Open access femtocell business feasibility with TV White Space usage

Transcription

1 Open access femtocell business feasibility with TV White Space usage For mobile indoor broadband CHRISTODOULOS CHIRAS Master of Science Thesis Stockholm, Sweden 2012

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3 Open access femtocell business feasibility with 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 Zander Supervisor: A/Prof. Jan Markendahl

4 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

5 Abstract Femtocell technology and TV White Space are two different entities that have not been thoroughly researched under the common goal of indoor mobile broadband access. In this thesis the combination of these two technologies is examined through the prism of four different actors: Mobile Network Operator, Facility Owner, Wi-Fi operator and TV White Space Only operator. The aim is to discover access benefits and evaluate the business feasibility of open 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 feasibility analysis both technological and economic aspects are taken into account for new market players as well. It is shown with no doubt that national roaming agreements is one of the most important aspects any market player should take into account before proceeding with any business plan. Additionally, the analysis found that the secondary usage of TV white space is technologically and economically feasible but no solid benefits were identified that can overthrow existing indoor mobile broadband implementations like the Wi-Fi systems. However the primary usage of femto-tvws is still recommended for some actors like the mobile network operator and the facility owner and the complimentary usage by the Wi-Fi operator. iii

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7 Acknowledgements For the production and completion of this thesis it took a lot of sucrifices not only from my self but also from my family and friends. Thus at this point i would like to express my graditute towards my family for the continious support towards the long course of my studies abroad. Also i would like to salute all the great people i met during my visit in Sweden and especially Ilias Karonis for his ubiquous and non-stop aid during the thesis construction. Last but not least, special thanks to the wireless department of KTH for the wonderfull hospitality and my supervisor Mr. Jan Markendahl for all his guidance, advices and understanding. Christodoulos Chiras Stockholm, September 2012 v

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9 Contents 1 Introduction Problem Formulation Related Work and Contribution Thesis Outline Methodology Work FLow Assumptions Method Data Collection Primary Data- Expert Interviews Secondary Data - Research and analysis of relevant scientific work Business Feasibility Analysis Background Access Network Architecture Legacy Iub over Ip Concentrator GAN (Generic Access Network)-based RAN Gateway IMS and SIP Air-interface technologies GSM Femtocells UMTS and HSPA Femtocells OFDM-based Femtocells Interference Co-layer Interference Cross-layer Interference Mobility Manager Femtocell characterization Femtocell identification Access control mechanisms Local Area Identity/Tracking area Identity Closed Access Mode ID Allowed Access List Access Control Triggers Access Control Location Access control for Open, Closed and Hybrid mode vii

10 viii Contents 3.5 Spectrum Licensed Unlicensed TV White Space Wi-Fi Sollution - An overview Wi-Fi af (Wifi using TVWS) Femtocell Wi-Fi integration ZeroShell rd Party Payment System Business Feasibility Analysis Preliminary asset analysis Asset analysis Model Construction and Cost Calculation Mobile network operator using TV White Space Facility owner using licensed spectrum Facility owner using TV white space spectrum Facility Owner Cost Estimation Wi-Fi operator using TV white space spectrum TV white space only operator Results-Actor Specific MNO Wi-Fi operator FO TVWSO Conclusions and Future work Research questions answers A more abstract perception Discussion & Future Work Bibliography 53 A Interviews 57 A.1 Interview with Tord Sjolund, President of Mic Nordic A.2 Interview with Orjan Fall, Vice-president of 3GNS A.3 Interview with Panayiotis Chiras

11 List of Tables 2.1 Interview respondents list Asset analysis for mobile network operator Asset analysis for Facility Owner Asset analysis for Wi-Fi operator Asset analysis for TV-shite space only operator ix

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13 List of Figures 3.1 Architecture of GAN-based HNB From smallcell forum white paper on Integrated Femtocell Wifi systems Low end present value calculation for years 3,4 and High end present value calculation for years 3,4 and xi

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15 List of Abbreviations 3GPP AAA AP ACL AKA ARPU ATM BSC CAM CAPEX CDMA CINR CN CPE DAS EAP EMS EUTRAN FBS FDD FMC GAN GANC GSM HAM HCS HLR 3rd Generation Partnership Program Authentication Authorization and Accounting Access Point Allowed Closed Access Mode List Authentication and Key Agreement Average Revenue Per User Asynchronous Transfer Mode Base Station Controller Closed Access mode Capital Expenditure Code Division Multiple Access Signal to Noise Ratio Core Network Customer Premises Equipment Distributed Antenna System Extensible Authentication Protocol Enhanced Message Service Evolved UTRAN Femtocell Base Station Frequency Division Duplexing Fixed Mobile Communications Generic Access Network Generic Network Access Controller Global System for Mobile communication Hybrid Access Mode Hierarchical Cell Structure Home Location Registry xiii

16 xiv List of Abbreviations HSS HNBS HNBGW HSDPA HSUPA IKE IMBA IMS IMSI LAC LAI LAU LTE MBS MGW MM NAS MNO NCL OAM OFDM OFDMA OPEX PCI PSC RADIUS RAN RNC RTP SA SeGW SGSN SNMP SIP SINR Home Subscriber Server Home Node Bs Home Node B Gateway High Speed Downlink Packet Access High Speed Uplink Packet Access Internet Key Exchange Indoor Mobile Broadband Access Ip Multimedia Subsystem International Mobile Subscriber Identifier Local Area Code Local Area Identity Local Area Update Long Term Evolution Macro-cell Base Station Media Gateway Controller Mobility Manager Non Access Stratum Mobile Network Operator Neighbouring Cell List Open Access Mode Orthogonal Frequency Division Multiplex Orthogonal Division Multiple Access Operational Expenses Physical Cell Identity Primary Scrabling Code Remote Authentication Dial-in Server Radio Access Network Radio Network Controller Real Time Transport Protocol Security Association Security Gateway Serving GPRS Support Node Simple Network Management Protocol Session Initiated Protocol Signal to Interference Noise Ratio

17 List of Abbreviations xv SON SRG TDD UE UMTS UTRAN UARFCN WAP WCDMA WiMAX WISP QoS Self Organizing Networks Signal Research Group Time Division Duplex User Equipment Universal Mobile Telecommunication System UMTS Terrestrial Radio Access Network UTRA Absolute Radio Frequency Channel Number Wireless Access Points Wideband CDMA WorldWide Interoperability for Microwave Access Wireless Internet Service Provider Quality of Service

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19 Chapter 1 Introduction Indoor mobile broadband access (IMBA) demand is on the rise and with continuously technological breakthroughs the Internet becomes available almost everywhere. While users get accustomed to this new any location internet access [32], new actors emerge and enter the IMBA market. The need for more capacity and bandwidth can be achieved with new spectrum allocation bands. However spectrum is a finite, non-exhaustible costly resource [35], [36] and therefore the use of secondary spectrum is a welcomed proposition. The secondary use takes advantage of un-used spectrum either in time, frequency or place. The so called TV White Space (TVWS) is the secondary spectrum under investigation in this work. Traditionally, IMBA services are provided by outdoor macro base stations (MBS) or indoor systems like distributed antenna system (DAS) or Wi-Fi access points. However a new small cell technology called femtocell promises high quality indoor coverage and capacity with advantages over competing technologies. Since the combination of these two technologies is not adequately investigated neither by the academic nor by the industrial community, this thesis purpose it to examine for four different market actors the business feasibility of open access femtocells using the available TVWS for IMBA services. The research questions and methodology focus on the business roles, customer relations, access mechanisms and payment options; aspects which current existing works have not taken into account. The main analysis is based on interviews with market experts inside and outside the telecommunication sector covering both 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 White Space Only operator (TVWSO). More information on these four actors is given in chapter 4. It must be noted that this thesis will not pay any emphasis on the Radio Access Network (RAN) components and cost nor the backhaul requirements for network operation 1. Secondary Usage. Specifically under investigation are the changes in the access control (technical view) and marketing adaptation (business view) in a multitude of scenarios. 1 This is mainly due to the reason that an ongoing parallel thesis is taking place precisely for this purpose so for more information on these topics visit Ilias Karonis thesis on RAN Evaluation of LTE-Femtocell Deployment and TV White Space 1

20 2 Chapter 1. Introduction 1.1 Problem Formulation Incumbent actors in telecommunication industry are in search of new business models as the legacy models become more and more mature and the prospects of margin and profit decline. Towards this quest, there is a great motivation to study from a techno-economic point of view the potential access and financial benefits, the usage of open access TV white space femtocells has to offer. Its the objective of this thesis to find what scenarios are more promising than others by conducting a relative analysis of what assets actors have or havent with an emphasis on customer relation and access control. In particular, based on a business feasibility analysis the main question to be examined is: What are the access benefits that femtocells and TVWS have to offer towards selected actors and in which scenario(s)? While the benefits and drawbacks for each proposed model will be outlined in a trial to weight for or against each mode, from the main question four sub questions are derived: 1. What are the benefits of femtocell networks when the actor is MNO and the spectrum band is TVWS? 2. What are the benefits of femtocell networks when the actor is Wi-Fi operator and the spectrum band is unlicensed or TV white space? 3. What are the benefits of femtocell networks when the actor is facility owner and the spectrum band is licensed, unlicensed or white space? 4. Is there a business case for a mobile broadband TV white space operator only (TVWSO)? 1.2 Related Work and Contribution Most literature study on indoor wireless systems focuses on interference analysis and technical design [47], [48] with little or no attention on the business aspects and deployment of femtocells. Any proposed business models take into account mainly the MNO as an actor and the analysis is on the deployment and technical mechanisms. Like for example in [46], a techno-economic analysis of large scale projects like TERA and TONIC is performed from the mobile operators perspective with focus on deployment strategies. In addition white papers from Small cell Forum have as target group single operator small office home office implementations 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 important for the provisioning of public Internet access services and the main finding of the analysis is that public local access provisioning to a large extent differs from the traditional operator business and that actors from outside the telecom sector slowly enter the telecom business with the main driver to support the core business. In [33] Nilson et al define that a femtocell network can

21 1.3. Thesis Outline 3 be of four types: one single-operator femtocell network, multiple singe operator networks, one multi operator network and multi operator solution based on roaming. In [34] Peng Li et al have proposed two schemes to maximize a MNOs revenue with the first scheme handling cross tier channel allocation and interference management for optimal revenue and with the second scheme optimal pricing and spectrum scheduling are combined for revenue maximization. In [35] Markendahl et al focus on the importance of the multiple factors that must be taken into account when testing a business model for TVWS based on macrocell networks with tower installation and operation, the conclusion was that even if the cost for cognitive radio equipment is the same as with the standard 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 and local area network operation must be examined. In [37] Katsiyiannis et al, analyze the business of local area access from the perspective of MNO and service application providers, constructing at the same time a techno-economic model to 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 access methods to femtocells and describe in detail the benefits and drawbacks of each. Furthermore, the business case, scenarios, and technical challenges of different access mechanisms along with some potential solutions are presented. In [41] Yen Chen et al introduce and compare various femtocell network architectures and also discuss various challenges the introduction of femtocells brings like interoperability with networks and handsets with potential solutions to address these issues. This thesis contribution is the proposition and evaluation of open access business scenarios for four different actors: MNOs, wireless internet access providers, facility owners and TV white space only operator (TVWSO). The proposed scenarios are SWOT analyzed to identify potential techno-economic benefits and also cost calculations (CAPEX and OPEX) for the AAA implementation requirements are performed in some cases. The analysis also takes other aspects into account like marketing, customer acquisition and service provisioning for indoor femtocell solutions with licensed, unlicensed, and white space spectrum usage. The consideration of the Wi-Fi operator, Facility Owner and TVWSO as actors for indoor and local area TVWS usage from the double techno-economic view 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 research questions formulation at Chapter 1.1 and the related work at Chapter 1.2. In Chapter 2, the methodology followed and applied is provided with details about the work flow of this thesis, on what technologic assumptions thesis is based on, the data collection methods. Additionally the business feasibility analysis is explained and broken down to its core components. Chapter 3 contains all the background information related to the problem

