Open access femtocell business feasibility with TV White …570126/FULLTEXT… · · 2012-11-16Open access femtocell business feasibility ... Open access femtocell business feasibility

Open access femtocell business feasibilitywith TV White Space usage

For mobile indoor broadband

CHRISTODOULOS CHIRAS

Master of Science ThesisStockholm, Sweden 2012

Open access femtocell business feasibilitywith TV White Space usage

For mobile indoor broadband

CHRISTODOULOS CHIRAS

Master of Science Thesis performed at

the Radio Communication Systems Group, KTH.

September 2012

Examiner: Prof. Jens ZanderSupervisor: A/Prof. Jan Markendahl

KTH School of Information and Communications Technology (ICT)Radio Communication Systems (RCS)

TRITA-ICT-EX-2012:228

c© Christodoulos Chiras, September 2012

Tryck: Universitetsservice AB

Abstract

Femtocell technology and TV White Space are two different entities that havenot been thoroughly researched under the common goal of indoor mobile broad-band access. In this thesis the combination of these two technologies is examinedthrough the prism of four different actors: Mobile Network Operator, FacilityOwner, Wi-Fi operator and TV White Space Only operator.

The aim is to discover access benefits and evaluate the business feasibility ofopen access femtocell networks using TV White Space for each individual actor.The work done, differs from related papers which focus on interference analysis,technical design and MNO deployment schemes as by using the business feasi-bility analysis both technological and economic aspects are taken into accountfor new market players as well.

It is shown with no doubt that national roaming agreements is one of themost important aspects any market player should take into account before pro-ceeding with any business plan. Additionally, the analysis found that the sec-ondary usage of TV white space is technologically and economically feasiblebut no solid benefits were identified that can overthrow existing indoor mobilebroadband implementations like the Wi-Fi systems. However the primary usageof femto-TVWS is still recommended for some actors like the mobile networkoperator and the facility owner and the complimentary usage by the Wi-Fioperator.

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Acknowledgements

For the production and completion of this thesis it took a lot of sucrifices notonly from my self but also from my family and friends. Thus at this point iwould like to express my graditute towards my family for the continious supporttowards the long course of my studies abroad. Also i would like to salute all thegreat people i met during my visit in Sweden and especially Ilias Karonis for hisubiquous and non-stop aid during the thesis construction. Last but not least,special thanks to the wireless department of KTH for the wonderfull hospitalityand my supervisor Mr. Jan Markendahl for all his guidance, advices and un-derstanding.

Christodoulos ChirasStockholm, September 2012

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Contents

1 Introduction 11.1 Problem Formulation . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Related Work and Contribution . . . . . . . . . . . . . . . . . . . 21.3 Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Methodology 52.1 Work FLow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.2 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.3 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.4 Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.4.1 Primary Data- Expert Interviews . . . . . . . . . . . . . . 62.4.2 Secondary Data - Research and analysis of relevant scien-

tific work . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.5 Business Feasibility Analysis . . . . . . . . . . . . . . . . . . . . 8

3 Background 93.1 Access Network Architecture . . . . . . . . . . . . . . . . . . . . 11

3.1.1 Legacy Iub over Ip . . . . . . . . . . . . . . . . . . . . . . 113.1.2 Concentrator . . . . . . . . . . . . . . . . . . . . . . . . . 113.1.3 GAN (Generic Access Network)-based RAN Gateway . . 123.1.4 IMS and SIP . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2 Air-interface technologies . . . . . . . . . . . . . . . . . . . . . . 153.2.1 GSM Femtocells . . . . . . . . . . . . . . . . . . . . . . . 153.2.2 UMTS and HSPA Femtocells . . . . . . . . . . . . . . . . 163.2.3 OFDM-based Femtocells . . . . . . . . . . . . . . . . . . . 17

3.3 Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.3.1 Co-layer Interference . . . . . . . . . . . . . . . . . . . . . 183.3.2 Cross-layer Interference . . . . . . . . . . . . . . . . . . . 19

3.4 Mobility Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . 203.4.1 Femtocell characterization . . . . . . . . . . . . . . . . . . 213.4.2 Femtocell identification . . . . . . . . . . . . . . . . . . . 223.4.3 Access control mechanisms . . . . . . . . . . . . . . . . . 223.4.4 Local Area Identity/Tracking area Identity . . . . . . . . 223.4.5 Closed Access Mode ID . . . . . . . . . . . . . . . . . . . 233.4.6 Allowed Access List . . . . . . . . . . . . . . . . . . . . . 233.4.7 Access Control Triggers . . . . . . . . . . . . . . . . . . . 233.4.8 Access Control Location . . . . . . . . . . . . . . . . . . . 243.4.9 Access control for Open, Closed and Hybrid mode . . . . 24

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viii Contents

3.5 Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.5.1 Licensed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.5.2 Unlicensed . . . . . . . . . . . . . . . . . . . . . . . . . . 253.5.3 TV White Space . . . . . . . . . . . . . . . . . . . . . . . 25

3.6 Wi-Fi Sollution - An overview . . . . . . . . . . . . . . . . . . . . 263.6.1 Wi-Fi 802.11af (Wifi using TVWS) . . . . . . . . . . . . . 273.6.2 Femtocell Wi-Fi integration . . . . . . . . . . . . . . . . . 27

3.7 ZeroShell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.8 3rd Party Payment System . . . . . . . . . . . . . . . . . . . . . 28

4 Business Feasibility Analysis 314.1 Preliminary asset analysis . . . . . . . . . . . . . . . . . . . . . . 31

4.1.1 Asset analysis . . . . . . . . . . . . . . . . . . . . . . . . . 324.2 Model Construction and Cost Calculation . . . . . . . . . . . . . 37

4.2.1 Mobile network operator using TV White Space . . . . . 384.2.2 Facility owner using licensed spectrum . . . . . . . . . . . 394.2.3 Facility owner using TV white space spectrum . . . . . . 394.2.4 Facility Owner Cost Estimation . . . . . . . . . . . . . . . 424.2.5 Wi-Fi operator using TV white space spectrum . . . . . . 444.2.6 TV white space only operator . . . . . . . . . . . . . . . . 45

4.3 Results-Actor Specific . . . . . . . . . . . . . . . . . . . . . . . . 464.3.1 MNO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 464.3.2 Wi-Fi operator . . . . . . . . . . . . . . . . . . . . . . . . 474.3.3 FO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.3.4 TVWSO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

5 Conclusions and Future work 495.1 Research questions answers . . . . . . . . . . . . . . . . . . . . . 49

5.1.1 A more abstract perception . . . . . . . . . . . . . . . . . 505.2 Discussion & Future Work . . . . . . . . . . . . . . . . . . . . . . 51

Bibliography 53

A Interviews 57A.1 Interview with Tord Sjolund, President of Mic Nordic . . . . . . 57A.2 Interview with Orjan Fall, Vice-president of 3GNS . . . . . . . . 57A.3 Interview with Panayiotis Chiras . . . . . . . . . . . . . . . . . . 58

List of Tables

2.1 Interview respondents list . . . . . . . . . . . . . . . . . . . . . . 7

4.1 Asset analysis for mobile network operator . . . . . . . . . . . . . 334.2 Asset analysis for Facility Owner . . . . . . . . . . . . . . . . . . 354.3 Asset analysis for Wi-Fi operator . . . . . . . . . . . . . . . . . . 364.4 Asset analysis for TV-shite space only operator . . . . . . . . . . 37

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List of Figures

3.1 Architecture of GAN-based HNB . . . . . . . . . . . . . . . . . . 133.2 From smallcell forum white paper on Integrated Femtocell Wifi

systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.1 Low end present value calculation for years 3,4 and 5 . . . . . . . 434.2 High end present value calculation for years 3,4 and 5. . . . . . . 43

xi

List of Abbreviations

3GPP 3rd Generation Partnership Program

AAA Authentication Authorization and Accounting

AP Access Point

ACL Allowed Closed Access Mode List

AKA Authentication and Key Agreement

ARPU Average Revenue Per User

ATM Asynchronous Transfer Mode

BSC Base Station Controller

CAM Closed Access mode

CAPEX Capital Expenditure

CDMA Code Division Multiple Access

CINR Signal to Noise Ratio

CN Core Network

CPE Customer Premises Equipment

DAS Distributed Antenna System

EAP Extensible Authentication Protocol

EMS Enhanced Message Service

EUTRAN Evolved UTRAN

FBS Femtocell Base Station

FDD Frequency Division Duplexing

FMC Fixed Mobile Communications

GAN Generic Access Network

GANC Generic Network Access Controller

GSM Global System for Mobile communication

HAM Hybrid Access Mode

HCS Hierarchical Cell Structure

HLR Home Location Registry

xiii

xiv List of Abbreviations

HSS Home Subscriber Server

HNBS Home Node Bs

HNBGW Home Node B Gateway

HSDPA High Speed Downlink Packet Access

HSUPA High Speed Uplink Packet Access

IKE Internet Key Exchange

IMBA Indoor Mobile Broadband Access

IMS Ip Multimedia Subsystem

IMSI International Mobile Subscriber Identifier

LAC Local Area Code

LAI Local Area Identity

LAU Local Area Update

LTE Long Term Evolution

MBS Macro-cell Base Station

MGW Media Gateway Controller

MM Mobility Manager

NAS Non Access Stratum

MNO Mobile Network Operator

NCL Neighbouring Cell List

OAM Open Access Mode

OFDM Orthogonal Frequency Division Multiplex

OFDMA Orthogonal Division Multiple Access

OPEX Operational Expenses

PCI Physical Cell Identity

PSC Primary Scrabling Code

RADIUS Remote Authentication Dial-in Server

RAN Radio Access Network

RNC Radio Network Controller

RTP Real Time Transport Protocol

SA Security Association

SeGW Security Gateway

SGSN Serving GPRS Support Node

SNMP Simple Network Management Protocol

SIP Session Initiated Protocol

SINR Signal to Interference Noise Ratio

List of Abbreviations xv

SON Self Organizing Networks

SRG Signal Research Group

TDD Time Division Duplex

UE User Equipment

UMTS Universal Mobile Telecommunication System

UTRAN UMTS Terrestrial Radio Access Network

UARFCN UTRA Absolute Radio Frequency Channel Number

WAP Wireless Access Points

WCDMA Wideband CDMA

WiMAX WorldWide Interoperability for Microwave Access

WISP Wireless Internet Service Provider

QoS Quality of Service

Chapter 1

Introduction

Indoor mobile broadband access (IMBA) demand is on the rise and with con-tinuously technological breakthroughs the Internet becomes available almosteverywhere. While users get accustomed to this new any location internet ac-cess [32], new actors emerge and enter the IMBA market. The need for morecapacity and bandwidth can be achieved with new spectrum allocation bands.However spectrum is a finite, non-exhaustible costly resource [35], [36] and there-fore the use of secondary spectrum is a welcomed proposition. The secondaryuse takes advantage of un-used spectrum either in time, frequency or place.The so called TV White Space (TVWS) is the secondary spectrum under in-vestigation in this work. Traditionally, IMBA services are provided by outdoormacro base stations (MBS) or indoor systems like distributed antenna system(DAS) or Wi-Fi access points. However a new small cell technology called fem-tocell promises high quality indoor coverage and capacity with advantages overcompeting technologies.

Since the combination of these two technologies is not adequately inves-tigated neither by the academic nor by the industrial community, this thesispurpose it to examine for four different market actors the business feasibilityof open access femtocells using the available TVWS for IMBA services. Theresearch questions and methodology focus on the business roles, customer rela-tions, access mechanisms and payment options; aspects which current existingworks have not taken into account. The main analysis is based on interviewswith market experts inside and outside the telecommunication sector coveringboth technical and business perspectives.

The four actors taken into account are the Mobile Network Operator (MNO),the Facility Owner, the Wi-Fi Operator and a fictional entity called TV WhiteSpace Only operator (TVWSO). More information on these four actors is givenin chapter 4. It must be noted that this thesis will not pay any emphasison the Radio Access Network (RAN) components and cost nor the backhaulrequirements for network operation1. Secondary Usage . Specifically under in-vestigation are the changes in the access control (technical view) and marketingadaptation (business view) in a multitude of scenarios.

1This is mainly due to the reason that an ongoing parallel thesis is taking place preciselyfor this purpose so for more information on these topics visit Ilias Karonis thesis on RANEvaluation of LTE-Femtocell Deployment and TV White Space

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2 Chapter 1. Introduction

1.1 Problem Formulation

Incumbent actors in telecommunication industry are in search of new businessmodels as the legacy models become more and more mature and the prospectsof margin and profit decline. Towards this quest, there is a great motivation tostudy from a techno-economic point of view the potential access and financialbenefits, the usage of open access TV white space femtocells has to offer. Its theobjective of this thesis to find what scenarios are more promising than othersby conducting a relative analysis of what assets actors have or havent with anemphasis on customer relation and access control. In particular, based on abusiness feasibility analysis the main question to be examined is:

What are the access benefits that femtocells and TVWS have to offertowards selected actors and in which scenario(s)?

While the benefits and drawbacks for each proposed model will be outlinedin a trial to weight for or against each mode, from the main question four subquestions are derived:

1. What are the benefits of femtocell networks when the actor is MNO andthe spectrum band is TVWS?

2. What are the benefits of femtocell networks when the actor is Wi-Fi op-erator and the spectrum band is unlicensed or TV white space?

3. What are the benefits of femtocell networks when the actor is facilityowner and the spectrum band is licensed, unlicensed or white space?

4. Is there a business case for a mobile broadband TV white space operatoronly (TVWSO)?

1.2 Related Work and Contribution

Most literature study on indoor wireless systems focuses on interference analysisand technical design [47], [48] with little or no attention on the business aspectsand deployment of femtocells. Any proposed business models take into accountmainly the MNO as an actor and the analysis is on the deployment and tech-nical mechanisms. Like for example in [46], a techno-economic analysis of largescale projects like TERA and TONIC is performed from the mobile operatorsperspective with focus on deployment strategies. In addition white papers fromSmall cell Forum have as target group single operator small office home officeimplementations and focus only on licensed band implementations [50].

