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Ericsson 1/2003REVIEWTHE TELECOMMUNICATIONS TECHNOLOGY JOURNALThe OpenMobile AllianceThe servicenetwork frameworkIRealizing the operator'sservice networkAdvanced baseband technologyin 3G radio base stations

Coven In September 2002, Ericsson wasfirst to demonstrate live dual-modeWCDMA/GSM calls with seamlesshandover between the two modes. TheSony Ericsson test units employed in thedemonstration were based on thecommercial platform developed byEricsson Mobile Platforms. In March,Sony Ericsson unveiled the Z1010, whichis the company's first commercial 3Gphone based on this same platform.

EricssonREVIEWTHE TELECOMMUNICATIONSTECHNOLOGY JOURNALThe purpose of Ericsson Review is toreport on the research, development andproduction achievements made in telecommunicationstechnology at Ericsson.The journal is distributed to readers inmore than 130 countries.Address:Telefonaktiebolaget LM EricssonSE-126 25 Stockholm, SwedenPhone: +46 8 719 00 00Fax: +46 8 681 27 10Internet:http://www.ericsson.com/reviewContentsNew subscriptions:http://www.ericsson.com/reviewAddress changes and distribution:Phone: +46 8 799 63 28Fax: +46 8 28 59 74ER @pressdata.seAddress: PressDataBox 3263SE-103 65 Stockholm, SwedenPublisher: Jan UddenfeldtEditorial board: Per O. Andersson, FredrikDahlgren, Thomas C. Eriksson, UrbanFjellstad, Magnus Frodigh, Jan Gabrielsson,Lars-Goran Hansson, Peter Lancia,Magnus Madfors, Eric Peterson, HelenaSchytt, Ulf Westin, Johan AkessonEditor: Eric PetersonProduction manager: Eva Karlsteineva.karlstein@lme.ericsson.seLayout: Paues Media, StockholmIllustrations: Claes-Goran Andersson, HaraPrinter: JMS Rulloffset i Koping ABISSN: 0014-0171Volume: 80, 2003© Telefonaktiebolaget LM EricssonHandover between WCDMA and GSMHandover between WCDMA and GSM allows the GSM network to be used to givefallback coverage for WCDMA technology. This means that subscribers can experienceseamless service, which is of importance to the commercial launches in 2003.6OMA—Changing the mobile standards gameThe role of the OMA in the value chain is meant to differ from that of previousstandards organizations. Its approach focuses mainly on interoperating services insteadof protocol stacks. The idea is to offer enabling technologies for deliveringrelevant, end-to-end, high-performance services. 12The service network framework—An architecturalblueprint for the service networkThe emergence of the Mobile Internet has focused special attention on the servicenetwork, which is where network operators can expect to develop, launch and billfor new services in a streamlined way. 18Realizing the operator's service network: Ericsson'ssystems integrationEricsson's systems integration gives operators the means of evolving their servicenetworks, enabling them to realize the true potential of the service network andmove toward fully third-generation-ready networks. 26Advanced baseband technology in third-generationradio base stationsBeing the kernel in WCDMA, the baseband platform must be able to efficientlyhandle the entire life cycle of an RBS. Moreover, it must do so while networks areevolving and expanding. New radio network functions and features will also beadded through base station hardware and software to perfect the WCDMA system.32Ericsson Review No. 1, 2003 1

ContributorsIn this issueGertie Alsenmyr joined Ericsson in 1995,working with standardization and systemdesign of the radio access network and corenetwork for GSM/GPRS. Since 2000, shehas been working with system design of theWCDMA radio access network. Beforejoining Ericsson she worked at Telia Mobilewith the standardization of GSM, andwith field tests of the GSM system. Sheholds an M.S. in electrical engineering fromthe Linkoping Institute of Technology,Sweden.gertie.alsenmyr@era.ericsson.seJoakim Bergstrom joined Ericsson Researchin 1998 to work with WCDMA. Hecurrently serves as the technical coordinatorofEricsson'sactivitiesin3GPPRANWG2,which is in charge of standardizingWCDMA radio layers 2 and 3. He holds anM.S. in electrical engineering from theRoyal Institute of Technology in Stockholm,Sweden.joakim.bergstrom@ecs.ericsson.seAnders Eriksson is a systems manager forPDU Network Databases and value-addedSolutions at Ericsson's Core Unit ServiceNetwork and Applications. He joinedEricsson in 1998, to work with the systemarchitecture for Ericsson's e-Services products.In 2000, he joined CSNA and has beenengaged in the development of the architectureof the service network framework.He holds an M.S. in computer science fromthe Lulea University of Technology,Sweden,anders.c.eriksson ©era.ericsson.seAke Gustafsson is systems manager atPDU Messaging and Enablers at Ericsson'sCore Unit Service Network and Applications.He joined Ericsson in 1986 as a softwaredeveloper for AXB-30. Since 1990,Ake Gustafsson has worked as System Managerwith different IP-based messaging systems—forexample, System-T for paging,MXE for voice mail and SMS, MoIP for unifiedmessaging, and IMPS for instant messaging.After five years at Ericsson MessagingSystems in New York, USA, he returnedto Sweden to begin defining the architectureof the service network framework.ake.gustafsson@eip.ericsson.seMattias Hagberg joined Ericsson in 1997.Since 1999, he has worked with the BSS, developingmobility between GSM andWCDMA. He holds an M.S.E.E degree fromthe Royal Institute of Technology, Stockholm.mattias.hagberg@era.ericsson.seFranz Heiser currently works as system engineerat Ericsson AB in Kista, Sweden.Since joining Ericsson, in 1998, he has,among other things, worked as technical coordinator,project manager, senior specialistand system node area manager of basebandsystem design for Ericsson's WCDMAbase stations. Franz studied physics at theTechnical University of Berlin, Germany,and holds a doctorate degree in engineering(Dr.-Ing.) from the same University.franz.x.heiser@era.ericsson.seJohan Hjelm joined Ericsson Research in1997. In 2001, he was appointed senior specialist,Internet information services andprotocol design. From 1997 to 2000 heserved as Ericsson's representative in W3C,and at present he is active in the Open MobileAlliance. Johan is also an active writerand author of more than ten books. He hasstudied economics at Uppsala Universityand holds a degree in journalism from PoppiusSchool of Journalism.johan.hjelm@era.ericsson.seAndy Johnston is a master designer currentlyworking as chief architect of the servicenetwork framework at the systems managementand technology unit of Ericsson'sCore Unit Service Network and Applications.Andy has been with Ericsson since1995 working in a number of technical andtechnical management positions. Prior tojoining Ericsson, he was the chief developerof the widely used CAMPUS® Database& CAE system. He has a degree in appliedcomputer science from Dublin City University,Ireland and is an active member ofthe IEEE and ACM organizations.andrew.johnston@eip.ericsson.seChamath Kodituwakku joined Ericsson in1997 to serve as a systems consultant, integratingBSS solutions into legacy systemsfor GSM networks, formulating solutionsfor BSS, billing, and O&M, and integratingCRM systems and core networks. From1998 to 1999 he worked with GPRS-STP,IP backbone design, and verification. Andfrom 2000 to 2001, he served as a mangerof global Mobile Internet solutions. He iscurrently a solution architect of servicelayer solutions, integrating service layer2 Ericsson Review No. 1, 2003

systems built from Ericsson's product portfoliointo legacy and third-party products.He holds an M.S. in information technologyfrom the University of Oslo, Norway.chamath.kodituwakku@ericsson.comJurgen Lerzer, who joined Ericsson in1997, is a senior systems engineer atEricsson Eurolab in Nuremberg, Germany,where he works with development and systemdesign of Ericsson's base stations forWCDMA. In particular, he works with thedevelopment of WCDMA baseband downlinkprocessing functions, including futurebaseband enhancements, such as high-speeddownlink packet-data access. Jurgen holdsa Dipl.-Ing. degree in electrical engineeringfrom the University of Erlangen-Nuremberg,Germany.juergen.lerzer@eed.ericsson.seHelmut Leuschner joined Ericsson in 1997to work with the development of the decoderpart of Ericsson's WCDMA test system forNTT DoCoMo. He was then put in chargeof systemizing the common baseband designused in all WCDMA base stations. In2000, he became responsible for the uplinkbaseband processing subsystem implementedon the RAX board. In addition, he workswith the systemization, design, verificationand quality aspects affecting the entire baseband.Helmuc holds a Dipl.-Ing. degreefrom the University of Applied Sciences ofNurnberg.helmut.leuschner@era.ericsson.seSebastian Lind joined Ericsson in 1996 asa project manager working with IS/IT projectsfor GSM and WCDMA production. In2000, he became a customer project managerat Ericsson Internet Applications,where he managed Mobile Internet projectsfor major European operators. He also supportedglobal customer units and local marketsin several sales activities related to servicenetwork enablers and solutions. Hepresently works as a strategic product managerfor the integration of MMS, wirelessstreaming and positioning solutions at thesystems integration division of EricssonGlobal Services. Besides this assignment,Sebastian is a member of various companywideprograms.sebastian.lind@eip.ericsson.seAnders Milen joined Ericsson in 1993 towork with GSM base station design. Helater joined the GSM BSS system designteam, working mainly with system characteristicsand end-user quality issues. In1999, after a period of evaluating theWCDMA trial system, he began workingwith UTRAN system design, serving asteam leader. Anders is currently a technicalcoordinator of mobile terminal interoperabilitytesting activities. He holds anM.S. in electrical engineering from the LundInstitute of Technology, Sweden.anders.milen@era.ericsson.seWalter Muller is presently senior specialistin WCDMA radio network system design.He joined Ericsson, in 1983, to work withhardware and software design for radio linkequipment. Since 1989, he has worked as asystem designer for mobile systems withemphasis on radio network functions. Heparticipated in the standardization ofD-AMPS (TDMA) and with system designof radio network functions. He also participatedin early PDC development and systemdesign. Between 1997 and 2000, hecontributed to the standardization of theWCDMA radio interface. Since 2000 he hasworked with system design of Ericsson'sradio access network system for WCDMA.Walter holds an M.S. in electrical engineeringfrom Chalmers University of Technologyin Gbteborg, Sweden,waiter, m u I ler@era. ericsson.seMagnus Olsson joined Ericsson in 1992 towork with GSM and BSC systems at EPKin Hassleholm Sweden. His duties rangedfrom development to object leader, andlater, systems instructor in the area of GSMand AXE. In 1996, he began working as aconsultant, developing tools for the developmentand simulation of handset software.In 1998, he joined ECS in Lund to work withMobile Internet standards. He has served aschairman of the WAP 2.0 architectureworking group, defining core technology forseveral OMA enablers. Recently, he hasserved as Ericsson's lead coordinator forJava-J2ME standards development and hashelped coordinate the EMP efforts for OMAstandards. Magnus Olsson holds a graduatedegree in telecommunication engineeringand telecommunication systems fromHassleholms Tekniska Skola, Sweden.Magnus.olsson@emp.ericsson.seHakan Palm is presently a senior specialistin radio resource control for mobile terminals.He joined Ericsson in 1989, workingEricsson Review No. 1, 2003 3