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

23 Chapter 2 Methodology This thesis took into account various existing indoor mobile broadband solutions and actors and compared these solutions under SWOT analysis to define the best business feasibility models. In this section the overall work flow, the data collection, the used models, assumptions and the approach for the business modeling 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 the technical solutions and/or the related business models and types of cooperation. 3. Perform a round of interviews and discussions with facility owners, local operators, Wi-Fi operators and industry experts. 4. Analyze and describe the business models by using the business feasibility tool; a custom tool that is made up by three stages: a) preliminary asset analysis, b) Model construction and cost calculation and c) SWOT analysis 2.2 Assumptions In this thesis, it is assumed that a femtocell radio access network exists that is fully functional and the CAPEX and OPEX cost for the installation and operation of the radio access network is not taken into account for any of the investigated scenarios 1. In section 4.2 where cost calculation takes place only the extra software and hardware required for the AAA are included. What is more, the analysis will make use of ideal conditions such as working technology, demand for a service and paying customers. The analysis that takes place 1 For more information on these topics visit Ilias Karonis thesis on RAN Evaluation of LTE-Femtocell Deployment and TV White Space 5

24 6 Chapter 2. Methodology in the business feasibility analysis tool is technologically neutral and assumes cooperation between the network components. Also, any co-operation among actors is possible with no regulatory restrictions. These assumptions followed an optimistic approach that examined a bestcase scenario for the TVWS secondary usage and unlicensed band operation. If the deployment and operation of a TVWS-based or unlicensed-based femto RAN turn up to be unattainable or bear no substantial benefits under these ideal conditions, then there would be no real motivation for the venture. In contrast, a promising techno-economic RAN model case proven under ideal assumptions would not eradicate underlying problems. As most of the aforementioned issues were crucial for the overall network evaluation, the above assumptions were removed during the SWOT and qualitative analysis procedures. In addition, it must be stated that the benefits and advancements of femtocell base stations and TV white space which this thesis is in search of are from an abstract point of view. Depending on the role adaptation, an actor might gain or lose responsibilities or technological advancements that lead to a benefit or a drawback. The benefits can be of financial aspect like capital expenditure and operational expenditure decrease, technological aspect like increased spectrum usability and security or decreased interference and complexity, SWOT analysis related, access related, or even customer related like user satisfaction. It must be stressed that business case of competing technologies is also taken into account as a business proposition might be feasible from technical view and operate flawlessly but competing technologies outperform it in the business domain. In this optimistic perspective of the thesis, if no solid benefits are found then the business feasibility can be considered as low. 2.3 Method Qualitative research is the research methodology that is applied for the successful completion of this thesis. The work assumption is optimistic and the aim is to check under the best possible scenarios if the proposed business scenarios are profitable, viable and implementable. In order to find answers to the research questions, a systematic predefined procedure and evidence collection is performed. Three main entities are used for the scenario construction and evaluation: Actors, Business roles and Relations. According to the model presented in [45] the Actors control and have certain knowledge of Resources which are examined at Preliminary asset analysis. When the Actors act upon the resources, a business role is created and by using co-operative type of scenarios the relations between actors and the distribution of business roles is shown. 2.4 Data Collection Primary Data- Expert Interviews A number of meetings and in-depth interviews have been conducted with representatives of market actors as presented on Table 1. The interviews with operators, vendors, facility owners and consultants were organized as semiconstructed, open-ended discussions around drivers and challenges for current

25 2.4. Data Collection 7 indoor mobile broadband femtocell solutions. Before each interview the participant was informed about the purpose of the study, the expected amount of time and confidentiality protection measurements (If asked) following the necessary ethics and oral consent procedures of qualitative study. All interviews were voice recorded for the convenient of the interviewer and more accurate interview analysis. For a summary of each interview refer to APPENDIX A. The empirical input data was collected through two methods: literature study and interviews. The literature study content included published papers from standardization bodies and academic institutions, textbooks, data sheets, and white papers from mobile actors such as operators, manufacturers, and telecommunication organizations. Facility Owner Technical Institute of Cyprus Vendor MIC Nordic COMMSCOPE Consultant 3GNS 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 implemented in 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-White space and femtocells? Do you consider any major show stopper for the use of TVWS? What is your opinion for the TVWSO operator? there be to enter the market? What challenges will Secondary Data - Research and analysis of relevant scientific work As a second means of data collection, research and analysis of background work like scientific papers, books and articles has taken place. In order to find and access the relevant work, well known search engines like and were used. The research was mostly related to: femtocell technology and architecture access modes and mechanisms for femtocells

26 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 work were used as an input basis for the construction and evaluation of business models in this thesis. Citation numbers in [] point to the referenced work where the 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 and the one that will provide answers to the research questions. It is composed by three 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 spectrum opportunities and the roles they can assume. The purpose of stage one is to select which scenarios will be further analyzed on stage two and which scenarios will require no further attention. Model construction and cost calculation: In the second stage of business feasibility analysis, for the forwarding actors and scenarios, business models will be proposed with an aim to cover a wide range of possible solutions an actor can implement. The assets already possessed and the ones required for the business model completion will be presented and a high level cost analysis will also be calculated in some cases. SWOT analysis: At the final stage of this activity is the evaluation of the proposed business models. The evaluation will use a SWOT analysis from both an economic and technical perspective taking a variety of factors into account as to conclude on the benefits, drawbacks and the feasibility of the proposed models.

27 Chapter 3 Background It is estimated that 2/3 of calls and 90% of data services in cellular networks occur indoors [1]. Thus it is important for cellular operators and other market actors to provide high quality indoor coverage both for voice and data services which are on rising demand. Particularly, Cisco visual networking index presents some interesting facts and predictions about the future of mobile broadband. Notably, global mobile data grew 2.3 fold in 2011, more than doubling in four years row and stands eight times bigger than the internet size of Additionally, smartphones represent only 12 percent of total global handsets in use today, but they represent over 82 percent of total global handset traffic. In 2011, the typical smartphone generated 35 times more mobile data traffic (150 MB per month) than the typical basic-feature cell phone (which generated only 4.3 MB per month of mobile data traffic)[2]. This rising demand for MBA services coupled with the poor indoor reception problem in which 45% of households and 30% of business suffer from creates a new challenge for the industry and the operators in general. One approach to provide better indoor coverage is the use of outdoor Macrocell base stations (MBS), a solution that curries a number of drawbacks. To begin with, its more expensive to provide indoor coverage by using outside transmitters since an indoor user will require higher power drain from the base station as to overcome the penetration loss. In addition for high capacity networks, high costs for MBS installation, operation and maintenance are required. Also the positioning of MSB in a dense city environment is a burden itself, raising at the same time the complexity of the network as planning and optimization for frequency, handover and interference management are required [1]. And with the introduction of 3G and 4G networks that normally operate at 2 GHz or above the building penetration becomes a big challenge and leaves no guarantees for indoor network performance from macro cell sites. Therefore, indoor systems like DAS (Distributed Antenna Systems), picocells and femtocells become more and more attractive and viable business solutions for hotspots such as shopping malls, hotels, office buildings and large business centers. These indoor solutions have the ability of improving the indoor coverage and at the same time promote high data services, offload data from the macro layer network and provide better satisfaction and QOS (Quality of service) to the end user. Globally, 33 percent of handset and tablet traffic was offloaded onto the fixed network through dual-mode or femtocell in By 2016, over 9

28 10 Chapter 3. Background 3.1 exabytes of mobile data traffic will be offloaded to the fixed network by means of dual mode devices and femtocells each month [2]. Femtocell base stations (FBS) are cellular access points that use the existing wired or wireless broadband connection to handle voice and data mobile traffic generated indoors without the use of the MBS. Femtocell units have the capabilities of a Node-B UMTS base station, include a RNC (Radio Network Controller) and core network elements. This way the FBS does not require a cellular network access but a DSL Internet connection from which it connects to the operators core network. By appearance FBS look like WAP (Wi-Fi Access Point) however the technologies and protocols each box supports are vastly different as the WAP implements technologies such as IEEE b, g and n where the FBS implements technologies like GSM/GPRS/LTE/HSPA and mobile WiMax. FBS have the ability of providing better indoor coverage and capacity, especially in areas with bad coverage. FBS usually operate in the spectrum licensed for cellular operators and can provide higher capacity and users receive a higher signal to noise ratio due to the short distance from the transmitter and the absence of wall attenuation [3]. In construct with picocells, femtocell installation is more user-friendly as it can be directly self-deployed by the users. Though, interference management techniques are required as to minimize interference with nearby MBS and FBS and thus the use of SON (Self organizing networks) techniques are adopted by FBS as to auto configure their working parameters like, transmitting power and channel allocation. In this way the FBS are cable of sensing the radio environment, localize and register their positions and continue operating stably after auto configuring their working parameters in their first run. The importance of femtocells and the expectation of large deployments reside in the benefits that can provide both to the operator and the subscriber. In general FBS can provide better coverage where MBS are unable off and at the same time offload 70-80% data from the MBS network, reducing in this way the CAPEX (Capital Expenditure) and OPEX (Operational Expenditure) of the operator. This is achieved as less MBS are required and the power consumption that is required by a macro cell is significantly higher than the one a FBS requires to operate and less effective at the same time. Also the total network capacity is improved by the indoors radio reuse and in combination with the low cost and reduced risk of femtocell deployment is a new cost-effective way for operators to build out network capacity. In addition, since FBS can provide excellent data rates not only the customer satisfaction and loyalty is improved but also the churn is reduce. Moreover, with excellent data rates operators can increase their ARPU (Average revenue per user) by introducing and providing richer services and overcome the revenue gap that flat rate voice faces nowadays [4]. Finally, femtocells can offer new market possibilities and alternative approaches to existing and new actors, the investigation of which is part of this thesis. From the subscribers perspective, femtocells are also beneficial as the user experience is radically improved, especially in areas with no or bad signal. Additionally, multimedia and video services can be used and enrich the user experience. Furthermore, FBS can improve the battery life of users mobile phones as the UE (User Equipment) requires less transmitting power towards the femtocell than a MBS. This is also crucial for any health concerns towards the use of mobile phones as the uplink emitting power which is close to the head is significantly less. Users can also benefit from zones plans and reduced price plans

29 3.1. Access Network Architecture 11 the operators offer for the femtocell deployment and have a single address book and billing account for land line phone, broadband and mobile phone. A research [5] made by SRG (Signals Research Group) in 2009 verifies all the above-mentioned benefits as data were collected by a group of operator and vendors in the U.S and the results showed that both the operator and the user can be benefited from the use of femtocells. For the operator the expected lifetime value of a user is increased by providing to the user cost savings and other benefits and additionally, in order for an operator to provide 2.5 Mbps broadband at home it costs 320 USD by using femtocell solutions and 900 USD by using the macro layer which is significantly higher. 3.1 Access Network Architecture The mobile industry has high hopes for femtocells, but before improved indoor coverage and increased throughput of data can be achieved a number of technical challenges must be addressed and one of these challenges is the standardization of how femtocells will integrate with the mobile core network. A number of important issues are raised with focus on security and scalability as the RAN (Radio Access Network) is made of hundreds of base stations that can be moved, added or changed by the users randomly and use the untrusted public Internet to connected to the RNC/BSC (Radio Network Controller/ Base Station Controller). So far there are four different 3G architecture frameworks for femtocell connection to the UMTS (Universal Mobile Telecommunication System) system Legacy Iub over Ip This architecture is proposed by RNC vendors and allows operators to control with the same RNC for NodeB the Home NodeB [6]. A standard 3GGP Iub interface connects the femtocell with the RNC and the Iub protocol stack is encapsulated in the IP signalling while IPsec provides network security. This solution fulfils the operators requirements for service transparency and low initial investment cost as they operate their core networks through standard interfaces like Iu-CS and Iu-PS. However scalability is the main concern of this implementation 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 B stations. After an initial feasibility study of 3GPP and with the scalability issue this architecture is no longer considered viable and thus will not be analysed any further Concentrator In order to overcome the scalability issue and towards a more proprietary Iub interface usage, an alternative approach has been proposed that uses a proprietary Concentrator/RNC that can handle thousands of HNBS. This solution is easy and seamless for an operator to implement as the current RNC needs to be changed with the proprietary one. However since the 3GPP initialised the standardization for femtocell network access architecture this technology did