Business papers:

In [32] Mkitalo et al seek out what kind of market actor will be the most im-portant for the provisioning of public Internet access services and the mainfinding of the analysis is that public local access provisioning to a large extentdiffers from the traditional operator business and that actors from outside thetelecom sector slowly enter the telecom business with the main driver to sup-port the core business. In [33] Nilson et al define that a femtocell network can

1.3. Thesis Outline 3

be of four types: one single-operator femtocell network, multiple singe oper-ator networks, one multi operator network and multi operator solution basedon roaming. In [34] Peng Li et al have proposed two schemes to maximize aMNOs revenue with the first scheme handling cross tier channel allocation andinterference management for optimal revenue and with the second scheme op-timal pricing and spectrum scheduling are combined for revenue maximization.In [35] Markendahl et al focus on the importance of the multiple factors thatmust be taken into account when testing a business model for TVWS based onmacrocell networks with tower installation and operation, the conclusion wasthat even if the cost for cognitive radio equipment is the same as with the stan-dard base stations, the key issue is if new sites need to be deployed or not,that significantly increase the cost. It is for this reason that the indoor andlocal area network operation must be examined. In [37] Katsiyiannis et al, ana-lyze the business of local area access from the perspective of MNO and serviceapplication providers, constructing at the same time a techno-economic modelto quantify the costs and required revenues local area access networks operation.

Technical papers:

In [40] Guillaume de la Roche et al provide an overview of the existing accessmethods to femtocells and describe in detail the benefits and drawbacks of each.Furthermore, the business case, scenarios, and technical challenges of differentaccess mechanisms along with some potential solutions are presented. In [41]Yen Chen et al introduce and compare various femtocell network architecturesand also discuss various challenges the introduction of femtocells brings like in-teroperability with networks and handsets with potential solutions to addressthese issues.

This thesis contribution is the proposition and evaluation of open access busi-ness scenarios for four different actors: MNOs, wireless internet access providers,facility owners and TV white space only operator (TVWSO). The proposed sce-narios are SWOT analyzed to identify potential techno-economic benefits andalso cost calculations (CAPEX and OPEX) for the AAA implementation re-quirements are performed in some cases. The analysis also takes other aspectsinto account like marketing, customer acquisition and service provisioning forindoor femtocell solutions with licensed, unlicensed, and white space spectrumusage. The consideration of the Wi-Fi operator, Facility Owner and TVWSO asactors for indoor and local area TVWS usage from the double techno-economicview is a new underexplored area that justifies the work of this thesis.

1.3 Thesis Outline

Chapter 1 contains introductory information to the problem area with the re-search questions formulation at Chapter 1.1 and the related work at Chapter1.2.

In Chapter 2, the methodology followed and applied is provided with detailsabout the work flow of this thesis, on what technologic assumptions thesis isbased on, the data collection methods. Additionally the business feasibilityanalysis is explained and broken down to its core components.

Chapter 3 contains all the background information related to the problem

4 Chapter 1. Introduction

area and shows the complexity of the research area from a technical perspective.In Chapter 4 -the corner stone of this thesis- combines all the data collection

from both technical and economical view with an aim to answer the researchquestions.

In Chapter 5, the conclusions and answers to the research area are given. Ageneral discussion about the thesis work is given at Chapter 6.

Chapter 2

Methodology

This thesis took into account various existing indoor mobile broadband solutionsand actors and compared these solutions under SWOT analysis to define thebest business feasibility models. In this section the overall work flow, the datacollection, the used models, assumptions and the approach for the businessmodeling and analysis are described.

2.1 Work FLow

The results in this paper have been obtained by doing the following work items:

1. Identify different technical indoor solutions for IMBA.

2. Identify and contact market actors that can provide information on thetechnical solutions and/or the related business models and types of coop-eration.

3. Perform a round of interviews and discussions with facility owners, localoperators, Wi-Fi operators and industry experts.

4. Analyze and describe the business models by using the business feasibil-ity tool; a custom tool that is made up by three stages: a) preliminaryasset analysis, b) Model construction and cost calculation and c) SWOTanalysis

2.2 Assumptions

In this thesis, it is assumed that a femtocell radio access network exists thatis fully functional and the CAPEX and OPEX cost for the installation andoperation of the radio access network is not taken into account for any of theinvestigated scenarios1. In section 4.2 where cost calculation takes place onlythe extra software and hardware required for the AAA are included. What ismore, the analysis will make use of ideal conditions such as working technology,demand for a service and paying customers. The analysis that takes place

1For more information on these topics visit Ilias Karonis thesis on RAN Evaluation ofLTE-Femtocell Deployment and TV White Space

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6 Chapter 2. Methodology

in the business feasibility analysis tool is technologically neutral and assumescooperation between the network components. Also, any co-operation amongactors is possible with no regulatory restrictions.

These assumptions followed an optimistic approach that examined a best-case scenario for the TVWS secondary usage and unlicensed band operation.If the deployment and operation of a TVWS-based or unlicensed-based femtoRAN turn up to be unattainable or bear no substantial benefits under these idealconditions, then there would be no real motivation for the venture. In contrast,a promising techno-economic RAN model case proven under ideal assumptionswould not eradicate underlying problems. As most of the aforementioned issueswere crucial for the overall network evaluation, the above assumptions wereremoved during the SWOT and qualitative analysis procedures.

In addition, it must be stated that the benefits and advancements of femtocellbase stations and TV white space which this thesis is in search of are from anabstract point of view. Depending on the role adaptation, an actor might gainor lose responsibilities or technological advancements that lead to a benefit or adrawback. The benefits can be of financial aspect like capital expenditure andoperational expenditure decrease, technological aspect like increased spectrumusability and security or decreased interference and complexity, SWOT analysisrelated, access related, or even customer related like user satisfaction. It must bestressed that business case of competing technologies is also taken into accountas a business proposition might be feasible from technical view and operateflawlessly but competing technologies outperform it in the business domain. Inthis optimistic perspective of the thesis, if no solid benefits are found then thebusiness feasibility can be considered as low.

2.3 Method

Qualitative research is the research methodology that is applied for the success-ful completion of this thesis. The work assumption is optimistic and the aimis to check under the best possible scenarios if the proposed business scenar-ios are profitable, viable and implementable. In order to find answers to theresearch questions, a systematic predefined procedure and evidence collectionis performed. Three main entities are used for the scenario construction andevaluation: Actors, Business roles and Relations. According to the model pre-sented in [45] the Actors control and have certain knowledge of Resources whichare examined at Preliminary asset analysis. When the Actors act upon theresources, a business role is created and by using co-operative type of scenariosthe relations between actors and the distribution of business roles is shown.

2.4 Data Collection

2.4.1 Primary Data- Expert Interviews

A number of meetings and in-depth interviews have been conducted with rep-resentatives of market actors as presented on Table 1. The interviews withoperators, vendors, facility owners and consultants were organized as semi-constructed, open-ended discussions around drivers and challenges for current

2.4. Data Collection 7

indoor mobile broadband femtocell solutions. Before each interview the par-ticipant was informed about the purpose of the study, the expected amount oftime and confidentiality protection measurements (If asked) following the nec-essary ethics and oral consent procedures of qualitative study. All interviewswere voice recorded for the convenient of the interviewer and more accurateinterview analysis. For a summary of each interview refer to APPENDIX A.The empirical input data was collected through two methods: literature studyand interviews. The literature study content included published papers fromstandardization bodies and academic institutions, textbooks, data sheets, andwhite papers from mobile actors such as operators, manufacturers, and telecom-munication organizations.

Facility OwnerTechnical Institute of CyprusVendorMIC NordicCOMMSCOPEConsultant3GNS Solutions

Table 2.1: Interview respondents list

Examples of questions used in the interviews are:

• What do you think of the IMBA market and its future?

• How are Authentication,Authorization and Accounting AAA implementedin your system?

• Do you consider using Femtocells in your network?

• Is it possible for a Facility owner to become a local area network provider?

• What are the required changes for a Wi-Fi operator to use the TV-Whitespace and femtocells?

• Do you consider any major show stopper for the use of TVWS?

• What is your opinion for the TVWSO operator? What challenges willthere be to enter the market?

2.4.2 Secondary Data - Research and analysis of relevantscientific work

As a second means of data collection, research and analysis of background worklike scientific papers, books and articles has taken place. In order to find and ac-cess the relevant work, well known search engines like http://scholar.google.comand www.ieeexplore.ieee.org were used. The research was mostly related to:

• femtocell technology and architecture

• access modes and mechanisms for femtocells

8 Chapter 2. Methodology

• secondary spectrum usage

• AAA procedures for MBA

• customer relations and marketing for industry actors

• current IMBA business models

• Market relations of involved actors

Thereafter conclusions and work assumptions of the acquired background workwere used as an input basis for the construction and evaluation of businessmodels in this thesis. Citation numbers in [] point to the referenced work wherethe reader can obtain more information from the actual work.

2.5 Business Feasibility Analysis

The business feasibility analysis tool is the final step of the methodology andthe one that will provide answers to the research questions. It is composed bythree stages each one with its own purpose:

• Preliminary asset analysis: In the first stage of business feasibility analysis,a preliminary asset analysis will take place for each actor, their spectrumopportunities and the roles they can assume. The purpose of stage one isto select which scenarios will be further analyzed on stage two and whichscenarios will require no further attention.

• Model construction and cost calculation: In the second stage of businessfeasibility analysis, for the forwarding actors and scenarios, business mod-els will be proposed with an aim to cover a wide range of possible solutionsan actor can implement. The assets already possessed and the ones re-quired for the business model completion will be presented and a highlevel cost analysis will also be calculated in some cases.

• SWOT analysis: At the final stage of this activity is the evaluation of theproposed business models. The evaluation will use a SWOT analysis fromboth an economic and technical perspective taking a variety of factors intoaccount as to conclude on the benefits, drawbacks and the feasibility ofthe proposed models.

Chapter 3

Background

It is estimated that 2/3 of calls and 90% of data services in cellular networksoccur indoors [1]. Thus it is important for cellular operators and other marketactors to provide high quality indoor coverage both for voice and data serviceswhich are on rising demand. Particularly, Cisco visual networking index presentssome interesting facts and predictions about the future of mobile broadband.Notably, global mobile data grew 2.3 fold in 2011, more than doubling in fouryears row and stands eight times bigger than the internet size of 2000. Addi-tionally, smartphones represent only 12 percent of total global handsets in usetoday, but they represent over 82 percent of total global handset traffic. In 2011,the typical smartphone generated 35 times more mobile data traffic (150 MBper month) than the typical basic-feature cell phone (which generated only 4.3MB per month of mobile data traffic)[2]. This rising demand for MBA servicescoupled with the poor indoor reception problem in which 45% of householdsand 30% of business suffer from creates a new challenge for the industry andthe operators in general.

One approach to provide better indoor coverage is the use of outdoor Macro-cell base stations (MBS), a solution that curries a number of drawbacks. Tobegin with, its more expensive to provide indoor coverage by using outside trans-mitters since an indoor user will require higher power drain from the base stationas to overcome the penetration loss. In addition for high capacity networks, highcosts for MBS installation, operation and maintenance are required. Also thepositioning of MSB in a dense city environment is a burden itself, raising at thesame time the complexity of the network as planning and optimization for fre-quency, handover and interference management are required [1]. And with theintroduction of 3G and 4G networks that normally operate at 2 GHz or abovethe building penetration becomes a big challenge and leaves no guarantees forindoor network performance from macro cell sites.

Therefore, indoor systems like DAS (Distributed Antenna Systems), picocellsand femtocells become more and more attractive and viable business solutionsfor hotspots such as shopping malls, hotels, office buildings and large businesscenters. These indoor solutions have the ability of improving the indoor coverageand at the same time promote high data services, offload data from the macrolayer network and provide better satisfaction and QOS (Quality of service) tothe end user. Globally, 33 percent of handset and tablet traffic was offloadedonto the fixed network through dual-mode or femtocell in 2011. By 2016, over

9

10 Chapter 3. Background

3.1 exabytes of mobile data traffic will be offloaded to the fixed network bymeans of dual mode devices and femtocells each month [2].

Femtocell base stations (FBS) are cellular access points that use the exist-ing wired or wireless broadband connection to handle voice and data mobiletraffic generated indoors without the use of the MBS. Femtocell units have thecapabilities of a Node-B UMTS base station, include a RNC (Radio NetworkController) and core network elements. This way the FBS does not require acellular network access but a DSL Internet connection from which it connects tothe operators core network. By appearance FBS look like WAP (Wi-Fi AccessPoint) however the technologies and protocols each box supports are vastly dif-ferent as the WAP implements technologies such as IEEE 802.11b, 802.11g and802.11n where the FBS implements technologies like GSM/GPRS/LTE/HSPAand mobile WiMax. FBS have the ability of providing better indoor coverageand capacity, especially in areas with bad coverage. FBS usually operate in thespectrum licensed for cellular operators and can provide higher capacity andusers receive a higher signal to noise ratio due to the short distance from thetransmitter and the absence of wall attenuation [3].

In construct with picocells, femtocell installation is more user-friendly as itcan be directly self-deployed by the users. Though, interference managementtechniques are required as to minimize interference with nearby MBS and FBSand thus the use of SON (Self organizing networks) techniques are adopted byFBS as to auto configure their working parameters like, transmitting powerand channel allocation. In this way the FBS are cable of sensing the radioenvironment, localize and register their positions and continue operating stablyafter auto configuring their working parameters in their first run.

The importance of femtocells and the expectation of large deployments residein the benefits that can provide both to the operator and the subscriber. Ingeneral FBS can provide better coverage where MBS are unable off and at thesame time offload 70-80% data from the MBS network, reducing in this way theCAPEX (Capital Expenditure) and OPEX (Operational Expenditure) of theoperator. This is achieved as less MBS are required and the power consumptionthat is required by a macro cell is significantly higher than the one a FBS requiresto operate and less effective at the same time. Also the total network capacity isimproved by the indoors radio reuse and in combination with the low cost andreduced risk of femtocell deployment is a new cost-effective way for operatorsto build out network capacity. In addition, since FBS can provide excellentdata rates not only the customer satisfaction and loyalty is improved but alsothe churn is reduce. Moreover, with excellent data rates operators can increasetheir ARPU (Average revenue per user) by introducing and providing richerservices and overcome the revenue gap that flat rate voice faces nowadays [4].Finally, femtocells can offer new market possibilities and alternative approachesto existing and new actors, the investigation of which is part of this thesis.