with GSM and PDC mobile systems andradio network functions implemented innetwork products. In 1997, he participatedin the system studies for 3G radio access networksand WCDMA. In 1999, he beganworking with terminal platform developmentat Ericsson Mobile Platforms. Today,he works with 3GPP radio interface standardization.He holds an M.S. in electricalengineering from the Linkoping Institute ofTechnology, Sweden.hakan.palm@era.ericsson.seMike Slssingar is systems manager at PDUNDVAS within Ericsson's Core Unit ServiceNetwork and Applications. Since 2000,he has been working in different roles to defineand introduce the service networkframework. He has coordinated the SNF AppliedWorkgroup and has worked to ensurearchitectural quality through his role aschairman of the SNF review board. He isnow working to support SNF system analysisand architecture coordination in CSNAR3 and R4.mike.slssingar@era.ericsson.seTorbjomSvanberg joined Ericsson in 1999working as customer project manager forsome of the first Mobile Internet solutionsEricsson delivered in joint projects withAsian and European operators. In 2001 hebegan working with the offering of professionalservices as a part of Ericsson's completesolution offering in the service layer.This position also included responsibilityfor implementation plans of the portal solutionsoffering in customer-specific projectsand tenders. Torbjorn currently worksas a strategic product manager for ServiceNetwork Solutions at Ericsson Global Services,which encompasses the definition andscoping of the overall offering to operators.He holds an MBA from the InternationalBusiness Program, Linkoping University,Sweden, and a master's degree in marketingfrom EADA Business School, Barcelona,Spain.torbjorn.svanberg@era.ericsson.seHimke van der Velde works with the standardizationof WCDMA. He representsEricsson in the 3GPP RAN WG2, which isin charge of standardizing the radio interfacearchitecture and protocols. Since joiningEricsson, in 1991, he has worked as systemsengineer on DECT-based cordless telephonyproducts for several application areas,including CTM (public pico-cellular), cordlessPBX and DECT/GSM. This involvedparticipation in several ETSI standardizationworkgroups. Before joining Ericsson heworked for the International TelecommunicationsUnion by assisting small telecommunicationadministrations in the SouthPacific. He graduated from the Twente Universityof Technology in Enschede, theNetherlands.himke.vander.velde@eln.ericsson.sePontUS Wallentin is a senior specialist inmobile systems architecture. He joinedEricsson in 1988, working with system designof GSM and TDMA radio access networkand core network products. Since1996, he has conducted research on theWCDMA radio access network, participatedin system studies, and served as a delegateof 3GPP standardization. He holds anM.S. degree in electrical engineering fromthe Linkoping Institute of Technology,Sweden.pontus.vallentin@era.ericsson.seFredrik Wallgren joined Ericsson's productiondivision in 1987, where he worked withproducibility analysis and testing. He leftEricsson and telecommunications for fouryears, but returned in 1995 to the marketingside of the business to work with mobilenetwork design, and later, technicalsales support and product marketing. From2000 to 2002 he served as marketing directorfor UMTS and GSM systems in EricssonSpain. Today, he is product manager forWCDMA radio access networks. He hasM.S. and Licentiate of Technology degreesfrom the Royal Institute of Technology inStockholm.fredrik.wallgren@era.ericsson.seZhongping Zhang joined Ericsson RadioSystems in Kista, Sweden to work with thedevelopment and design of the basebandsystem for the WCDMA base station forNTT DoCoMo. This became the firstWCDMA base station to be put in commercialuse. In 2001, he was put in chargeof baseband system design for Ericsson'sWCDMA RBS3000. Zhongping has studiedelectrical engineering at Tongji Universityof Shanghai, China, the Technical Universityof Munich, Getmany, and the TechnicalUniversity of Vienna, Austria. Heholds a Ph.D. in electrical engineering fromthe Technical University of Vienna.zhongping.zhang@era.ericsson.se4 Ericsson Review No. 1, 2003

EditorialEric PetersonSince joining the staff of Ericsson Review in1997, numerous articles on a variety of topicshave passed across my desk. We (the publisher,editorial board and myself) are fairlyselective when choosing articles for publication,so I assume that every article inEricsson Review is of interest to our industry.But obviously, some articles also hold a specialpersonal interest to me as an end-user.That is, given the insights I have gainedfrom reading and preparing articles for publicationin Ericsson Review, I have eagerlylooked forward to the day when I would seereal consumer services and products basedon, say, Bluetooth, xDSL, WLAN, GPRS,SyncML, GPS and more. Two years ago, Ipredicted that that day would come beforeyear's end 2001. A year later, however, I hadto eat my words—if you weren't (a) an earlyadopter or (b) actively looking for it, thenyou probably hadn't noticed anything thateven remotely resembled what we call theMobile Internet. But today that's allchanged. The Mobile Internet is all aroundus and is fast becoming an integral part ofordinary people's lifestyles.We often read about or hear that the industryis in a slump. Well, it is. But don't tellthe end-users! Given all that has happenedon the consumer/end-user side of things—the advent of some really great mobile terminals,and a maturing of standards, servicesand applications—I am convinced that theworld of mobile telecommunications hasnever been more exciting. Face it, the averageend-user cares nothing for the actualtechnology in use—all he or she really wantsare hassle-free services.In my own case, the single largest factor propellingme toward a richer Mobile Internetexperience was the switch to a new handset—inFebruary, I traded my trustyEricsson R380s for a Sony Ericsson P800.Today, I enjoy e-mail and Web-based servicesvia GPRS, I frequently use Bluetoothfor transferring fdes between my phone andlaptop, and thanks to remote-synchronizationservices, I can keep my contact and calendarinformation up-to-date on multipledevices. Hey, as an end-user, I'm in serviceheaven! And the best part of all is that I knowthis is just the beginning—better, more potentand really useful services are on the way.In this issue of Ericsson Review you can read,among other things, how the industry,through the Open Mobile Alliance, is takingsteps to make services interoperable.You will also read about Ericsson's servicenetwork framework, which provides architecturalprinciples for creating horizontallylayered service networks. Furthermore, youcan read how Ericsson is prepared to helpoperators to realize the true potential of theservice network and move toward fullythird-generation-ready networks. Like Isaid, better, more potent and really usefulservices are on the way!Eric PetersonEditorEricsson Review No. 1, 2003

Figure 1Encapsulation of the GSM handover messagein a "container" that is part of theWCDMA handover message.sages. The pre-defined WCDMA radiochannel configuration describes bit rates,data block sizes and other radio parametersof voice or video call service.Although the network solely communicateswith the mobile terminal using one accesstechnology at a time, the mobile terminalneeds to perform measurements onGSM while communicating in WCDMAand vice versa. Since WCDMA uses continuoustransmission and reception in activemode, a regular mobile terminal cannotmeasure GSM cells while communicating inWCDMA. To overcome this obstacle,Ericsson has introduced what it calls thecompressed mode method. As seen in Figure2, a short gap is created in transmissionand reception. To maintain a perceived constantbit rate, the actual transmission bitrate is increased just before and after the gap.A constant bit rate is required for servicessuch as voice, but for Web browsing andsimilar services, a constant bit rate is notnecessary. In the latter case, the transmissioncan thus be delayed to create a gap.When the mobile terminal is not in activemode it uses discontinuous transmissionand reception, and can therefore measureGSM cells.results are compared with a technologyspecificthreshold. Furthermore, additionalparameters, such as adjustable offsets, areprovided to control the selection betweenWCDMA and GSM cells. Where the GSMmeasurement of WCDMA cells is concerned,the main challenge is to fit the informationinto existing GSM messages.Figure 2Compressed mode creates gaps or idle spaces in time that WCDMA mobile terminals useto perform measurements on GSM cells.Since WCDMA and GSM are differenttechnologies, it is difficult to compare themeasurement results from these technologies.To overcome this challenge, the measuredEricsson Review No. 1, 2003 7

Figure 3Interoperability of mobile terminals andnetwork equipment from different vendorsis crucial for handover between WCDMAand GSM. Ericsson network equipment, incommercial operation in Japan since 2002(here represented by the Indoor MacroRBS 3202), has been publicly shown (at3GSM World Congress in Cannes, February18-21) to interoperate in WCDMA withall major mobile terminal vendors—hererepresented by two Sony Ericsson Z1010terminals.Figure 4Overview of the GSM and WCDMA nodesand interfaces involved in the cell reselectionand handover procedures.As mentioned above, a mobile terminal inWCDMA makes use of compressed mode tomeasure GSM. That is, if the mobile terminalhas a single radio receiver, it requirescompressed mode. If, on the other hand, themobile terminal contains separateWCDMA and GSM radio receivers, it canuse each receiver in parallel, performingGSM measurements without compressedmode in the downlink. Notwithstanding,each solution—compressed mode and dualreceivers—reduces talk time due to higherpower consumption in the terminal.In idle mode, standby time of the mobileterminal is mainly affected by how often itneeds to wake up to monitor radio channelsand perform measurements for cell reselection.Since a dual-mode terminal mustmeasure WCDMA and GSM cells, this hasa negative effect on standby time comparedto GSM-only mobile terminals. To improvestandby time, the mobile terminal is allowedto inhibit measurements on the otheraccess technology (for example, WCDMAwhen in GSM) when the quality of the currentaccess technology is adequate for thenetwork settings. Furthermore, comparedto re-selection between GSM cells, the measurementrequirements in the standard aremore relaxed for re-selection betweenWCDMA and GSM cells.Mobility procedures for interworkingbetween WCDMA and GSMThere are two basic modes of operation forhandling mobility:• the mobile terminal-controlled mode;and• the network-controlled mode.In the mobile terminal-controlled mode, themobile terminal selects the cell to which itwill connect. However, the network canbroadcast various parameters to influencethis process.In the network-controlled mode, the networkexplicitly orders the mobile terminalto connect to a specific cell. Ordinarily, thenetwork bases its decisions on measurementinformation provided by the mobile terminal.For either mode of operation, the networkshould consider cells that use each accesstechnology. Besides radio link quality,the network might also consider other aspectswhen selecting the cell, for example,the current load of the established service.Two procedures have been defined bywhich the network can order the mobile terminalto connect to a cell using another technology,namely the handover and cellchange order procedures. These are employedwhen the mobile terminal uses a dedicatedchannel. The handover procedureprovides a higher level of service, since it involvesa preparation phase in which resourcesin the target cell are reserved priorto the actual handover. Accordingly, thehandover procedure is employed when themobile terminal is providing circuitswitchedservice—for instance, voice. Thecell change order procedure applies whenthe mobile terminal is providing packetswitchedservice, such as Web browsing.Cell re-selection betweenWCDMA and GSMWhile in WCDMA, the mobile terminalperforms cell re-selection• in idle mode; and• in connected mode when common channelsare used for packet-switched service.The dual-mode mobile terminal re-selects aGSM cell when that cell is ranked higherthan the current WCDMA cell or any otherWCDMA cell. WCDMA and GSM cells areranked together according to signalstrength. This same type of ranking appliesin GSM.When performing cell re-selection inWCDMA, the mobile terminal either measuresGSM cells continuously or when thequality of the serving WCDMA cell fallsbelow a given threshold. The mobile terminalis solely allowed to select a newWCDMA or GSM cell when the average receivedquality and average signal strengthexceed a minimum threshold. Theminimum-quality threshold (signal-tonoiseratio) ensures that the mobile terminalcan receive the information transmittedEricsson Review No. 1, 2003

y the potential target cell. The minimumthreshold for signal strength ensures thatthe network can receive the information forcell re-selection transmitted by the mobileterminal in the target cell. This criterionalso takes into account• the maximum transmit power that themobile terminal is allowed to use whenaccessing the cell; and• the maximum radio frequency (RF) outputpower that the mobile terminal cantransmit.Frequent re-selections can be avoided withmechanisms such as penalty time and temporaryoffset. Likewise, mechanisms are definedto keep fast-moving mobile terminalsfrom re-selecting small-sized cells when alarge overlay cell has been configured.The network can configure these optionsby broadcasting parameters in theWCDMA cell.When the mobile terminal is actively providingpacket-switched data service in aWCDMA cell and re-selects a GSM cell, itestablishes the radio connection to the GSMbase station subsystem (BSS) and then initiatesthe routing area update procedure.During this procedure, the core networkmay retrieve information from the UMTStertestrial radio access network (UTRAN)on the context ofthe mobile terminal, whichincludes any data packets waiting in thedownlink queue. When complete, the connectionto UTRAN is released. Finally, thecore network confirms the routing area update.Figure 5 shows the message sequenceafter cell re-selection from WCDMA to aGSM cell in idle mode.Figure 5WCDMA-to-GSM cell re-selection.the mobile terminal has a circuit-switchedservice and the signal strength falls below agiven threshold, the WCDMA network ordersthe mobile terminal to perform GSMmeasurements. Typically, the mobile terminalis instructed to send a measurementFigure 6Handover from WCDMA to GSM.WCDMA-to-GSM cell change orderThe mobile terminal measures GSM cellsand sends measurement reports to che network,which orders the mobile terminal toswitch to GSM. The measurement procedureand the use of compressed mode areidentical to that described below for theWCDMA-to-GSM handover procedure.The signaling in the cell-change-orderprocedure is identical to that in the cell reselectionprocedure described in Figure 5 exceptthat the network selects the target GSMcell and initiates the procedure by sendinga cell-change-order from the UTRAN message.This message includes the infotmationon the target GSM cell.Handover from WCDMA to GSMFigure 6 shows the message sequence forhandover from WCDMA to GSM. WhenEricsson Review No. 1, 2003 9

