1 dB

TMA insertion loss LTMA 0.4 dB

UE noise figure Nf: 7 dB

Antenna height 40m

A0 = 155.1 – 13.82log40 = 133 (see 6.11) 2. In Figure 6.4, the relative load at which the curve for DLmarg = 25 dB crosses the 1.5 km range

is found: approx. 40%. This is below the maximum load limit.

3. The Mpole value for Speech 12.2 kbps is found in Table 6.4 i.e : 110 users.

4. Finally, the supported relative load is calculated: 110 x 0.4 ≈ 44 simultaneous users.

Thus, one cell would be able to support approximately 44 simultaneous voice users using the

assumptions stated above. [8]



• Mixed Services

In the same way as for the uplink, the total load can be distributed amongst different services

according to equation. If instead of the 44 speech users at 40% loading, as calculated in the

example earlier, the load is shared between data users and speech users, the number of

simultaneous users changes. At 50% Circuit 64 kbps users and 50% speech 12.2 kbps users, the

number of simultaneous users can be calculated using equation 6.5 :

Five voice users and five CS 64 kbps users can use the resources simultaneously.

0.5 x 14

0.4 0.5 x = 110

x = 9.9 M1 = M2 = 4.9 ≈5 +



6.5 Link Budget Margins

This section describes the purpose and the values of the margins that have been used in the

formulas in previous sections. In an ideal situation the maximum possible path loss between a

RBS and an UE would be the difference between the output power of the UE and the RBS

sensitivity. However in a network design, various margins must be added in order to cater for

such things as body loss and fading. These margins are:

6.5.1 Log –Normal Fading

The signal strength value predicted by wave propagation algorithms can be considered as a

mean value of the signal strength in a small area. The value is determined by the resolution and

accuracy of the model. Assuming that fast fading has been removed (averaged out), the local

mean value of the signal strength fluctuates in a way not modeled in the prediction algorithm.

This deviation of the local (measured) mean has nearly a normal distribution in dB, compared to

the predicted mean. Therefore this variation is called lognormal fading.

In the result from a prediction in for example WCDMA planner, 50% of the locations (for

example at the cell borders) can be considered to have a signal strength that exceeds the

predicted value. In order to plan for more than 50% probability of signal strength above the

threshold, a lognormal fading margin, LNFmarg, is added to the threshold during the design

process. [8]

The value of the required margins has been determined through simulations. For a typical

urban environment and 95% probability of coverage a lognormal fading margin of

approximately 4 dB is easily derived from Figure 6.5.



Figure 6.5 Lognormal fading margins. Handover gain is included in these curves. [8]

6.5.2 Handover gain

The log-normal fading margins presented above reflect the case where the UE has the

possibility to make soft handover to other cells when experiencing poor coverage. Allowing

handover means that the log-normal fading margins can be reduced as compared to the single

cell case. This reduction is referred to as handover gain and is included in the values for log-

normal fading margins. [8]

6.5.3 Power Control Margin

In a WCDMA system fast power control (1500 Hz) is employed. For slowly moving UEs the

power control has the ability to compensate for the fast fading, thus reducing the Eb/Io. However,

due to the characteristics of the fast fading, more power will be required in the fading dips than



the corresponding reduction in the fading tops. The result is that each UE (BS), has to increase

its average power in order to combat fast fading. This effect is called TX increase. Sensitivity

degradation for UEs located at cell borders also appears, since the UE power control at cell

borders no longer can fully compensate for fading dips. To cater for the combined effect of TX

increase and the sensitivity degradation at cell borders a power control margin PCmarg of

typically 2 .0 - 5.0dB is used in the link budget. It is sometimes considered as Fast Fading

Margin. [8]

6.5.4 Slant Loss

A drawback of cross-polarized antennas is that the propagation characteristic of the horizontal

component is somewhat worse than for the vertical component. Therefore, if cross-polarized

antennas (two antenna arrays with ±450 polarization) are used, a “slant loss” of 1 dB should be

added to the propagation.

DL slant loss Lslant = 1 dB

6.5.5 Body Loss

The human body has several negative effects on the UE performance. For example the head

will absorb energy, and the antenna efficiency of some UEs can be reduced. To cater for these

effects a margin for body loss has to be included in the link budget. The body loss margin

recommended by ETSI is 3 dB.