From the subscribers perspective, femtocells are also beneficial as the userexperience is radically improved, especially in areas with no or bad signal. Ad-ditionally, multimedia and video services can be used and enrich the user expe-rience. Furthermore, FBS can improve the battery life of users mobile phonesas the UE (User Equipment) requires less transmitting power towards the fem-tocell than a MBS. This is also crucial for any health concerns towards the useof mobile phones as the uplink emitting power which is close to the head is sig-nificantly less. Users can also benefit from zones plans and reduced price plans

3.1. Access Network Architecture 11

the operators offer for the femtocell deployment and have a single address bookand billing account for land line phone, broadband and mobile phone.

A research [5] made by SRG (Signals Research Group) in 2009 verifies allthe above-mentioned benefits as data were collected by a group of operator andvendors in the U.S and the results showed that both the operator and the usercan be benefited from the use of femtocells. For the operator the expectedlifetime value of a user is increased by providing to the user cost savings andother benefits and additionally, in order for an operator to provide 2.5 Mbpsbroadband at home it costs 320 USD by using femtocell solutions and 900 USDby using the macro layer which is significantly higher.

3.1 Access Network Architecture

The mobile industry has high hopes for femtocells, but before improved in-door coverage and increased throughput of data can be achieved a number oftechnical challenges must be addressed and one of these challenges is the stan-dardization of how femtocells will integrate with the mobile core network. Anumber of important issues are raised with focus on security and scalability asthe RAN (Radio Access Network) is made of hundreds of base stations thatcan be moved, added or changed by the users randomly and use the untrustedpublic Internet to connected to the RNC/BSC (Radio Network Controller/ BaseStation Controller). So far there are four different 3G architecture frameworksfor femtocell connection to the UMTS (Universal Mobile TelecommunicationSystem) system.

3.1.1 Legacy Iub over Ip

This architecture is proposed by RNC vendors and allows operators to con-trol with the same RNC for NodeB the Home NodeB [6]. A standard 3GGPIub interface connects the femtocell with the RNC and the Iub protocol stack isencapsulated in the IP signalling while IPsec provides network security. This so-lution fulfils the operators requirements for service transparency and low initialinvestment cost as they operate their core networks through standard interfaceslike Iu-CS and Iu-PS. However scalability is the main concern of this implemen-tation as RNC will face difficulties to serve thousands of HNBS (Home NodeBs)as the initial design of RNCs is to handle a low number of high capacity Node Bstations. After an initial feasibility study of 3GPP and with the scalability issuethis architecture is no longer considered viable and thus will not be analysedany further.

3.1.2 Concentrator

In order to overcome the scalability issue and towards a more proprietary Iubinterface usage, an alternative approach has been proposed that uses a propri-etary Concentrator/RNC that can handle thousands of HNBS. This solution iseasy and seamless for an operator to implement as the current RNC needs tobe changed with the proprietary one. However since the 3GPP initialised thestandardization for femtocell network access architecture this technology did


not move any further as well and was not adopted by the market and thus willnot be analysed any further.

3.1.3 GAN (Generic Access Network)-based RAN Gate-way

One other proposal for femtocell integration to the core network is generallyreferred as RAN Gateway solution which is based on a new network controller-RAN Gateway that operates between the IP access network and the operatorscore network. The RAN Gateway aggregates the traffic of a large number offemtocells coming from the internet that use the new Iu-over-Ip interface andpasses this traffic to the core network by using the Iu-CS and Iu-PS interfaces.Flat-ip architecture is used by the RAN Gateway that allocates a number ofRNC functionalities to the femtocell making it more intelligent and autonomouswhile dealing this way with the scalability issues as well. Specifically, the HNBis responsible for the radio aspects and the HNBGW (Home NodeB Gateway) isresponsible for CN (Core Network) connectivity. Figure 2, illustrates the GANIu mode architecture as described in [7].

In general the GAN architecture is an established solution for uncoordi-nated HNB integration to the CN through unmanaged IP networks. It providesmutual authentication, confidentiality and integrity protection by using IP sectunnels between the access device and the operators network. It can help theHNB to discover the correct default serving gateway in the initial set-up andthus provides a flexibility to the network to scale up as the HNB will automat-ically find the corresponding gateway. It can register a UE for services as onlyregistered UE are served by the HNBGW. Furthermore, it promotes QoS bynot only establishing RTP connections for redundancy of VoIP call across theInternet but also by monitoring the Uplink quality for any necessary handoverto the macro layer. The main components of this architecture are:

I User Equipment: A 3G capable handset

II Home Node-B: A CPE (Customer Premises Equipment) that enables stan-dard radio Uu connectivity to the UE and the necessary extensions toconnect to the HNBGW as defined in 3GPP TS 43.318 [8].

III Home Node-B Gateway: Same as the GANC (Generic Access NetworkController) functionality defined for GANC Iu mode and allows differentCPE devices to connect to the generic IP network. This entity works mostlybetween the Iu interface and the GAN Iu mode Up interface using thecontrol plane functionality and the user plane functionality.

IV Control Plane functionality: Responsible for encapsulation and encryptionof Up interface control plane packets by setting up an IPsec tunnel betweenSeGw and HNB

V User Plane functionality: Responsible for the interconnection of circuitswitched data and the Up interface.

VI Coexistence with UTRAN and interconnection with the CN via standardinterfaces

3.1. Access Network Architecture 13

VII Generic ip access network that provides IP connectivity among HNB andHNB-GW

VIII Use of AAA (Authentication, Authorization and Access) server on Wminterface according to the 3GPP TS 29.234 [9] specifications and is used toauthenticate the HNB when there is a secure channel setup.

IX HNB management System that uses a standard CPE devices managementinterface in order to manage in a scalable way the configuration of HNB.

Figure 3.1: Architecture of GAN-based HNB

The SeGW and the AAA server components will be further explained andanalysed as are of importance for the scope of this thesis, while components likeRAN network controller, MGC (Media Gateway Controller), signalling gatewayand access point management system will not.

3.1.3.1 Security Gateway

The SeGW is a scalable 3GPP based product that connects securely the RANGW to the core network by authenticating and terminating FBS originatingIPsec tunnels. It executes Authentication, Authorization and Accounting pro-cedures as it interfaces with the AAA server via the Wm. It can ensure a secureaccess for GTP (GPRS Tunnel Protocol) tunnels that terminate on the CNby using IP as a transport method for the GPRS tunnels. In addition, SeGWcan maintain for each femtocell a high capacity IP sec tunnel termination withintegrity and encryption as required and distribute and manage IP addressesto remote FBS. It can also serve multiple RAN network controller and media


gateways at the same time and manage the authentication process by handlingthe IKE (Internet Key Exchange) for SA (Security Association) purposes. TheSeGW is compatible with the 2, 3, 8, 10-14 3GPP standards.

3.1.3.2 Authentication Authorization and Accounting Server

The AAA server improves the security the RAN GW provides as by a set ofservices it supports. It has an SS7 MAP-D interface with which an IMSI (Inter-national Mobile Subscriber Identity) can securely register with a RAN GW andcan support EAP-SIM/EAP-AKA authentication services between a FBS and aHLR (Home Location Registry). The AAA server is incorporated in the SeGWby using the diameter Wm interface on the SeGW site and the S1 Radius inter-face on the RAN network controller and is capable of handling multiple SeGWand RAN-GW requests per server. Additionally, the AAA server can be used forService Access Controls, UE session parameters and logging of UE registrationevents when required by the operator.

3.1.3.3 Internal and External Interfaces

According to [1]1 there are three types of interfaces used:

1. Interfaces between FBS and RAN GW

• Up/Iu-h is now known as Iu-h. Iu-h interface is the standard Iu modeprotocol for the transport of 3G UMTS protocols and services overthe IP access network.

• RTP (Real Time Transport) is the protocol for circuit switched bearertraffic over the public Internet between the FAP and the MGW.

• GTP-U is the protocol for packet switched bearer traffic between theFBS and the SGSN.

• IPsec is the protocol for integrity and encryption of all traffic betweenthe FBS and the RAN GW.

• TR-069 is the management protocol for managing the FBS commu-nity from the RAN GW.

2. Interface between RAN GW and Core Network

• Interface D: Supports the authentication services between the accessnetwork and the HLR[1].

• Iu-CS Control and User Plane Iu-CS traffic transports messages overATM towards core network.

• Iu-CS user plane traffic transports over IP from RAN GW towardscore network.

3. Interfaces within RAN GW

• H.248 H.248 is the MGW control protocol to enable the RAN networkcontroller to manage the MGW bearer paths.

1Book pages 51-53

3.2. Air-interface technologies 15

• SIGTRAN is the Iu-CS/PS control plane over a standard SIGTRANtransport between the RAN network controller and the signalinggateway. The signaling gateway is embedded within the MGW andperforms the protocol translation between the RAN GW and the corenetwork for the Iu control plane.

• SNMP (Simple Network Management Protocol) is the protocol forEMS (Enhanced Messaging Service).

• Wm is the protocol for Extensible Authentication Protocol (EAP)-SIM/Authentication and Key Agreement (AKA) authentication be-tween the SeGW and the AAA server. RADIUS (Remote Authenti-cation Dial-In user Services) is the protocol for access controls andauthorization between the RAN network controller and the AAAserver.

3.1.4 IMS and SIP

A SIP (Session Initiated Protocol) based protocol between core network andhome node B is an alternative way to integrate femtocells to the core network.This approach however is more costly and complex and it requires installationand operation of a new core service network that works in parallel with theexisting packet switched and circuit switched network. Nevertheless, since thisarchitecture embraces the characteristics of all-Ip networks and 3GPP IMS (IpMultimedia Subsystems), the operators are positive towards this architecture asthey believe that eventually their networks will transition towards an IMS andSIP based infrastructure. A drawback of this solution is the higher complexity ofservice continuity between indoor and outdoor systems as the two use differenttechnologies. The standardization of integration of femtocell access networksinto IMS infrastructure is present from Release-8 and on in 3GPP specifications.

3.2 Air-interface technologies

Various technologies exist that can be used for wireless data access in an indoorenvironment. From UMA (Unlicensed Mobile Access) to IEEE 802.11, GSM,UMTS and HSPA all can be used and in a way are competing alternativesfor indoor connections. Thus a brief explanation and analysis of these RFtechnologies that femtocells are or will be based is necessary for the scope ofthis thesis.

3.2.1 GSM Femtocells

GSM when compared with LTE and UMTS is an old system however it is welltested and the biggest number of subscribers is still using GSM. Also GSMfemtocells are less costly to manufacture when compared with 3G capable ones,gaining this way advantage towards WiFi and UMA networks. In February2007, Ericsson and Tesco made an agreement in which, Ericsson was to produceGSM femtocells to be installed in Tescos network in the UK [10]. However, thepower management of GSM femtocells is less flexible than a 3G one, hinderingconcerns about the interference management towards the macro layer. Mostimportantly, the GPRS output of 2G technology can in the best case deliver a


high quality voice service, which is notably less than what 3G femtocells candeliver. The frequency allocation for GSM is not the same in every country butmost networks worldwide in the 900, 1800, and 2100 MHz Countries in Europeoperate mostly in 900 and 1800 MHz, North America in the 850 and 1800MHzand Eastern Europe and Russia in the 450 MHz band. Since the femtocells willbe operating mostly in the country were the purchase was made, it is wiser toequip the femtocells only with the required RF transmitters for that country.

3.2.2 UMTS and HSPA Femtocells

Universal Mobile Telecommunications System (UMTS) [11] is a set of radio tech-nologies specified by 3GPP (Third Generation Partnership Project) [12]. Theair interface of UMTS is UTRA (UMTS Terrestrial Radio Access) and is basedon FDD and TDD modes, contrary to GSM that only uses FDD. The mediumaccess used in UTRA is the CDMA (Code Division Multiple Access) and theimplementation of CDMA in UTRA is the WCDMA (Wideband CDMA) dis-tinguishing it from other implementations like CDMA2000. CDMA allows theusers to simultaneously transmit over the available bandwidth through the useof orthogonal codes [13]. UMTS technology is better suited for femtocell de-ployment as the 3GPP specifications make the networks more access flexible,with IP-based connections to the core network made feasible without the usageof a SGSN. Also with the use of WCDMA receivers to separate UMTS signalsat very low levels of SINR, the UMTS is better capable to deal with the inter-ference management than a GSM one and given the proven fact that UMTSdeliver higher speed rates and is a well tasted technology, most manufacturershave focused on the UMTS femtocell production which from 2008 it is standard-ised in TS 22.220[14]. One of the main differences of UMTS and GSM is the useof ATM (Asynchronous Transfer Mode) as the transport protocol for signallingand information currying which relies on Iu interface to connect the RNC withNodeB. The RAN and the RNC functionality are possible to be integrated intoa femtocell device and the Iu messages to be transferred to the CN using IPencapsulation. This approach is called Iu-tunnel and is suitable for small andmedium business.

3GPP release 5 introduced the HSDPA (High Speed Downlink Packet Ac-cess) with several improvements to the downlink architecture. In HSDPA thetransport channel DSCH is replaced with HSDCH (High-Speed DSCH) for datatransport. Theoretically, HSDPA can deliver speeds of 14.4Mbps where UMTSin plain form can deliver up to 2Mbps. However due to the Iu interface, thisdata rate is often limited. In order to avoid this bottleneck, the Iu-tunnelarchitecture can be used as the RNC functionality is controlled by the FBS.Additionally, data are buffered in the NodeB for faster retransmission in caseof errors where in the UMTS architecture, the buffer is kept at the RNC. Inrelease 6 of 3GPP the specifications for HSUPA (High Speed Uplink Packet Ac-cess) were released and PicoChip was the first company to manufacture HSUPAfemtocells [15] capable of uplink speeds of 1.46 Mbps. Compared with UMTS20dB , HSUPA incorporates a dynamic range for power control of 70dB whichadd greater abilities in fading management.

3.3. Interference 17

3.2.3 OFDM-based Femtocells

OFDMA (Orthogonal Frequency Division Multiple Access) in an architecturethat uses OFDM techniques to distribute users along a frequency by exploitingthe spectrum arrangement in subcarriers. It allows a user to use only a subgroupof the spectrum, permitting to other users to transmit simultaneously and thusmaximizing the frequency reuse. This architecture requires the assignment ofsubcarriers to users by using dynamic frequency assignment algorithms. Fur-thermore, this subdivision allows for a more efficient spectrum and interferencemanagement in two layer networks. Due to its high efficiency, OFDM is themulticarrier technology selected by WiMAX and LTE and is a candidate to re-place UMTS technology. However, UMTS use of CDMA copes with interferenceis a better way as for OFDMA femtocell a self-organizing network is requiredto cope with interference, either my FBS measurements of the environment orby collected UE data. Generally, multicarrier modulations like OFDM haverobustness against multipath and narrowband interference from close stations,high spectral efficiency and frequency diversity for multiple user access.