Figure 7Handover from GSM to WCDMA.Figure 8System capacity can be increased by selecting service-based radio access technology.The blue and red triangles describe system capacity to handle voice and data traffic in twoseparate access technologies, blue and red. If we combine these technologies and enableservice-based handover between them, the capacity can vary depending on how the serviceis allocated. To achieve maximum capacity, all data users should be allocated to theblue technology and all voice users to the red (dashed black line). Minimum capacity willresult if all data users are allocated to the red technology and all voice users to the blue(solid black line).10report when the quality of a neighboringGSM cell exceeds a given threshold and thequality from WCDMA is unsatisfactory.When UTRAN receives the measurementreport message, it initiates the handover,given that all the criteria for handoverhave been fulfilled—for example, providedthe mobile terminal is not involved in servicesthat require WCDMA. UTRAN thenasks the target BSS to reserve resources. Thetarget BSS prepares a handover commandmessage, which includes the details of theallocated resources. This GSM message,which is sent to the mobile terminal via theWCDMA radio interface, is transferredwithin a container that is transparentlypassed on by the different network nodes.When the mobile terminal receives thehandover command, it moves to the targetGSM cell and establishes the radio connectionin accordance with the parameters includedin the handover command message.The mobile terminal indicates successfulcompletion of the handover by sending ahandover complete message to the BSS, afterwhich the GSM network initiates the releaseof the WCDMA radio connection.Handover from GSM to WCDMAFigure 7 shows the message sequence forhandover from GSM to WCDMA. The networkorders the dual-mode mobile terminalto perform WCDMA measurements bysending the measurement information message,which contains information on neighboringWCDMA cells and the criteria forperforming and reporting measurements.When the criteria for handover toWCDMA have been met, the BSS initiatesthe allocation of resources to the WCDMAcell. Encapsulated in these messages, the BSSalso sends information to UTRAN on theWCDMA capabilities of the mobile terminal.When the resources of the WCDMA targetcell have been allocated, UTRAN compilesthe handover-to-UTRAN-commandmessage, which typically includes the identityof the pre-defined configuration for theservice in use. This message is then senttransparently to the mobile terminalthrough the core network and BSS.When the mobile terminal receives thehandover-to-UTRAN command message ittunes to the WCDMA frequency and beginsradio synchronization. The mobile terminalthen indicates that the handover was successfulby sending the handover-to-UTRAN-complete message, after which theresources in GSM are released.Ericsson Review No. 1, 2003

Figure 9Successful handover between WCDMAand GSM requires a holistic perspective.From coverage fallback tonetwork optimizationAs described above, the first WCDMA commercialnetworks provide basic coveragefallback to GSM. This fallback is merely thefirst step on the way toward a true seamlessnetwork 2 , where WCDMA and GSM, togetherwith other access technologies, combineto form a single network.There are two important areas in this evolution.The first relates to minimizing theperceived impact on the user when the mobileterminal changes between WCDMAand GSM. The Third-generation PartnershipProject (3GPP) is currently working onenhancements to the WCDMA and GSMstandards (such as inter-system packethandover) that will reduce the actual interruptionin user data transfer from seconds tofractions of a second during packet-switchedservice.The other area relates to the ability of thesystem to select the access technology thatis best capable of providing the requestedservice and quality. This includes the triggercriteria for moving between GSM andWCDMA access technologies. By triggeringa change of radio access technology on,for example, the requested service type, it ispossible to provide the appropriate qualityof service for the call, and to increase theoverall capacity of the system. Figure 8shows the increase in system capacity thatcan be obtained, provided the system—onthe basis of requested services—can allocatetraffic on access technologies.ConclusionThanks to interworking between WCDMAand GSM, users of third-generation mobileterminals can enjoy seamless coverage fromthe very start. The challenges of interworkingbetween WCDMA and GSM havebeen overcome using• dual-mode mobile terminals;• compressed mode channel measurements;• cell re-selection between WCDMA andGSM;• WCDMA-to-GSM cell change order; and• handover between WCDMA and GSM.Ericsson has successfully demonstrated handoverbetween WCDMA and GSM using dualmodemobile terminals in a live network. Thisevent, which required a holistic perspective,was the tesult of a long-term effort (ten years)in research, standardization, system developmentand interoperability testing.Ericsson is also a total system provider inthe area of WCDMA-to-GSM interworking.The set of features described in this article,such as compressed mode and handoverfrom WCDMA to GSM, is available inthe Ericsson WCDMA and GSM networkinfrastructure and in the mobile terminalplatform products being commerciallylaunched in 2003.REFERENCESBirkedal, A., Corbett, E., Jamai, K. andWoodfield, K.: Experiences of operating apre-commercial WCDMA network.Ericsson Review Vol. 79(2002): 2, pp. 50-61.Heickero, R. Jelvin, S. and Josefsson, B.:Ericsson seamless network. EricssonReview Vol. 79(2002):2, pp.76-83.Hedberg, T. and Parkvall, S.: EvolvingWCDMA. Ericsson Review Vol.78(2001 ):3, pp. 124-131.Aimers, P., Birkedal, A., Seungtai, K.Lundqvist, A. and Milen, A.: Experiencesof the live WCDMA network in Stockholm,Sweden. Ericsson Review Vol. 77(2000):4,pp. 204-215.Ericsson Review No. 1, 2003 11

OMA—Changing the mobile standards gameMagnus L Olsson and Johan HjelmThe Open Mobile Alliance was formed on June 12, 2002, after severalmonths of discussions among the leading companies of the mobileindustry—operators as well as manufacturers. IT companies and contentproviders were also invited to join. From the very start, the role of theOMA in the value chain was meant to differ from that of previous standardsorganizations. Likewise, its approach focuses mainly on interoperatingservices instead of on a stack of protocols. The idea is to offerenabling technology for delivering relevant, end-to-end, high-performanceservices.The authors explain how, while taking into account the true needs ofthe market and complying with business requirements, the OMA providesvarious parties interested in service layer functionality with the means ofdeveloping standards. The authors also show why it is important to providesolutions that fulfill the visions of the OMA.TRADEMARKSCDMA2000 is a trademark of the TelecommunicationsIndustry Association (TIA).Java is a trademark or registered trademarkof Sun Microsystems, Inc. in the UnitedStates and other countries.BOX A, TERMS AND ABBREVIATIONS3GPP Third-generation PartnershipProjectCDMA Code-division multiple accessCSS Cascading style sheetDRM Digital Rights ManagementETSI European TelecommunicationsStandards InstituteGPRS General packet radio servicesGPS Global positioning systemGSM Global system for mobilecommunicationIT Information technologyJ2ME Java 2 Micro EditionJCP Java community processMGIF Mobile Games InteroperabilityForumMMS Multimedia messaging serviceMMS IOT MMS interoperability groupThe blueprintBy minimizing market fragmentation andenabling seamless interoperability, theOpen Mobile Alliance (OMA) hopes tostimulate the growth of mobile services. Accordingly,it works to implement open andglobal standards in unified service platforms,thereby enabling vendors to implementtheir branded products while maintainingthe interoperability of personalizedservices across markets and a broad range ofmobile terminals.More specifically, the objectives of theOMA are• to enable consumer access to interoperableand easy-to-use mobile services acrossgeographies, operators and mobile terminals;• to define an open standards-based frameworkfor permitting services to be built,MWIFOASISOMAOSARTPSCSSIPSNFSVGSyncMLW3CWAPWCDMAXHTMLMobile Wireless Internet ForumObject-oriented administrativesystems - developed in incrementalstepsOpen Mobile AllianceOpen service architectureReal-time protocolService capability serverSession initiation protocolService network frameworkScalable vector graphicsSynchronization markup languageWorld Wide Web ConsortiumWireless application protocolWideband CDMAExtensible hypertext markuplanguagedeployed, and managed efficiently and reliablyin a multi-vendor environment;• to establish a standards forum (the OMA)for the mobile industry to function as thedriving force for creating service levelinteroperability; and• to drive the implementation of open servicesand interface standards, using a usercentricapproach that guarantees rapidand broad adoption of mobile services.The implementationIn the text that follows we will explain howthe objectives should be interpreted fromthe perspective of various stakeholders aswell as what might be the perceived impactfrom this new approach on the consumers.We will also show how Ericsson activelystrives to fulfill the needs of different stakeholderswhile creating new opportunities forappreciated and well-integrated mobile ser-Interoperable mobile servicesAnother aim of rhe OMA is to unify a growingnumber of srandards for Mobile Internetservices and technology. In particular,the OMA works to integrate these technologiesinto a common framework that isindependent of the radio technology(WCDMA, GPRS/GSM or CDMA2000).The OMA framework provides the basis fora multitude of new and consistent sets of serviceenablers with proven end-ro-end interoperability.The consolidation of standards into theOMA framework further srrengthens theoutcome of the affiliated standards by combining,for example, the features of locationbasedservices with messaging, therebygreatly adding to potential business propositions.It is expected that a vast number ofend-user needs will put many and diverseexpectations on a growing set of mobile services.Open standards frameworkThe Internet developer community aboundsin creativity, as does the nascent but continuouslygrowing community of developerswho specialize in mobile solutions. TheOMA framework furrher enhances the creationof new services by introducing commonand popular Internet solutions, such asWeb service technology (based on specificationsfrom the World Wide Web Consortium,W3C).By exposing existing capabilities and ser-12 Ericsson Review No. 1, 2003

Figure 1OMA high-level goals.By exposing existing capabilities and servicesof the mobile networks, the OMA mobileWeb services and consolidated standardtechnologies offer the tools that mobile networkproviders need to give developers aconsistent service creation environment. Inaddition, mobile device technology and mobileplatform middleware ensure that themobile services give the end-user a richer,more interactive experience.Certainly, there is no lack of standards.Most functions that can be used to fulfillend-user services have already been standardizedeither in the OMA or in other forasuch as the W3C, OASIS or ThirdgenerationPartnership Project (3GPP).Therefore, the challenge is not to come upwith new areas for standardization, butrather to make all the different standardswork together (interoperability).Figure 2The challenge of getting unlike standardsto work together.Ericsson Review No. 1, 2003 13

Figure 3The OMA enables wireless content andservices using Internet solutions.Figure 4Affiliated standards integrated into theOMA.Service level interoperabilityThe plethora of existing proprietary solutionseffectively prevents service providersfrom marketing, providing and charging fortheir services in an efficient and economicway. By contrast, the OMA Web servicetechnology makes numerous service enablersaccessible to any service provider.Service providers benefit from simplified,standardized mechanisms for providing andmanaging services. The confidence of contentproviders (if not the same as the serviceprovider) will be further strengthenedthrough the introduction of interoperablemechanisms for downloading rich mediacontent in a secure and manageable fashion—forexample, using OMA solutions fordownloading content and managing digitalrights.Rapid and broad adoptionThe OMA acts quickly to adopt necessarystandard solutions. This is possible becauseit does not effectively recreate technologybut instead reuses specifications from affiliatedorganizations, each with a specific setof technology. For instance, SyncML, WirelessVillage, the Location InteroperabilityForum, MMS Interoperability (MMS IOT),and the WAP Forum provide sets of newand existing specifications that can be unifiedwithin a common OMA framework.OMA—the greatconsolidatorWhen the OMA was formed, the WAPForum changed its name and scope to OpenMobile Alliance. But the OMA is not theWAP Forum in new clothes—the workingmethods are entirely new, and five small industryfora have since joined the alliance tohelp shape the future of the mobile industryas a whole, instead of focusing exclusively onthe technologies they were active in.14 Ericsson Review No. 1, 2003

