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The Role of WiMAX Technology on Broadband Access Networks Economic Model

WIMAX, New Developmentsindividual pair of Unshielded Twisted Pair (UTP), called the local loop(Figure 1) DSLes existing twisted-pair phone lines for broadband connlimitation of this technology is that theds dewhen copper localAn hFC network is normally a cable television network that includesal fiber(between head end and the fiber node) and coaxial cables(from fiber nodes toCPE) Initially, the original HFC networks were designed to support only downstreabroadcasts Currently, upstream traffic must also be supported using Cable Modems(CM)full Internet access The bandwidth provided by cable networks will allow for 160 Mbpsonstream and 120 Mbps upstream for end-users(using Docsis 30 standard)

HFCshared medium, therefore the bandwidth will also have to be shared by end-users Typicallyhere are 500-1000 subscribers in a single local distribution point, whichlown to about 250 on averageThe FTTH(PON) technology connects Optical Line Terminal (OLT) at the Central Office(CO) to Optical Network Units (ONUs) at subscribers homes andOLT) This technology prmuch higher bandwidth than DSL and Cable Modem Aa maximum distance of 20 km from the olt to the onu under normalnditions, pon allows 16 ONUs at a maximum distance of 20 km from the olt andONUs at a maximum distance of 10 km from the OLT supporting up to 1 Gbpsmedium voltage electricity grid to provide telecommunication services(Little, 2004) TheVoltage (Lv) electricalr distribution network represents the most attractivemedium for high-speed digital communication purposes due to an ever-increasing demandsed by the advances in communication and information technologies(Lim etNotwithstanding the benefits that the availability of an extensive infrastructurer the moment thebandwidth provided through BPL is still being questioned (sarrocco Ypsilanti, 2008)

The Role of WiMAX Technology on Broadband Access Networks: Economic Modelomadic) The selection of the best option is based on four output results: NPV, IRR, Coster subscriber in year 1, and Cost per subscriber in year n Thete a single infrastThen, for each sub-area we verify if the best solution is: a)the use of wired technolo(FTTH, DSL, HFC, and PLC) to support the stmobility; or b) the use of WiMAX technology to support the Fixed and NomadcomponentAverageEqupmentg

9 Techno-economic parametersuilding blocks(Montagne ef nl, 2005): Area definition (geograInfrastructure sir eachtariffs, such as network dimensioning rules and cost trends of relost models for investments(CAPEX) and operation costs (OPEX); Discounted cash flotThe model analyzes several technical parameters (distances, bandwidservice pricing, demographic distribution, etc ) The model simulates the evolution of the

WIMAX, New Developmentsbusiness from 5 to 25 years This means that each parameterdifferent value eachuseful for reflecting factors that evolve over tinork defines the network starting from a single central office (or headding at a subscriber CPE At the CO, we consider only the devices thatort the connection to the access network (OLtsers are usually classified in four main categories: Home(residential customers), SOHOall Offices and Home Offices), SME(Small- to Medium-size Enterprises) and LE (Largenterprises)

The tool implements a methodology for the techno-economic analysis of accessetworks for residential customers and smeNetworkousIngand includes thePhysicalISof the materialscomponentCablingthe necessary fiber optic, twisted pair, orThe trenching cost is the cost of the labor requiredrenchingnd ducts (burieditches andyor optical deviceetween Co and splitters) needed to carry the trafficNetworksubscriber houseThe price and other properties of the Access node, asSubscriber Equipment well as the nature of the CPE unit, depend stronglythe access techneTable 1 General Model AssumptionsAccess networks (for Wired technologies)have two separate but related componentsdepend primarily on the labor andts associated withthan on the specific technologynetwork costs can be grouped into two categories( Baker et al 2007): the costs ofthe network before services can be offered(homes passed), and the costs ofconnections tots consists of exchange/CO fit out, feeder cables and civil works,binet and splitters and distribution cables and civilent costcalculationsptions suppose that all construction work required teall homes passed takes place during the first year(deployment phase) However, only thenecessary electronic equipments are deployed in the Co as well as the aggregation nodescommodate the initial assumption for the take rate

The Role of WiMAX Technology on Broadband Access Networks: Economic Model312 Input ParametersAs mentioned beforehand, the definition of the input attributes is fundamental to obtain theght outputs, The model divides the inputs into two main categories: general andcharacteristidthe technologies The specific parameterstechnological termshese parameters are divided into three main groups: Equipment Components; CableInfrastructure and Housing The housing cost is the price to build any strinets, closures etc) Thisand the subscriber house With regard to the cable infrastructure, the percentage ofcable corresponds to the need of theable required, and theparameter takes intoboth underground and aerial lines The civil work cost is basedparameters(for example: ofonduit(Underground/ Aerial)etc )and on the Database cost