30 12 Chapter 3. Background not move any further as well and was not adopted by the market and thus will not be analysed any further GAN (Generic Access Network)-based RAN Gateway One other proposal for femtocell integration to the core network is generally referred as RAN Gateway solution which is based on a new network controller- RAN Gateway that operates between the IP access network and the operators core network. The RAN Gateway aggregates the traffic of a large number of femtocells coming from the internet that use the new Iu-over-Ip interface and passes 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 of RNC functionalities to the femtocell making it more intelligent and autonomous while dealing this way with the scalability issues as well. Specifically, the HNB is responsible for the radio aspects and the HNBGW (Home NodeB Gateway) is responsible for CN (Core Network) connectivity. Figure 2, illustrates the GAN Iu mode architecture as described in [7]. In general the GAN architecture is an established solution for uncoordinated HNB integration to the CN through unmanaged IP networks. It provides mutual authentication, confidentiality and integrity protection by using IP sec tunnels between the access device and the operators network. It can help the HNB to discover the correct default serving gateway in the initial set-up and thus provides a flexibility to the network to scale up as the HNB will automatically find the corresponding gateway. It can register a UE for services as only registered UE are served by the HNBGW. Furthermore, it promotes QoS by not only establishing RTP connections for redundancy of VoIP call across the Internet but also by monitoring the Uplink quality for any necessary handover to 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 standard radio Uu connectivity to the UE and the necessary extensions to connect to the HNBGW as defined in 3GPP TS [8]. III Home Node-B Gateway: Same as the GANC (Generic Access Network Controller) functionality defined for GANC Iu mode and allows different CPE devices to connect to the generic IP network. This entity works mostly between the Iu interface and the GAN Iu mode Up interface using the control plane functionality and the user plane functionality. IV Control Plane functionality: Responsible for encapsulation and encryption of Up interface control plane packets by setting up an IPsec tunnel between SeGw and HNB V User Plane functionality: Responsible for the interconnection of circuit switched data and the Up interface. VI Coexistence with UTRAN and interconnection with the CN via standard interfaces

31 3.1. Access Network Architecture 13 VII Generic ip access network that provides IP connectivity among HNB and HNB-GW VIII Use of AAA (Authentication, Authorization and Access) server on Wm interface according to the 3GPP TS [9] specifications and is used to authenticate the HNB when there is a secure channel setup. IX HNB management System that uses a standard CPE devices management interface 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 and analysed as are of importance for the scope of this thesis, while components like RAN network controller, MGC (Media Gateway Controller), signalling gateway and access point management system will not Security Gateway The SeGW is a scalable 3GPP based product that connects securely the RAN GW to the core network by authenticating and terminating FBS originating IPsec tunnels. It executes Authentication, Authorization and Accounting procedures as it interfaces with the AAA server via the Wm. It can ensure a secure access for GTP (GPRS Tunnel Protocol) tunnels that terminate on the CN by using IP as a transport method for the GPRS tunnels. In addition, SeGW can maintain for each femtocell a high capacity IP sec tunnel termination with integrity and encryption as required and distribute and manage IP addresses to remote FBS. It can also serve multiple RAN network controller and media

32 14 Chapter 3. Background gateways at the same time and manage the authentication process by handling the IKE (Internet Key Exchange) for SA (Security Association) purposes. The SeGW is compatible with the 2, 3, 8, GPP standards Authentication Authorization and Accounting Server The AAA server improves the security the RAN GW provides as by a set of services it supports. It has an SS7 MAP-D interface with which an IMSI (International Mobile Subscriber Identity) can securely register with a RAN GW and can support EAP-SIM/EAP-AKA authentication services between a FBS and a HLR (Home Location Registry). The AAA server is incorporated in the SeGW by using the diameter Wm interface on the SeGW site and the S1 Radius interface on the RAN network controller and is capable of handling multiple SeGW and RAN-GW requests per server. Additionally, the AAA server can be used for Service Access Controls, UE session parameters and logging of UE registration events when required by the operator 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 mode protocol for the transport of 3G UMTS protocols and services over the IP access network. RTP (Real Time Transport) is the protocol for circuit switched bearer traffic over the public Internet between the FAP and the MGW. GTP-U is the protocol for packet switched bearer traffic between the FBS and the SGSN. IPsec is the protocol for integrity and encryption of all traffic between the FBS and the RAN GW. TR-069 is the management protocol for managing the FBS community from the RAN GW. 2. Interface between RAN GW and Core Network Interface D: Supports the authentication services between the access network and the HLR[1]. Iu-CS Control and User Plane Iu-CS traffic transports messages over ATM towards core network. Iu-CS user plane traffic transports over IP from RAN GW towards core network. 3. Interfaces within RAN GW H.248 H.248 is the MGW control protocol to enable the RAN network controller to manage the MGW bearer paths. 1 Book pages 51-53

33 3.2. Air-interface technologies 15 SIGTRAN is the Iu-CS/PS control plane over a standard SIGTRAN transport between the RAN network controller and the signaling gateway. The signaling gateway is embedded within the MGW and performs the protocol translation between the RAN GW and the core network for the Iu control plane. SNMP (Simple Network Management Protocol) is the protocol for EMS (Enhanced Messaging Service). Wm is the protocol for Extensible Authentication Protocol (EAP)- SIM/Authentication and Key Agreement (AKA) authentication between the SeGW and the AAA server. RADIUS (Remote Authentication Dial-In user Services) is the protocol for access controls and authorization between the RAN network controller and the AAA server IMS and SIP A SIP (Session Initiated Protocol) based protocol between core network and home node B is an alternative way to integrate femtocells to the core network. This approach however is more costly and complex and it requires installation and operation of a new core service network that works in parallel with the existing packet switched and circuit switched network. Nevertheless, since this architecture embraces the characteristics of all-ip networks and 3GPP IMS (Ip Multimedia Subsystems), the operators are positive towards this architecture as they believe that eventually their networks will transition towards an IMS and SIP based infrastructure. A drawback of this solution is the higher complexity of service continuity between indoor and outdoor systems as the two use different technologies. The standardization of integration of femtocell access networks into 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 indoor environment. From UMA (Unlicensed Mobile Access) to IEEE , GSM, UMTS and HSPA all can be used and in a way are competing alternatives for indoor connections. Thus a brief explanation and analysis of these RF technologies that femtocells are or will be based is necessary for the scope of this thesis GSM Femtocells GSM when compared with LTE and UMTS is an old system however it is well tested and the biggest number of subscribers is still using GSM. Also GSM femtocells are less costly to manufacture when compared with 3G capable ones, gaining this way advantage towards WiFi and UMA networks. In February 2007, Ericsson and Tesco made an agreement in which, Ericsson was to produce GSM femtocells to be installed in Tescos network in the UK [10]. However, the power management of GSM femtocells is less flexible than a 3G one, hindering concerns about the interference management towards the macro layer. Most importantly, the GPRS output of 2G technology can in the best case deliver a

34 16 Chapter 3. Background high quality voice service, which is notably less than what 3G femtocells can deliver. The frequency allocation for GSM is not the same in every country but most networks worldwide in the 900, 1800, and 2100 MHz Countries in Europe operate mostly in 900 and 1800 MHz, North America in the 850 and 1800MHz and Eastern Europe and Russia in the 450 MHz band. Since the femtocells will be operating mostly in the country were the purchase was made, it is wiser to equip the femtocells only with the required RF transmitters for that country UMTS and HSPA Femtocells Universal Mobile Telecommunications System (UMTS) [11] is a set of radio technologies specified by 3GPP (Third Generation Partnership Project) [12]. The air interface of UMTS is UTRA (UMTS Terrestrial Radio Access) and is based on FDD and TDD modes, contrary to GSM that only uses FDD. The medium access used in UTRA is the CDMA (Code Division Multiple Access) and the implementation of CDMA in UTRA is the WCDMA (Wideband CDMA) distinguishing it from other implementations like CDMA2000. CDMA allows the users to simultaneously transmit over the available bandwidth through the use of orthogonal codes [13]. UMTS technology is better suited for femtocell deployment as the 3GPP specifications make the networks more access flexible, with IP-based connections to the core network made feasible without the usage of a SGSN. Also with the use of WCDMA receivers to separate UMTS signals at very low levels of SINR, the UMTS is better capable to deal with the interference management than a GSM one and given the proven fact that UMTS deliver higher speed rates and is a well tasted technology, most manufacturers have focused on the UMTS femtocell production which from 2008 it is standardised in TS [14]. One of the main differences of UMTS and GSM is the use of ATM (Asynchronous Transfer Mode) as the transport protocol for signalling and information currying which relies on Iu interface to connect the RNC with NodeB. The RAN and the RNC functionality are possible to be integrated into a femtocell device and the Iu messages to be transferred to the CN using IP encapsulation. This approach is called Iu-tunnel and is suitable for small and medium business. 3GPP release 5 introduced the HSDPA (High Speed Downlink Packet Access) with several improvements to the downlink architecture. In HSDPA the transport channel DSCH is replaced with HSDCH (High-Speed DSCH) for data transport. Theoretically, HSDPA can deliver speeds of 14.4Mbps where UMTS in plain form can deliver up to 2Mbps. However due to the Iu interface, this data rate is often limited. In order to avoid this bottleneck, the Iu-tunnel architecture can be used as the RNC functionality is controlled by the FBS. Additionally, data are buffered in the NodeB for faster retransmission in case of errors where in the UMTS architecture, the buffer is kept at the RNC. In release 6 of 3GPP the specifications for HSUPA (High Speed Uplink Packet Access) were released and PicoChip was the first company to manufacture HSUPA femtocells [15] capable of uplink speeds of 1.46 Mbps. Compared with UMTS 20dB, HSUPA incorporates a dynamic range for power control of 70dB which add greater abilities in fading management.

35 3.3. Interference OFDM-based Femtocells OFDMA (Orthogonal Frequency Division Multiple Access) in an architecture that uses OFDM techniques to distribute users along a frequency by exploiting the spectrum arrangement in subcarriers. It allows a user to use only a subgroup of the spectrum, permitting to other users to transmit simultaneously and thus maximizing the frequency reuse. This architecture requires the assignment of subcarriers to users by using dynamic frequency assignment algorithms. Furthermore, this subdivision allows for a more efficient spectrum and interference management in two layer networks. Due to its high efficiency, OFDM is the multicarrier technology selected by WiMAX and LTE and is a candidate to replace UMTS technology. However, UMTS use of CDMA copes with interference is a better way as for OFDMA femtocell a self-organizing network is required to cope with interference, either my FBS measurements of the environment or by collected UE data. Generally, multicarrier modulations like OFDM have robustness against multipath and narrowband interference from close stations, high spectral efficiency and frequency diversity for multiple user access WiMAX technologies Designed for last mile connectivity, WiMAX was published in 2004 under IEEE d standard and in 2005 evolved to IEEE e which incorporates mobile connectivity. The working group of WiMAX designed an end to end IP network architecture which makes it especially suitable for femtocell deployment [16]. WiMAX is also suitable for mobile centric femtocell applications as it can support up to 70 Mbps symmetric rates which ensure high QoS. The industrys interest in WiMAX is high due to the fact that the emission licenses have already been auctioned for Europe and USA and the standards have been published since 2004 and 2005, making WiMAX femtocells a feasible alternative to UMTS and HSPA. There are some cases where companies purchased frequency bands to be used solely by the WiMAX [17] femtocells and eliminating this way the cross-layer interference. However such strategies luck in spectrum reuse efficiency and add cost of the operator LTE 3GPP release 8 in December 2008, commonly known as LTE introduces higher throughputs, more flexible spectrum management and spectral bandwidth. It is expected that legacy GSM and UMTS mobile networks worldwide will upgrade to LTE [18], making it the more widely used mobile access technology. LTE evolves the HNB to Home enodeb (HeNB) making it the main point for radio access. Since May 2008 PicoChip, developed and manufactured LTE femtocells based on the technical specifications of that time. There is still a long way before the marketability of femtocells is certain as the auctioning of LTE license has not taken place yet. 3.3 Interference With the introduction of femtocells some changes occur in a macro cellular network, a new layer is added and thus the architecture is composed by two