Several affiliated fora—the Location InteroperabilityForum, SyncML Forum,Wireless Village, MMS IOT, the MobileGaming Interoperability Forum (MGIF),and the Mobile Wireless Internet Forum(MWIF)—have contributed enabling technologyor specifications that fit into agreaterconcept of a service layer. These contributionscombine to create an offering for endusersthat is more interesting and easier tooperate and manage than previous solutions.These affiliate fora constitute the kernelof new working groups—which sometimesalso include technology from the WAPForum or from another of the affiliates—began their work in earnest at the OMAmeeting in Hawaii in November 2002.The OMA is also actively developing relationshipswith the 3GPP and 3GPP2. The3GPP, for example, has already adopted theOMA Digital Rights Management (DRM)standards. This relationship will deepenthrough time. The OMA will also establish relationswith numerous other industry bodies.OMA and ParlayThe OMA and the open service architecture(OSA) might seem to overlap, but forEricsson, a leader in Parlay and OMA, thisrelationship is par for the course.Parlay/OSA was designed to solve a specificset of problems. Some of the Parlay servicecapability servers (SCS) do, in fact, overlapthe OMA enablers, but the scope of theOMA enablers is much broader. At the sametime, Parlay has a strong position in thefixed-line environment, an area that is outsidethe scope of the OMA. The Parlay/OSAwork will continue in the Parlay Group and,with strong liaisons with the OMA, in thejoint ETSI, 3GPP, and Parlay workinggroup.The OMA will take on the work of theParlay Web services and Parlay/X, enhancingits development of Web services andmoving OMA and Parlay closer to a commonindustry standard. This is the strategythat Ericsson is driving in the OMA Frameworkand Mobile Web Services groups.Not reinventing the wheelOne unusual item in the charter of the OMAstates that the organization does not wantto create technology if that technology alreadyexists. Simply put, there are alreadytoo many standards where mobile service enablersare concerned.Since the OMA is an attempt to concentrateindustry efforts, each working group istasked with• analyzing the requirements and use-casesfor the enabler it proposes; and• ensuring that there is not a technology onthe market or in standardization which alreadyfulfills the requirements.An active liaison is required with other standardscommunities, since if the work hasbeen started, clear requirements can ofteninfluence it.Moreover, the OMA inherited from theWAP Forum a tradition of formulating mobileprofiles from existing technologies. ForFigure 5The OMA interoperates across technologiesand value chains.Ericsson Review No. 1, 2003 15

instance, the WAP Forum created mobileprofiles of the cascading style sheet (CSS)language and the extensible hypertextmarkup language (XHTML), which areused in WAP 2.x. Work is also underwayto incorporate a mobile profile for scalablevector graphics (SVG), a technology used inmultimedia messaging service (MMS). Eachof these activities is part of a larger collaborationwith the W3C, which is the originatorof these technologies.Interoperability—animportant componentProducing a specification is not enough; youmust also ensure that the products that implementthe standard work together. Consequently,one of the most active parts of theOMA is the interoperability group, in whichEricsson has a very active role (for example,Ericsson chaired the group during its crucialformation stage).In the OMA, each specification must beaccompanied by a set of static conformancerequirements. Each implementation of aspecification must fulfill its set of these requirements.Likewise, there are several testcases to which the implementer must conform.Conformance is tested at Test Fest(test party) events organized by the OMAInteroperability Process group for each enablerrelease. A Test Fest is less formal thancertification testing, but still makes certainthat the various implementations work together.Requirements-driven processIn many cases, the development of standardsin the mobile industry has been driven bytechnology itself—that is, a given technologyhas often been standardized without regardto the market in which it will be employed.Some would claim that the perceivedfailure of early WAP technology canbe attributed to this phenomenon. By contrast,the OMA, inspired by standard initiatives,such as ETSI and 3GPP, togetherwith experiences gained from its affiliates,will respond to market needs through a requirements-drivenprocess.The OMA requirements group is responsiblefor coordinating requirements.Whereas the requirements create a set ofgoals that the standard must fulfill, eachnew work must also show that the activityis necessary. The requirements are marketbased,and are intended to be a filter andprovide the proper orientation for standardization.The requirements group is the focuspoint for many mobile operators. As a membetof this group, Ericsson is working to introducemodels and methods from EricssonConsumer Lab and elsewhere to speed up theprocess and improve its focus.OMA—the achievementsInstead of starting from square one, theOMA is gradually generating a host of comprehensivedeliverables, including new initiativesthat promote industry convergence.For instance, the OMA is finalizing agreementsof cooperation with the industry. Examplesof such agreements include LibertyAlliance and Parlay. The OMA is alsoadding to cooperation with the 3GPP and3GPP2. Moreover, numerous OMA IOPTest Fests are held for areas such as SyncMLand Wireless Village. Finally, the work ofthe OMA is not tied to any particular operatingsystem. Instead, as part of its architecture,it adds detailed working principlesfor every specification group.OMA and Ericsson—the solutionsThe technologies of the OMA cover the entireend-to-end spectrum of services availableto the end-user. This means that theOMA's agenda includes terminal technologiesas well as server-based systems.Emerging OMA solutions will be based onstandard technology that uses advanced, richmedia-capablemobile platforms, such as• multimedia messaging;• enhanced graphical Internet browsingbased on XML; and• network-based location technology withsupport for existing legacy mobile devicesand full-featured GPS-enabled mobile devices.More advanced third-generation mobile devicesbased on open-standard technology,such as XML (W3C), J2ME-Java (JCP), andSIP/RTP, will further facilitate the developmentof new and compelling services formultimedia entertainment, interactivegaming and advanced instant messagingand presence solutions.OMA in the mobile platform andterminalsThe OMA Mobile Applications Group iscontinuing to develop the Mobile ApplicationsEnvironment, the heir to the WAPForum Wireless Application Environment,which contains support for an address book,calendar, scripting language, and browserfunctions. The imminent affiliation of theEricsson Review No. 1, 2003

Figure 6Example of the OMA concept withenablers, interfaces and APIs.Mobile Games Interoperability Forum, willput a function that depends heavily on standardizingterminals squarely on the OMAagenda. Obviously this will affect the workin the OMA and the direction it takes in thefuture.Third-generation phones from SonyEricsson and other manufacturers will greatlybenefit from the specifications of theOMA, since they are based on open and interoperablestandards and service enablersthat provide the best possible quality endto-end,as implemented by Ericsson MobilePlatforms. For the sake of performance, it isstill more efficient to petform many functionsin the service layer of the fixed network.But with the addition of more technologyin the mobile phone, the creation ofentirely new end-user services is not far off.OMA in the (service) networkThe OMA does not define network technologies,since this lies outside of the scopeset by its founders. The main task of theOMA is to provide enablers which simplifythe development and deployment of enduserservices that use mobile technologies.Ericsson's service network framework(SNF), for example, and the OMA architectureoverlap, but not entirely.By following the intent of the EricssonSNF work and by capitalizing on select technology,Ericsson can make a strong contributionto the OMA standards (as well asmake a noticeable impact on the industry).At best, by providing contributions that arebased on ready-made Ericsson technology,Ericsson can stay one step ahead of the competition.Eticsson's customers will thus benefitftom fast roll-out of OMA technology,which is based on a complete and featurerichSNF solution.ConclusionSince every stakeholder can benefit from thework produced by the OMA, it is paramountthat end-users find it worthwhile to endeavorinto a mobile experience for businessand pleasure. Sony Ericsson is at the forefrontwith another generation of media-richdevices that create a mobile bridge to theentertainment industry. Technology fromEricsson's infrastructure business andEricsson Mobile Platforms will make thispossible.Standards-development activities withinthe Ericsson infrastructure side with keensupport from the Ericsson Mobile Platformsin Lund, Sweden, will play a great and importantrole in making the OMA a successfor an entire industry. Ericsson Mobile Platformswill be committed to deliver the necessarytechnology and support to further enhancethe end-user experience of advancedend-to-end mobile services.Ericsson Review No. 1, 2003 17

The service network framework—An architecturalblueprint for the service networkAndy Johnston, Ake Gustafsson, Anders Eriksson and Mike SlssingarThe emergence of the Mobile Internet has focused special attention onthe service network, which is where network operators can expect todevelop, launch and bill for new services in a streamlined way, tappingvaluable new sources of revenue. Service networks are complex multivendor,multi-technology environments defined by many different interfacesand standards. Consequently, numerous aspects need to beaddressed during the design stage if the service network is to deliver onits promise. Some key drivers for development in the service network arereduced costs and increased revenue.The authors describe Ericsson's service network framework and itsarchitectural approach to the service network.BOX A, TERMS AND ABBREVIATIONS3GPP Third-generation PartnershipProgramBGW Border gatewayBM Business managementCAE Central authentication entityCAS Customer administration systemCAZE Central authorization entityCCE Common charging entityCDS Common directory systemCME Central management entityCN Core networkCPE Central provisioning entityCSE Central session entityFW FirewallFWLB Firewall load balancerHE-VASP Home environment - VASPHTTPIETFHypertext transfer protocolInternet Engineering Task ForceThe combination of mobility and the Internetis creating a new and powerful industrythat will deliver attractive, content-rich servicesto users on the move. However, deliveringon the promise of the Mobile Internetrequires innovation and effort in every layerof the network, including what is commonlycalled the service layer.Being the proving ground for many newservices in development, much functionalityresides in the service layer. This functionalityis needed to ensure that services getlaunched, billed for, and maintained in a secureenvironment. In the service layer, applicationsand content are separated fromunderlying networks, the resulting servicesbeing accessed by users from any device andvia any network.The Ericsson reference architecture forcreating horizontally layered solutions inthe service layer (Figure 1) is called the servicenetwork framework (SNF). This is definedas an architectural framework thatconsists of reusable designs for products andsolutions in the service layer.IMSIPL2SWLANLBLDAPNMO&MRFSSCRSLASNUEUMTSVASPVLANW3CIP multimedia systemInternet protocolLayer 2 switchLocal area networkLoad balancingLightweight directory access protocolNetwork managementOperation and maintenanceRequest for studySystem component registryService level agreementService networkUser equipmentUniversal mobiletelecommunications systemValue-added service providerVirtual LANWorld Wide Web ConsortiumEricsson believes that the use of astandards-oriented and product-neutral referencearchitecture is instrumental in deliveringwell-designed service networks whichpossess the set of technical qualities that isrequired to efficiently, flexibly and reliablydeliver functionality in the service layer.The SNF is designed to help operators tocreate service networks that possess severalarchitectural qualities. For example, the servicenetworks must be supportive of variousbusiness models and processes. They shouldalso be horizontally layered with commonservices available via open interfaces, andhave clear integration points with peer networksin an end-to-end service environment.Similarly, they must be modular, secure,scalable, available, manageable andstandards-compliant.The service networkconceptEricsson's solutions in the service layer aretermed service networks. These are designedusing the SNF, which defines a service networkas any collection of products and solutionsthat fulfills business needs in the servicelayer.The emphasis in this definition is on fulfillingbusiness needs while retaining particulararchitectural qualities in the resultantnetwork. Ideally, the architecturalqualities foster a reliable, scalable, flexibleand cost-effective network solution at anypoint in time during the evolution of thenetwork.Creating service networks that fulfill thebusiness needs of the network operatormeans satisfying the diverse needs and expectationsof various stakeholders. Users, forexample, want simple, quick and inexpensiveaccess to quality services. Netwotk operatorswant to grow their business and increasecompetitiveness. Service providerswant to be premium suppliers of services toas many users as possible. Application developerswant to capitalize on the services ofmobile networks in their applications. Contentproviders want to inctease their customerbase and find new channels towardexisting customers. And Ericsson wants tocreate quality service network solutions thatsolve the business needs of its customers.Network operators who deploy new serviceshave long realized the value of deployingservice networks with common architecturesthat foster common functionsand qualities. An important step in master-18 Ericsson Review No. 1,2003

ing the complexity of service network designentails applying reference architecturesof reusable patterns and clear conceptswhich are based on industry standards andare specifically designed for creating adaptablesolutions.The SNF provides architectural principlesfor creating horizontally layered service networks.By drawing on the architectural componentsfor common management, commonprovisioning, common charging and othercommon services, the framework supportsthe shift from a vertically structured to ahorizontally structured service network.Any system that adheres to the SNF architecturemay be plugged into the frameworkand benefit from common provisioning,management, charging, and so on.Figure 1The service layer.Architectural recipesThe SNF architecture is guided by a set ofarchitectural policies that are intended topromote and conserve particular qualities inthe architectural framework itself. The policiesdeal with• problem solving—the SNF solves real engineeringproblems;• preciseness—the SNF is an abstracrframework but provides precise specifications;• coherency—the SNF uses a coherent architecturalframework throughout;• protocol centricity—the SNF uses protocolsas a basic currency for interfaces;standards orientation—the SNF embracesstandards;modularity—the SNF emphasizes modularitythroughout;openness—the SNF applies open interfaces,standards and technologiesthroughout;product neutrality—the SNF is fullyproduct neutral; andindependence of operating system andprogramming language—the SNF isfully independent of operating systemsand programming languages.Figure 2Stakeholders of the service network.Ericsson Review No. 1, 2003 19