The cost of the labor also takes into account the cabling eitherperator has to choose from a set ofes The cost structure maysignificantly from one technology to the other inable costmaintenance costs Each technology type hasments which are dedicated like modems andWhile some costs like equipment pricing, are easy to compute given the data in the Costcosts (ie trenching and fiber)and equipment housing costs (which depend on distance anddensity)do, so they require optimization(Weldon Zane, 2003)the technnomic analysis of a broadbandnetwork These include the selection ofhe geographical areas and customer segments to be served, the services to be provided, anddefinition of the input attributes is fundamental to obtain the right outputs Then, we definearee main activities: Area Definition (Area parameters), Requested Services(Servicercial Parameters and Type of AThe financial analysis requires several outputs from the tool The financial analysis isute the amount of equipment that needs tobe installed each year for providing the service; to compute the amount of money spent onions and Maintenance, Customer Support, Service Provisioning,arketing); to compute the yearly income, taking into account that existingfor 12 months; to compute the net profit obtained each year; and the NPV(Net PresentValue)of the yearly profits The calculated outputs are presented in Table

WIMAX, New DevelopmentsDescriptioneront costs oost per home passedper home passedquipment and installation and the ongoing costs of maintaining andCAPEXPEXI Operation costsationTotalwill pay for their telecommunicatiom of global discounted investments and globalLife Cycle CostThe Cash Balance (accumulated discounted Cash flowProfit per year (cashgenerated, the cash flow turns positive and theEnding Cash BalanceThe balance in the Cash Accountend of the reporting period andmulated Cash Flow)n the ending balance sheetPeriod(NPV The NPv is today s value of the sum oftant discounted cash fleNet present vnnual investments and running costs), or the volume of money whichIntemal Rate of Return than the opportunity cost of money(that is, interest of an average igheris the discount rate at which the NPv is zero If the IRR is higherTable 2 Output Results2 Access Network ArchitectureOur model studies thpart of the network, starting at the central office and ending atthe subscribers CPE (see Fig

10) The cost model is based on a single central office,connecting the subscribers throughThe goal is to optimize the network in order to minimize the cost for a given performanceand fiber deploymentare incurred for allassed Despite he costs of the CPEs, ports in the fiber noa home subscribes

The Role of WiMAX Technology on Broadband Access Networks: Economic ModelSecond Mle Network園k Ca tFig 10 Network architecture(Pereira, 2007a)del is divided into three maind end user In the co the different traffic flows armultiplexed/ demultiplexed for further uplink connection to metropolitan and transporttched or routed back to the acor the Co we consider the following components: OLT ports, OLT chassis and passivesegment is divided into three main parts: the feeder,(for HFC technology the distribution segment is dividsegment comprise the network between the Coincludes not only the cost of equipment( Fiber repeatg(street caleet cabinets

Thedes depend on the technology In the nextill present the elements for the five technin study The distributionetwork links the aggregation nodes with CPE Like feeder networks, in distribution, theodel includes not only the cost of equipment (copperand LV grid repeaters), but

WIMAX, New DevelopmentsAggregation Nod!Fig 11 Block diagram for Access Technologies(Pereira Ferreira, 2009)32

1 Access Network Componentsable 3 show the components used in ouronents are divided intesolutions Optimally, there would eventualfibers reaching the ONTs of 32 homes(Pereira, 2007b) Forx4 and the secondary split is 1x8, thenhe network splitting ratio (or split scenario)will be 32 This means that a single feederPports 32

The Role of WiMAX Technology on Broadband Access Networks: Economic ModelOpticalpeaterCopper(Trenching2) Installat3)Housinction pointequipmentTable 3 comts used for wired technologiesode, distribution and endsegments have different components,The components for WiMAX technology are presented in the next section(see Table 4)However, the inside plant and feeder components are the same as the wired technologies3

22 Access Network Architecture for wiMAXg 12 shows the wiMastem architecture used in our model The"air"segmentsreplace the distribution and drop segment presented in table

The Role of WiMAX Technology on Broadband Access Networks: Economic Model2 Broadband Wireless Access NetworkGenerally, wireless broadband refers to technologies that use point-to-point or point-to-multipoint microwave in various frequencies between 25 and 43 GHz to transmit signalscess and backbone infrastructure so, it is in the access network where wireless broad bandtually proliferating Asquence, the terms "wireless broadband"ande used interchangeably(Corning, 2005) Hwireless access networks show limits in terms of data rate and Qos(El Zein Khaleghi,Wireless broadband is the" great equalizer"of broadband technologies It enables evenper, coaxial cable, fiber,r competition for theroadband dollar It therefore expands the definition of who can be a carrier (WiMAForum, 2005b) Unlike fixed technologies, wirelessand scalable, both inerms of their physical layout and their logical ar

chitecture Due to the cost advantainvestments are now within the reach of local organizations which are ableof infrastructurage well suited to small villages (Sarrocco Ypsilanti, 2008)(Fernando, 2008) Thenfrastructure can therefore expand from the bottom-preconceivednked to the needs and attributes (geographical, demographic, and economic) of localunities, The distribution of telunications infrastructures has traditionally beenWireless networking technologies can be divided into three main categories( Carcelle etThe range performances for a WPAN is typically from 1 meter to a few dozens meters, andis designed for low data rate(usually 100-200 kbps), WPAN technologies comprise: ZigBee,luetooth and UWB In WLAN technologies the rangees are typically from ate(usually 1 to 20 Mbps)