36 18 Chapter 3. Background separated layers: the macro layer and the femtocell layer. A network architecture like the one described is called two-tier or two-layer network, with the one layer being composed of traditional macro base stations and the second layer by several shorter range base stations which are randomly located inside the emitting range of the first layer. This design however introduces new problems and design challenges. Transmitters from the two layers, when using the same RF in the same geographic area, will cause confusion to receiving systems making it harder to distinguish the source of the signal. This is the interference problem and is one of the main challenges of telecommunication systems that femtocell deployment needs to face. System like CDMA which are interference limited in order not be greatly affected will need the introduction of interference avoidance techniques like power control and time hopping while capacity limited systems as OFDMA will need intelligent frequency planning technology to adapt with the femtocell interference presence. If the fore mentioned techniques are not applied dead zones can be created which will disrupt the macro layer service near a working femtocell Co-layer Interference As the femtocell deployment is random and opportunistic is highly possible that several femtocells will be installed in proximity with other either horizontally or vertically in apartments and houses causing interference one to another. There are two types of interference source: the downlink (originating from FBS) and the uplink (originating from UE). This is co-layer interference and only affects the femtocell layer architecture and the unwanted signalling received by a femtocell reduces the communication quality. The scenario gets worst when signals from nearby femtocells at any location are concentrated and overpower the femtocell power levels causing dead zones problems and connectivity issues to the user. The access mode any given femtocell operates greatly impacts the co-layer interference with the OAM (Open access mode) reducing the dead zone problem and CAM (Closed Access mode) increasing it. In addition, based on measurements made in [1], it is shown that as QoS increases so does the dead zone problem.in TDD systems if all femtocells are synchronised then the transmission of femtocell A will cause downlink interference to users of femtocell B and in the same way the uplink transmission of UE A will be sensed as uplink interference to UE B. In case however where the femtocells are not synchronised, then the emitting time is random, causing transmissions to overlap between uplink and downlink making the interference much harder to cope with. Therefore, timing is important aspect of TDD-based FBS which at the same time is tricky problem CDMA In CDMA systems, 3GPP in [19] suggests the use of interference management techniques to cope with the high power UE transmission levels that reduces the coverage area of a victim femtocell. Power limit to be imposed by femtocell to subscribed UE is one solution in which the noise rise in the uplink can be controlled. To achieve this, the FBS scans and gather information about the environment and the received power by nearby UE and then set a maximum

37 3.3. Interference 19 UE transmit power for the desired CINR. In order to cope with the downlink interference to a victim UE caused by nearby FBS, it is recommended that FBS strictly control their emission power by relying on adaptive power techniques. Especially in CAM scenarios where the UE is served by the FBS it is subscribed to and not by the one that receives the best signal from. These two solutions are for UMTS and HSUPA systems OFDMA For OFDMA systems, it is not required to sense the full transmission band for emissions in proximity. According to the QoS, only some sub channels are allocated to the user by the FBS, which in this case selects the ones that are not subject to interference. The uplink interference is more important to cope with than with the downlink one, as the uplink interference affects all the users of a femtocell while as the downlink only the interfered user. When compared with CDMA systems where the transmission uses the entire available band, the selection of sub channels by OFDMA systems makes the interference more manageable to handle with. Thus the allocation of sub channels frequencies has an important role in the interference impact in OFDMA systems and the creation of dead zones Cross-layer Interference Cross-layer interference happens when the source of a signal and the receiver belong in two different layers, for example a femtocell transmission affecting the downlink quality of UE at the edge of a MBS. On the contrary, uplink interference can also occur when a macro layer UE is interfering with the uplink quality of a FBS user. CDMA networks are mostly affected by cross layer interference and the spectrum used is the same for both the macro and femtocell layer. In [20] and [21] it is suggested that an operator uses the spectrum splitting technique in which a RF band X for example is divided to X1 and X2, with X1 = X-X2. Then the X1 is used only be the macro layer and X2 in dense femtocell deployment regions. On the one hand splitting the spectrum will eliminate cross-layer interference but on the other hand due to the high price and scarcity of electromagnetic spectrum this would lead to inefficient spectrum usage. In OFDMA systems, with the usage of subcarriers cross layer and co layer interference is mitigated and handled in a more efficient way, making this way OFDMA femtocells a welcome solution. Still, OFMDA systems are subject to different problems as time and frequency synchronization which in severe cases can cause loss of orthogonality among subcarriers and disruption of the whole network CDMA In CDMA networks there are two scenarios under which cross-layer uplink interference can occur. In the first scenario the femtocell users interfere with the Macro node B. If the femtocell is working under CAM then the transmissions originating from femtocell layer UE are the source of interference to the macro layer, 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

38 20 Chapter 3. Background OAM, then the UE can camp freely on the base station with the highest signal either it be a femtocell or a macro cell, requiring the minimum transmission power and in this way causing the less interference in the network. On the opposite scenario, the macro layer users transmit in high power to reach the MBS and at the same time interfere with the femtocell operation. Since the MBS is unaware of the exact location of the user and if there is a femtocell in proximity then considering the worst case interference scenario an appropriate upper 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 with macro layer users and in case the signal is strong enough then dead zones can appear in the macro layer. A 3GPP proposed solution for UMTS and HSDPA networks is to limit the FBS maximum transmit power. However a fixed limit on the transmit power is not an efficient solution as the circumstances are not always the same, requiring adaptive power control on femtocells which can increase their cost. In cases where the femtocell is located at the edge of a macro cell, then with good indoor isolation the interference is minimised. If on the other hand, the femtocell is located to close to a MBS, the coverage of a FBS is greatly reduced resulting even in corruption of service. Noticeably, a study made by Femto Forum in [22] shows that if a user is located at least 250 meters from the closest microcell and 1000m from the closest macro cell then 14.4 Mbps throughputs can be achieved in HSDPA networks OFDMA With the division of the spectrum into OFDMA sub channels and the assignment to each network layer, cross layer interference is practically avoided with only adjacent channel interference remaining. In co-channel femtocell operation, when a FBS is at the edge of a MBS coverage area, the passing of a UE that is connected with a MBS can cause uplink interference to a FBS user that is using the same sub channel, especially if required by the MBS to increase the transmission power due to the long distance. It is therefore important that femtocells at the edge of a macro base station to plan their uplink sub channel allocation taking into consideration the any spectral occupancy. If the femtocell is located to close to the MBS and requires from a user to increase the transmit power then the users of the macro layer that are on the same sub channel with the femtocell user, loose their connectivity with the macro cell. Just like with CDMA, it is required in this case for the FBS to limit the power control of its users.for downlink interference to appear an operating FBS and a macro cell user walking down the road are on the same sub channels, for example a femtocell and a macro cell serving both their users in sub channels 1 to 4. In this case the noise ratio of the macro cell user will increase dramatically and heavy interference will occur. The femtocell user will also experience some interference but reduced due to the wall attenuation and the better signal from the short distance to the FBS. 3.4 Mobility Manager Mobility management is a challenging issue in femtocell deployment especially for mobile power consumption and signalling load. The initial assumption is

39 3.4. Mobility Manager 21 that no specific MM (Mobility Management) is required for femtocells as the operation takes place in the same network. However this is far from truth as implementation falsifies many aspects of macro layer network assumptions. To begin with in high density femtocell areas it is possible that the 512 PSC ( Primary Scrambling Codes) in UMTS and 504 PCI (Physical Cell Identities) in LTE will not be sufficient to distinguish all the FBS identities and information in a network. In addition the neighbouring cell list is dynamic and custom to random changes when compared with the static macro layer neighbouring cell list. Furthermore, FBS do not operate all in the same access mode and those in CAM can affect the cell measurements of a large number of UE Femtocell characterization As described above femtocells cannot be treated as macro base station in mobility management with implications to the network performance. The introduction of identifiers and mechanism that can describe the aspects of femtocells is necessary to improve the mobility procedures for femtocell support. In this way the network is divided into two layer architecture and the introduction of new techniques can reduce the signalling overhead among the two layers. 3GPP proposed layer 1 and layer2 methods are described in the following sections Hierarchical Cell Structure Based on [23], HSC (Hierarchical Cell Structure) can be used to distinguish more efficiently femtocells from macro cells as it allows operators to set priorities from 0 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 in UMTS and GSM hot spots and high traffic demand areas Different Femtocell PLMN ID 3GPP pre-release 8 introduced another way for distinguishing femtocells from macro cells which is adopted by the majority of femtocell manufacturers. By using different PLMN ID there is less signalling towards CN and better power consumption on UE as the selection of the right base station is straight forward according the settings assigned to each UE by an operator [23]. However some compatibility issues may rise with old SIM/UICC cards and also the operator might be lacking the required additional PLMN ID for the separation of the two networks Reverse Frequency and PSC/PCI 3GPP release 8, simplifies the problem for femtocell identification by taking into account only CAM cells. CAM femtocells and macrocells broadcast information regarding CAM deployment which can be used by UE which are not allowed access on CAM femtocell to avoid cell measurements and power consumption. In deployments with shared carrier frequency all CAM femtocells broadcast their reserved PSC information while the OAM femtocells may sporadically broadcast this information as well. This information must be noted that is only effective in the UARFCN (UTRA Absolute Radio Frequency Channel Number) for the PLMN where the user is receiving this information. Any PSC information

40 22 Chapter 3. Background regarding CAM femtocells is considered valid and used by the UE for the next 24 hours CAM Indicator According to [24] and [25], a layer 2 approach in 3GPP is the usage of a CAM indicator which is transmitted with the MIB (Master Information Block) in UMTS and LTE network architectures and its purpose is to indicate the access mode a FBS is operating in Femtocell identification The use of NCL (Neighbouring Cell List) makes it possible and easy for a UE to identify surrounding macro cells. The NCL is created locally at a FBS with self-executed algorithms and in case of outbound mobility from femto layer to macro layer can inform a UE of near MBS and FBS. However the opposite is not 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] to camp on. The UE which is not configured for CAM cell can disable the search function [27]. Intra-frequency and inter-frequency measurements can assist the search function for reserved PSC/PCI. The autonomous search from release 9 will support open and hybrid access modes 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 FBS will serve all the clients that receive greater signal from the FBS instead of the MBS. In CAM a FBS will only serve the register users which normally are owners of the femtocell and their friends. In HAM a predefined limited amount of resources are open for public use while the remaining resources are for private use in CAM [40]. An experiment done in [42] shows that overall network throughput of open access mode outperforms the closed access mode. Nevertheless, based on the same work, OAM reduces the femtocell performance as the resources are shared and a survey made in [44] confirms that for this reason consumers tend to prefer the CAM. Additionally, OAM increases the signaling for handover attempts in a network, increasing the possibility of a dropped call. As access control mechanisms are of great importance in mitigating crosstier interference and handover attempts a careful selection must be made. In a macro cell network, access control usually takes place when a UE requests access to a service or data transmission. In order to avoid unnecessary overhead and signalling and to distinguish the users of femtocells and macro cells, the use of Local Area Identity/Tracking area Identity and CAM ID is recommended Local Area Identity/Tracking area Identity When a UE receives a LAU (Local Area Update) rejection from a femtocell it stores this information on its USIM and does not tries to reconnect to a LAI (Local Area Identity) femtocell that belongs to the forbidden list, saving battery life and lowering signalling overhead. Unfortunately, assigning a unique