Figure 3Architectural views of the SNF.Architectural viewsThe architectural framework of the SNF isexpressed using a set of architectural views.Each view provides insight into a particulararchitectural aspect. These views cover domain,structure, system type, deployment,tier, data model and applied areas. Each viewworks in concert with the other views to capturethe architectural statements providedby the framework and, over time, to enablethe addition of further statements.In addition, the architectural rules andbest practices, which are presented alongfunctional and qualitative lines, add supportin helping to apply the architecture and provideguidelines. These are held in theSNF rule and SNF guideline catalogs respectively.Domain viewThe domain view describes an ideal boundaryfor the service network and defines howFigure 4SNF domain view.Ericsson Review No. 1, 2003

Figure 5SNF structural view.the service network interconnects and collaborateswith other systems present in itsenvironment. Service networks are createdin the context of existing technical environments—thatis, established groupings offunctionality interact with the business andtechnical functions located in the servicenetwork. The domain view captures and reflectsthe SNF view of the service networkenvironment and identifies the domainswith which service networks generally collaborate,making explicit the demarcationand interfaces (reference points) between itand other domains (Box B).may be provided from a compound system,a system or a component.Finally, within this view, the service contractis the description that specifies how aservice can be accessed. It is a combinationof the functionality in the service and theprotocol transfer mechanisms—for example,the lightweight directory access protocol(LDAP) in conjunction with a specificLDAP schema as opposed to the protocol byitself. The service contract is independentof, and is not connected to, a specific compoundsystem, system or component.StructuralviewThe structural view provides a set of abstractionsthat architects can use for uniformlyanalyzing, modeling and expressingSNF architectures. Uniform expression is anecessity for creating solutions from a portfolioof reusable systems.The highest level in the view is a compoundsystem, which consists of one or moresystems. Much of the architectural guidancein the SNF comes from what it terms thesystem level, which defines a system as a logicaland modular building block that providescertain services over established interfaces.A set of systems works as such a buildingblock to deliver the services that areavailable in a service network.A service is an object that represents a collectionof functionality accessed via protocols.The service is the SNF mechanism forindicating interfaces. One or more servicesFigure 6SNF system and service.Ericsson Review No. 1, 2003 21

Figure 7SNF system type view.Sysfem fype w'ewThe system type view introduces and specifiesa recurring set of SNF systems, whichin essence, are a set of logical building blocksfor creating service networks. Each systemtype (Box C) plays a special role in a servicenetwork and is specified in terms of responsibilityand service (interface).Solution architects may thus refer to systemtypes as specifications for logical buildingblocks within the service network (Figure 7).DeploymentviewMuch of the SNF architecture rests on theassumption that Internet protocol (IP) connectivityis present in the complete solution.BOX B, DOMAINS OF THE SERVICE NETWORKService network (SN)Provides a set of end-points that supportseach of the interfaces to adjacent domains.The actual content of a particular service networkdomain varies depending on the set ofadjacent domains and the business needs.Business management (BM)Includes entities, such as customer administrationsystems (CAS), that the operator usesto conduct traditional business managementactivities—for example, network-wide subscribermanagement.Network management (NM)Includes the entities, such as network managementsystems, that the network operatoruses to conduct network-wide operation andmaintenance (O&M) tasks.User equipment/client (UE)Includes the entities that are expected toaccess SNF-compliant products and solutions.Internet (IN)Represents the Internet services and qualitiesemployed by the service networkdomain. These are primarily Internet naming,addressing and routing services and standards.Core network (CN)Contains the access and connectivity functionsto the control layer of mobile networks.The control layer controls calls and mobilityand contains the entities in GSM, GPRS,UMTS and IP multimedia system (IMS) networks.Value-added service provider (VASP)The term value-added service provider indicatesa business entity that provides servicesto customers of the home environment (HE)service provider. In terms of business andtechnology, the VASP is only loosely affiliatedwith the HE service provider.Home environment VASP (HE-VASPAn HE-VASP is a VASP that has a servicelevel agreement (SLA) with the HE serviceprovider. The HE-VASP is strongly affiliatedin terms of business and technology with theHE service provider (strong trust betweenparties).Ericsson Review No. 1, 2003

BOX C, SNF SYSTEM TYPESSNF systemServes as the root of the entire system hierarchyand provides a minimum set of interfaceswith which each system must comply. Everysystem type must provide the services providedby the SNF system. The SNF system thusserves as a template specification for everysystem in the service network.SNF applicationIs responsible for providing services that areconsumed directly by users.SNF enablerIs responsible for providing services that areconsumed by application systems. The SNFdefines various enablers, such as the commondirectory system (CDS), which serves as acentral directory for user- and service-relateddata that exposes a lightweight directoryaccess protocol (LDAP) interface.SNF gatewayIs responsible for providing services that allowsystems to delegate protocol handling or conversiontasks. The SNF defines various gateways,such as the border gateway (BGW),which supports single sign-on for HTTP traffic.SNF managerIs responsible for providing service networkwideservices. The SNF defines various managers,such as the central provisioning entity(CPE).The IP network is a key aspect of the deploymentenvironment for every system inthe service network.The SNF deployment view provides guidancefor ensuring that the IP network possessesa set of common services and qualitieson which every deployed system can rely.Examples of common services include naming,addressing, routing, load-balancing,firewall and security gateway services. Likewise,common qualities include performance,scalability, flexibility, security, andhigh availability.Figure 8 is a conceptual depiction of howsystems are deployed ro, and make use of,an IP network with various common servicesand qualities.Figure 9 shows an example of how a highlyavailable IP network infrastructure can berealized when systems are deployed onto virtuallocal area networks (VLAN). In rhis example,the application servers have been deployedon VLAN 1, whereas rhe gatewayshave been deployed on VLAN N.Tier viewThe use of N-tier architectures is an acceptedand proven approach toward partitioningor organizing distributed computing architecturesthat require high levels of scalabilityand availability. The SNF recommendsthat N-tier architecture should be employedfor organizing systems into scalable andavailable solutions in a distributed computingenvironment.The various tiers include client, presentation,business, integration, resource, anddata. The client tier is concerned with everydevice that accesses systems or applications.Figure 8SNF deployment view.Ericsson Review No. 1, 2003 23

Figure 9High-availability deployment environment.Figure 10SNF tier view.Data model viewData modeling is an important part of allarchitectural efforts. The SNF data modelview specifies a uniform data model for userandservice-related data and associated provisioningwithin the service network. TheSNF data model has been designed• to support various business and servicelife-cycle models;• to enable designs that distribute userrelateddata throughout the service network;• to support and enable the SNF commonprovisioning model;• to support information on how services aredependent on various systems; and• to support extensions that accommodatesolution-specific requirements.Deployment of the data model is generallymade through a directory server (systemtype CDS) within an actual service network.Although the data model can be used toprovide access to all user and servicerelateddata in a service network, it does notnecessarily follow that all data is modeledwithin the data model. Instead, data can bereferenced, which allows for easy integrationof existing, stand-alone data models, calledaffiliate data models. This gives the solutionarchitect room to design service networksusing the main data model and affiliate datamodels.Applied viewThe applied view introduces the SNF blueprint,which provides a reference architecturethat maps SNF system types, their interfaces,and collaborations to a single view.Some typical and important collaborationsdepicted in the SNF blueprint are• the central provisioning entity (CPE),CDS, and system component registry(SCR)—to achieve common provisioningof SNF systems that require provisioning;• the central management entity (CME)collaborating with all other SNF systems—toachieve common management;• the common charging entity (CCE) collaboratingwith all other SNF systems—to achieve common charging; and• the border gateway (BGW), central authenticationentity (CAE), and centralsession entity (CSE)—to achieve singlesign-on for HTTP.SNF rule catalogThe SNF rule catalog is a set of architecturalrules presented along functional and qual-24 Ericsson Review No. 1, 2003

itative lines that serves to assist in applyingthe architecture provided in the various SNFviews within product and solution development.SNF guideline catalogThe SNF guideline catalog is a set of architecturalbest practices presented along functionaland qualitative lines. Capturing architecturalbest practices that solve particulardesign problems in the service layer isa key part of providing a useful and extensiblereference architecture for the servicenetwork.SNF and standardsAs one of its prime architectural policies, theSNF embraces all standards from 3GPP,IETF, W3C and others. This is central to itsstrategy of maintaining the quality and utilityof the framework architecture. As newstandards emerge, the SNF will evolve accordingly.SNF and productsOne of Ericsson's prime sttategies is to applythe SNF in product and solutions engineeringwithin the service layer. Products arethus designed and developed according tothis strategy, and product road map informationis updated accordingly.SNF evolutionThe SNF is being evolved continuously. Theevolution is initiated via requests for study(RFS), and work is carried out by an open,collaborative community of workgroupsthroughout Ericsson.ConclusionThe SNF provides solution architects witha reliable architectural framework fromwhich to design and build competitive servicenetworks. By depicting the service networkthrough a series of easily accessibleviews, designers can focus on the differentcomponents within the network, highlightingareas where different elements canbe reused. This promotes greater openness,optimization of resource utilization, andgteater economies of scale. Furthermore, itallows designers to add functionality andprovide the overall solution with better performance,reliability, scalability and lowercosts of ownership.Figure 11SNF data model view—extract.Figure 12SNF blueprint.Ericsson Review No. 1, 2003 25

Realizing the operator's service network:Ericsson's systems integrationTorbjorn Svanberg, Sebastian Lind and Chamath KodituwakkuThe service network represents two major propositions for operators: onthe one hand, it exists as a highly complex environment, defined by multivendorproducts and software, applications and services, and many differentcommunication standards and protocols. This suggests thatimmense expertise is needed to make sense of it. On the other hand, theservice network offers operators extremely rich opportunities to earn newrevenues. But to realize the true potential of the service network andmove toward third-generation-ready networks, the operator must fullyunderstand the technical complexity and business issues involved.The authors explain how systems integration provides operators withthe means of evolving and realizing their service networksIn today's highly competitive telecommunicationsenvironments, operators need todevelop and launch new, easily accessibleservices that will help them in their bid toattract subscribers, retain existing ones,make a profit, and gain market share. Reachingthese objectives is dependent on severalfactors that affect the service network. First,thete is a need for truly open environmentsthat do not restrict operators in what theycan use or offer. There is also a need for ahigh degree of flexibility in managing services,the third-party partners, and thecharging arrangements between them.Finally, to allow for future growth, the servicenetwork must be scalable.By implementing a service network withcommon functions for vertical applications,the operator can enable rapid developmentand a subsequent launch of services that providenew streams of revenue. However, theimplementation requires in-depth technicalknowledge, skill and business expertise plusthe ability to manage numerous interrelationshipsbetween third parties, such as serviceproviders, content providers, electronicretailers (e-tailers), advertisers, equipmentsuppliers and software vendors. Theseparties must also agree on revenue sharing,content, and the provisioning of services andapplications (Figure 1).What is more, end-users—individualsubscribers and enterprise customers—must be quizzed to reveal what they expectin terms of services, what they want to see,how much they are willing to pay, and soon. This important aspect can be addressedthrough continuous consumer research andconsultancy.Ericsson's step-by-step approach to systemsintegration is a highly efficient methodthat provides a profound understanding ofthe business issues and technical matters tobe considered.Figure 1Different stakeholder needs are met in theservice network.26Ericsson Review No. 1, 2003