3.2.3.1 WiMAX technologies

Designed for last mile connectivity, WiMAX was published in 2004 under IEEE802.16d standard and in 2005 evolved to IEEE 802.16e which incorporates mo-bile connectivity. The working group of WiMAX designed an end to end IPnetwork architecture which makes it especially suitable for femtocell deploy-ment [16]. WiMAX is also suitable for mobile centric femtocell applications asit can support up to 70 Mbps symmetric rates which ensure high QoS. Theindustrys interest in WiMAX is high due to the fact that the emission licenseshave already been auctioned for Europe and USA and the standards have beenpublished since 2004 and 2005, making WiMAX femtocells a feasible alterna-tive to UMTS and HSPA. There are some cases where companies purchasedfrequency bands to be used solely by the WiMAX [17] femtocells and elimi-nating this way the cross-layer interference. However such strategies luck inspectrum reuse efficiency and add cost of the operator.

3.2.3.2 LTE

3GPP release 8 in December 2008, commonly known as LTE introduces higherthroughputs, more flexible spectrum management and spectral bandwidth. It isexpected that legacy GSM and UMTS mobile networks worldwide will upgradeto LTE [18], making it the more widely used mobile access technology. LTEevolves the HNB to Home eNodeB (HeNB) making it the main point for radioaccess. Since May 2008 PicoChip, developed and manufactured LTE femtocellsbased on the technical specifications of that time. There is still a long waybefore the marketability of femtocells is certain as the auctioning of LTE licensehas not taken place yet.

3.3 Interference

With the introduction of femtocells some changes occur in a macro cellularnetwork, a new layer is added and thus the architecture is composed by two


separated layers: the macro layer and the femtocell layer. A network architec-ture like the one described is called two-tier or two-layer network, with the onelayer being composed of traditional macro base stations and the second layer byseveral shorter range base stations which are randomly located inside the emit-ting range of the first layer. This design however introduces new problems anddesign challenges. Transmitters from the two layers, when using the same RFin the same geographic area, will cause confusion to receiving systems making itharder to distinguish the source of the signal. This is the interference problemand is one of the main challenges of telecommunication systems that femtocelldeployment needs to face. System like CDMA which are interference limited inorder not be greatly affected will need the introduction of interference avoidancetechniques like power control and time hopping while capacity limited systemsas OFDMA will need intelligent frequency planning technology to adapt withthe femtocell interference presence. If the fore mentioned techniques are notapplied dead zones can be created which will disrupt the macro layer servicenear a working femtocell.

3.3.1 Co-layer Interference

As the femtocell deployment is random and opportunistic is highly possible thatseveral femtocells will be installed in proximity with other either horizontally orvertically in apartments and houses causing interference one to another. Thereare two types of interference source: the downlink (originating from FBS) andthe uplink (originating from UE). This is co-layer interference and only affectsthe femtocell layer architecture and the unwanted signalling received by a fem-tocell reduces the communication quality. The scenario gets worst when signalsfrom nearby femtocells at any location are concentrated and overpower the fem-tocell power levels causing dead zones problems and connectivity issues to theuser.

The access mode any given femtocell operates greatly impacts the co-layerinterference with the OAM (Open access mode) reducing the dead zone problemand CAM (Closed Access mode) increasing it. In addition, based on measure-ments made in [1], it is shown that as QoS increases so does the dead zoneproblem.In TDD systems if all femtocells are synchronised then the transmis-sion of femtocell A will cause downlink interference to users of femtocell B and inthe same way the uplink transmission of UE A will be sensed as uplink interfer-ence to UE B. In case however where the femtocells are not synchronised, thenthe emitting time is random, causing transmissions to overlap between uplinkand downlink making the interference much harder to cope with. Therefore,timing is important aspect of TDD-based FBS which at the same time is trickyproblem.

3.3.1.1 CDMA

In CDMA systems, 3GPP in [19] suggests the use of interference managementtechniques to cope with the high power UE transmission levels that reduces thecoverage area of a victim femtocell. Power limit to be imposed by femtocellto subscribed UE is one solution in which the noise rise in the uplink can becontrolled. To achieve this, the FBS scans and gather information about theenvironment and the received power by nearby UE and then set a maximum

3.3. Interference 19

UE transmit power for the desired CINR. In order to cope with the downlinkinterference to a victim UE caused by nearby FBS, it is recommended that FBSstrictly control their emission power by relying on adaptive power techniques.Especially in CAM scenarios where the UE is served by the FBS it is subscribedto and not by the one that receives the best signal from. These two solutionsare for UMTS and HSUPA systems.

3.3.1.2 OFDMA

For OFDMA systems, it is not required to sense the full transmission bandfor emissions in proximity. According to the QoS, only some sub channels areallocated to the user by the FBS, which in this case selects the ones that arenot subject to interference. The uplink interference is more important to copewith than with the downlink one, as the uplink interference affects all the usersof a femtocell while as the downlink only the interfered user. When comparedwith CDMA systems where the transmission uses the entire available band,the selection of sub channels by OFDMA systems makes the interference moremanageable to handle with. Thus the allocation of sub channels frequencieshas an important role in the interference impact in OFDMA systems and thecreation of dead zones.

3.3.2 Cross-layer Interference

Cross-layer interference happens when the source of a signal and the receiverbelong in two different layers, for example a femtocell transmission affectingthe downlink quality of UE at the edge of a MBS. On the contrary, uplinkinterference can also occur when a macro layer UE is interfering with the uplinkquality of a FBS user. CDMA networks are mostly affected by cross layerinterference and the spectrum used is the same for both the macro and femtocelllayer. In [20] and [21] it is suggested that an operator uses the spectrum splittingtechnique in which a RF band X for example is divided to X1 and X2, withX1 = X-X2. Then the X1 is used only be the macro layer and X2 in densefemtocell deployment regions. On the one hand splitting the spectrum willeliminate cross-layer interference but on the other hand due to the high priceand scarcity of electromagnetic spectrum this would lead to inefficient spectrumusage. In OFDMA systems, with the usage of subcarriers cross layer and co layerinterference is mitigated and handled in a more efficient way, making this wayOFDMA femtocells a welcome solution. Still, OFMDA systems are subject todifferent problems as time and frequency synchronization which in severe casescan cause loss of orthogonality among subcarriers and disruption of the wholenetwork.

3.3.2.1 CDMA

In CDMA networks there are two scenarios under which cross-layer uplink in-terference can occur. In the first scenario the femtocell users interfere with theMacro node B. If the femtocell is working under CAM then the transmissionsoriginating from femtocell layer UE are the source of interference to the macrolayer, requiring this way power control measures from an operator on the femto-UE to reduce the noise production. If however, the femtocell is working under


OAM, then the UE can camp freely on the base station with the highest signaleither it be a femtocell or a macro cell, requiring the minimum transmissionpower and in this way causing the less interference in the network. On theopposite scenario, the macro layer users transmit in high power to reach theMBS and at the same time interfere with the femtocell operation. Since theMBS is unaware of the exact location of the user and if there is a femtocell inproximity then considering the worst case interference scenario an appropriateupper limit must be set to a macro layer UE. Just like in the uplink scenario,downlink interference can occur when a FBS is transmitting in proximity withmacro layer users and in case the signal is strong enough then dead zones canappear in the macro layer. A 3GPP proposed solution for UMTS and HSDPAnetworks is to limit the FBS maximum transmit power. However a fixed limiton the transmit power is not an efficient solution as the circumstances are notalways the same, requiring adaptive power control on femtocells which can in-crease their cost. In cases where the femtocell is located at the edge of a macrocell, then with good indoor isolation the interference is minimised. If on theother hand, the femtocell is located to close to a MBS, the coverage of a FBSis greatly reduced resulting even in corruption of service. Noticeably, a studymade by Femto Forum in [22] shows that if a user is located at least 250 metersfrom the closest microcell and 1000m from the closest macro cell then 14.4 Mbpsthroughputs can be achieved in HSDPA networks.

3.3.2.2 OFDMA

With the division of the spectrum into OFDMA sub channels and the assign-ment to each network layer, cross layer interference is practically avoided withonly adjacent channel interference remaining. In co-channel femtocell opera-tion, when a FBS is at the edge of a MBS coverage area, the passing of a UEthat is connected with a MBS can cause uplink interference to a FBS user thatis using the same sub channel, especially if required by the MBS to increasethe transmission power due to the long distance. It is therefore important thatfemtocells at the edge of a macro base station to plan their uplink sub channelallocation taking into consideration the any spectral occupancy. If the femtocellis located to close to the MBS and requires from a user to increase the transmitpower then the users of the macro layer that are on the same sub channel withthe femtocell user, loose their connectivity with the macro cell. Just like withCDMA, it is required in this case for the FBS to limit the power control of itsusers.For downlink interference to appear an operating FBS and a macro celluser walking down the road are on the same sub channels, for example a fem-tocell and a macro cell serving both their users in sub channels 1 to 4. In thiscase the noise ratio of the macro cell user will increase dramatically and heavyinterference will occur. The femtocell user will also experience some interferencebut reduced due to the wall attenuation and the better signal from the shortdistance to the FBS.

3.4 Mobility Manager

Mobility management is a challenging issue in femtocell deployment especiallyfor mobile power consumption and signalling load. The initial assumption is

3.4. Mobility Manager 21

that no specific MM (Mobility Management) is required for femtocells as theoperation takes place in the same network. However this is far from truth asimplementation falsifies many aspects of macro layer network assumptions. Tobegin with in high density femtocell areas it is possible that the 512 PSC (Primary Scrambling Codes) in UMTS and 504 PCI (Physical Cell Identities) inLTE will not be sufficient to distinguish all the FBS identities and informationin a network. In addition the neighbouring cell list is dynamic and custom torandom changes when compared with the static macro layer neighbouring celllist. Furthermore, FBS do not operate all in the same access mode and thosein CAM can affect the cell measurements of a large number of UE.

3.4.1 Femtocell characterization

As described above femtocells cannot be treated as macro base station in mo-bility management with implications to the network performance. The intro-duction of identifiers and mechanism that can describe the aspects of femtocellsis necessary to improve the mobility procedures for femtocell support. In thisway the network is divided into two layer architecture and the introduction ofnew techniques can reduce the signalling overhead among the two layers. 3GPPproposed layer 1 and layer2 methods are described in the following sections.

3.4.1.1 Hierarchical Cell Structure

Based on [23], HSC (Hierarchical Cell Structure) can be used to distinguish moreefficiently femtocells from macro cells as it allows operators to set priorities from0 to 7 to different customised categories of network cells(macro, micro, pico).HSC is considered to be one of the most effective ways of solving conflicts inUMTS and GSM hot spots and high traffic demand areas.

3.4.1.2 Different Femtocell PLMN ID

3GPP pre-release 8 introduced another way for distinguishing femtocells frommacro cells which is adopted by the majority of femtocell manufacturers. Byusing different PLMN ID there is less signalling towards CN and better powerconsumption on UE as the selection of the right base station is straight forwardaccording the settings assigned to each UE by an operator [23]. However somecompatibility issues may rise with old SIM/UICC cards and also the operatormight be lacking the required additional PLMN ID for the separation of the twonetworks.

3.4.1.3 Reverse Frequency and PSC/PCI

3GPP release 8, simplifies the problem for femtocell identification by taking intoaccount only CAM cells. CAM femtocells and macrocells broadcast informationregarding CAM deployment which can be used by UE which are not allowedaccess on CAM femtocell to avoid cell measurements and power consumption. Indeployments with shared carrier frequency all CAM femtocells broadcast theirreserved PSC information while the OAM femtocells may sporadically broadcastthis information as well. This information must be noted that is only effectivein the UARFCN (UTRA Absolute Radio Frequency Channel Number) for thePLMN where the user is receiving this information. Any PSC information


regarding CAM femtocells is considered valid and used by the UE for the next24 hours.

3.4.1.4 CAM Indicator

According to [24] and [25], a layer 2 approach in 3GPP is the usage of a CAMindicator which is transmitted with the MIB (Master Information Block) inUMTS and LTE network architectures and its purpose is to indicate the accessmode a FBS is operating in.

3.4.2 Femtocell identification

The use of NCL (Neighbouring Cell List) makes it possible and easy for a UEto identify surrounding macro cells. The NCL is created locally at a FBS withself-executed algorithms and in case of outbound mobility from femto layer tomacro layer can inform a UE of near MBS and FBS. However the opposite isnot as simple due to the high density and number of FBS. For this reason,release of 3GPP introduced the UE autonomous search for CAM cells [26] tocamp on. The UE which is not configured for CAM cell can disable the searchfunction [27]. Intra-frequency and inter-frequency measurements can assist thesearch function for reserved PSC/PCI. The autonomous search from release 9will support open and hybrid access modes.

3.4.3 Access control mechanisms

There are three access control mechanisms for FBS: open access mode (OAM),closed access mode (CAM) and hybrid access mode (HAM). In OAM the FBSwill serve all the clients that receive greater signal from the FBS instead ofthe MBS. In CAM a FBS will only serve the register users which normally areowners of the femtocell and their friends. In HAM a predefined limited amountof resources are open for public use while the remaining resources are for pri-vate use in CAM [40]. An experiment done in [42] shows that overall networkthroughput of open access mode outperforms the closed access mode. Never-theless, based on the same work, OAM reduces the femtocell performance asthe resources are shared and a survey made in [44] confirms that for this reasonconsumers tend to prefer the CAM. Additionally, OAM increases the signal-ing for handover attempts in a network, increasing the possibility of a droppedcall. As access control mechanisms are of great importance in mitigating cross-tier interference and handover attempts a careful selection must be made. Ina macro cell network, access control usually takes place when a UE requestsaccess to a service or data transmission. In order to avoid unnecessary overheadand signalling and to distinguish the users of femtocells and macro cells, the useof Local Area Identity/Tracking area Identity and CAM ID is recommended.