Generally, body loss is not applied for data services since the users will most likely not have the

terminal by the ear. [8]

Body loss for data services BLdata = 0 dB

Body loss for speech services BL = 3 dB



6.5.6 Car Penetration Loss

When a UE is placed in a car without external antenna, an extra margin has to be added in order

to cope with the penetration loss to reach inside the car. This extra margin is approximately 6 dB.

Car penetration loss CPL = 6 dB

6.5.7 Indoor Margins

By indoor coverage is understood the percentage of the ground floors of all the buildings in the

area where the signal strength is above a required signal level. Indoor coverage in this concerns

calculation of that required margin to achieve a certain indoor coverage in a fairly large area

compared to the average macro cell size. It is assumed that it is the macro cells in the area that

provides the major part of the indoor coverage. Hotspot micro cells in the area will of course

improve on the indoor coverage but that effect is not considered here. [8]

6.5.7.1 Building penetration loss

Building penetration loss is defined as the difference between the average signal strength

immediately outside the building and the average signal strength over the ground floor of the

building. Typical values of the mean building penetration loss, BPL, are given in Table 6.

Table 6.5 Typical values of building penetration loss, and log-normal fading environment

classification parameter σ LNF for different area types. [8]

The building penetration loss for different buildings is log-normally distributed with a standard

deviation of σBPL. Variations of the loss over the ground floor could be described by a stochastic

Environment BPL [dB] σ σ σ σ LNF(o ), [dB] σσσσ LNF(i ), [dB] σσσσ LNF(o+i ), [dB]

Dense urban 18 10 9 14Urban 18 8 9 12Suburban 12 6 8 10



variable, which is log-normally distributed with a zero mean value and a standard deviation of

σfloor.

Here σBPL and σfloor is lumped together by adding the two as were they standard deviations in two

independent log-normally distributed processes. The resulting standard deviation, indoor or

σ LNF(i), could be calculated as the square root of the sum of the squares. Typical values of σ LNF(i)

are presented in Table 6.5.

The total log-normal fading is composed of both the outdoor log-normal fading, σ LNF(o),and the

indoor log-normal fading outdoor σ LNF(i).The total standard deviation of the log-normal fading

is given by the square sum:

Values of σ LNF(o+i) are presented in Table 6.5. These are the values that should be used in the link

budgets when calculating the LNFmarg, required to achieve a certain area coverage probability

indoor. [8]

6.5.8 Interference Margin

The interference margin is needed in the link budget because the loading of the cell, the load

factor, affects the coverage. The more loading is allowed in the system, the larger is the

interference margin needed in the uplink, and the smaller is the coverage area. For coverage-

limited cases a smaller interference margin is suggested, while in capacity-limited cases a larger

interference margin is used. In the coverage-limited cases the cell size is limited by the

maximum allowed path loss in the link budget, and the maximum air interface capacity of the

base station site is not used. Typical values for the interference margin in the coverage-limited

cases are 1.0 -3.0 dB, corresponding to 20 to 50% loading. [8]

σ LNF(o) 2 + σ LNF(i) 2 σ LNF(o+i) =



7. LINK BUDGET –Examples

7.1 Maximum allowed Path Loss for – 12.2 kbps

As the coverage is normally “uplink limited” we shall use equation 6.9 to calculate the maximum

pathloss. The sample link budget illustrated in the table 7.1 is for 12.2 kbps voice service for in

vehicle users at speeds of 120 Km /hr, which allows for the soft handovers and also includes an

6 dB loss for in car use. [1]


12.2 Kbps voice Value Formula UnitUEMaximum UE TX power 0.25 WMaximum UE TX power 21 PUE dBmBase StationThermal Noise Density -174 Nt dBm/Hz

BS receiver noise figure without TMA 4 Nf dB

Service Rate of RAB (excluding retransmission) 12200 Ruser Bits /SecEb/Io (ref: Table 6.1) 4.2 Eb/Io dBRadio Base Station SensitivityRBSsens= Nt + Nf+10.log(Ruser)+Eb/Io -124.9 RBSsens dBmNoise RiseSystem Loading 50 Loading %Noise rise = 10.log (1/1-50%) 3 IUL dBFading MarginCoverage Probability 95 %Log normal fading margin @ 95 % from fig 6.5 4 LNFmarg dB