Figure 2An example service network.The service network—Ericsson's visionEricsson's vision of the ideal service networkis an IP network which consists of many disparatesystem products, such as applicationservers, access gateways, service enablers,and management platforms, that co-exist tofacilitate the creation and launch of services(Figure 2).Within the service network, areas such asprovisioning management, sign-on, charging,subscriber and services directories, operation,and management are all treated ascommon functions. Traditionally, thesehave been integrated in a vertical fashion,which entails separating functions for differentservices, such as voice, data andstreaming. However, in the new service networkenvironment, these areas are integratedin a horizontal layer—to facilitate thesharing of functions, the applications areseparated from the underlying infrastructure.BOX A, TERMS AND ABBREVIATIONS3GPPAPICRMIETFIPMMSO&MOMASDKSNFW3CThird-generation PartnershipProjectApplication program interfaceCustomer relationshipmanagementInternet Engineering Task ForceInternet protocolMultimedia messaging serviceOperation and maintenanceOpen Mobile AllianceService development kitService network frameworkWorld Wide Web ConsortiumEricsson Review No. 1, 2003 27

Figure 3Consultative approach to meeting needs.The service network is fundamentallyabout developing a controllable productionenvironment for the operator—for creating,launching, managing and charging for servicesbeyond voice. It is in this domain thatthe operator addresses content, manages servicesdevelopment and launches services.Prepaid billing, roaming and customer relationshipmanagement (CRM) are just afew of the aspects that pertain to the servicenetwork.Consultancy front-endBy following a step-by-step approach,Ericsson provides a consultative front-end atthe beginning of each customer project toassess the operator's current business andtechnical environments. Typically, consultantswill analyze the operator's legacy environment,identifying components thatcan be retained and reused in the service networksolution. This assessment provides aninventory of what the operator has in termsof legacy systems, and what can be reused inrelation to functions, systems, products andsoftware.The consultancy stage first focuses onbusiness requirements. From these it devisesa complete technical solution. The consultantslook at the operator's entire businessmodel and business chain and the implicationsthat these might have on thechoice of technology and implementation.Eticsson can draw on a broad portfoliofrom its services business, which is designedto understand the operator's businessprocesses and systems (Figure 3). This portfolioincludes advisory services, such as businessopportunity analysis, strategic planning,and cost analysis, whereby the operatorobtains an overall picture of the opportunitiesand risks involved. Other servicesare designed to look at the operator's marketingoperations, including sales strategyand revenue forecasting.A holistic view of the operator environmentis essential, since every aspect of thebusiness must be considered openly. Definingthe service network from every anglemeans viewing it as a business-critical system.This perspective also enables solutiondesigners to create and deploy new servicesquickly, safely, and in a controlled and sttuctutedway.Ericsson's consultants also have a key rolein advising an operatot on which services itshould launch. This advice is based on analysisof the operator's target market segmentsand on what end-users are willing to pay for.Any services that the opetatot requests havea direct impact on how the solution is to bedesigned and how much the opetator cancharge.To support this role, Ericsson carries outcontinuous market research through itsworld-class Enterprise and ConsumerLab,which looks into what services and functionalityconsumers want in their handsets,how much they are willing to pay, and soon.Service networkframeworkEricsson's systems integration experts usethe service network framework (SNF) for designingsolutions.' This reference architectureis a product-neutral framework that iscomposed of reusable designs and based onopen standards and protocols through whichcustomer requirements can be met in the solutiondesign. The SNF covers a set of architecturalpolicies and views that definehow the framework should be applied, andprovides insights into diffetent aspects ofthe architecture and supporting rules. It isEricsson Review No. 1, 2003

also a tool for helping realize the operator'sservice network, by demonstrating how thearchitectural design should be implemented.It takes into account• the technology derived from existingstandards organizations and groups, suchas the IETF, 3GPP, OMA and W3C; and• the operator's existing functions andproducts in the network.Systems integration consultants have a keyrole in applying the service network framework.Moreover, since the SNF is independentof products and operating systems, itfacilitates the process of problem-solving.Solution design specifies how all the componentsand products are to be integratedand, by detailing the architecture and variousinterfaces, how this is to be carried out.Given today's multi-vendor environments,the case for an open architecture isclear. Moreover, due to the convergence ofthe telecommunications and Internet industries,there is an area of overlap where themindset and business rules of each industryneed to be considered when making technicalchoices. The architecture of the SNF canhelp companies with a background in theInternet industry, for example, to lift outthe functionality for mobile users. This isnot as easy as it sounds, since the requirementsput on protocols in the wireless worldare totally different from those of the Internet.Therefore, new algorithms or compressionfor certain protocols might be neededto deliver the same quality of service in amobile environment.A framework for complete solutiondesignEricsson's architectural approach facilitatesthe development of a solution. For instance,if the operator is considering incorporatingmultimedia messaging service (MMS), thearchitectural approach would look at certaincommon functions within the network.These could be business support systems,such as provisioning, charging, billing, operationsand management. The intention isto prove to the operator that adopting an architecturalframework will yield commonprovisioning or operation and maintenance(O&M) tasks that can be used for more thanone service. This is where the operator beginsto save on costs and increase revenue bylaunching additional services using thesame functionality. When common functionsare available in the network, new servicescan be brought to market much morerapidly. Therefore, operators who want todevelop a service for a specific segment cando so with relative ease and without havingto go out to the market to source new functionality.These capabilities are built into the servicenetwork and supported by the guidelinesand documentation from the operator'sapplied architecture. This is the link betweendirect technical choices and the businessmodel. Subsequent marketing materialsor market launches are only indirectly affectedby what the operator has in the network.This is where an operator can reallyshorten time to revenue.The architectural approach also highlightsone of the most crucial issues facingall operators—that of launching servicesthat can be charged for from day one. Enduserswant to be able to access services simplythrough a single sign-on and withouthaving to configure each service separately.This aspect should be completely transparent,since research shows that as complexityincreases there is a proportionate decreasein the willingness of end-users to pay for anduse services.A new challenge when integrating systemsis that more and more functionality residesin devices and the service network. Interms of end-to-end integration, certain servicesrequire handsets with specific clientsfor specific needs—for instance Javaenabledhandsets. In other words, certainevents have to be handled and certain sessionshave to be managed. In the operator'sservice network, some common applicationenvironments are concerned with the launchof these services by facilitating service developmentkits (SDK) and application programinterfaces (API). These can be reusedto deliver applications with shorter time tomarket.The SDKs—when provided by the operator—givethird-party application developersa direct interface to applications and services.Via a developers zone, hosted by theoperator, developers and other interestedparties can monitor the use of a particularapplication and even add functionality beforeuploading the application to the servicenetwork.Once the solution has been completed, itcan be integrated. Ericsson can draw on avast pool of resources to carry out the actualintegration, while its experienced customerproject managers and solution architects,who are well versed in the architecturalframework, oversee the solution implementation.Ericsson Review No. 1, 200329

Figure 4MMS integration interfaces.Ericsson's understanding of customer requirementsand its long experience of customizingsolutions using a structured approachprovide unique potential. Many operatorslack an existing architecture in theirnetwork and thus stand to benefit from anarchitectural approach, particularly in thearea of data modeling. The SNF is also aproduct-agnostic environment that opensthe way for incorporating virtually anyproduct on the market into the solution. Theoperator can thus take control of processesand guidelines, dictating how the functionsand systems in the service network are towork together. Since the SNF is based onopen standards and protocols as well as anopen architecture, it is applicable to all-IPnetworks and mobile standards.Typical first step: integrating MMSBy providing a foretaste of the potential ofthird-generation systems and services,MMS is an ideal example of a typical systemsintegration project. The consultancystage involves market testing and planningas well as the planning of content. The overallbusiness strategy must also be analyzedand assessed. At this point, Ericsson is solelyinterested in the operator's businessprocesses and organization and how anMMS solution will fit into the business requirements.Before beginning the integration phase,Ericsson conducts feasibility and solutionstudies that look at the technical solutionrelative to the system architecture and howthe various software and hardware componentsare to be integrated to provide a platformfor use in the mass market. Since eachcustomet situation is different, these studiesusually involve a complex assessment of theoperator's entire service network environmentand existing interfaces. Deliverables,in the form of final reports, detail the requirementsspecification and propose a solutionthat fulfills the operator requirements.Solution integration and implementationcome after the feasibility study. The focus ison how the MMS solution is to be integratedinto existing and new applications, theoperator's existing environment, and legacysystems (Figure 4), such as prepaid or postpaidsystems, provisioning systems, customercare systems and network managementsystems. Due to the nature of the operator'senvironment, several standard andnon-standard protocols and interfaces mighthave to be customized to evolve and alignoperations to match the needs of the businessprocess. To ensure minimal risk to theintegrity of existing applications, each activityis carried out according to the solutiondesign specification.The third stage of the integration processinvolves the planning of content followedby content integration. Multimedia contentenablers are integrated into the solution sothat operators can customize applications tomeet their own customer and businessneeds. Specific expertise and knowledge ofTRADEMARKSJava is a trademark or registered trademarkof Sun Microsystems, Inc. in the UnitedStates and other countries.30 Ericsson Review No. 1, 2003

the features, standards and protocols thatneed to be addressed are essential. When thesolution has been tested and knowledgetransfer is complete the content providerscan integrate their offerings into the MMSsolution.The solution must be managed in its entirety,since it evolves over time, in responseto changing business models, processes andtechnology. Applying experience of the completeintegration project makes it easier toprovide additional support as well as maintainand evolve the solution in keeping withnew technical and business requirements.ConclusionThrough a properly conducted, wellcontrolledconsultative phase, Ericsson candetermine the nature of the operator's business,both in terms of business and technology.By fully understanding the operator'sbusiness objectives and its existing technicalenvironment, consultants can streamlineand expedite the design phase, helping toreduce time to revenue.Having an architectural framework as amain reference point is also crucial to thesuccess of Ericsson's systems integration solutions.Realizing the service networkthrough a structured approach can benefitthe operator in many ways. For example, theoperator can protect past investments, reducecosts and continue development basedon the architectural guidelines. Moreover,operations will be more efficient, since thesolution is specifically adapted to the businessprocesses and organization (and hasbeen developed in a multi-vendor environment—havingan open architecture allowsthe operator to use available best-in-classtechnology).The new set-up enables additional functionsto be implemented when needed, relativelyeasily and at a controlled cost. It alsofacilitates future integration. Each of theseattributes significantly reduces time to revenue.In addition, the operator experiencesless risk by having best-of-breed partnersand the involvement of a well-establishedand experienced integrator—Ericsson.Figure 5A step-by-step approach to achieving a structured service network.Ericsson's services organization has the capacityand competence to successfully performthe roles of solution architect, businessprocess consultant and customer projecrmanager in an end-to-end integration project.Ericsson has already successfully completednumerous integration projectsaround the world, enabling operators to takecharge of their service netwotk evolutionand realize a greatet share of their potential.The consultative front-end gives operatorsthe information they need to make a wellthought-out business investment; the integrationprocess makes it happen. Furthermanagement can help to protect the operator'sinvestment, maximizing value and providingroom for growth.REFERENCES1 Johnston, A., Gustafsson, A., Eriksson, A.and Mike Slssingar: The service networkframework—An architectural blueprint forthe service network. Ericsson Review Vol.80(2003): 1, pp.Ericsson Review No. 1, 2003 31