3.4.4 Local Area Identity/Tracking area Identity

When a UE receives a LAU (Local Area Update) rejection from a femtocellit stores this information on its USIM and does not tries to reconnect to aLAI (Local Area Identity) femtocell that belongs to the forbidden list, savingbattery life and lowering signalling overhead. Unfortunately, assigning a unique

3.4. Mobility Manager 23

LAI to each femtocell in a network is infeasible for existing core network nodesand using pseudo LAI or reusing LAI over distant femtocells can cause networkimplications. One such problem can arise when a user is passing by a femtocellwith the same LAI in his home but not allowed access of course. Then theUE will update the LAI to the forbidden list and might not access even itsresidential femtocell.

3.4.5 Closed Access Mode ID

A CAM ID is used to identify CAM cells, which is a 27 bit unique numericidentifier [28]. This identifier is broadcasted in SIB 3 and SIB 1 in UMTS andLTE networks respectively by the CAM cell. When a UE is not allowed accesson a cell, a corresponding message #25 Not authorised for this CAM cell isreceived to the UE [29]. Contrary to the pre-release 8 procedures, the UE willnot add the LAC (Location area Code) to the forbidden LAI list and neither willblock the entire frequency in this way not only allowing alternative coverage ifavailable on the same frequency but also avoiding the femtocell LAI reselectionconflicts.

3.4.6 Allowed Access List

For a UE to access a femtocell, a list containing the allowed IMSI users whichis stored on the femtocell or a list with allowed femtocells access which is storedon the UE is required. In the first case, a list containing all the allowed IMSIis locally stored on a femtocell on which the user or the operator can modifythe allowed users. The advantage of this implementation is that less signallingis sent to the CN as it is handle at the FBS but with the disadvantage thatIMSI should only be available is the NAS (Non-Access Stratum) to protect theusers identity and confidentiality. When the IMSI is locally saved this createssecurity issues and vulnerabilities. In the second case, an ACL (Allowed CAMList) defines which CAM cells a UE can connect to and it is stored with usersinformation inside the CN [26]. The most suitable location for storing thisinformation is to a server similar with the HSS (Home Subscriber Server). Acopy should also be kept at the MME/SGNS but also inside the USIM of aUE as to avoid signalling towards forbidden FBS [27]. The synchronizationbetween the CN and a UE regarding the ACL can happen manually by addingand removing CAM ID according to LAU messages from FBS or automatic byupdating the ACL first in the CN and the notifying the UE with a message.

3.4.7 Access Control Triggers

It is commonly accepted that access control is initiated by an LAU/TAU [30]and in cases like this a specific LAI is assigned to each femtocell different ofcourse from the macro cell ensuring this way inbound mobility from macro tofemto layer. In residential scenarios, this also ensures that a UE will not campon an unauthorised neighbours femtocell. In larger scale scenarios though, thefemtocells are better assigned the same LAI as they belong to the same companyand avoid extra signalling. A drawback however is that in pre-release 8, an accessdenied UE will ban the whole frequency of the target femtocell for 300 seconds.To lessen the out of service time, a secondary layer should be available where


LAI can access on. A different solution is to allow UE to camp on non-allowedfemtocells by means of roaming until a service is required [30], in which casethe UE will be redirected to a macro cell for service. This approach resultsin less signalling as the same LA can be used in femtocell region and a theLAU signalling is no longer necessary when a user is passing from a femtocellto another. In case however when the macro cell signal is low or disrupted, aradio connection failure might occur when redirecting a UE to the macro layer.

3.4.8 Access Control Location

In pre-release 8 UTRAN, access control takes place in CN for macro cells andin FBS or FBS gateway for femtocells. In the case of femtocells, the requestingUE asks for access and the check takes place in the locally stored IMSI allowedlist reducing the signalling towards the CN. This implementation as a positiverequires no modifications on the CN or to the UE and as a negative requiresextra management and implementation efforts. In addition, for better supportto legacy UE, the access control takes place in the FBS gateway by fetchingthe ACL from the MME/SGSN increasing somehow the network overhead [31].Since the legacy UE are mostly CAM unaware will try to camp on any nearbyfemtocell and by placing the check at the gateway the signalling towards theCN is reduced. In release 8, the CAM-capable UE can execute some basicaccess control procedures to accelerate the process and enhance the mobility.The UE selects only the femtocells which are on the allowed ACL to camp onand avoids any signalling with prohibited cells. Though, this procedure requiresfrequent SIB decoding from the UE to extract the CAM ID which can reducethe active service quality and any out of date ACL can negatively affect theuser experience. In release 8 EUTRAN (Evolved UTRAN) the access controltakes place in the MME for the CAM-capable UE when attaching, detachingand requesting from a EUTRAN cell with the same procedures taking place inUTRAN CAM cells. For the access to take place, the FBS needs to send itsCAM ID to the MME and then a check upon the ACL will allow or deny accessto the UE. By selecting the allowed femtocells, a UE can reduce the signallingrequired for the authentication procedure towards the MME.

3.4.9 Access control for Open, Closed and Hybrid mode

In OAM the femtocell operates as non-CAM cell and no specific UE accesscontrol is required. For legacy UE with no CAM capabilities the femtocelluses the TMSI/PTMSI of the UE to register it to the femto-gateway whichshould always be accepted and assigned back context ID. In UE with CAMcapabilities the absence of CAM ID requires no further control from the femtocellor exchange of messages with the CN. In CAM the femtocell always performsa check when a UE wants to associate with it and rejects any non-allowed UEthat do not belong to the subscription group. An identity request to obtain theIMSI is required by non-CAM UE in order to register it with the femto gatewaywhich will then check the permissions of the UE. In case of CAM capable UEthe femtocell sends also its CAM ID with the request to the CN where it will bechecked against the ACL. In HAM, that is available feature from release 9, theFBS works at OAM and CAM at the same time. The UE that do not belongto the CAM ID can still camp on the FBS and get resources but with lower

3.5. Spectrum 25

priority compared to the CAM belonging UE. In case of legacy UE and sincethe femtocell needs to distinguish between high and low priority users, the IMSIof the UE is fetched and sent to the femto-GW where a check reveals to theFBS to which category and service differentiation the UE belongs to. The sameapplies to UE with CAM capabilities but by using the CAM ID the UE belongsto and not the IMSI.

3.5 Spectrum

There are three spectrum types that are in use nowadays for wireless communi-cations each with its own unique features. In the following section the Licensed,Unlicensed and TVWS spectrum types are briefly introduced.

3.5.1 Licensed

Licensed spectrum is the most commonly used type of spectrum for wirelesscommunications by Mobile network operators as the spectrum can offer interfer-ence and congestion protection while at the same time preventing an-authorisedusers from access and usage. By using licensed spectrum the MNO rest assurethat there will be no ”suprices” in store in the near future as an end-to-end QoSprovision can be ensured. However, its the most costly resource used in the wire-less ecosystem and for this reason its regulated by national and internationalauthorities like the US Federal Communications Commission.

3.5.2 Unlicensed

Contrary to the previous type of spectrum, the unlicensed spectrum is open andaproval free under international regimes. By this anyone and at anytime -atspecific geografic locations- can use specific bandwidths as allocated by nationallaws to emit radio signals for wireless communication. Ofcourse this has bothpositive and negative outcomes. On the one hand various technologies haveflourished over the use of free spectrum like the Wi-Fi system. On the otherhand, the ad-hoc nature of unlicensed spectrum can not provide QoS when everneeded.

3.5.3 TV White Space

Spectrum is a rare commodity and the air-interface is the most expensive thanbackhaul provision (interview with rjan) posing the major entry barrier for newactors to enter the market. With recent changes in the Television broadcast,fromanalogue to digital, significant chunks of spectrum are freed and therefore can beused for secondary services i.e Mobile broadband access. Thus on-going researchin COST-TERRA and FP7 project QUASSAR study the usage of secondary useof spectrum that has mainly been allocated for other primary services [35].

However in order to use the several MHz belonging to this category newtechnologies and regulations are needed. Most importantly, secondary usagemust not cause interference to primary users. Technologies like cognitive radio,software defined radio and dynamic spectrum access can maximize the secondaryspectrum usage but pose a cost barrier for any business schemes at the same time


as technical challenges exist for the identification and monitor of the availablefree band and interference avoidance among competing secondary usersfor thesame available band. It must be noted that the implementation and networkdeployment can affect the available TV white space i.e the usage of TVWS byMBS will cause interference over large areas and reduce the TVWS availabilitywhereas the usage of TVWS by small cell like femtocell in indoor deploymentsthe interference will be limited and the availability greater [35]. Besides thetechnical implications, regulatory and business implications also exist as theswift from traditional licensed business model will shift requiring new models,new actors, new value constellations and new regulation policies and directives.

3.6 Wi-Fi Sollution - An overview

The basic access mechanism in 802.11x protocol is the well-known Currier SenseMultiple Access with Collision Avoidance (CSMA/CA) mechanism which wasfirstly introduced in Ethernet technologies. In CSMA/CA a station that wantsto transmit, senses the medium and starts the transmission only if no otherstation is transmitting [52]. Wireless Lan system are All-Ip based networksand follow the IP-systems philosophy. IEEE 802.11 protocols transmit in the2.4-2.5 GHz frequencies and 5.5 GHz frequency with achievable speeds of upto 300 Mbps. For a station to join an existing Cell it can either wait for abeacon from an AP with synchronization information or make an active searchby transmitting Probe Requests and awaiting Probe Replies from the AP. Oncethe base station is located then the authentication process starts in which aseries of message exchange occurs where each side provides knowledge of a pass-word. There are three encryption protocols which lead to association: WEP,WPA and WPA2 with pre-shared Key. After a successful authentication thenext step is the association process where a set of information regarding thestation and BSS capabilities are exchanged. Once association is completed thestation can transmit and receive frames [52]. The authentication process caneither take place locally between the AP (based on a local database) and theclient, usually in home environments, or by using a Network AuthenticationServer (NAS) and a RADIUS server in larger scale networks. A RADIUS serverwhich stands for Remote Authentication Dial In User Service is a networkingprotocol that provides centralized Authentication, Authorization and Account-ing management. NAS server is a single point of access to a remote resourceand is used as a trusted gateway in the network for credential exchange withnew clients. RADIUS is a client/server protocol operating in the applicationlayer of OSI stack, using UDP as transport. The three main functions of RA-DIUS are to authenticate clients before granting access to a network, authorizethe client for resource requests and to account the clients usage. Each of thethree functionalities is based on a series of request/response messages betweenthe client and the server. When a user wants to connect to a WLAN, the NASserver will prompt for the users username and password and will then sent thecredentials to the RADIUS server where a database check will notify the NASserver to allow or deny access to the user.

3.6. Wi-Fi Sollution - An overview 27

3.6.1 Wi-Fi 802.11af (Wifi using TVWS)

Since September 2010 when the Federal Communications Commission (FCC)revised the rules regarding access to unused UHF spectrum industry and stan-dardization bodies have shown interest in using TVWS to provide extendedWi-Fi like service. Cambridge TV White space consortium which aims to dis-cover how TVWS can be used to provide broadband services in the UK [54]and the Microsofts attempt of the WhiteFi network are good examples of theongoing effort [55]. Also a working group named IEEE 802.11af was thus cre-ated to define a standard for the protocol implementation [56]. In general, it isbelieved that operating in the free white spaces of TV, Wi-Fi will benefit fromgreater speeds, extended range and better QoS [53]. A study made in [57] onthe feasibility of large-scale Wi-Fi networks operating at TVWS shows that isviable and less expensive than alternative/completive cellular next generationnetworks. However, a recent work [53],that takes into account inter AP interfer-ence and congestion shows that operating Wi-Fi hotspots in outdoor rural areasis more viable and possible than outdoor urban areas where the user density ishigher, with interference limiting the network capacity. For indoor deploymentscenarios, the authors argue that due to the better propagation and wall pen-etration features of low frequency TVWS, WhiteFi can be used but a carefultechno-economic analysis is necessary before any call.

3.6.2 Femtocell Wi-Fi integration

As both femtocells and Wi-Fi technologies were developed for indoor small areacoverage to provide general Internet access to end users at first sight it seemedthat these two technologies are competing each other. However it was soon re-alized that they could actually co-exist and complement each other with variousbenefits for the users and the providers. Some of the benefits are drive scaleof economics of integrated devices and services, increased user satisfaction andalternative connection technology and service continuity on 3G UMTS voiceand data applications to Wi-Fi [51]. In Figure 3.2, an abstract IFW systemarchitecture is shown.

A 3G WiFi/Femto cell is operating in a hotspot providing both cellularand WiFi cervices to end users. It is important to note that the Wi-Fi con-troller which is responsible for the AP co-ordination is placed within the hotspotpremises and uses SNMP protocol for management whereas FAPs are managedby the Femto Provisioning Server using the TR-069 3GPP standard. IPsecis used to encapsulate packets traversing the Internet towards the Core Net-work for Femtocell originated traffic and the GRE protocol for the WiFi ones.The ubiquitous management and provision of both technologies is challengingand opportunistic at the same time as a single entity for the management ofCM/AM/PM is desirable. On solution is to proxy the WiFI protocol over TR-069 by mapping SNMP MIB to TR-069 DM or the other way around. In IFWnetworks it is possible to use WiFi for data offload towards the Femtocell whichdiffers from femtocell offload towards MNOs with potential advantages whenthe femtocell is operating in licensed mode. Additionally, seamless handover ispossible from Femto to WiFI and vice versa based on handover protocols at theIP level. Furthermore, a unique feature is the flow segregation technique wherehttp traffic is directed to the WiFi interface and Voice traffic to the Femto in-


Figure 3.2: From smallcell forum white paper on Integrated Femtocell Wifisystems.

terface [51]. The TS 23.234 protocol is describing the internetworking betweencellular and wifi networks with handover procedures being standardized in TS23.237. The TS 23.403 protocol describes how untrusted WLANs can access anEvolved Packet Core (EPC) network.

3.7 ZeroShell

Zeroshell is an open source free Linux-based distribution for servers and em-bedded systems that provides the main network services a LAN requires [38]with support for UMTS/HSDPA technologies. Among other features Zeroshellcan provide Radius server functionality for authentication, authorization and ac-counting, traffic encryption and QoS and traffic control over a congested networkwith minimum bandwidth guarantee to users. The RADIUS can be configuredwith various cost classes, connection limits and prepaid connections. No limi-tations exist on the number of users that can be saved, besides the hard diskcapacity.