One technology of this family is Wi-Fi The WWAN is mainlycused for long-distance point-to-point connections with high data rateWireless broadband access systems have been dd at frequencies ranging from 400MHz to about 30 GHz(Lehr et al, 2004) Different parts of the spectrumdifferent physical properties For example, at 30 GHz, signals attenuate rapidly withce, they are limited by rainfall, and to Line-of-Sight(LOS) deploymentsuencies have been usedften as a substitute for high-capacity point-to-point linkserprise customers to connect backboneor buildings In contrast, at lower frequencies, below say 10GHz,encumbered by legacy incumbents and licensees are ty pically limited to smalleand can operate in Non-Line-of-Sight(NLOS)situations (eg it reaches inside buildings to adesktop or mobile antenna), and requires less costly technology The lower the frequenc

WIMAX, New Developmentsthe better the penetration of buildings or of foliage, besides immunity to rainfall, but there ise look from the line of sightpective, wireless technolotegorized into those requiring Line-of-Sight(LOS)and those that do not(NLOS)(Corning,5): Line of sigobstructed path from the CPE antenna to theint antenna If the som the CPE to the access pointreflected by objects, such as trees, the situation is called non-line of sight NLOS systemsch combats multipath interference, thereby permitting the distancethe cpe and theint to reach u50 kilometersMMDS bandHowever, NLOS systems are more expensive than LOS systems(Ibe, 2002)2

WiMAXWIMAXrldwide Interoperability for Microwave Access) is a standardized form ofork(WMAN) technology that has historically been baroprietary solutions, such as MMDS and LMDS The firststandardcompleted in October 2001 and defines the air interface and medium accessvide( Ghosh et al, 2005)es up to 75 Mbps and have a maximum range of about 50 km Becahic areas without theinfrastructure requirement to display cable links to individual sites, the technologexpand and should lead tobiquitous broad bandireless broadband promises to bring high-speed data to multitudes of peoplgraphical locations where wired transmission is too costly, inconvenient, or unavailable

The Role of WiMAX Technology on Broadband Access Networks: Economic Modelsalvekar et al, 2004) The 80216 standard uses Orthogonal Frequency Division Multiplemultiple(OFDMA), which is similar to OFDM in the way that it divides the carle sub-carriers OFDMA, however, goes a step further by then grouping multiple sub-gof the sub-channels within the carrier space, or multiple clients might alsoa portion of the total number of sub-channels simultaneously(Konhthe RF front-end, wiMAX uses oFDM, which is robust in adverse channel conditions andbles NLOS operaThis feature simplifies installation issues and improves coveragehile maintaining a high level of spectral efficiency Modulation and coding can be adaptedencyailing link conditionsders will operate WiMAX both on licensed and unlicensed frequencies Thedistance wirelwith speeds up to 75 Mprovide very high data rates and extended coverage HorMHz or less) reducing the mbandaidEven theachievable under optimal conditions and with a reduced datarate(a few Mbps), the typicge will be around 5 km with indoor CPE(NLOS)and around 15 km with a CPE connected to an external antenna (LosTo keep from serving too many customers and thereby greatly reducing each usersthan 500 subscribers(Vaughan-Nichols, 2004)Onety to deploy broadbandn large areas without physical cables

These characteristics give to telecommunicationer the capacity to implement new broadband telecommunication infrastructures veryuickly, and with a lower cost than the wired networksTo sum up, the main advantages of the wiMAX technology in relation to other connectione: it does not need cable installation whichte places; it is rather quick to deploy This technology could have an acceshich is 30 times higher than basic ADSL technology Besides frequency range is between 2and 11 GHz, with the maximum range of 50 km from the base station, and data transmissionto 70 Mbps So, one BS sectorrve different businesses or many homes with DSL-rateconnectivity Another advantage is the high capacity to service modulation(data and voiceto perform symmetric transmission(the sara fixed broadbao key elements: base station( BS)and customer premises equipment(CPE) Thethe network backbone andoutdoor antenneqreby eliminating the need for extensive and expensivwireline infrastructure and providing highly flexible and cost-effective last-mile solutionsFWa base station equipment multiplexes the traffic from multiple sectors and providesnterface to the backbone network For each sector a radio transceiver module and a sectorntenna is also required The multiplexer(such as a switch) aggregates the traffic from the