41 3.4. Mobility Manager 23 LAI to each femtocell in a network is infeasible for existing core network nodes and using pseudo LAI or reusing LAI over distant femtocells can cause network implications. One such problem can arise when a user is passing by a femtocell with the same LAI in his home but not allowed access of course. Then the UE will update the LAI to the forbidden list and might not access even its residential femtocell Closed Access Mode ID A CAM ID is used to identify CAM cells, which is a 27 bit unique numeric identifier [28]. This identifier is broadcasted in SIB 3 and SIB 1 in UMTS and LTE networks respectively by the CAM cell. When a UE is not allowed access on a cell, a corresponding message #25 Not authorised for this CAM cell is received to the UE [29]. Contrary to the pre-release 8 procedures, the UE will not add the LAC (Location area Code) to the forbidden LAI list and neither will block the entire frequency in this way not only allowing alternative coverage if available on the same frequency but also avoiding the femtocell LAI reselection conflicts Allowed Access List For a UE to access a femtocell, a list containing the allowed IMSI users which is stored on the femtocell or a list with allowed femtocells access which is stored on the UE is required. In the first case, a list containing all the allowed IMSI is locally stored on a femtocell on which the user or the operator can modify the allowed users. The advantage of this implementation is that less signalling is sent to the CN as it is handle at the FBS but with the disadvantage that IMSI should only be available is the NAS (Non-Access Stratum) to protect the users identity and confidentiality. When the IMSI is locally saved this creates security issues and vulnerabilities. In the second case, an ACL (Allowed CAM List) defines which CAM cells a UE can connect to and it is stored with users information inside the CN [26]. The most suitable location for storing this information is to a server similar with the HSS (Home Subscriber Server). A copy should also be kept at the MME/SGNS but also inside the USIM of a UE as to avoid signalling towards forbidden FBS [27]. The synchronization between the CN and a UE regarding the ACL can happen manually by adding and removing CAM ID according to LAU messages from FBS or automatic by updating the ACL first in the CN and the notifying the UE with a message 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 of course from the macro cell ensuring this way inbound mobility from macro to femto layer. In residential scenarios, this also ensures that a UE will not camp on an unauthorised neighbours femtocell. In larger scale scenarios though, the femtocells are better assigned the same LAI as they belong to the same company and avoid extra signalling. A drawback however is that in pre-release 8, an access denied 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

42 24 Chapter 3. Background LAI can access on. A different solution is to allow UE to camp on non-allowed femtocells by means of roaming until a service is required [30], in which case the UE will be redirected to a macro cell for service. This approach results in less signalling as the same LA can be used in femtocell region and a the LAU signalling is no longer necessary when a user is passing from a femtocell to another. In case however when the macro cell signal is low or disrupted, a radio connection failure might occur when redirecting a UE to the macro layer Access Control Location In pre-release 8 UTRAN, access control takes place in CN for macro cells and in FBS or FBS gateway for femtocells. In the case of femtocells, the requesting UE asks for access and the check takes place in the locally stored IMSI allowed list reducing the signalling towards the CN. This implementation as a positive requires no modifications on the CN or to the UE and as a negative requires extra management and implementation efforts. In addition, for better support to legacy UE, the access control takes place in the FBS gateway by fetching the 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 nearby femtocell and by placing the check at the gateway the signalling towards the CN is reduced. In release 8, the CAM-capable UE can execute some basic access control procedures to accelerate the process and enhance the mobility. The UE selects only the femtocells which are on the allowed ACL to camp on and avoids any signalling with prohibited cells. Though, this procedure requires frequent SIB decoding from the UE to extract the CAM ID which can reduce the active service quality and any out of date ACL can negatively affect the user experience. In release 8 EUTRAN (Evolved UTRAN) the access control takes place in the MME for the CAM-capable UE when attaching, detaching and requesting from a EUTRAN cell with the same procedures taking place in UTRAN CAM cells. For the access to take place, the FBS needs to send its CAM ID to the MME and then a check upon the ACL will allow or deny access to the UE. By selecting the allowed femtocells, a UE can reduce the signalling required for the authentication procedure towards the MME Access control for Open, Closed and Hybrid mode In OAM the femtocell operates as non-cam cell and no specific UE access control is required. For legacy UE with no CAM capabilities the femtocell uses the TMSI/PTMSI of the UE to register it to the femto-gateway which should always be accepted and assigned back context ID. In UE with CAM capabilities the absence of CAM ID requires no further control from the femtocell or exchange of messages with the CN. In CAM the femtocell always performs a check when a UE wants to associate with it and rejects any non-allowed UE that do not belong to the subscription group. An identity request to obtain the IMSI is required by non-cam UE in order to register it with the femto gateway which will then check the permissions of the UE. In case of CAM capable UE the femtocell sends also its CAM ID with the request to the CN where it will be checked against the ACL. In HAM, that is available feature from release 9, the FBS works at OAM and CAM at the same time. The UE that do not belong to the CAM ID can still camp on the FBS and get resources but with lower

43 3.5. Spectrum 25 priority compared to the CAM belonging UE. In case of legacy UE and since the femtocell needs to distinguish between high and low priority users, the IMSI of the UE is fetched and sent to the femto-gw where a check reveals to the FBS to which category and service differentiation the UE belongs to. The same applies to UE with CAM capabilities but by using the CAM ID the UE belongs to and not the IMSI. 3.5 Spectrum There are three spectrum types that are in use nowadays for wireless communications each with its own unique features. In the following section the Licensed, Unlicensed and TVWS spectrum types are briefly introduced Licensed Licensed spectrum is the most commonly used type of spectrum for wireless communications by Mobile network operators as the spectrum can offer interference and congestion protection while at the same time preventing an-authorised users from access and usage. By using licensed spectrum the MNO rest assure that there will be no suprices in store in the near future as an end-to-end QoS provision can be ensured. However, its the most costly resource used in the wireless ecosystem and for this reason its regulated by national and international authorities like the US Federal Communications Commission Unlicensed Contrary to the previous type of spectrum, the unlicensed spectrum is open and aproval free under international regimes. By this anyone and at anytime -at specific geografic locations- can use specific bandwidths as allocated by national laws to emit radio signals for wireless communication. Ofcourse this has both positive and negative outcomes. On the one hand various technologies have flourished over the use of free spectrum like the Wi-Fi system. On the other hand, the ad-hoc nature of unlicensed spectrum can not provide QoS when ever needed TV White Space Spectrum is a rare commodity and the air-interface is the most expensive than backhaul provision (interview with rjan) posing the major entry barrier for new actors to enter the market. With recent changes in the Television broadcast,from analogue to digital, significant chunks of spectrum are freed and therefore can be used for secondary services i.e Mobile broadband access. Thus on-going research in COST-TERRA and FP7 project QUASSAR study the usage of secondary use of spectrum that has mainly been allocated for other primary services [35]. However in order to use the several MHz belonging to this category new technologies and regulations are needed. Most importantly, secondary usage must not cause interference to primary users. Technologies like cognitive radio, software defined radio and dynamic spectrum access can maximize the secondary spectrum usage but pose a cost barrier for any business schemes at the same time

44 26 Chapter 3. Background as technical challenges exist for the identification and monitor of the available free band and interference avoidance among competing secondary usersfor the same available band. It must be noted that the implementation and network deployment can affect the available TV white space i.e the usage of TVWS by MBS will cause interference over large areas and reduce the TVWS availability whereas the usage of TVWS by small cell like femtocell in indoor deployments the interference will be limited and the availability greater [35]. Besides the technical implications, regulatory and business implications also exist as the swift 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 x protocol is the well-known Currier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism which was firstly introduced in Ethernet technologies. In CSMA/CA a station that wants to transmit, senses the medium and starts the transmission only if no other station is transmitting [52]. Wireless Lan system are All-Ip based networks and follow the IP-systems philosophy. IEEE protocols transmit in the GHz frequencies and 5.5 GHz frequency with achievable speeds of up to 300 Mbps. For a station to join an existing Cell it can either wait for a beacon from an AP with synchronization information or make an active search by transmitting Probe Requests and awaiting Probe Replies from the AP. Once the base station is located then the authentication process starts in which a series of message exchange occurs where each side provides knowledge of a password. There are three encryption protocols which lead to association: WEP, WPA and WPA2 with pre-shared Key. After a successful authentication the next step is the association process where a set of information regarding the station and BSS capabilities are exchanged. Once association is completed the station can transmit and receive frames [52]. The authentication process can either take place locally between the AP (based on a local database) and the client, usually in home environments, or by using a Network Authentication Server (NAS) and a RADIUS server in larger scale networks. A RADIUS server which stands for Remote Authentication Dial In User Service is a networking protocol that provides centralized Authentication, Authorization and Accounting management. NAS server is a single point of access to a remote resource and is used as a trusted gateway in the network for credential exchange with new clients. RADIUS is a client/server protocol operating in the application layer of OSI stack, using UDP as transport. The three main functions of RA- DIUS are to authenticate clients before granting access to a network, authorize the client for resource requests and to account the clients usage. Each of the three functionalities is based on a series of request/response messages between the client and the server. When a user wants to connect to a WLAN, the NAS server will prompt for the users username and password and will then sent the credentials to the RADIUS server where a database check will notify the NAS server to allow or deny access to the user.

45 3.6. Wi-Fi Sollution - An overview Wi-Fi af (Wifi using TVWS) Since September 2010 when the Federal Communications Commission (FCC) revised the rules regarding access to unused UHF spectrum industry and standardization bodies have shown interest in using TVWS to provide extended Wi-Fi like service. Cambridge TV White space consortium which aims to discover 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 the ongoing effort [55]. Also a working group named IEEE af was thus created to define a standard for the protocol implementation [56]. In general, it is believed that operating in the free white spaces of TV, Wi-Fi will benefit from greater speeds, extended range and better QoS [53]. A study made in [57] on the feasibility of large-scale Wi-Fi networks operating at TVWS shows that is viable and less expensive than alternative/completive cellular next generation networks. However, a recent work [53],that takes into account inter AP interference and congestion shows that operating Wi-Fi hotspots in outdoor rural areas is more viable and possible than outdoor urban areas where the user density is higher, with interference limiting the network capacity. For indoor deployment scenarios, the authors argue that due to the better propagation and wall penetration features of low frequency TVWS, WhiteFi can be used but a careful techno-economic analysis is necessary before any call Femtocell Wi-Fi integration As both femtocells and Wi-Fi technologies were developed for indoor small area coverage to provide general Internet access to end users at first sight it seemed that these two technologies are competing each other. However it was soon realized that they could actually co-exist and complement each other with various benefits for the users and the providers. Some of the benefits are drive scale of economics of integrated devices and services, increased user satisfaction and alternative connection technology and service continuity on 3G UMTS voice and data applications to Wi-Fi [51]. In Figure 3.2, an abstract IFW system architecture is shown. A 3G WiFi/Femto cell is operating in a hotspot providing both cellular and WiFi cervices to end users. It is important to note that the Wi-Fi controller which is responsible for the AP co-ordination is placed within the hotspot premises and uses SNMP protocol for management whereas FAPs are managed by the Femto Provisioning Server using the TR-069 3GPP standard. IPsec is used to encapsulate packets traversing the Internet towards the Core Network for Femtocell originated traffic and the GRE protocol for the WiFi ones. The ubiquitous management and provision of both technologies is challenging and opportunistic at the same time as a single entity for the management of CM/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 IFW networks it is possible to use WiFi for data offload towards the Femtocell which differs from femtocell offload towards MNOs with potential advantages when the femtocell is operating in licensed mode. Additionally, seamless handover is possible from Femto to WiFI and vice versa based on handover protocols at the IP level. Furthermore, a unique feature is the flow segregation technique where http traffic is directed to the WiFi interface and Voice traffic to the Femto in-

46 28 Chapter 3. Background Figure 3.2: From smallcell forum white paper on Integrated Femtocell Wifi systems. terface [51]. The TS protocol is describing the internetworking between cellular and wifi networks with handover procedures being standardized in TS The TS protocol describes how untrusted WLANs can access an Evolved Packet Core (EPC) network. 3.7 ZeroShell Zeroshell is an open source free Linux-based distribution for servers and embedded systems that provides the main network services a LAN requires [38] with support for UMTS/HSDPA technologies. Among other features Zeroshell can provide Radius server functionality for authentication, authorization and accounting, traffic encryption and QoS and traffic control over a congested network with minimum bandwidth guarantee to users. The RADIUS can be configured with various cost classes, connection limits and prepaid connections. No limitations exist on the number of users that can be saved, besides the hard disk capacity rd Party Payment System With the emergence of e-commerce a new payment solution is needed for online transactions and peer to peer payments. Some of these systems are imitations of offline payments like checks and credit cards while others introduce digital currency technology. There are numerous solutions available and not all can

47 3.8. 3rd Party Payment System 29 be used, thus a well-known solution for Business to consumer transaction, the online credit card payment system is the one chosen. The advantages of this system are the word wide acceptance and usage and penetration, privacy, acceptability, convenience and low financial risk [39].