3.8 3rd Party Payment System

With the emergence of e-commerce a new payment solution is needed for onlinetransactions and peer to peer payments. Some of these systems are imitationsof offline payments like checks and credit cards while others introduce digitalcurrency technology. There are numerous solutions available and not all can

3.8. 3rd Party Payment System 29

be used, thus a well-known solution for Business to consumer transaction, theonline credit card payment system is the one chosen. The advantages of thissystem are the word wide acceptance and usage and penetration, privacy, ac-ceptability, convenience and low financial risk [39].

Chapter 4

Business FeasibilityAnalysis

4.1 Preliminary asset analysis

Assets for the purpose of this analysis are any tangible or intangible possessionsand roles in the value constellation each actor has or assumes and thereforegaining advantage over the others. As for-mentioned the four actors which areunder examination are the Mobile network operator, the Wi-Fi operator, theFacility owner and a fictional entity a TV-White space only operator. Theirrespective spectrum opportunities are the licensed spectrum, unlicensed andTV-white space. The seven roles each actor is capable of assuming are:

1. Provisioning of backbone capacity

2. Radio access network operation

3. Site operation

4. Customer acquisition

5. Access Provisioning

6. ID &Trust provisioning

7. Charging & billing

Analytically, the scenarios that will be examined in round one are the fol-lowing:

1. Mobile network operator using unlicensed spectrum

2. Mobile network operator using TV white space

3. Wi-Fi operator using TV white space

4. Facility owner using licensed spectrum

5. Facility owner using TV white space

31

32 Chapter 4. Business Feasibility Analysis

6. TV white space operator using unlicensed spectrum

7. TV white space operator using TV white space

The following scenarios are excluded either because they are currently in useor not applicable:

I Mobile network operator using licensed spectrum (currently in use)

II Wi-Fi operator using licensed spectrum (not applicable)

III Wi-Fi operator using unlicensed spectrum (currently in use)

IV Facility operator using unlicensed spectrum (currently in use)

V TV-white space operator using licensed spectrum (not applicable)

4.1.1 Asset analysis

The asset analysis makes use of terminology that is explained in the follow-ing section. For each actor a table is created, with the first row containingthe general assets and the following rows, scenario specific assets. In this waycomparisons and conclusions can be made as to what scenarios will be furtherinvestigated. In the tables, symbol Xmeans that the actor can assume the rolepersonally or possess the asset and with that the actor needs to co-operate inorder to assume the role or gain an asset.

4.2.1.1 Terminology

Private spectrum: The ability to use solely a licensed spectrum for RF trans-mission.Free spectrum: Any unlicensed or white space spectrum that can be used onthe fly for RF transmission.Radio access network operation: The provision and ownership of the requiredtechnology in order to provide to customers the ability to access via a radiofrequency the network.Core Network operation: The operation and maintenance of the core network.Backhaul provision: The provision and ownership of the established connectionbetween radio access network and core network.Site Operation: The ownership and operation of a premise or building wherethe owner has full control.Customer Acquisition: The ability to attract and provide MBA services to newcustomers.Access Provisioning : The ability to check what services a requesting UE canhave access to.ID & Trust Provisioning : The ability to check and allow access to a UE.Charging & Billing : The ability charge and collect money for the offered ser-vices to a customer.Macro base stations operation: Installation, operation and ownership of MBSWide area coverage: The ability to provide MBA services in multiple locationsover a city or country1 .

1Based on the findings of the QUASAR project, wide area coverage is most likely to bepossible in rural areas mostly.

4.1. Preliminary asset analysis 33

Registered customers: Customers details are enlisted in a database and have along term contract is issued with the provider.Unregistered customers: Customers that pay for MBA services one-time only.Core business attraction: The ability to attract high volumes of potential cus-tomers daily in a specific location or premise.Market push: The ability to promote via marketing techniques and customerdatabase a new service in the market.Facility wiring : The installation and deployment of a Local area network in afacility.

4.2.1.2 Mobile network operator

Mobile network operator is large scale cell phone carrier that owns the equipmentand infrastructure for radio access network and offers mobile phone services inlicensed bands. An MNO is an actor that can assume all roles by making useof a vertically integrated value chain when the deployment is with MBS andall roles besides site operation when the deployment is based on FBS. MNOsare key actors of the market mostly due to the infrastructure and customerdatabase they have. It is common for MNOs to allow access to users of otheroperators as roaming and even partner up for the construction of the radio accessnetwork. There is motivation behind the MNO to use FBS and TVWS as thiswill allow for more licensed spectrum usage for outdoor coverage, ensure highquality indoor reception and thus reduce the customer churn, increase customerroyalty and delivery of bandle services.

Asset / ActorMNO MNO with MNO with

in General Licensed TV-white spacePricate spectrum XFree Spectrum X XRAN Operation X X XCore Network Operation X X XBackhaul Provision X X XSite OperationCustomer Acquisition X X XAccess Provisioning X X XId & Trust Provisioning X X XCharging and Billing X X XMBS Operation X XWide Area Coverage X XRegistered Customers X X XUnregistered CustomersCore Business AttractionMarket Push X X XFacility Wiring

Table 4.1: Asset analysis for mobile network operator

From Table 4.1, it can be easily concluded that the MNO is a complete entitythat can operate without the need of any other actor in the value constellation.


An MNO has the power to use a private spectrum by operating and maintainingall the network components that are required for a complete network operation:The RAN, the backbone connection, Authentication, Authorization & Account-ing services, macro base stations for the RF transmission that provide wide areacoverage and the core network operation.

Additionally, the MNO has marketing tools that attract new customers im-proving at the same time the market push of new products and services. How-ever, the only association and partnership an MNO needs is an agreement witha facility owner for the installation and operation of the MBS, as in general,MBS are installed on top of high buildings in rural environments, where thefree space for MBS is scarce. When comparing the unlicensed spectrum withthe TV-White Space, it is observed that the MNO in the first case lucks ofthe ability to use the MBS and loses the wide area coverage. That is becausean MNO is not allowed to consume the entire available unlicensed spectrumand block the usage of it from nearby users. In the TV-White space scenariothought; this is avoided by the use of cognitive radio techniques that will notconsume all the available RF and allow competing users for RF usage. Thus thescenario of MNO using Unlicensed space will not be further investigated in thisthesis, while the usage of TV-white space will forward on round two analysisfor business model construction.

4.2.1.3 Facility Owner

Facility owners are big building and infrastructure owners that attract highvolume of customers due to the core business, i.e. hotel and in addition try toincrease the user satisfaction by providing internet access either complimentaryor for a fee. Facility owners on one hand they have a large interest to providebroadband connection to the customers, but on the other little or no interestis observed for MBA provision in their buildings [31]. Hot spots like cafeterias,shopping malls and trains are example of places where the facility owner canassume a multitude of roles for MBA service to the customers. At first thefacility owner can implement its own personal infrastructure, not only cover allthe expenses in its own but also keep all the revenues as well. Secondly, thefacility owner can lease the premises to a MNO or a Wi-Fi operator and letthem handle all the expenses and revenues. Finally, a facility owner can use amiddle ground agreement where the expenses and revenues are partially sharedwith a Wi-Fi operator or an MNO.

In the first column of table 4.2, only the pure assets of a facility owner areselected, the ones that require no further expenses or cooperation with a thirdparty to be achieved. A facility owners greater asset is the facility itself, as itmakes customer acquisition easier with the core business attraction. In this waythe Facility owner can gain some market push but less than the one a MNOpossess. From table 4.2, it is observed that the facility owner has the choiceof using a licensed spectrum after an agreement and partnership with a mobilenetwork operator, in which case the MNO will install and operate the RAN,make backhaul provision, enable AAA services, arrange roaming agreements forthird party mobile users and use technician experts for the facility wiring. Themain benefit of this scenario is the cost effective deployment of the network.On the negative site is the sharing of the revenues with a MNO. In the thirdcolumn of table 4.2, another scenario for the facility owner is shown, to install the

4.1. Preliminary asset analysis 35

Asset / ActorFO FO with FO with

in General Licensed TV-white spacePricate spectrum ?Free Spectrum XRAN Operation ? XBackhaul Provision ? XSite Operation X X XCustomer Acquisition X X XAccess Provisioning ? XId & Trust Provisioning ? XCharging and Billing ? ?MBS OperationWide Area CoverageRegistered Customers X X XUnregistered Customers X X XCore Business Attraction X X XMarket Push X X XFacility Wiring ? X

Table 4.2: Asset analysis for Facility Owner

facility wiring, the RAN which will emit over unlicensed spectrum or TVWS andthe AAA server for its registered and unregistered customers, operating mostlyin independent way as the cooperation with 3rd party billing company is stillneeded. By following this scenario, the facility owner can co-operate with localMNOs and provide roaming agreements over a fee. This scenario can on theone hand provide higher profits to the facility owner but on the other requiresgreat capital expenditure, technical skills and roaming agreement with MNOsfor all customers satisfaction. Both the licensed and TV-White space scenariosare selected to forward for custom business model creation in round two.

4.2.1.4 Wi-Fi Operator

WI-FI operators take advanatage of the fee unlicensed spectrum band to of-fer nomadic WLAN access in hot spots. They are responsible for deploymentand operation of the network and usually have both registered and nomadiccustomers. The customers can originate from another business after a type ofco-operation with a hotel for example and thus the customer acquisition is pro-vided by the core business [33]. In the same way charging and payments canbe managed by other actors like a hotel, credit card companies, and paymentproviders or by using the mobile phone subscription. The spectrum currentlyused is the 2.4 GHz band which is unlicensed and free for anyone to use for.Wi-Fi operators can use open business models like The Cloud, closed businessmodels like internet on trains and vertical models like the-fore mentioned coop-eration with a facility owner [32].

The Wi-Fi operators business entity cornerstone is the usage of unlicensedfree spectrum in hot spot areas either with registered or unregistered customers.The Wi-Fi operator is a market entity that can build and operate a RAN usingown resources and technicians. However, there are various implementations of


Asset / ActorWi-Fi Wi-Fi with

in General TV-white spacePricate spectrumFree Spectrum X XRAN Operation X XCore Network OperationBackhaul Provision ? ?Site OperationCustomer Acquisition ? ?Access Provisioning X XId & Trust Provisioning X XCharging and Billing ? ?MBS OperationWide Area Coverage ? ?Registered CustomersUnregistered CustomersCore Business AttractionMarket Push ? ?Facility Wiring ? ?

Table 4.3: Asset analysis for Wi-Fi operator

Wi-Fi operators in the market differentiating them and their assets accordingly.For example, the Wi-Fi can implement fully AAA service or implement the au-thentication and authorization part with the need of a third party company forthe billing and accounting. Furthermore, depending on the business model ofthe Wi-Fi operator, it can also operate its own backhaul connection towards thecore network of an ISP, have a marketing department for customer acquisitionand therefore market push. In addition, the Wi-Fi operator can have registeredcustomers with long term agreements when there is wide area coverage, or un-registered random customers in case of a hot spot like a hotel. However, thecomparison between the current usage of unlicensed spectrum and TV-Whitespace shows no differentiation in the access and customer acquisition part of aWi-Fi. Therefore, only the TV-White space scenario will be further investigatedin the second and third round.

4.2.1.5 TVWSO

TV white space operator only is a fictional mobile network operator that ownsthe infrastructure and uses only the available TV white space spectrum to offerMBA. A TVWSO operator can cover both indoor access with the aid of fem-tocells and outdoor access by installing macro-base stations. Even though aTWSO operator does not exist as an entity in the market yet, this thesis willinvestigate the possibility and profitability of such existence.

A TV-white space only operator as an entity inherits the characteristics ofa mobile virtual operator with the difference in the spectrum used. A MVNOafter an agreement with a MNO buys in whole price recourses of the networkand sells in retail prices to its customers. This is beneficial for the MNO as thereis better resource consumption and profit generation and also for the MVNO as

4.2. Model Construction and Cost Calculation 37

Asset / ActorTV-white space only operator

Pricate spectrumFree Spectrum XRAN Operation XCore Network OperationBackhaul Provision ?Site OperationCustomer Acquisition XAccess Provisioning XId & Trust Provisioning XCharging and Billing XMBS Operation ?Wide Area Coverage ?Registered Customers XUnregistered CustomersCore Business AttractionMarket Push XFacility Wiring

Table 4.4: Asset analysis for TV-shite space only operator

the initial CAPEX is lower than the one required starting business from scratchbut still a significantly large investment. The best scenario for a TWSO operatorto start business from ground zero is to use the advantage of free spectrum andfocus on the indoor MBA market, building capacity inside out with the use ofFemtocell solutions and with agreements provide outdoor service to its customerby using third party MBS. This is the scenario that will be investigated furtheron, on this thesis.

4.2 Model Construction and Cost Calculation

In this part of the business evaluation round, for the forwarding actors andscenarios, business scenarios are proposed and presented with aim to cover awide range of possible solutions an actor can implement. The assets alreadypossessed and the ones required for the business model completionare presentedand a high level cost analysis is also calculated for the facility owner’s scenar-ios2 In this way a SWOT analysis can take place in order to come up withresults, conclusions and answers to the research questions. From round one theforwarding scenarios are: i) Mobile network operator using TV White spacespectrum, ii)Facility owner using licensed spectrum, iii)Facility owner using TVWhite space spectrum, iv)Wi-Fi operator using TV White space spectrum andv)TV white space only operator.

2Only the FO is taken into account as the MNO already posses a core network with AAAservices and likewise the Wi-Fi operator. As for the TVWSO for the same number of usersthe same cost is implied.


4.2.1 Mobile network operator using TV White Space

4.3.1.1 Scenario: Femtocell deployment for residential and SME usage

MNO’ss in the UK, USA and other parts of the world have already implementedresidential femtocell deployments mainly to expand the thin macro layer cover-age or increase their network capacity. In this case, the licensed spectrum heldby the operator is the same one that is used for the FBS operation. Thus on theone hand, the re-use of the spectrum increases the utilization but on the otherhand increases also the cross layer interference. For this reason, an MNO canchoose to deploy femtocells throughout its network using the available TV whitespace and use the licensed spectrum only by the MBS for wide area coverage.

Strengths

• Cross layer interference is eliminated.

• MBS site installation is avoided or delayed and the user pays for theelectricity and backhaul connection [34].

• The authentication, authorization and accounting aspects remain the sameand no new investments are required.

• Customer database already exists.

• No changes either in the business model already implemented or in thenetwork infrastructure.