Fast fading 2 PCmarg dBSoft handover margin (included in LNFmarg)LossesBody Loss 3 BL dBFeeder and jumper loss 2 Lf+j dBGainRBS antenna gain 17.5 GRBS-ant dBi

UE antenna gain 0 GUE- ant dBiCollective gain Gant = GRBS-ant +GUE-ant 17.5 Gant dBiIn car penetration loss 6 CPL dBMaximum pathloss (In car) from equation 6.9 143.4 Lpathmax-Incar dB

Table7.1 Link budget example 12.2 kbps voice



7.2 Maximum allowed Path Loss for – 144 kbps

The sample link budget illustrated in the table 7.2 is for an 144 kbps data service for indoor user,

which allows for the soft handovers and also includes an 18 dB loss for in building usage.

144 Kbps Data (Inbuilding coverage) Value Formula UnitUEMaximum UE TX power 0.25 WMaximum UE TX power 24 PUE dBmBase StationThermal Noise Density -174 Nt dBm/Hz


Service Rate of RAB (excluding retransmission) 14400 Ruser Bits /SecEb/Io (ref: Table 6.1) 1.5 Eb/Io dBRadio Base Station SensitivityRBSsens= Nt + Nf+10.log(Ruser)+Eb/Io -116.9 RBSsens dBmNoise RiseSystem Loading 50 Loading %Noise rise = 10.log (1/1-50%) 3 IUL dBFading MarginCoverage Probability 95 %Log normal fading margin @ 95 % from fig 6.5 4 LNFmarg dB


UE antenna gain 2 GUE- ant dBiCollective gain Gant = GRBS-ant +GUE-ant 19.5 Gant dBiBuilding Penetration Loss 18 BPL dBMaximum pathloss (In door) from equation 6.9 131.4 Lpathmax-Indoor dB

Table7. 2 Link budget example 144 kbps



7.3 Maximum allowed Path Loss for – 384 kbps

The sample link budget illustrated in the table 7.2 is for an 144 kbps data service for indoor user,

which allows for the soft handovers and also includes an 18 dB loss for in building usage.

384 Kbps Data (Indoor User) Value Formula UnitUEMaximum UE TX power 0.25 WMaximum UE TX power 24 PUE dBmBase StationThermal Noise Density -174 Nt dBm/Hz


Service Rate of RAB (excluding retransmission) 384000 Ruser Bits /SecEb/Io (ref: Table 6.1) 1 Eb/Io dBRadio Base Station SensitivityRBSsens= Nt + Nf+10.log(Ruser)+Eb/Io -113.2 RBSsens dBmNoise RiseSystem Loading 50 Loading %Noise rise = 10.log (1/1-50%) 3 IUL dBFading MarginCoverage Probability 95 %Log normal fading margin @ 95 % from fig 6.5 4 LNFmarg dB


UE antenna gain 2 GUE- ant dBiCollective gain Gant = GRBS-ant +GUE-ant 19.5 Gant dBiBuilding Penetration loss 18 BPL dBMaximum pathloss (In door) from equation 6.9 127.7 Lpathmax-Indoor dB

Table 7. 3 Link budget example 384 kbps



7.4 Cell Size Calculation Once the maximum path is calculated we can compute the maximum cell range for urban

environment, using equation 6.14.

R = 10 α , where α = [Lpathmax – 155.3 + 18 log(Hb – 17)]/38………………..……..………..(6.14)

• For 144 Kbps sevice

R = 10[Lpathmax – 155.3 + 18 log(Hb – 17)]/38

Hb = Node B antenna height is taken 30 m R = 10[131.4 – 155.3 + 18 log(30 – 17)]/38

R = 0.8 Km

• For 384 Kbps sevice

R = 10[Lpathmax – 155.3 + 18 log(Hb – 17)]/38

Hb = Node B antenna height is taken 30 m R = 10[127.7 – 155.3 + 18 log(30 – 17)]/38

R = 0.6 Km

Figure 7.1 Cell coverage comparision

As we can see from the figure 7.1 the radio coverage of a cell varies for different services. Which

creates a major concern while planning a UTRAN network.

Cell range for 384 Kbps service = 600 Mts.

Cell range for 144 Kbps service = 800 Mts.