48

49 Chapter 4 Business Feasibility Analysis 4.1 Preliminary asset analysis Assets for the purpose of this analysis are any tangible or intangible possessions and roles in the value constellation each actor has or assumes and therefore gaining advantage over the others. As for-mentioned the four actors which are under examination are the Mobile network operator, the Wi-Fi operator, the Facility owner and a fictional entity a TV-White space only operator. Their respective spectrum opportunities are the licensed spectrum, unlicensed and TV-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 following: 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

50 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 use or 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) Asset analysis The asset analysis makes use of terminology that is explained in the following section. For each actor a table is created, with the first row containing the general assets and the following rows, scenario specific assets. In this way comparisons and conclusions can be made as to what scenarios will be further investigated. In the tables, symbol means that the actor can assume the role personally or possess the asset and with that the actor needs to co-operate in order to assume the role or gain an asset Terminology Private spectrum: The ability to use solely a licensed spectrum for RF transmission. Free spectrum: Any unlicensed or white space spectrum that can be used on the fly for RF transmission. Radio access network operation: The provision and ownership of the required technology in order to provide to customers the ability to access via a radio frequency the network. Core Network operation: The operation and maintenance of the core network. Backhaul provision: The provision and ownership of the established connection between radio access network and core network. Site Operation: The ownership and operation of a premise or building where the owner has full control. Customer Acquisition: The ability to attract and provide MBA services to new customers. Access Provisioning: The ability to check what services a requesting UE can have 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 services to a customer. Macro base stations operation: Installation, operation and ownership of MBS Wide area coverage: The ability to provide MBA services in multiple locations over a city or country 1. 1 Based on the findings of the QUASAR project, wide area coverage is most likely to be possible in rural areas mostly.

51 4.1. Preliminary asset analysis 33 Registered customers: Customers details are enlisted in a database and have a long 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 customers daily in a specific location or premise. Market push: The ability to promote via marketing techniques and customer database a new service in the market. Facility wiring: The installation and deployment of a Local area network in a facility Mobile network operator Mobile network operator is large scale cell phone carrier that owns the equipment and infrastructure for radio access network and offers mobile phone services in licensed bands. An MNO is an actor that can assume all roles by making use of a vertically integrated value chain when the deployment is with MBS and all roles besides site operation when the deployment is based on FBS. MNOs are key actors of the market mostly due to the infrastructure and customer database they have. It is common for MNOs to allow access to users of other operators as roaming and even partner up for the construction of the radio access network. There is motivation behind the MNO to use FBS and TVWS as this will allow for more licensed spectrum usage for outdoor coverage, ensure high quality indoor reception and thus reduce the customer churn, increase customer royalty and delivery of bandle services. Asset / Actor MNO MNO with MNO with in General Licensed TV-white space Pricate spectrum Free Spectrum RAN Operation Core Network Operation Backhaul Provision Site Operation Customer Acquisition Access Provisioning Id & Trust Provisioning Charging and Billing MBS Operation Wide Area Coverage Registered Customers Unregistered Customers Core Business Attraction Market Push Facility 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 entity that can operate without the need of any other actor in the value constellation.

52 34 Chapter 4. Business Feasibility Analysis An MNO has the power to use a private spectrum by operating and maintaining all the network components that are required for a complete network operation: The RAN, the backbone connection, Authentication, Authorization & Accounting services, macro base stations for the RF transmission that provide wide area coverage and the core network operation. Additionally, the MNO has marketing tools that attract new customers improving at the same time the market push of new products and services. However, the only association and partnership an MNO needs is an agreement with a 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 the free space for MBS is scarce. When comparing the unlicensed spectrum with the TV-White Space, it is observed that the MNO in the first case lucks of the ability to use the MBS and loses the wide area coverage. That is because an MNO is not allowed to consume the entire available unlicensed spectrum and block the usage of it from nearby users. In the TV-White space scenario thought; this is avoided by the use of cognitive radio techniques that will not consume all the available RF and allow competing users for RF usage. Thus the scenario of MNO using Unlicensed space will not be further investigated in this thesis, while the usage of TV-white space will forward on round two analysis for business model construction Facility Owner Facility owners are big building and infrastructure owners that attract high volume of customers due to the core business, i.e. hotel and in addition try to increase the user satisfaction by providing internet access either complimentary or for a fee. Facility owners on one hand they have a large interest to provide broadband connection to the customers, but on the other little or no interest is observed for MBA provision in their buildings [31]. Hot spots like cafeterias, shopping malls and trains are example of places where the facility owner can assume a multitude of roles for MBA service to the customers. At first the facility owner can implement its own personal infrastructure, not only cover all the expenses in its own but also keep all the revenues as well. Secondly, the facility owner can lease the premises to a MNO or a Wi-Fi operator and let them handle all the expenses and revenues. Finally, a facility owner can use a middle ground agreement where the expenses and revenues are partially shared with a Wi-Fi operator or an MNO. In the first column of table 4.2, only the pure assets of a facility owner are selected, the ones that require no further expenses or cooperation with a third party to be achieved. A facility owners greater asset is the facility itself, as it makes customer acquisition easier with the core business attraction. In this way the Facility owner can gain some market push but less than the one a MNO possess. From table 4.2, it is observed that the facility owner has the choice of using a licensed spectrum after an agreement and partnership with a mobile network operator, in which case the MNO will install and operate the RAN, make backhaul provision, enable AAA services, arrange roaming agreements for third party mobile users and use technician experts for the facility wiring. The main 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 third column of table 4.2, another scenario for the facility owner is shown, to install the

53 4.1. Preliminary asset analysis 35 Asset / Actor FO FO with FO with in General Licensed TV-white space Pricate spectrum Free Spectrum RAN Operation Backhaul Provision Site Operation Customer Acquisition Access Provisioning Id & Trust Provisioning Charging and Billing MBS Operation Wide Area Coverage Registered Customers Unregistered Customers Core Business Attraction Market Push Facility Wiring Table 4.2: Asset analysis for Facility Owner facility wiring, the RAN which will emit over unlicensed spectrum or TVWS and the AAA server for its registered and unregistered customers, operating mostly in independent way as the cooperation with 3rd party billing company is still needed. By following this scenario, the facility owner can co-operate with local MNOs and provide roaming agreements over a fee. This scenario can on the one hand provide higher profits to the facility owner but on the other requires great capital expenditure, technical skills and roaming agreement with MNOs for all customers satisfaction. Both the licensed and TV-White space scenarios are selected to forward for custom business model creation in round two Wi-Fi Operator WI-FI operators take advanatage of the fee unlicensed spectrum band to offer nomadic WLAN access in hot spots. They are responsible for deployment and operation of the network and usually have both registered and nomadic customers. The customers can originate from another business after a type of co-operation with a hotel for example and thus the customer acquisition is provided by the core business [33]. In the same way charging and payments can be managed by other actors like a hotel, credit card companies, and payment providers or by using the mobile phone subscription. The spectrum currently used 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 business models like internet on trains and vertical models like the-fore mentioned cooperation with a facility owner [32]. The Wi-Fi operators business entity cornerstone is the usage of unlicensed free 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 using own resources and technicians. However, there are various implementations of

54 36 Chapter 4. Business Feasibility Analysis Asset / Actor Wi-Fi Wi-Fi with in General TV-white space Pricate spectrum Free Spectrum RAN Operation Core Network Operation Backhaul Provision Site Operation Customer Acquisition Access Provisioning Id & Trust Provisioning Charging and Billing MBS Operation Wide Area Coverage Registered Customers Unregistered Customers Core Business Attraction Market 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 authentication and authorization part with the need of a third party company for the billing and accounting. Furthermore, depending on the business model of the Wi-Fi operator, it can also operate its own backhaul connection towards the core network of an ISP, have a marketing department for customer acquisition and therefore market push. In addition, the Wi-Fi operator can have registered customers with long term agreements when there is wide area coverage, or unregistered random customers in case of a hot spot like a hotel. However, the comparison between the current usage of unlicensed spectrum and TV-White space shows no differentiation in the access and customer acquisition part of a Wi-Fi. Therefore, only the TV-White space scenario will be further investigated in the second and third round TVWSO TV white space operator only is a fictional mobile network operator that owns the infrastructure and uses only the available TV white space spectrum to offer MBA. A TVWSO operator can cover both indoor access with the aid of femtocells and outdoor access by installing macro-base stations. Even though a TWSO operator does not exist as an entity in the market yet, this thesis will investigate the possibility and profitability of such existence. A TV-white space only operator as an entity inherits the characteristics of a mobile virtual operator with the difference in the spectrum used. A MVNO after an agreement with a MNO buys in whole price recourses of the network and sells in retail prices to its customers. This is beneficial for the MNO as there is better resource consumption and profit generation and also for the MVNO as

55 4.2. Model Construction and Cost Calculation 37 Asset / Actor Pricate spectrum Free Spectrum RAN Operation Core Network Operation Backhaul Provision Site Operation Customer Acquisition Access Provisioning Id & Trust Provisioning Charging and Billing MBS Operation Wide Area Coverage Registered Customers Unregistered Customers Core Business Attraction Market Push Facility Wiring TV-white space only operator Table 4.4: Asset analysis for TV-shite space only operator the initial CAPEX is lower than the one required starting business from scratch but still a significantly large investment. The best scenario for a TWSO operator to start business from ground zero is to use the advantage of free spectrum and focus on the indoor MBA market, building capacity inside out with the use of Femtocell solutions and with agreements provide outdoor service to its customer by using third party MBS. This is the scenario that will be investigated further on, on this thesis. 4.2 Model Construction and Cost Calculation In this part of the business evaluation round, for the forwarding actors and scenarios, business scenarios are proposed and presented with aim to cover a wide range of possible solutions an actor can implement. The assets already possessed and the ones required for the business model completionare presented and a high level cost analysis is also calculated for the facility owner s scenarios 2 In this way a SWOT analysis can take place in order to come up with results, conclusions and answers to the research questions. From round one the forwarding scenarios are: i) Mobile network operator using TV White space spectrum, ii)facility owner using licensed spectrum, iii)facility owner using TV White space spectrum, iv)wi-fi operator using TV White space spectrum and v)tv white space only operator. 2 Only the FO is taken into account as the MNO already posses a core network with AAA services and likewise the Wi-Fi operator. As for the TVWSO for the same number of users the same cost is implied.

56 38 Chapter 4. Business Feasibility Analysis Mobile network operator using TV White Space Scenario: Femtocell deployment for residential and SME usage MNO ss in the UK, USA and other parts of the world have already implemented residential femtocell deployments mainly to expand the thin macro layer coverage or increase their network capacity. In this case, the licensed spectrum held by the operator is the same one that is used for the FBS operation. Thus on the one hand, the re-use of the spectrum increases the utilization but on the other hand increases also the cross layer interference. For this reason, an MNO can choose to deploy femtocells throughout its network using the available TV white space 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 the electricity and backhaul connection [34]. The authentication, authorization and accounting aspects remain the same and no new investments are required. Customer database already exists. No changes either in the business model already implemented or in the network 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 operation and would like to use as much as possible for MBS operation [35]. More efficient spectrum usage with improved capacity saves resources on the MBS and dead zone problem avoidance [34]. MNO is in the best position from the rest of actors to make roaming agreements in the femtocell layer area coverage, since the agreements most probably exist for the macro layer coverage already. Threats The MNO must be able to provide quality of service and quality of experience to its customers, retaining this way its good reputation and market position. The use of TV white space might not be able to provide high level QoE in urban areas where the available free spectrum is less than the required one. For this reason, the MNO can make a case study of available white space and in low availability areas to use the licensed spectrum to ensure Qos and QoE. Customers with high bandwidth demands might churn to another MNO.