Weaknesses

• The resource of TVWS cannot guarantee spectrum dedication.

• Additional cost for the femtocell production.

• No QoE and QoS guarantees.

Opportunities

• MNO’s are less willing to allocate spectrum bands for femtocell operationand would like to use as much as possible for MBS operation [35].

• More efficient spectrum usage with improved capacity saves resources onthe MBS and dead zone problem avoidance [34].

• MNO is in the best position from the rest of actors to make roamingagreements in the femtocell layer area coverage, since the agreements mostprobably exist for the macro layer coverage already.

Threats

• The MNO must be able to provide quality of service and quality of expe-rience to its customers, retaining this way its good reputation and marketposition. The use of TV white space might not be able to provide highlevel QoE in urban areas where the available free spectrum is less than therequired one. For this reason, the MNO can make a case study of availablewhite space and in low availability areas to use the licensed spectrum toensure Qos and QoE.

• Customers with high bandwidth demands might churn to another MNO.


4.2.2 Facility owner using licensed spectrum

4.3.2.1 Scenario: Agreement with MNO

A facility owner comes to agreement with an established MNO that can alsoprovide roaming agreement for third party customers. The infrastructure al-ready exists or is implemented by the MNO following the company standardsand procedures. In the value constellation the MNO will assume all roles be-sides the site operation. The customers can be already subscribed to the MNOor receive roaming services if they are subscribed to other companies.

Strengths

• Increased user satisfaction.

• Data offload that prolongs MBS installation and reducea cost access topublic places [37] from the MNO’s perspective

• Core business support from the facility owner’s perspective.

• No investments are required either for AAA service or customer acquisitionfrom the FO.

Weaknesses

• The facility owner cannot decide autonomously and must follow the willof the MNO.

Opportunities

• This implementation covers not only IMBA services but other telephonyservices like voice and SMS allowing for greater revenue generation.

Threats

• The willingness of an MNO for investments according to [33] varies; withthe highest willingness found where the users are employees of a businesscustomer of an operator or where there is large share of public users likean airport.

4.2.3 Facility owner using TV white space spectrum

4.3.3.1 Scenario A: Infrastructure exists

A facility owner has already a wireless infrastructure with WAP (wireless accesspoints), cabling and connection, switches and routers and AAA services. Theservice can be provided free of charge to the customers as a complimentaryservice to the core business or after a fee (one time or subscription).

Strengths

• The main attribute of a facility owner is the core business attraction whichrequires little or no effort to acquire customers. Thus it can be speculatedthat no investments are needed for marketing and customer acquisition.

• The site owner assumes all roles in value constellation besides provisioningof backbone capacity [32].


• Able to make short term contracts [33] and core business support [32].

• The usage of secondary spectrum has advantages itself as it provides free-dom of operation from operators and interference elimination with MBS.

• Customer database exists

Weaknesses

• Investments in equipment are needed to upgrade the existing network tofemto-able3

Opportunities

• Low entry cost in a new market.

• Indoor capacity for operators or own customers.

• No more wall attenuation problem

• Offloads traffic from more costly macrocell networks [35].

• Low cost price of FBS against competing solutions like picocells, DAS andrepeaters [44].

Threats

• The level of QoS and QoE towards the customers must overcome the QoSand QoE a best effort Wi-Fi system can provide otherwise it will not bewise to upgrade the system at all.

4.3.3.2 Scenario B: Infrastructure needs to be deployed

Strengths

• No marketing and customer acquisition investments are required

• The site owner assumes all roles in value constellation besides provisioningof backbone capacity [32].

• Able to make short term contracts [33]

• Core business support [32].

• The usage of secondary spectrum has advantages itself as it provides free-dom of operation from MNO’s.

Weaknesses

• Unlike the previous scenario, no infrastructure exists and thus the initialCAPEX is greater.

• AAA system must be placed and an electronic billing support system tobe installed

3Particularly, the WAPs need to be replaced with FBS probably LTE-based since theexisting system is IP-based, the cost calculation of which is out of the thesis scope and anAAA server in case the service was free of charge before and thus also an electronic billingsupport system like JCC will be needed so as the customers prepay for the service.


• No customer database

Opportunities

• It is more efficient to design and install a network from the beginning andnot modify an existing one like in the previous scenario (from interview).

• Indoor capacity for operators or own customers which on the one handovercomes the wall attenuation problem and on the other offloads trafficfrom more costly macrocell networks [35].

• Low cost price of FBS against competing solutions like picocells, DAS andrepeaters [44].

Threats

• The level of QoS and QoE towards the customers must overcome the QoSand QoE a best effort Wi-Fi system can provide otherwise it will not bewise to install the system at all.

• It is for this reason that measurements on the available TV white spaceon the facility location needs to be taken before any plans and changestake place.

4.3.3.3 Scenario C: Roaming agreements

Having a shared femtocell system along the premises that allows for roamingto third party users is highly recommended for a facility owner. By using theterm Roaming in this thesis, it is ment that the user camping on a femtocell canreceive and originate calls to and from other macrocell cellural networks. Whilewhen using the term Offloading, the capacity of the indoor network is rentedout to a third-party regardless if roaming agreements exist or not.

Strengths

• System utilization and customer satisfaction is maximized.

• Reduced interference and more licensed spectrum for MBS usage [35].

• The user can subscribe for indoor MBA service and still be able to receivecalls originating outside the facility.

Weaknesses

• Coming to an agreement with all existing operators might be cumbersomeand hard to achieve and is proportional to the network size and capacityof the facility owner.

Opportunities

• As the facility owner will be paid for the roaming services, the profitgeneration will be higher with roaming agreements

• In a multi-operator environment, the cost savings could be up to 66

• Offloading data capability.

Threats

• It is extremely difficult to make national roaming agreements at this point(from interview)


4.3.3.4 Scenario D: No roaming agreements

Strengths

• Low-cost indoor capacity network for renting purposes

Weaknesses

• With no roaming agreements, the facility owner cannot serve any userswith existing subscriptions to third party companies.

• The main issue arises when a user inside the facility wants to use both thelocal MBA services offered and the cellular connection with the MNO. Inthis case the user will have to choose one between the two services as bothcannot co-exist, creating a cumbersome problem for both the user and theFO.

Opportunities

• Revenue generation by providing offloading services.

Threats

• Fewer customers

• Not providing national roaming could be a show stopper in this scenario4.

4.2.4 Facility Owner Cost Estimation

For the cost estimation5a two level analysis will take place. The low end willestimate CAPEX and OPEX for no more than 10 users in a network and thehigh end for more than 1000 users. In this way a cost dimensioning can takeplace.

4.3.4.1 Low end CAPEX and OPEX

For a small network of ten users, still some dedicated equipment is required.Therefore, a server PC is acquired that runs open software like Zeroshell andpatron soft for the AAA implementation. A 12-port switch handles the in-door/outdoor Ethernet traffic generated from the femtocell use. For the main-tenance no dedicated personnel exists but a 24/7 contract with a remote-supportcompany. Figure 4.1 summarizes the average cost per year and the present val-ues for years 3,4 and 5.

4.3.4.2 High-end CAPEX and OPEX

For a larger capacity network of 1000 users, a dedicated room for server instal-lation is required with redundant air-conditioning system in which the structurecabling ends up in a rack. It is estimated that the cost of cabling installation of

4From interview with Orjan Fall. For more information visit the APPENDIX A5The input for the required equipment for both the low and high end estimations and

other necessary components that consist a self-sustained AAA service were received from theinterview with Panayiotic Chiras -a network administration at the Technical University ofCyprus


Figure 4.1: Low end present value calculation for years 3,4 and 5

each access point is 20 euros and another 50 euros are spent on CAT 6 cable.A layer 3 switch like the CISCO 4503 is used in this example that providesenough ports for the femtocells operation and also optic link connections viathe SPF card for the termination of the backhaul lines. In this scenario a serverpc that runs zero shell and patron soft can manage the AAA with no extraCAPEX or OPEX requirements. However, it must be noted that a CISCO ACSsystem costs around 45000 euro. For the maintenance and remote support anagreement is made with a company for round the clock service, thus no furtherpersonnel is required. If high redundancy is needed then the whole amount mustbe doubled. Figure 4.2 summarizes the average cost per year and the presentvalues for years 3,4 and 5

Figure 4.2: High end present value calculation for years 3,4 and 5.


4.2.5 Wi-Fi operator using TV white space spectrum

4.3.5.1 Scenario: Co-operation with a Facility Owner

Based on the work in [32] the co-operation of a Wi-Fi operator with a facilityowner can be two fold. In the first case the operator takes most of the businessroles, is the dominant actor and handles the business relation with the customerthrough subscriptions. The service is either offered for free to subscribers or foran extra fee to non-subscriber. In the value constellation the operator assumesall roles besides site operation. The identification, authentication and billing canbe handled either by the MNO or a 3rd party company. Customer acquisitionand marketing are also Wi-Fi operators responsibility.

Strengths

• Strong commercial name and national access at hot spots for businessusers (TeliaHomerun).

Weaknesses

• The main drawback is the lack of roaming.

• Investments are needed for the RAN, backbone capacity, AAA implemen-tation and customer acquisition.

• No guarantees and risk of bad reputation

Opportunities

• The facility owner needs to make no investments and simply shares therevenues.

• Support for core business and new partners

Threats

• Customers with high bandwidth requirements will choose a different provider.

• Potential high prices might lead customers to other places.

In the second scenario according to [32], there is a closer co-operation amongthe two actors with the Facility owner being responsible for the customer acqui-sition and the WiFi operator for the site survey and operation of local network.The main drive is to support the core business. The AAA can be managedeither by the operator or by the Facility owner or by a 3rd party company.Investment wise, the facility owner only needs to make investments in case theAAA implementation is his responsibility. Otherwise for customer acquisitionthere is no investment needed and the RAN and backhaul provisioning are leftto Wi-Fi operator.

Strengths

• Shared amount of cost and responsibility

• Open business model with many actors

Weaknesses

• No returning/loyal customers but mostly one time-fees.


Opportunities

• Support to core business and revenue increase for both actors

Threats

• Networks with open access or national roaming

4.3.5.2 Scenario: Transition from unlicensed spectrum to TV whitespace

In this scenario, a Wi-Fi operator chooses to offer indoor MBA using femtocelltechnology and the available TV white space.

Strengths

• No further expenses for AAA, marketing, customer acquisition or account-ing department.

• The UE requires no dual mode operation

Weaknesses

• The issue is restructuring the business model and what customers expect.

• On what level the Wi-Fi operator wants to offer services.

Opportunities

• Use of White-Fi and take advantage of the benefits TVWS has to offerwithout any changes in the infrastructure.

Threats

• The challenge for the Wi-Fi operator is changing the company from WiFito WISP, where the Wi-Fi is low cost best effort and the WISP (WirelessInternet Service Provider) ensures QoE and QoS.

• The billing price depends on the business model and who the WiFI oper-ator is competing with.

4.2.6 TV white space only operator

4.3.6.1 Scenario: TV white space only operator business start up

There are three proposed business scenarios for a TVWSO each with differentbenefits and drawbacks:

1. A TVWSO comes to agreements with existing MNOs so that a customerof MNO A that pays only for voice and SMS services can purchase indoormobile broadband from TVWSO B and use both services with the sameIMSI and SIM card. In this way, the user can have indoor femtocellmobile broadband and telephony at home and national roaming outdoors.Technically the TVSWO will roam voices and SMS services at home andthe MNO will roam MBA services outdoors. In this scenario, based on[35] this is a difficult business case if new sites need to be deployed. Itwould be wiser to act as mobile virtual operator so as the investments


in network guarantee proportional bigger capacity than investments insecondary macro base station spectrum offer. The key issues accordingto [35] are related to market entry, large investments in infrastructure,service and billing platforms, marketing and customer relations.

2. Based on the business model of FON, a TVWSO could follow the samemodel for expansion and network deployment. Since the access is open,for a subscriber of TVWSO A, where ever there is an operating femtocellof TVWSO A the IMBA service is free for any subscriber, even if thelocation is a different city, creating a decentralized wide area network.Technically, this is feasible as the authentication and authorization servercould check the requesting IMSI of the user and allow or deny access. Itmust be noted that FONs business model allows for revenue sharing withthe users.

3. The TVWSO does no roaming agreements with MNOs thus providing onlyindoor MBA services locally.

Strengths

• Free spectrum itself as the radio interface is more expensive than backhaulnowadays(from interview)

Weaknesses

• The CAPEX and OPEX investments are greater than the one of a facilityowner or a Wi-Fi operator6.

• TVWSO will need to offer a descent amount of volume at a good cost justlike an MNO or a WiFi operator does.

Opportunities

• Elimination of traditional market entry barriers

Threats

• Unlike the MNO, the possession of spectrum can provide QoS and controlthe company destiny, something TV white space cannot guarantee.

4.3 Results-Actor Specific

4.3.1 MNO

• For the standalone scenario of MNO, as long as the available TVWS canprovide QoS and QoE the MNO can and should implement femtocells withTVWS. In this way not only the MNO will allocate licensed spectrum forMBS usage but also eliminate the cross-layer interference. From all theinvestigated scenarios, the MNO is in the best position to implement abusiness model since providing national coverage with roaming agreementsis already possible. In the unlike event where the available TVWS is unableto provide QoS and QoE then the MNO should not use TVWS in orderto avoid a bad reputation and customer churn to a competitor.

6A TVWSO will need besides the radio access network and backhaul connection invest-ments, marketing department, AAA servers, an accounting department, office(s), customersupport department and technical support department.

4.3. Results-Actor Specific 47

4.3.2 Wi-Fi operator

• From the two scenarios investigated it is concluded that it is not wise fora Wi-Fi operator to switch to femtocell operation only, as there will becustomer loss due to connectivity issues with non-cellular devices. Addi-tionally, a Wi-Fi operator even as a charged service is still a best effortsystem and users are satisfied and accustomed to it. Transitioning toWireless provider instead of a Wi-Fi operator will need changes in theorganization and business structure - entering in a new more demandingmarket- and not only to the network components. It is therefore, moresuitable for a Wi-Fi operator to integrate femtocell access points in thenetwork as to provide a more complete network service. Also the use ofWhite-Fi is recommended to be taken into account for the benefits it hasagainst traditional Wi-Fi.