Advanced baseband technology in third-generationradio base stationsVZhongping Zhang, Franz Heiser, Jtirgen Lerzerand Helmut LeuschnerWCDMA, one of the technologies selected for the air interface of the3GPP standard, is widely used in emerging third-generation mobile communicationsystems. This interface supports data rates of up to 2 Mbit/son a common 5 MHz frequency carrier. Moreover, with the introduction ofHSDPA, the peak service rate for packet access in the downlink can beincreased to more than 10 Mbit/s.Ericsson's radio base station has been designed to comply with the3GPP standard. The kernel part of WCDMA technology has been implementedin the baseband of the radio base station. Compared to previousgenerations, the baseband signals in WCDMA are spread with a highchip-rate code at 3.84 megachips per second on a 5 MHz frequency band.This is much wider than the frequency band used in GSM, cdmaOne andCDMA2000, or PDC. Therefore, to process the signals, more advancedtechnology is deployed in WCDMA baseband. Ericsson's baseband technologyuses the very latest ASIC, DSP, and FPGA technologies.Numerous requirements are being channeled toward the basebandplatform, both to support a technical implementation of WCDMA and tosatisfy operator and radio network management points of view. Being thekernel in WCDMA, the baseband platform must be able to efficiently handlethe entire life cycle of an RBS, from initial deployment, with a lowcost,low-content focus, to subsequent scaling for newly developed servicesand traffic growth. Moreover, it must do so while networks areevolving and expanding with more users and new mixes of end-user services.New radio network functions and features will also be addedthrough base station hardware and software to perfect the WCDMA system.The authors describe the implementation of Ericsson's WCDMA baseband.They also show how it has been prepared to grow with and meetthe needs of future developments by facilitating small, incrementalupgrades and thanks to a flexible architecture that supports the expansionof the uplink and downlink together with critical functionality thatresides in loadable hardware.Figure 1Indoor RBS and baseband subrack.Architecture of the radiobase stationThe functionality of a radio base station(RBS) is divided into two main parts: userplanefunctions and control-plane functions.The user-plane functions are associated withtransport, baseband, radio and the antenna.The control-plane functions pertain to thetransmission of user data and operation andmaintenance (O&M) data. Ericsson's RBS isbased on the connectivity packet platform(CPP, formerly called Cello packet platform)—thatis, the RBS employs the infrastructureof hardware and software modulesprovided in CPP. 1Figure 1 shows a typical indoor RBS withpower subrack, baseband subrack, radio frequencysubrack and power amplifier subrack.2 User-plane signals from the radio networkcontroller (RNC) via the lub interfaceare input directly via CPP boards to thebaseband parts, whereas control-plane signalsare input to the baseband parts via thetraffic and O&M control parts of the mainprocessor. Figure 2 shows the architectureof the Ericsson RBS3000. 1 Please note thatfor simplicity's sake the CPP parts and mainprocessor are not shown.The archirecture can be broken down intoa cell-specific part and a non-cell-specificpart. The cell-specific part contains transceiver(TRX) boards, multicarrier poweramplifier (MCPA) boards and antenna interfaceunit (AIU) boards, whereas the commonpart contains boards for baseband processing.In Figure 2, rhe baseband processinghas been split between the transmitter(TX) and random access and receiver (RAX)boards. The TX board handles downlinkprocessing and enables coding, spreadingand modulation. The RAX board handlesuplink processing and enables demodulation,de-spreading and decoding.Baseband functionsThe physical layer functions on the basebandboards have been implemented to include• the mapping and de-mapping of physicalchannels and transport channels;• multiplexing and demultiplexing;• channel coding and decoding;• spreading and de-spreading;• modulation and demodulation;• physical layer procedures; and• physical layer measurements.In addition, the baseband boards in a radiobase station perform the following functions:32 Ericsson Review No. 1, 2003

• radio base station configuration;• cell control;• the distribution of system information;• radio link configuration for dedicated andcommon channels;• lub data-stream handling; and• node synchronization and distribution.The baseband functions in the radio base stationthus provide a platform for radio networkfunctions, configuration functions,and O&M functions. Accordingly, the basebandconstitutes a platform of resources forhandling common and dedicated channelsfor higher layers.Figure 3 gives an overview of standardchannel mapping between logical channels,transport channels and physical channels.''' 5The upper part pertains to the downlinkchannels and the lower part (shown in darkblue) pertains to the uplink channels. TheThird-generation Partnership Project''(3GPP) has defined the• synchronization procedures for cells, commonchannels and dedicated channels;• random-access procedures; and• inner- and outer-loop power control procedures.To improve the performance of the radiolink connection, the 3GPP has recommendedpossible enhancements, such asopen-loop and closed-loop transmit diversity.After the baseband boards have been configuredproperly with respect to the interfacesto other subsystems, they can be putinto traffic operation. If the traffic load onthe baseband is light, all or part of the boardcan be put into power save mode to reducepower consumption. By contrast, supervisionand protection mechanisms reduce therisk of dropped calls when the traffic loadon the baseband boards is too heavy.Figure 2Baseband in RBS and interfaces.Figure 3Channel-mapping model. Area marked in red is for HSDPA.Baseband design aspectsEricsson's baseband has been designed tocomply with 3GPP standards for WCDMA.In addition, the baseband architecture hasbeen designed to meet requirements for operatingradio base stations. These includeconfiguration flexibility, effective use of resources,easy roll-out, compatibility andfuture-proof hardware. By introducing thevery latest in digital signal processor (DSP),field-programmable gate array (FPGA)and application-specific integrated circuit(ASIC) technologies, Ericsson has significantlyincreased the capacity for ttaffic andcontrol signaling, measured in terms ofchannel elements for the dedicated physicalEricsson Review No. 1, 2003 33

channels. A channel element is defined asthe equivalent baseband resource (hardwareand software) needed to transmit a voicechannel at 30 kbit/s.Configuration flexibility and efficientuse of resourcesOperators want a radio base station that canbe adapted to handle different site and radioconfigurations. Ericsson's baseband implementationgives operators this flexibility,allowing them to change radio configurationswithout having to physically visit thesite. Flexible interfaces have been providedbetween the subsystems of the radio base station,and the baseband parts have been designedin a modular fashion. Each basebandunit provides a certain amount of traffic capacityfor dedicated and common transportchannels. This modular design enables operatorsto configure the radio base station forvarious traffic scenarios and load.Baseband board types—TX boardand RAX boardObviously, the use of separate basebanddownlink and uplink modules makes it easierto upgrade the system and to better adaptit to the asymmetric traffic associated withthird-generation services. Ericsson'sRBS3000 has two baseband board types: theTX board handles downlink traffic, and theRAX board handles uplink traffic.Traffic over the air interface is expected tobe asymmetrical—that is, there will be moretraffic in the downlink than in the uplink.By adding separate TX and RAX boards,operators can increase capacity in small orlarge increments eithet symmetrically orasymmetrically.BOX A, TERMS AND ABBREVIATIONS3GPPAICHAIUASICBCCHBCHBPCCCHCCHCCTrGHCDMACPICHCPPCRCDCCHDCHDL-TPCDPDPCCHDPCHDPDCHDSCHDSPDTCHDTXFACHFPFPGAGPRSGSMHS-DPCCHThird-generation PartnershipProjectAcquisition indication channelAntenna interface unitApplication-specific integratedcircuitBroadcast control channelBroadcast channelBoard processorCommon control channelCommon channelCoded composite transportchannelCode-division multiple accessCommon pilot channelConnectivity packet platformCyclic redundancy checkDedicated control channelDedicated channelDownlink TPCData processingDedicated physical controlchannelDedicated physical channelDedicated physical data channelDownlink shared channelDigital signal processorDedicated traffic channelDiscontinuous transmissionForward access channelFrame protocolField-programmable gate arrayGeneral packet radio serviceGlobal system for mobilecommunicationHigh-speed dedicated physicalcontrol channelHS-PDSCHHSDPAHS-SCCHMCPAMUXO&MPCCHP-CCPCHPCHP-CPICHPDCPICHPFtACHRACHRAKERAXRBSRFRNCS-CCPCHSCHSIRTFCITPCTrCHTRXTXUEUL-TPCWCDMAHigh-speed physical downlinkshared channelHigh-speed downlink packetdataaccessHigh-speed shared controlchannelMulticarrier power amplifierMultiplexing unitOperation and maintenancePaging control channelPrimary common controlphysical channelPaging channelPrimary CPICHPersonal digital cellularPaging indicator channelPhysical random access channelRandom access channelName of WCDMA receiverRandom access and receiverRadio base stationRadio frequencyRadio network controllerSecondary common controlphysical channelSynchronization channelSignal-to-interference ratioTransport format combinationindicatorTransmission power controlTransport channelTransceiverTransmitterUser equipmentUplink TPCWideband CDMAEricsson Review No. 1, 2003

Modularity of the basebandTraffic load and distribution vary over timein different sectors and frequencies. TheEricsson baseband architecture employspooling w optimize the use of available resources.This approach also guarantees thatconfigurations can be flexible. Figute 4shows the advantages of modularity andpooled resources in two different radio configurations.Some operators require redundancy in theradio base station. The modular basebanddesign easily restricts the loss of traffic dueto, say, a faulty component or unit in basebandprocessing.Easy roll-out of third-generationinfrastructureEstablished GSM and GSM/GPRS operatorscan more easily roll out third-generation infrastructureby reusing site locations and infrastructure.Most operators starting out inthe third-generation business want lowcost,low-capacity RBSs. Later, when thenumber of subscribers has increased andmore advanced services are to be introduced,they will need RBSs that can handle greatertraffic capacity in individual cells. The basebandboards have been designed with scalabilityin mind—greater capacity can be hadby adding hardware units (TX boards andRAX boards).Another way of increasing traffic capacityis to deliver and install prepared hardwareon site. As operatot needs grow, more capacitycan be activated successively bymeans of software functions. This approachadvocates the use of simple, standard hardwareconfigurations.A further advantage of baseband scalabilityis that the RBS can be equipped with asmany baseband units as needed to satisfytraffic, site conditions, and air-interface capacityfor a given frequency band. This helpsoperators to avoid wasting unnecessary resources.Future-proof and compatibleAs mentioned above, most operators juststarting out in the thitd-generation businesswant low-cost, low-content RBSs. Later,however, apart from increasing capacity inthe RBS, they will also need more functionalityand more advanced features. In designingthe baseband, Ericsson has carefullyconsidered various evolution scenarios,making allowances for customer-specific requirementsfor functions, services, capacity,redundancy, and site conditions.Figure 4Baseband modularity and pooled resources.In general, the functions in the physicallayer have been implemented in hardware(ASIC) or close to hardware (DSP); the controlfunctions have been implemented insoftware on DSPs and board processors. Toavoid the logistical problems and costs associatedwith frequent on-site updates orupgrades, Ericsson has prepared the hardwarefor future functions—these can becomeavailable via remote software andfirmware updates. Ericsson calls this featureforward hardware compatibility.On the other hand, new baseband boardsmust work in environments that use oldbaseband boards. This is called backwardhardware compatibility. Ericsson's basebandhardware and software are forwardhardware and backward hardware compatible.Future-proofness—in terms of additionalradio configurations, services, functions,and greater capacity—is an importanceaspect of Eticsson's baseband design.Figure 5 illustrates the forward hardwarecompatibility concept. Function Z has beenprovided in hardware. A remote softwateupgrade can thus activate the entire func-Figure 5Forward hardware compatibility.Ericsson Review No. 1, 2003 35

Figure 6Backward hardware compatibility.tion. Figure 6 shows the backward hardwarecompatibility concept. The baseband unit,C, is added to the existing RBS to improvefunctionality and capacity.Downlink processingboard—TX boardDownlink processing functionsFigure 7 shows the main function blocks forprocessing the downlink. Each of theseblocks also contains other baseband functions(not pictured). The first process is frameprotocol (FP) handling (pictured left). Afterconfirming when the data frames on the commonchannels (paging channel, PCH, andforward access channel, FACH) and the dedicatedchannels (DCH) arrived from the lubinterface, the frame protocol handler alignsthe frames and extracts the payload part ofthe data frame. The payload part contains thedata of the uncoded transport channels.For the dedicated channels, the encodingfunction block• generates the cyclic redundancy check(CRC);• concatenates the transport blocks;• segments the coding blocks;• performs convolutional coding or turbocoding;• inserts the first discontinuous transmission.(DTX);• matches rates; and• performs the first interleaving.To fit the 10 ms radio frame, the transportblocks from different transport channels aremultiplexed in the multiplexing unit(MUX) function block. This activity is followedby insertion of the second DTX, thesecond interleaving, and multicode splitting.Data and control information are thensent to the cell-split function block. Thecontrol information contains transport formatcombination indicator (TFCI) bits andcorresponding transmission power control(TPC) commands which have been mappedwith pilot bits onto the dedicated physicalcontrol channel (DPCCH).After the frame protocols have been handled,the broadcast channel (BCH, which ismapped to the primary common controlphysical channel, P-CCPCH, and to PCHand FACH) and PCH and FACH (which aremapped to the secondary common controlphysical dedicated channel, S-CCPCH) areprocessed in a manner similar to that describedfor the dedicated channels. The cellsplitfunction identifies the common anddedicated physical channels that belong toone cell carrier. These processes are followedby modulation, spreading and weighting,36 Ericsson Review No. 1, 2003