WIMAX, New Developmentssectors and forwards it toter thaected to the service providersbackbone ip networ2002)Thkbone connectiot-to-nt radio link or a fiber cable, and can be either ip or atm-based The distance betweenbandwhich it operates The CPE with an indoor antenna can be installed by the customershemsetechniWhen we need to define a point-to-multipoint wireless system, several parameters are verynportant: the characteristics of the geographical area (for example, mountains), thandwidth required, Qos, thwith a high traffic demand and or high subscriber denspacity becomes aThrough a careful selection of networkparameters, tradeotbe made between coverage and capacity objectives to besthe end users within the service area( wanichkorm, 206時g

3 WiMAX System ArchitectureThe WiMAX wireless link operates with a central BS through a sectorized antenna that iscapable of handling multiple independent sectors simultaneous2 System ComponentsAs previously referred to, base station equipment and customer premise equipment are thethe customersess wide area nk(WAN) The BS controls theaol the cpe inctor The following figure shows the basic componentsadio communication system

The Role of WiMAX Technology on Broadband Access Networks: Economic Modelsitting AntennaReceiving AntennaConverts RF signal intIncoming DataReceived dataMedium(Free Space)Converts informatian to beConverts the receiVerransmitted into a RF signalignal into a des red format221 Customer Premise Equipment -CPEevidential cpesed to be available in a fully integrated indoor self-installable unita high-gain antenna for use on customer sitessimilarDSL modem, providesFor customers located several kiloay from the wimAx base statione isolated customers, a directive antenna pointing to theWiMAX base station may be requiredOutdoorndoorTransceiverUpstreamCoaxial CableUSBC+IF FeedModemRF to/fromase stationFig 5

FWA Subscriber Configuration(Outdoor CPE)CPE or terminals are expected to be available in a number of configurations for customer specifiplications and for different types of customers Households in multi-tenant buildings can beling a high throughputDSLAM (Digital Subscriber Line Access Multiplexer) as an in-buildingdevice utilizinbuilding telephone wiring to reach individual apartments or by installing an individualWiMAX terminal in each household (WiMAX Forur5a) These units are priced higher forthe business case, consistent with the added performance(WiMAX Forum,and the antenna The modem device provides an interface between the customers networkand the fixed broadband wirelessnetwork, while the radio proviterface

WIMAX, New Developmentsetween the modem and the antenna As a matter of facendors integrate thesemponents to form a compact CPE, while others have the three units as standalone systembe, 2002) The CPE antenna type depends on the Non-Line-of-Sight capabilities of thea professional technician

In Non-Line-of-Sight systems, theeamwidth of the CPE antenna is typically larger, and in the case of user-installable CPEthe antenna should be omnidirectional (Smura, 2004)advantage of adaptive moat inside one bs sector each CPuse the most suitable modulation andBase StationSector 1 RadoMultiplexeSector N radioWA celnd the modulator dern odulator equinment (see fig 6 and fig d the antenna unitthe outdoor part of the base station, and is composed of an antenna, aantennas has a great impact on the capacity and coverage of fixed wireless systenThe bs consists of one or mch of which connects to several cpesinside a sectorized area In the BS one directional sector antenna is required for each sector

The Role of WiMAX Technology on Broadband Access Networks: Economic Modelector antennastenna and the beamwidth depends both on the servicecapacIof the systemarter of the capacity of a four-sector system(Anderson,2003) The modemulates and mixes together each flow over the If cableSector AntennaRadio TransceiveFiber FeedeMultiplexFig 7 Base Station componentsFig 7, each FWa base station consists of a number of sectors

The trafficties of these sectors depend mtantly on the modulacoding methods,well as on the bandwidth of the radio channel inThe sector capacity is divideddic)and three layers Inhe static perspective, users are stationary and normally require data,es These subscribers demand great bandwidth Innomadic/ mobilityFocus of the wireless networkwhile that of theired access networks is be advancement ofchnology wireless networks such asband and highos services competing with wired access networks recently(Fernando, 2008) Theproposed model divides the

WIMAX, New Developmentssub-areas, but the model can divide the main area between 1 andThe central office isocated in the center of theand each sub-area will have one or more AggregationNodes(AGN) depending on the technology in usebork to supoort個個work to supportmobility個Perspective 2- ic(Mobility) componentee in Fig 8, the frameweparatedthree main laversrea,as well as the total nomadic users(Mobility analysis) The proposed model initiapartes these two components because they have different characteristics

In layer B, theFor the static anWiMAX PLC For the nomadic analysis we use the WiMAX technology The final result ofthis layer is the best technological solution to support the different needs(Static and