57 4.2. Model Construction and Cost Calculation Facility owner using licensed spectrum Scenario: Agreement with MNO A facility owner comes to agreement with an established MNO that can also provide roaming agreement for third party customers. The infrastructure already exists or is implemented by the MNO following the company standards and procedures. In the value constellation the MNO will assume all roles besides the site operation. The customers can be already subscribed to the MNO or receive roaming services if they are subscribed to other companies. Strengths Increased user satisfaction. Data offload that prolongs MBS installation and reducea cost access to public 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 acquisition from the FO. Weaknesses The facility owner cannot decide autonomously and must follow the will of the MNO. Opportunities This implementation covers not only IMBA services but other telephony services like voice and SMS allowing for greater revenue generation. Threats The willingness of an MNO for investments according to [33] varies; with the highest willingness found where the users are employees of a business customer of an operator or where there is large share of public users like an airport Facility owner using TV white space spectrum Scenario A: Infrastructure exists A facility owner has already a wireless infrastructure with WAP (wireless access points), cabling and connection, switches and routers and AAA services. The service can be provided free of charge to the customers as a complimentary service 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 which requires little or no effort to acquire customers. Thus it can be speculated that no investments are needed for marketing and customer acquisition. The site owner assumes all roles in value constellation besides provisioning of backbone capacity [32].

58 40 Chapter 4. Business Feasibility Analysis Able to make short term contracts [33] and core business support [32]. The usage of secondary spectrum has advantages itself as it provides freedom of operation from operators and interference elimination with MBS. Customer database exists Weaknesses Investments in equipment are needed to upgrade the existing network to femto-able 3 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 and repeaters [44]. Threats The level of QoS and QoE towards the customers must overcome the QoS and QoE a best effort Wi-Fi system can provide otherwise it will not be wise to upgrade the system at all 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 provisioning of 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 freedom of operation from MNO s. Weaknesses Unlike the previous scenario, no infrastructure exists and thus the initial CAPEX is greater. AAA system must be placed and an electronic billing support system to be installed 3 Particularly, the WAPs need to be replaced with FBS probably LTE-based since the existing system is IP-based, the cost calculation of which is out of the thesis scope and an AAA server in case the service was free of charge before and thus also an electronic billing support system like JCC will be needed so as the customers prepay for the service.

59 4.2. Model Construction and Cost Calculation 41 No customer database Opportunities It is more efficient to design and install a network from the beginning and not modify an existing one like in the previous scenario (from interview). Indoor capacity for operators or own customers which on the one hand overcomes the wall attenuation problem and on the other offloads traffic from more costly macrocell networks [35]. Low cost price of FBS against competing solutions like picocells, DAS and repeaters [44]. Threats The level of QoS and QoE towards the customers must overcome the QoS and QoE a best effort Wi-Fi system can provide otherwise it will not be wise to install the system at all. It is for this reason that measurements on the available TV white space on the facility location needs to be taken before any plans and changes take place Scenario C: Roaming agreements Having a shared femtocell system along the premises that allows for roaming to third party users is highly recommended for a facility owner. By using the term Roaming in this thesis, it is ment that the user camping on a femtocell can receive and originate calls to and from other macrocell cellural networks. While when using the term Offloading, the capacity of the indoor network is rented out 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 receive calls originating outside the facility. Weaknesses Coming to an agreement with all existing operators might be cumbersome and hard to achieve and is proportional to the network size and capacity of the facility owner. Opportunities As the facility owner will be paid for the roaming services, the profit generation 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)

60 42 Chapter 4. Business Feasibility Analysis 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 users with existing subscriptions to third party companies. The main issue arises when a user inside the facility wants to use both the local MBA services offered and the cellular connection with the MNO. In this case the user will have to choose one between the two services as both cannot co-exist, creating a cumbersome problem for both the user and the FO. Opportunities Revenue generation by providing offloading services. Threats Fewer customers Not providing national roaming could be a show stopper in this scenario Facility Owner Cost Estimation For the cost estimation 5 a two level analysis will take place. The low end will estimate CAPEX and OPEX for no more than 10 users in a network and the high end for more than 1000 users. In this way a cost dimensioning can take place 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 and patron soft for the AAA implementation. A 12-port switch handles the indoor/outdoor Ethernet traffic generated from the femtocell use. For the maintenance no dedicated personnel exists but a 24/7 contract with a remote-support company. Figure 4.1 summarizes the average cost per year and the present values for years 3,4 and High-end CAPEX and OPEX For a larger capacity network of 1000 users, a dedicated room for server installation is required with redundant air-conditioning system in which the structure cabling ends up in a rack. It is estimated that the cost of cabling installation of 4 From interview with Orjan Fall. For more information visit the APPENDIX A 5 The 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 the interview with Panayiotic Chiras -a network administration at the Technical University of Cyprus

61 4.2. Model Construction and Cost Calculation 43 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 provides enough ports for the femtocells operation and also optic link connections via the SPF card for the termination of the backhaul lines. In this scenario a server pc that runs zero shell and patron soft can manage the AAA with no extra CAPEX or OPEX requirements. However, it must be noted that a CISCO ACS system costs around euro. For the maintenance and remote support an agreement is made with a company for round the clock service, thus no further personnel is required. If high redundancy is needed then the whole amount must be doubled. Figure 4.2 summarizes the average cost per year and the present values for years 3,4 and 5 Figure 4.2: High end present value calculation for years 3,4 and 5.

62 44 Chapter 4. Business Feasibility Analysis Wi-Fi operator using TV white space spectrum Scenario: Co-operation with a Facility Owner Based on the work in [32] the co-operation of a Wi-Fi operator with a facility owner can be two fold. In the first case the operator takes most of the business roles, is the dominant actor and handles the business relation with the customer through subscriptions. The service is either offered for free to subscribers or for an extra fee to non-subscriber. In the value constellation the operator assumes all roles besides site operation. The identification, authentication and billing can be handled either by the MNO or a 3rd party company. Customer acquisition and marketing are also Wi-Fi operators responsibility. Strengths Strong commercial name and national access at hot spots for business users (TeliaHomerun). Weaknesses The main drawback is the lack of roaming. Investments are needed for the RAN, backbone capacity, AAA implementation and customer acquisition. No guarantees and risk of bad reputation Opportunities The facility owner needs to make no investments and simply shares the revenues. 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 among the two actors with the Facility owner being responsible for the customer acquisition 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 managed either 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 the AAA implementation is his responsibility. Otherwise for customer acquisition there is no investment needed and the RAN and backhaul provisioning are left to 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.

63 4.2. Model Construction and Cost Calculation 45 Opportunities Support to core business and revenue increase for both actors Threats Networks with open access or national roaming Scenario: Transition from unlicensed spectrum to TV white space In this scenario, a Wi-Fi operator chooses to offer indoor MBA using femtocell technology and the available TV white space. Strengths No further expenses for AAA, marketing, customer acquisition or accounting 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 offer without any changes in the infrastructure. Threats The challenge for the Wi-Fi operator is changing the company from WiFi to WISP, where the Wi-Fi is low cost best effort and the WISP (Wireless Internet Service Provider) ensures QoE and QoS. The billing price depends on the business model and who the WiFI operator is competing with TV white space only operator Scenario: TV white space only operator business start up There are three proposed business scenarios for a TVWSO each with different benefits and drawbacks: 1. A TVWSO comes to agreements with existing MNOs so that a customer of MNO A that pays only for voice and SMS services can purchase indoor mobile broadband from TVWSO B and use both services with the same IMSI and SIM card. In this way, the user can have indoor femtocell mobile broadband and telephony at home and national roaming outdoors. Technically the TVSWO will roam voices and SMS services at home and the 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. It would be wiser to act as mobile virtual operator so as the investments

64 46 Chapter 4. Business Feasibility Analysis in network guarantee proportional bigger capacity than investments in secondary macro base station spectrum offer. The key issues according to [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 same model for expansion and network deployment. Since the access is open, for a subscriber of TVWSO A, where ever there is an operating femtocell of TVWSO A the IMBA service is free for any subscriber, even if the location is a different city, creating a decentralized wide area network. Technically, this is feasible as the authentication and authorization server could check the requesting IMSI of the user and allow or deny access. It must be noted that FONs business model allows for revenue sharing with the users. 3. The TVWSO does no roaming agreements with MNOs thus providing only indoor MBA services locally. Strengths Free spectrum itself as the radio interface is more expensive than backhaul nowadays(from interview) Weaknesses The CAPEX and OPEX investments are greater than the one of a facility owner or a Wi-Fi operator 6. TVWSO will need to offer a descent amount of volume at a good cost just like 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 control the company destiny, something TV white space cannot guarantee. 4.3 Results-Actor Specific MNO For the standalone scenario of MNO, as long as the available TVWS can provide QoS and QoE the MNO can and should implement femtocells with TVWS. In this way not only the MNO will allocate licensed spectrum for MBS usage but also eliminate the cross-layer interference. From all the investigated scenarios, the MNO is in the best position to implement a business model since providing national coverage with roaming agreements is already possible. In the unlike event where the available TVWS is unable to provide QoS and QoE then the MNO should not use TVWS in order to avoid a bad reputation and customer churn to a competitor. 6 A TVWSO will need besides the radio access network and backhaul connection investments, marketing department, AAA servers, an accounting department, office(s), customer support department and technical support department.

65 4.3. Results-Actor Specific Wi-Fi operator From the two scenarios investigated it is concluded that it is not wise for a Wi-Fi operator to switch to femtocell operation only, as there will be customer loss due to connectivity issues with non-cellular devices. Additionally, a Wi-Fi operator even as a charged service is still a best effort system and users are satisfied and accustomed to it. Transitioning to Wireless provider instead of a Wi-Fi operator will need changes in the organization and business structure - entering in a new more demanding market- and not only to the network components. It is therefore, more suitable for a Wi-Fi operator to integrate femtocell access points in the network as to provide a more complete network service. Also the use of White-Fi is recommended to be taken into account for the benefits it has against traditional Wi-Fi FO There were 5 different scenarios under investigation for the facility owner and the most important aspect that must be stressed out is the national roaming ability 7. Since access benefits is what this thesis is after then not providing national roaming could be a show stopper. This is because a user will not choose a service in which in order to gain IMBA will lose cellular connectivity. Therefore, from the five scenarios the most feasible are: the one where there is co-operation with MNO from the start and the one where roaming agreements are made. From that point the existence of an infrastructure is the best way for a facility owner to upgrade to femtocell network as the initial investment is lower when compared to a new network construction from ground zero. Also an existing networks applies there is existing customers, a database and in a general a work flow of operation. However, before changing the existing Wi-Fi system, the facility owner must measure the available TVWS 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 and accustomed to it. Installing a new system that could also affect the cellular use of UE can disappoint the customers and thus diminish the core business as well. Additionally, users of Wi-Fi also need to connect laptop computers and tablets to the network and not just cellular phones. Thus, the use of femtocells will benefit the mobile phone users with seamless connection but will unfortunately eliminate other users from access. While with Wi-Fi all UE is able to receive MBA service. It is for this reason a facility owner can also implement alternative solutions like White-Fi or a femto-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 10 since; the cost per user is around 1/10 when the network is for 1000 users than 10. Obviously the profit margin in larger networks is bigger but with also larger initial investments. What is interesting, is that the initial 7 Roaming 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 and cellular connectivity to a user

66 48 Chapter 4. Business Feasibility Analysis investment of 1000 users network is proportional to the cost per user; being also 10 times bigger TVWSO Overall its a feasible business case with high risk as the free spectrum eliminates a traditional market entry barrier but cannot guarantee the future destiny of operation. Although, just because the spectrum is free this does not mean that no CAPEX or OPEX investments will be required at all. A careful more in-depth analysis should be made to measure the required initial investment for a complete network operation and maintenance which can then be used to calculate any possible return of investment and decide about the viability of the Tv White Space only operator.