4.3.3 FO

• There were 5 different scenarios under investigation for the facility ownerand the most important aspect that must be stressed out is the nationalroaming ability7. Since access benefits is what this thesis is after then notproviding national roaming could be a show stopper. This is because auser will not choose a service in which in order to gain IMBA will losecellular connectivity. Therefore, from the five scenarios the most feasibleare: the one where there is co-operation with MNO from the start andthe one where roaming agreements are made.

From that point the existence of an infrastructure is the best way for afacility owner to upgrade to femtocell network as the initial investment islower when compared to a new network construction from ground zero.Also an existing networks applies there is existing customers, a databaseand in a general a work flow of operation. However, before changingthe existing Wi-Fi system, the facility owner must measure the availableTVWS and be sure about the QoE the network will be able to provide.The Wi-Fi is a best effort system and still users are quite satisfied andaccustomed to it. Installing a new system that could also affect the cel-lular use of UE can disappoint the customers and thus diminish the corebusiness as well. Additionally, users of Wi-Fi also need to connect laptopcomputers and tablets to the network and not just cellular phones. Thus,the use of femtocells will benefit the mobile phone users with seamless con-nection but will unfortunately eliminate other users from access. Whilewith Wi-Fi all UE is able to receive MBA service. It is for this reason afacility owner can also implement alternative solutions like White-Fi or afemto-Wi-Fi system as to provide a complete system for all the users.

When it comes to CAPEX, OPEX and NPV for the AAA implementation,it is obviously more efficient to build a network for 1000 users than 10since; the cost per user is around 1/10 when the network is for 1000 usersthan 10. Obviously the profit margin in larger networks is bigger butwith also larger initial investments. What is interesting, is that the initial

7Roaming agreements can even be achieved by means of offloading services to an MNO.What is the important is not the terminology but the service offering of both IMBA andcellular connectivity to a user


investment of 1000 users network is proportional to the cost per user;being also 10 times bigger.

4.3.4 TVWSO

• Overall its a feasible business case with high risk as the free spectrum elim-inates a traditional market entry barrier but cannot guarantee the futuredestiny of operation. Although, just because the spectrum is free this doesnot mean that no CAPEX or OPEX investments will be required at all. Acareful more in-depth analysis should be made to measure the required ini-tial investment for a complete network operation and maintenance whichcan then be used to calculate any possible return of investment and decideabout the viability of the Tv White Space only operator.

Chapter 5

Conclusions and Futurework

5.1 Research questions answers

1. What are the benefits of femtocell networks when the actor isMNO and the spectrum band is TVWS?-As shown from the analysis is Chapter 4, the MNO by using the avail-able TVWS can benefit from increased capacity, more licensed spectrumavailability for macro-layer usage and cross-layer interference elimination.This is important in dense networks where high interference levels caneven cause service disruption.

2. What are the benefits of femtocell networks when the actor isWi-Fi operator and the spectrum band is unlicensed or TV whitespace?-The analysis results showed no substantial benefits for the unlicensedspectrum band and therefore its not advised to be adopted or used bya Wi-Fi for femtocell operation. Most importantly operating WAPs andFAPs at the same band will create competition for the limited spectrumresource and will negatively affect both services.Likewise the unlicensedspectrum, neither the TVWS shows noticeable benefits for standalonefemtocell network. However as mentioned earlier the usage of White-Fiis proposed for further investigation and a combined network with WAPsand FAPs will increase the network connectivity and customer satisfaction.

3. What are the benefits of femtocell networks when the actor isfacility owner and the spectrum band is licensed, unlicensed orwhite space?-Licensed: Providing offload services towards an MNO after a co-operationagreement will benefit all three involved parties: the FO, the MNO andthe end user. This is achieved through better indoor reception and seam-less IMBA connection for UE, data offload for the MNO with cost savingsand core business support and revenue generation for the FO.-Unlicensed: There was no hard evidence discovered in the analysis topromote the usage of unlicensed spectrum with femtocell networks over

49

50 Chapter 5. Conclusions and Future work

the existing Wi-Fi networks.-TVWS: Under the optimistic view of available TVWS the FO can benefitfrom freedom of operation from MNOS and act independently. Of coursethe initial investment and running expenses are higher but the analysisshows that large scale networks have proportionally larger profit margins.

4. Is there a business case for a mobile broadband TV white spaceoperator only (TVWSO)?-Yes and No. Theoretically there is a business feasibility case for a TVWSOeither as VMNO with offloading indoor operation or with a concept likeFON. However, the service must match the one a MNO provides or theremust be a sustainable service with a much lower price in order to attractcustomers. The main attribute of the TVWSO as mentioned before is theusage of free spectrum and thus the easy market entry. Although buildingand operating a core network even with no MBSs is still investment wisehard. Thus the best proposed business model for a TVWSO to enter theMBA market is to act as MVNO with a FON concept deployment. Auser/customer that installs a femtocell at his house can also access IMBAwhenever in proximity with a femtocell of the same operator for free andwhen the user is outdoors then national coverage is provided by usinga third-party mobile network. This is the most complete scenario thatmakes efficient use of the 70-90% indoor access but still lies in the theo-retic sphere. A more in depth research must be conducted for more solidconclusions.

What are the access benefits that femtocells and TVWS have tooffer towards selected actors and in which scenario(s)? From all theabove, it can be concluded that femtocells using TVWS have both benefits anddrawbacks. From the technical point of view, TVWS usage can benefit with lesscross-layer interference, increased capacity and coverage but its not a fail-safeactivity for stakeholders and market players. From an economic point of view,TVWS usage even if obvious- its a free open resource for anyone to use andwith the right design, implementation and usage can give new market playersa soft push in their market entry with revenue generation or simply a capac-ity network that can be used accordingly to individual demands. Among theresults its shown that its not yet recommended to replace existing working so-lutions like Wi-Fi with femto-TVWS networks. Its better to improve the Wi-Finetworks with complimentary femto-TVWS solutions as this combination willovercome any drawbacks each individual technology has. Since Wi-Fi is an IPbased network then the integration of femtocells in an existing network basedon LTE for example should under optimistic assumptions (working technologyfrom different vendors) be feasible with no or small investments. What shouldbe highly considered by any actor and for any scenario its the ability to providenational IMBA and cellular roaming.

5.1.1 A more abstract perception

Setting aside the actors and the business scenarios and assuming a more abstractview on the femtocell and TVWS concept some observations are made. First,

5.2. Discussion & Future Work 51

it must be stated that the general concept of femtocells is not in a mature stateyet. This naturally carries along implications in various aspects i.e businessschemes and user adoption. While on the other side of the fence Wi-Fi is on thepeak state of its long course with interoperability and ease of use as two strongweapons. FBS are more expensive when compared to WAP and it comes to nosurprise since its a new technology. One of the assumptions that this work isbased on is that there is vendor interoperability but as it was discussed amongthe interviewees this is not the case. At the same time it was also assumed thatany type of co-operation among actors is possible under the regulation law whichin practice might not stand so tall. Hence the complexity of femtocell networksincreases. There is of course motivation for market actors to get involved as thefirst one to introduce five bar indoor signal to its customers will reduce the churnbut maybe when many actors are sharing a distributed femtocell network thecase is not the same. The service/product offered by different and competingactors will be of the same quality thus the motivation to get involved declines.What is probably needed more and can push the femtocell usage in general is thevalue added services and the localized services the FBS can provide to end users.To successfully deliver value added services requires end-to-end QoS and the bigquestion is if there is sufficient spectrum for this cause. Looking at the technicalaspect of femtocells, there is a need for traffic separation between the macro andfemto layer at the core network with differentiated accounting and marketingschemes for femto-users while at the same time the security among untrustedchannels and paths must be ensured. All of the above hold the femtocell erafrom taking off but it is the author’s personal belief that femtocells -regardless ofspectrum- will flourish when the need for high speed and high quality broadbandaccess overcomes the need for cellular telephony and those days are not far away.

5.2 Discussion & Future Work

The thesis drafting was a more difficult and challenging work than originallyexpected. The main issue was the drifting around when searching for scientificwork as the majority of related papers that were researched at the end werenot used. It was also challenging to arrange interviews with industry experts asit was originally planned to make more meetings but to unknown reasons theyfailed. For the actual research area and work conducted in this thesis, the authorsuggests that the business structure and model of a TVWSO as proposed in thisthesis to be researched additionally that will make a business estimation basedon the FON concept model. Likewise the usage of TVWS by a Wi-Fi operatorwith femtocell integration it is speculated to create an improved broadband net-work and should be examined more. Last but not least other rising alternativesthat were not dully considered in this work like the LTE technology are alsoproposed for usage as all interviewees mentioned that the future is LTE. Sincethere is an ongoing parallel work at the Wireless department of KTH that takesinto account the radio access network cost structure deployment, which is anaspect not measured in this thesis, for a wider and better understanding on theresearch area, it is advised to read the work of Ilias Karonis on the RAN Eval-uation of LTE-femtocell Deployment and TV White Space Secondary Usage .By combining the results and the cost structures provided in the two works,complete cost estimations for the femtocell network installation and operation

52 Chapter 5. Conclusions and Future work

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[38] Zeroshell Forum http://www.zeroshell.net/eng/

[39] Dr. Sumanjeet, Emergence of Payment Systems in the Age of ElectronicCommerce: The State of Art, First Asian Himalayas Conference, 2009

[40] Guillaume de la Roche, Alvaro Valcarce, David Lpez-Prez, and Jie Zhang,Access control mechanisms for femtocells, University of Bedfordshire Jan-uary 2010

[41] Jen Chen, Jen Chen, Peter Rauber, Damanjit Singh, Chandru Sundarra-man, Peerapol Tinnakornsrisuphap, Mehmet Yavuz Femtocells Architec-ture & Network Aspects, 2010

[42] D. Lpez-Prez et al., Access Methods to WiMAX Femtocells: A DownlinkSystem-Level Case Study, IEEE Intl. Conf. Commun. Sys., Guangzhou,China, Nov. 2008.

[43] Normann R, Ramirez R, From Value Chain to Value Constellation: De-signing Interactive Strategy, Harvard Business Review, Jul/Aug93, Vol.71, Issue 4.

[44] M. Latham, Consumer Attitudes to Femtocell Enabled In-Home ServicesC Insights From a European Survey, FemtoCells Europe 2008, June 2008.

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[45] David Ford, Lars-Erik Gadde, Hkan Hkansson, Ivan Snehota, AlexandraWaluszewski, ANALYSING BUSINESS INTERACTION

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Appendix A

Interviews

A.1 Interview with Tord Sjolund, President ofMic Nordic

After a small presentation on our work and research area, Tord was interestedto know about the available TV White space in Sweden and on what frequencyband was on. He then stressed out the fact that to his best knowledge nohandsets exists that work on the 400 MHz band, which is one of the workingassumptions of the thesis. We have a free band on 800 MHz but its just forspeech and its for GSM voice solutions only. So femtocell is an opportunityto integrate it with the existing network so you can get speech and broadband.Local mobile broadband is as project we are working on which in like the facilityowner in your case he said. When asked about his background, he replied: Westarted the indoor communication company in 2007 and the focus was to coverindoor systems. I have a background from Telia and also the supplier site. Thereis a problem with indoor communication in buildings and even now in new onesthey dont take measures for it. Its more expensive to do it afterwards and moredifficult. We currently have three base stations active in conference centers inSweden. Tord mentioned that We are not using any billing system yet but itsin the switch function. We are just using a laptop with software for the localaccess. A statement by Tord which is a showstopper for the facility owners caseis With this system you cannot make any calls to your ordinary number, only atlocal numbers. However he continued saying the next step is to provide nationalroaming, which is ofcourse is possible but also hard to achieve and you needco-operation with someone else. The good thing about Local Mobile Operatoris that your employees get to use the service for free

A.2 Interview with Orjan Fall, Vice-president of3GNS

Orjan has experience in consulting services over 20 years and before that he wasin the RnD of base stations for companies like Nokia and Erickson. He was inthe development of 2G and 3G base stations for macro layer networks. In 2001he was involved in a project for Picocells construction with the idea to offload

57

58 Appendix A. Interviews

data. As he mentioned the idea was 10 years ahead of time and I failed toconvice my boss to market it, but now the future is brighter for small cell basestations. In March started with 3GNS as vice president. After our introductionto the problem area, Orjan gave us all the information he knows on the subject:If you look at the femtocells there is a substantial deployment. AT&T hasaround 500,000 HNB in their network, because the network layer is thin andhas holes. So the aim is to provide service to the customers. From a RANperspective there is no interference since there is no capacity anyway. Howeveryou need to consider if you are an island approach or if you are integrated inthe network. You can integrate a big number of HNB in the network. Take wi-fifor example, is an island approach. You can only change your frequency butwithout any co-ordination and femtocells need to be part of the network. MNOsbuilt their networks with extra capacity and push the market to use the dataservices. In a way MNOs need to defend their spectrum investment but mostimportantly you need to work close with system vendors and system integratorsbecause everyone is pointing fingers. So its not just the cost or cost saving ofother solutions but also other aspects need to be taken in. One reason cellulardeployment is bigger than Wi-Fi is that possession of spectrum can provide QoSand can control your destiny. Something free spectrum can never guarantee.-What is your opinion about a Facility owner using Femtocells with TVWS forIMBA?I believe the solution is Wi-Fi, as they need to offer service to all their clients.It might be best effort but it works very well. National roaming agreements aretechnically easy but are a show stopper for a F.O. today.-When it comes to the Wi-Fi operator, what are the AAA changes required toswitch to a femtocell network?The challenge is changing the company from Wi-Fi operator to Wireless serviceprovider. The first is a low cost best effort service where the latter is a bigmarket player with QoE. So switching to from Wi-Fi to LTE is relatively easywith no changes in the backhaul. The big question is on what level you want tooffer services?-And what about the TVWSO as a new market entity?Its a big positive that there is a not license fee and thus a traditional barrieris removed. But free space can provide no plan or guarantee for quality. Anoperator like this in the long run will need to offer a decent volume at a goodcost. Overall its a feasible business case.

A.3 Interview with Panayiotis Chiras

Panayiotis Chiras is a network engineer with experience in design and imple-mentation of large scale networks. He has been actively involved with enterprisenetworks like the International airport of Cyprus and currently works as the net-work administrator of Cyprus Institute of technology. For the discovery of therequired network components related to the AAA service implementation andtheir prices, Panayiotis kindly filled up the blank spots and gave directions foralternative free solutions that are used in this work.

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