Base station



7.5 Calculation of number of sites required in a region

At this point is would be useful to examine through an example the number of sites required in a

region

Example : a network to be designed that should cover an area of 1000 km 2

The base station to be used are 3 sectored. Each sector (cell) covers a range of 1.2 Km

Thus, area covered by each site = k*R 2

Where k= 1.95

Area covered by each site= 1.95 *1.2 2 = 2.8 KM2

Thus : total number of sites = 1000/17.55 = 357.14 � 357 sites.



8. EXPANDING CAPACITY BY CONFIGURATION MODIFICATION

8.1 Adding new frequency carriers

An obvious and straightforward expansion method to improve the system’s performance is to

add new frequency carriers. Going from one to two frequency carriers, the planned capacity is

roughly doubled.

Expanding a three-sector site from one to two frequency carriers can be achieved without

adding a new cabinet at the site, for the indoor cabinet solution. Adding a third or a fourth carrier

if that much spectrum has been assigned in the license will of course further expand the capacity

in the system. [32]

8.2 Increase number of sectors

An alternative to adding new frequency carriers when expanding the network is to increase the

number of sectors. An obvious possibility is to go from three to six sectors. The sectorisation can

of course also be increased even further.

When increasing the number of sectors, the antenna beams will be narrower, which leads to

higher antenna gain. By reducing the beam width to a half, the gain is increased approximately

with 3 dB.

Further, adding more sectors also means that the site can handle more traffic. The

improvements that are achieved, when going to six sectors, can be used to improve coverage,

capacity or both of them. If the planned load in a sector exceeds 50-60%, advanced radio

network functionality is needed. [32]



8.3 Using repeater solutions

Adding power, adding new frequencies and increasing the number of sectors can all be used to

improve the coverage in the system. Another alternative, for increasing the coverage, is to use

repeater solutions, i.e. RF repeaters or optical distribution systems. Both of them can be used for

coverage gap filling as well as augmenting the coverage area of a given sector.

The characteristic of a coverage gap filling is that the area to fill often is surrounded by the

sector communicating with the repeater, e.g. indoor locations or tunnels. While when

augmenting, or moving, the shape of the sector is altered, for instance when extending highway

coverage. [33]

8.4 Adding distributed antennas

Distributed antennas can be used to increase both coverage and capacity. In cases where the

traffic concentration is quite low, each antenna can be allowed to transmit the same signal. While

for areas with high capacity demand, more advanced functionality is required, so that the signal

intended for a certain user is transmitted to the antennas close to that user. By doing that, the

interference level in the system is reduced.

In areas with distributed antennas, the interference level in the system is very low, as the users

always are close to at least one antenna. This means that RBSs with distributed antennas can be

deployed in frequency bands that are already used by another RBS. Further, if the distributed

antenna system is located

8.5 Sites Addition

Adding new sites can be used to improve the coverage, the capacity or both of them.



8.6 Cell split

Assuming that the number of sites in a certain area is doubled, then the area covered by each

cell is half as large as previously. The added sites can be used for increasing coverage (for high

bit rate services at the cell border), capacity or both of them.

If the focus is on coverage, then the system with the added sites can offer full area coverage for

services using higher bit rates. This means that full area coverage for 64 kbps best effort services

can be expanded to full area coverage for 128 kbps best effort services. [33]

8.7 Layered Network

A layered network simply means that there exists different cell layers in the system, i.e. macro

layer, micro layer and perhaps also a pico layer. One simple approach of a layered network is to

have a macro layer and then deploy micro base stations in a separate band in the high traffic

demand areas.

One special example of a layered network is hot spot deployment. A hot spot is defined to be a

very limited area, typically a few blocks, with very high load. One example of handling local hot

spots is to add sites in an already used frequency band. [33]



9. PRODUCT EVOLUTION

Additional features for boosting coverage as well as capacity will be introduced in the future.

Some of the important methods for improving the performance that various companies studying,

are listed below.

9.1 Adaptive Antenna

Adaptive antenna arrays is a technology that will boost both capacity and/or Coverage.

Investigations are ongoing with field trials among many other tests to evaluate this technique.