67 Chapter 5 Conclusions and Future work 5.1 Research questions answers 1. What are the benefits of femtocell networks when the actor is MNO and the spectrum band is TVWS? -As shown from the analysis is Chapter 4, the MNO by using the available TVWS can benefit from increased capacity, more licensed spectrum availability for macro-layer usage and cross-layer interference elimination. This is important in dense networks where high interference levels can even cause service disruption. 2. What are the benefits of femtocell networks when the actor is Wi-Fi operator and the spectrum band is unlicensed or TV white space? -The analysis results showed no substantial benefits for the unlicensed spectrum band and therefore its not advised to be adopted or used by a Wi-Fi for femtocell operation. Most importantly operating WAPs and FAPs at the same band will create competition for the limited spectrum resource and will negatively affect both services.likewise the unlicensed spectrum, neither the TVWS shows noticeable benefits for standalone femtocell network. However as mentioned earlier the usage of White-Fi is proposed for further investigation and a combined network with WAPs and FAPs will increase the network connectivity and customer satisfaction. 3. What are the benefits of femtocell networks when the actor is facility owner and the spectrum band is licensed, unlicensed or white space? -Licensed: Providing offload services towards an MNO after a co-operation agreement will benefit all three involved parties: the FO, the MNO and the end user. This is achieved through better indoor reception and seamless IMBA connection for UE, data offload for the MNO with cost savings and core business support and revenue generation for the FO. -Unlicensed: There was no hard evidence discovered in the analysis to promote the usage of unlicensed spectrum with femtocell networks over 49

68 50 Chapter 5. Conclusions and Future work the existing Wi-Fi networks. -TVWS: Under the optimistic view of available TVWS the FO can benefit from freedom of operation from MNOS and act independently. Of course the initial investment and running expenses are higher but the analysis shows that large scale networks have proportionally larger profit margins. 4. Is there a business case for a mobile broadband TV white space operator only (TVWSO)? -Yes and No. Theoretically there is a business feasibility case for a TVWSO either as VMNO with offloading indoor operation or with a concept like FON. However, the service must match the one a MNO provides or there must be a sustainable service with a much lower price in order to attract customers. The main attribute of the TVWSO as mentioned before is the usage of free spectrum and thus the easy market entry. Although building and operating a core network even with no MBSs is still investment wise hard. Thus the best proposed business model for a TVWSO to enter the MBA market is to act as MVNO with a FON concept deployment. A user/customer that installs a femtocell at his house can also access IMBA whenever in proximity with a femtocell of the same operator for free and when the user is outdoors then national coverage is provided by using a third-party mobile network. This is the most complete scenario that makes efficient use of the 70-90% indoor access but still lies in the theoretic sphere. A more in depth research must be conducted for more solid conclusions. What are the access benefits that femtocells and TVWS have to offer towards selected actors and in which scenario(s)? From all the above, it can be concluded that femtocells using TVWS have both benefits and drawbacks. From the technical point of view, TVWS usage can benefit with less cross-layer interference, increased capacity and coverage but its not a fail-safe activity 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 and with the right design, implementation and usage can give new market players a soft push in their market entry with revenue generation or simply a capacity network that can be used accordingly to individual demands. Among the results its shown that its not yet recommended to replace existing working solutions like Wi-Fi with femto-tvws networks. Its better to improve the Wi-Fi networks with complimentary femto-tvws solutions as this combination will overcome any drawbacks each individual technology has. Since Wi-Fi is an IP based network then the integration of femtocells in an existing network based on LTE for example should under optimistic assumptions (working technology from different vendors) be feasible with no or small investments. What should be highly considered by any actor and for any scenario its the ability to provide national IMBA and cellular roaming A more abstract perception Setting aside the actors and the business scenarios and assuming a more abstract view on the femtocell and TVWS concept some observations are made. First,

69 5.2. Discussion & Future Work 51 it must be stated that the general concept of femtocells is not in a mature state yet. This naturally carries along implications in various aspects i.e business schemes and user adoption. While on the other side of the fence Wi-Fi is on the peak state of its long course with interoperability and ease of use as two strong weapons. FBS are more expensive when compared to WAP and it comes to no surprise since its a new technology. One of the assumptions that this work is based on is that there is vendor interoperability but as it was discussed among the interviewees this is not the case. At the same time it was also assumed that any type of co-operation among actors is possible under the regulation law which in practice might not stand so tall. Hence the complexity of femtocell networks increases. There is of course motivation for market actors to get involved as the first one to introduce five bar indoor signal to its customers will reduce the churn but maybe when many actors are sharing a distributed femtocell network the case is not the same. The service/product offered by different and competing actors 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 the value 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 big question is if there is sufficient spectrum for this cause. Looking at the technical aspect of femtocells, there is a need for traffic separation between the macro and femto layer at the core network with differentiated accounting and marketing schemes for femto-users while at the same time the security among untrusted channels and paths must be ensured. All of the above hold the femtocell era from taking off but it is the author s personal belief that femtocells -regardless of spectrum- will flourish when the need for high speed and high quality broadband access 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 originally expected. The main issue was the drifting around when searching for scientific work as the majority of related papers that were researched at the end were not used. It was also challenging to arrange interviews with industry experts as it was originally planned to make more meetings but to unknown reasons they failed. For the actual research area and work conducted in this thesis, the author suggests that the business structure and model of a TVWSO as proposed in this thesis to be researched additionally that will make a business estimation based on the FON concept model. Likewise the usage of TVWS by a Wi-Fi operator with femtocell integration it is speculated to create an improved broadband network and should be examined more. Last but not least other rising alternatives that were not dully considered in this work like the LTE technology are also proposed for usage as all interviewees mentioned that the future is LTE. Since there is an ongoing parallel work at the Wireless department of KTH that takes into account the radio access network cost structure deployment, which is an aspect not measured in this thesis, for a wider and better understanding on the research area, it is advised to read the work of Ilias Karonis on the RAN Evaluation 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

70 52 Chapter 5. Conclusions and Future work can be made.

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73 Bibliography 55 [31] 3GPP RAN, Reply LS on access control for CSG cells, 3GPP-TSG RAN, Prague, Czech Republic, Tech. Rep. R , Oct [32] Jan Markendahl, sten Mkitalo, Analysis of business models and market players for the local wireless internet [33] Jan Markendahl, Mats Nilson, Business models for deployment and operation of femtocells networks; -Are new cooperation strategies needed for operators and real estate owners?, 21st European Regional ITS Conference, Copenhagen September [34] Peng Lin, Jin Zhang, Yanjiao Chen, and Qian Zhang, Macro-Femto Heterogeneous Network Deployment and Management: From Business Models to Technical Solutions, IEEE Wireless Communications, June Available at: [35] Jan Makerkendahl, sten Mkitalo, Analysis of business opportunities of secondary use of spectrum. The case of TV white space for mobile broadband access, 22nd European Regional ITS Conference, Budapest, September, 2011 [36] Markendahl Jan, Mkitalo sten, Mlleryd Bengt G, Werding Jan Mobile Broadband Expansion Calls for More Spectrum or Base Stations - Analysis of the Value of Spectrum and the Role of Spectrum Aggregation 21st European Regional ITS Conference, Copenhagen 2010 [37] Michail Katsigiannis, Thomas Casey, Timo Smura, Antti Sorri Quantitative modeling of public local area access value network configurations Berlin, Germany 2011 [38] Zeroshell Forum [39] Dr. Sumanjeet, Emergence of Payment Systems in the Age of Electronic Commerce: 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 January 2010 [41] Jen Chen, Jen Chen, Peter Rauber, Damanjit Singh, Chandru Sundarraman, Peerapol Tinnakornsrisuphap, Mehmet Yavuz Femtocells Architecture & Network Aspects, 2010 [42] D. Lpez-Prez et al., Access Methods to WiMAX Femtocells: A Downlink System-Level Case Study, IEEE Intl. Conf. Commun. Sys., Guangzhou, China, Nov [43] Normann R, Ramirez R, From Value Chain to Value Constellation: Designing Interactive Strategy, Harvard Business Review, Jul/Aug93, Vol. 71, Issue 4. [44] M. Latham, Consumer Attitudes to Femtocell Enabled In-Home Services C Insights From a European Survey, FemtoCells Europe 2008, June 2008.

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75 Appendix A Interviews A.1 Interview with Tord Sjolund, President of Mic Nordic After a small presentation on our work and research area, Tord was interested to know about the available TV White space in Sweden and on what frequency band was on. He then stressed out the fact that to his best knowledge no handsets exists that work on the 400 MHz band, which is one of the working assumptions of the thesis. We have a free band on 800 MHz but its just for speech and its for GSM voice solutions only. So femtocell is an opportunity to 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 facility owner in your case he said. When asked about his background, he replied: We started the indoor communication company in 2007 and the focus was to cover indoor systems. I have a background from Telia and also the supplier site. There is a problem with indoor communication in buildings and even now in new ones they dont take measures for it. Its more expensive to do it afterwards and more difficult. We currently have three base stations active in conference centers in Sweden. Tord mentioned that We are not using any billing system yet but its in the switch function. We are just using a laptop with software for the local access. A statement by Tord which is a showstopper for the facility owners case is With this system you cannot make any calls to your ordinary number, only at local numbers. However he continued saying the next step is to provide national roaming, which is ofcourse is possible but also hard to achieve and you need co-operation with someone else. The good thing about Local Mobile Operator is that your employees get to use the service for free A.2 Interview with Orjan Fall, Vice-president of 3GNS Orjan has experience in consulting services over 20 years and before that he was in the RnD of base stations for companies like Nokia and Erickson. He was in the development of 2G and 3G base stations for macro layer networks. In 2001 he was involved in a project for Picocells construction with the idea to offload 57

76 58 Appendix A. Interviews data. As he mentioned the idea was 10 years ahead of time and I failed to convice my boss to market it, but now the future is brighter for small cell base stations. In March started with 3GNS as vice president. After our introduction to 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 has around 500,000 HNB in their network, because the network layer is thin and has holes. So the aim is to provide service to the customers. From a RAN perspective there is no interference since there is no capacity anyway. However you need to consider if you are an island approach or if you are integrated in the network. You can integrate a big number of HNB in the network. Take wi-fi for example, is an island approach. You can only change your frequency but without any co-ordination and femtocells need to be part of the network. MNOs built their networks with extra capacity and push the market to use the data services. In a way MNOs need to defend their spectrum investment but most importantly you need to work close with system vendors and system integrators because everyone is pointing fingers. So its not just the cost or cost saving of other solutions but also other aspects need to be taken in. One reason cellular deployment is bigger than Wi-Fi is that possession of spectrum can provide QoS and can control your destiny. Something free spectrum can never guarantee. -What is your opinion about a Facility owner using Femtocells with TVWS for IMBA? 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 are technically 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 to switch to a femtocell network? The challenge is changing the company from Wi-Fi operator to Wireless service provider. The first is a low cost best effort service where the latter is a big market player with QoE. So switching to from Wi-Fi to LTE is relatively easy with no changes in the backhaul. The big question is on what level you want to offer 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 barrier is removed. But free space can provide no plan or guarantee for quality. An operator like this in the long run will need to offer a decent volume at a good cost. Overall its a feasible business case. A.3 Interview with Panayiotis Chiras Panayiotis Chiras is a network engineer with experience in design and implementation of large scale networks. He has been actively involved with enterprise networks like the International airport of Cyprus and currently works as the network administrator of Cyprus Institute of technology. For the discovery of the required network components related to the AAA service implementation and their prices, Panayiotis kindly filled up the blank spots and gave directions for alternative free solutions that are used in this work.