DL/UL l/fFigure 7Downlink processing function blocks.with power information for the downlinkpower control, and scrambling.TX board implementationFigure 8 shows the downlink processingboard (TX board), which is divided into twomain parts: the board processor and boardspecifichardware. The board processor controlsthe board and parts of the traffic. Theboard-specific hardware, which processesuser data sent to the air interface, containsthe lub user-plane interface handler,symbol-rate processor, chip-rate processor,and the physical layer processing controller.The lub user-plane interface handler handlesthe lub interface user-plane protocol forthe DCH and CCH data streams to the radionetwork controller.The symbol-rate processor handles thetransport channel (TrCH), the coded compositetransport channel (CCTrCH), thephysical channel for the primary and secondarycommon control physical channels,the paging indicator channel (PICH), andthe dedicated physical channel (DPCH).The chip-rate processor handles the distributionof physical channels, generates thesynchronization channel (SCH), the primarycommon pilot channel (P-CPICH) andacquisition indicator channel (AICH), andtransmits the distributed output sequencesto the TRX. It also measures the transmittedcode power and handles all cell-carrierprocessing-related functionality.The physical layer processing controllerhandles the configuration of the symbol-Figure 8TX board implementation.Ericsson Review No. 1, 2003 37

Figure 9TX board of the RBS3000 series.and chip-rate processing parts with respectto the control of measurements, set-up, release,and reconfiguration of cell-carriersand channels.The functionality of the lub user-plane interfacehandler and the physical layer processingcontroller is implemented in DSPsto give flexible implementation of• the controller functions;• external interfaces to the RNC for the userdata interface; and• interfaces to the board processor for thecontrol interface.The symbol-rate processing functionality isimplemented in FPGAs due to processingdelay and varying requirements put on thethroughput of user data. Some flexibility isalso provided in view of changing requirementsfor the implemented functionality.The chip-rate processing functionality isimplemented in ASICs. This approach employsparallel processing to meet the demandfor limited processing delay. It alsoallows synchronous transmission of the distributedoutput sequence to the TRX.Figure 9 shows a TX board used in anRBS3000. The board can handle multiplecell-carriers with more than one antennabranch.Interlace between the TX and RAX boardsThe interface between the TX and RAXboards supports fast signaling for controllingcall set-up and power. When the user equipment(UE) sets up a call to the RBS, the correspondingRAX board in the RBS reservessufficient resources. The RAX board thensends a layer-1 acknowledgement signal viathe TX board to the UE, indicating that theUE may send the RACH message part. Tocontrol power in the downlink, the RAXboard detects the TPC commands and sendsthem to the TX board, which adjusts downlinktransmission power.To control power in the uplink, the RAXboard compares the signal-to-interferenceratio (SIR) target with the SIR of the receivedsignals and generates the TPC commands,which it sends to the UE in thedownlink DPCCH.Uplink processingboard —RAX boardUplink processing functionsIn the uplink, the signals received from theair interface are input to the baseband in adigital signal format from the TRX radiopart of the RBS (Figure 10). For the dedicatedphysical channel (DPCH), the incomingsignals from the TRX are processed inthe demodulator function block, which containsa searcher and RAKE receiver. The demodulator• performs de-spreading;38Ericsson Review No. 1, 2003

Figure 10Uplink processing function blocks.• recovers the uplink control channel dataand DPDCH data;• generates uplink TPC (UL-TPC) commands;• detects downlink TPC (DL-TPC) commands;and• decodes and de-maps the TFCI.SearcherIn multipath propagation environments,the RAKE receiver must know when themultipath rays arrive—that is, it must determinethe position of the multipath raysalong the delay axis, so that it can allocatethe RAKE fingers to positions where themultipath components hit with signalpower. The task of the searcher in the basebandis to synchronize the RAKE fingers.To speed up the searching process, a narrowsearcher window is placed where themultipath rays are expected. However, insome cases, such as soft-handover set-up, thepropagation delay is unknown; therefore, awide searcher window is needed that correspondsto the entire cell range. The searcheralso estimates the profiles of radio channeldelay and sends them to the RAKE receiver.RAKE receiverThe RAKE receiver separates the multipathcomponents and combines them coherentlyinto a large signal vector that provides gooddemodulation conditions. This increases theprobability of making correct decisions andimproves receiver performance.Given the proper spreading code, theRAKE receiver can de-spread all detectedmultipath rays. Using the pilot bits to estimatechannel amplitude, phase, frequencyoffset and Doppler spread, the RAKE receiverprocesses the multipath rays with thecorresponding weighting, and combinesthe rays. Before combining the rays, however,each ray is processed by one RAKEfinger.To make efficient use of the hardware resources,the RAKE fingers can be treated as apool of hardware resources. They can also beflexibly allocated between users on the sameRAX. This allocation is made according tothe position information delivered by thesearcher. Fewer RAKE fingers are needed inrural settings with a line-of-sight connectionbetween UEs and the radio base station thanin urban settings with multipath fading.During softer handover, which is thehandover between cells in the same RBS andon the same carrier, the detected signals arecombined.The DPCH signals are demultiplexed andde-mapped to the DCH of the transportchannel for the next step of processing in thedecoder. The decoder input signal consistsof interleaved soft bits from the demodulator.The following tasks are performed in thedecoder block:Ericsson Review No. 1, 2003 39

Figure 11RAX board implementation.• the second de-interleaving;• desegmentation of the physical channel;• service demultiplexing;• rate matching;• radio frame de-segmentation;• the first de-interleaving;• convolutional and turbo decoding; and• error detection by the CRC.When the UE tries to contact a radio basestation, the random-access receiver detectsthe preamble that contains the signatureused for the RACH message part. When ithas detected the preamble, it determineswhich signature the RACH message part isusing, and whether sufficient baseband resourcesare available. If so, it sends alayer-1 Ack or Nack message to the UE viadownlink processing and begins processingthe RACH message part in a similar manneras described for the DCH.The frame protocol function for the DCHand RACH assembles frame protocol data,which consists of a header part and a payloadpart (user data). Frame protocol dataframes are sent to the RNC via the lub userplane.The RAX board recovers and restores theinformation originally transmitted from theincoming radio signal for random access anddedicated channels. The 3GPP has definedthe requirements put on uplink receptionperformance. 7 Reception sensitivity,signal-to-interference performance, and thecapacity of the physical channels determinethe characteristics of the receiver.RAX board implementationThe uplink processing board (RAX board)is divided into two main parts: the boardprocessor (BP), and board-specific userdata-processing(DP) hardware. The boardprocessor controls the board and parts of thetraffic. The DP hardware processes user datareceived from the air interface to the lub interface.Figure 11 shows the blocks on aRAX board in the RBS3000.The DP part contains blocks for processingthe CCH chip rate, DCH chip rate, CCHsymbol rate, and DCH symbol rate.The CCH chip-rate processing block detectsthe preamble, generates the acquisitionindicator, and detects and extracts the messages(DPDCH/DPCCH) for the physicalrandom access channel (PRACH) from thedata received on the air interface.The DCH chip-rate processing block detectsand extracts the DPCH(DPDCH/DPCCH) from the data availableon the air interface, including power controlsupport.The CCH symbol-rate processing blockprocesses the CCTrCH provided by theCCH chip-rate processing block into decodedTrCH, which is sent via the lub frameprotocol to the radio network controller.The DCH symbol-rate processing blockprocesses the CCTrCH provided by theDCH chip-rate processing blocks intodecoded TrCH, which is sent via the lubframe protocol to the radio networkcontroller.Algorithms and functionality for processingstable user data have been implementedin fixed hardware (ASIC) to yield highcapacity. By contrast, algorithms for processingvariable user data, such as channelestimation, are allocated in loadable hardware(DSP or FPGA). New functionality,due to enhancements to 3GPP standards, isalso implemented in loadable hardware(DSP and FPGA).The block structure (Figure 11) and themix of fixed and loadable hardware resultsin a future-proof architecture:• Reception sensitivity can be improved byupgrading the algorithms in loadablehardware and software.• The hardware has been prepared to supportfuture 3GPP functions (future releases).This means that basic functional-40 Ericsson Review No. 1, 2003

ity and extensions of the 3GPP physicallayer can be upgraded.• The scalable nature of the DCH and CCHensures that the capacity of each block canbe increased using new ASIC, FPGA, andDSP technologies.• The block structure supports integrationwithin as well as between processingblocks. This also leads to greater capacity.Ericsson's use of modular building blocksenables operators to vary the implementationas needed. For example, a low-capacityDCH/CCH solution would make use ofseparate low-capacity DCH/CCH chiprateprocessing and combined symbol-rateprocessing, whereas a high-capacityDCH/CCH solution would make use ofseparate, scalable, high-capacity DCHchip- and symbol-rate processing and combinedCCH chip- and symbol-rate processing.Figure 12 shows a RAX board used in theRBS3000. The board supports two-waydiversity and can handle multiples of 16-channel elements serving up to six cell carriers.Future basebandenhancementsHigh-speed downlink packet-dataaccessHigh-speed downlink packet-dara access(HSDPA) can be introduced in the downlinkfor best-effort services. This enhancementcan increase the bit rate to more than10 Mbit/s in the existing frequency band. 3HSDPA can be implemented in the TXboard for the downlink by exploiting moreadvanced baseband technology.Interference cancellationInterference cancellation can be introducedin the uplink DCH receiver ro improve coverageor to increase capacity. The main effectof interference cancellation is reducedinterference received from users in the samecell as the target user. This technique caneither increase the amount of uplink trafficor reduce the interference margin in the dimensioning,thus increasing coverage.The configuration can be serial or parallel.Serial configurations yield the greatestimprovement in performance and requireless processing power, but result in greaterdelay. Parallel configurations, which offer areasonable improvement in performance, re-Figure 12RAX board of RBS3000 product series.quire greater processing power, but resultin shorter delay. Parallel configurations arethus preferred for voice service.ConclusionThe baseband part of Ericsson's RBS3000provides a hardware platform for thirdgenerationradio network functions andcomplies in full with the 3GPP WCDMAstandard. All physical layer functions andframe protocol processing are implementedon the baseband boards.The baseband design supports free allocationof baseband resources to frequency andsectors, thereby supporting operator needsfor flexibility in configuring the radio networkfor different sites. The architecturescales easily to meet operator demands forcapacity. The baseband software and hardwaresupport forward hardware preparation—forfuture functional enhancements.The baseband architecture is also backwardcompatible—that is, operators will be ableto insert futute-generation hardware into anexisting platform running the RBS infrastructure.Planned enhancements to the basebandinclude HSDPA, to increase the bit rate forbest-effort service in the downlink, and interferencecancellation, to improve coverageor capacity in the uplink.REFERENCES1 Kling, L, Lindholm, A., Marklund L. andNilsson G: CPP—Cello packet platform,Ericsson Review Vol. 79(2002):2, pp. 68-752 Zune, P.: Family of RBS 3000 products forWCDMA systems, Ericsson Review Vol.77(2000):3, pp. 170-1773 Hedberg, T. and Parkvall, S.: EvolvingWCDMA, Ericsson Review Vol. 77(2000):2,pp. 124-1314 3GPP WCDMA Technical Specification25.2115 3GPP WCDMA Technical Specification25.3016 3GPP WCDMA Technical Specification25.2147 3GPP WCDMA Technical Specification25.104Ericsson Review No. 1, 2003 41

Previous issuesNo. 3, 2002Packet data in the Ericsson CDMA2000 radio access networkEricsson Telecom Server Platform 4AAL2 switching in the WCDMA radio access networkMicrowave transmission in mobile networksNo. 2, 2002Experiences of operating a pre-commercial WCDMA networkRNC3810—Ericsson's first WCDMA radio network controllerCPP—Cello packet platformEricsson seamless networkEricsson's GSM RAN capacity solutionsNo. 1,2002Real-time performance monitoring and optimization of cellular systemsIP technology in WCDMA/GSM core networksThe future of communication using SIPEricsson Mobile Operator WLAN solutionNo. 4, 2001Secure electronic transactions—The mobile phone evolution continuesOn-demand mobile media—A rich service experience for mobile usersWAP 2.x architecture—Features, services and functionsRF multicarrier amplifier for third-generation systemsEricsson's family of carrier-class technologiesBuilding a reliable, cost-effective and future-proof fiber optical access networkNo. 3, 2001MMS—Building on the success of SMSSyncML—Getting the mobile Internet in syncFurther evolution of the GSM/EDGE radio access networkEvolving WCDMATelecom management for ENGINEApproach to E2E service assurance on the mobile InternetCDMA2000—A world view

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