The adaptive antenna gives better performance in both up- and downlink. [8]

9.2 Interference Cancellation

Interference cancellation (IC or Multi-User Detection) is another promising technology, which

could improve up-link capacity. This will give a capacity benefit mainly in the up-link. [8]

9.3 Transmit Diversity

Transmit diversity has initially been studied in both ARIB and ETSI and the work is now

continued in 3GPP. It has been shown through simulations that transmit diversity provides a

significant gain in some scenarios. [8]



10. CONCLUSION & FUTURE WORK

Network Planning is a major task for operators. It is both time consuming and labor intensive

& it is expensive. Moreover, it is never ending process, which forces a new round of work with

each step in the network’s evolution and growth. Sometimes extra capacity is needed temporarily

in a certain place, and network planning is neded to boost the local capacity.

Tight and fast power control is one of the most important aspects in WCDMA, in particular on

the uplink. Without it, a single overpowered mobile could block a whole cell. A care needs to be

taken while degining a network

The quality of network planning process has a direct influence on the operator’s profits. Poor

planning results in a configuration in which some places are awash in used or underused capacity

and some areas may suffer from blocked calls because of the lack of adequate capacity. The

income flow will be smaller than it could be, some customers will be unhappy, and expensive

equipment may possibly be bought unnecessarily.

The detailed network planning phase includes the exact design of the radio network . Quite

often it is not possible to obtain the optimum cell site. The owner of the site may not want to sell

it, it may be unusable (e.g. in the middle of a pond) , or located in a restricted area.

Environmental and health issues can also have an impact . Base station towers in an open

country landscape may irritate some people. All these issues have to be taken into

considerations. The number of Handovers has to be minimised as it creates signalling traffic in

the network. This can be done for example with large macrocells. Sectorisation has to be

considered and implemented when required.



This report has covered the main issues associated with coverage, breaking down link budget

along with the required specific parameters and providing some examples of expected coverage

ranges. Interference and all important fading margin have been discussed, including soft hand

over gains, Eb/No, and the processing gain. Both coverage and capacity with relation to link

budget have been revived. Further topic such as maximum allowed path loss calculation for

different bit rate have also been given.

In UMTS different services have different SNR requirement, which has made 3G network

planning a complex balancing act between all the variables in order to achieve the optimal

coverage, capacity and Quality of Service simultaneously. The obtained methods of effective 3G

planning may be considered as a basis for software design, in order to automate the planning

process.

FUTURE WORK

There are several investigations that could follow to develop the work carried out in this

project. An important extension could be the actual designing of software based on the methods

described in the report for calculation of RAN parameters and then simulating results on a

simulation software like OPNET.



REFERENCES

[1] Chris Braithwaite & Mike Scott, ‘UMTS Network Planning and Development’, Design

and Implementation of the 3G CDMA Infrastructure, First edition, Newnesress 2004.

[2] Ajay Ranjan Mishra,’ Fundamentals of Cellular Network Planning and Optimisation:

2G. 2.5G. 3G. Evolution to 4G’, First Edition, John Wiley and sons Ltd. 2004.

[3] Qualcomm UMTS University Technology Journal [Online]

Available: http://www.umtsuniversity.com/umts/

[4] Journal on “UMTS Radio Interface System Planning and Optimization” from Bechtel

Telecommunications December 2002 by Esmael Dinan; Kurochkin; Sam Kettani.

[5] UMTS system Architecture [Online]

Available: http://www.ericsson.com/pl/technology/umts_struktura_sieci.shtml

[6] Overview of The Universal Mobile Telecommunication System [Online]

Available: http://www.umtsworld.com/technology/overview.htm

[7] UMTS elements description [Online]

Available:www.mpirical.com/companion/UMTS/Node_B.htm

[8] WCDMA Radio Network Design, Training LZU 108 5173 R4A, from Ericsson inc

Sweden [Online]

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MI_material/32_1550-FAP130506_WCDMA_RAN P2_1.pdf

[9] Web ProForum Tutorials (http: //www.iec.org) The international Engineering

Consortium. [Online]

Available: http://alpha.ttt.bme.hu/~szaszi/mobil/9UMTS.PDF

[10] UMTS OTSR White paper from Nortel [Online]

Available:http://www.nortel.com/solutions/wireless/collateral/nn_110660.01-17-

05.pdf?NT_promo_T_ID=utranpdf_wls_docs_new



[11] 3G Technology Breakdown [Online]

Available: http://www.cellular-news.com/3G/3g_technology.shtml

[12] Heikki Kaaranen, Ari Ahtiainen, Lauri Laitinen, Siamak MAghian and Valtteri Niemi,

‘UMTS Networks’, Architecture, Mobility and Services, First Edition, John Wiley and

Sons Ltd., 2001.

[13] Krzysztof Welsolowski, ‘Mobile Communication Systems’, First Edition, John Wiley

and Sons Ltd., 2002.

[14] Wideband Code Division Multiple Access [Online]

Available: http://www.ericsson.com/technology/tech_articles/WCDMA.shtml

[15] Electronics & Communication Engineering Journal June 2000 “UMTS overview” by

K. W. Richardson.

[16] White Paper on “Basic Concepts of WCDMA Radio Access Network”. [Online] Available: http://www.ericsson.com/products/white_papers_pdf/e207_whitepaper_ny_k1.pdf

[17] Workshop proceedings “Cellular Networks - Past, Present and Future”2004-2005 by

Uday Raktale, School of Engineering, Design and Technology, University of Bradford

[18] Online Tutorial on “Cellular Communication Fundamentals” from International

Engineering Consortium [Online]

Available: http://www.iec.org/online/tutorials/cell_comm/

[19] Ph.D Thesis on “Intermodulation interference probabilities in cellular mobile radio

systems : development of prediction methods for - due to intermodulation originating in

both transmitters and receivers” by Hu Yim Fun 1987, University of Bradford.

[20] William C Y Lee, ‘Mobile Cellular Telecommunication’, Macgrawhill, Second Edition,

2002

[21] COST231, final report, 1999.



[22] PhD thesis on Radio Network Planning and Optimization for WCDMA by Jaana Lahio

July 2002, Helsinki University of Technology (Espoo, Finland)

[23] Public Land Mobile Network Network Cell Planning [Online]

Available: http://www.ericsson.com/support/telecom/part-d/d-10-4.shtml#d.10.4.1

[24] Air Interface Design and Optimization Services: Nominal Cell Planning [Online]

Available: http://www.grm33.dial.pipex.com/what_we_do/air-interface/ncp.htm

[25] Juha Korhonen, ‘Introduction to 3G Mobile Communication’, First Edition, Artech

House Publisher, Boston London., 2000

[26] Ph. D Thesis on “Quality of Service and Resource Management in UMTS”, by Frank Y.

Li Department of Telematics, Norwegian University of Science and Technology (NTNU)

[27] Publication Proceedings submitted on “Quality of Service Support in the UMTS

Terrestrial Radio Access Network” by Ana-Belén García, Manuel Alvarez-Campana,

Enrique Vázquez, Julio Berrocal of Departamento de Ingeniería de Sistemas Telemáticos,

Ciudad Universitaria, 28040 Madrid, Spain

[28] Samuel C. Yang, "CDMA RF System Engineering (Artech House Mobile

Communications Library)", Artech House Publishers, 01 May, 1998.

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[30] Aircom International “Applied UMTS Planning for Experienced Radio Engineers” 5

days training.

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cdma2000 network for voice and packet data services” of SK Telecom Network R&D

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IEEE VTS 54th



[32] Laiho, Wacker, Novosad “Radio Network Planning and Optimisation for UMTS”, First

edition, John Wiley and Sons Ltd., 2005

[33] Jonathan P Castro, ‘The UMTS Network and Radio Access Technology’, First Edition,

John Wiley and Sons Ltd., 2001



GLOSSARY:

2G the second (Cellular) generation

3G the third (cellular) generation

AuC authentication centre

BS base station

CDMA code division multiple access

Eb energy per bit

GGSN (Gateway GPRS [General Packet Radio System] Support Node)

SGSN Serving GRPS support node

GMSC gateway mobile service switching centre

GPRS general packet radio service

GSM global system for mobile communication

HLR home location register

Lu interface between RAN and node B

Kbps kilobits per second

Mcps mega chips per second

Node B base station in 3G

PSTN public –switched telephone network

PLMN public land mobile network

RAKE type of receiver utilizing multi-path propagation

RNC radio network controller

RNS radio network subsystem

RX receiving functionality/receiver

SIR signal to interference ratio

SNR signal to noise ratio

UE user equipment

UMTS universal mobile telephone system

UTRAN universal terrestrial radio access network

Uu Interface between the UE and Node – B

VLR visitor location register

W-CDMA wideband code division multiple access

umts ran planning by uday raktale

Documents