Alcatel Broadband

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ALCATEL TELECOMMUNICATIONS REVIEW

Alcatel Telecommunications Review - 2 nd Quarter 2005

UNIVERSAL ACCESS

CONTENTSAlcatel Telecommunications Review is the quarterly technical journal of Alcatel, reporting its research, development and production achievements worldwide.

Connect me anywhere, any time, any way

EDITORIALProject Lightspeed Ernie Carey

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INTRODUCTIONM. Peruyero, Y. TJoensEDITORIAL BOARDNiel Ransom Alcatel, Paris, France Ron Spithill Alcatel, Paris, France Olivier Baujard Alcatel, Paris, France Jolle Gauthier Alcatel, Paris, France Pierre Tournassoud Alcatel, Paris, France Alistair Urie Alcatel, Paris, France Vince Pizzica Alcatel Asia Pacific, Shanghai, Peoples Republic of China Guido H. Petit Alcatel, Antwerp, Belgium

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Universal Broadband AccessMaking User-Centric Broadband in Access a RealityA seamless combination of fixed, mobile and broadcast access offers users an always best connected experience.

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Ph. Lain, L. Le Gouriellec, J. De Vriendt

Any AccessUniversal Broadband Access: Going Wireless and Mobile 99

Are the emerging broadband wireless and mobile technologies a threat or an opportunity? Will they compete or complement one another?

J-L.Hurel, J. Brouet, L. Le Gouriellec, M. Peruyero Software Defined Radio: A Promising Technology for Multi-Standard Base Stations 106

GUEST EDITORPierre Tournassoud Alcatel, Paris, France

EDITORSWillem Zevenbergen Editor in Chief, Paris, France Catherine Camus Managing Editor, Paris, France

SDR is an important step towards offering every user at any location the best bandwidth and mobility, in line with Alcatels vision of a usercentric broadband world.

B. Haberland, W. Koenig, A. Pascht, U. Weiss Standardization: Key to Mass DeploymentStandards have evolved to make DSL technology a credible building block for triple-play deployments.

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CONTRIBUTING EDITORSGustavo Arroyo Spanish edition, Madrid, Spain Mike Deason English edition, Braintree, UK

F. van der Putten, S. Ooghe Optical Fibers Pave the Way to Faster Broadband AccessEmerging services and increasing competition are forcing carriers to deploy optical fibers in the access network, ultimately serving each subscriber over a dedicated fiber link.

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Th. Pfeiffer, E. Ringoot, A. Granger, D. Wang

Articles marked @ are the web supplement to this edition at www.alcatel.com/atrwww.alcatel.com/atr

Extending Broadband Reach by SatelliteCombining broadband satellite solutions with terrestrial wireline and wireless solutions can rapidly extend the reach of IP multimedia applications to underserved parts of the world.

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Alcatel Evolium Multi-standard Radio Access SystemMulti-standard radio access is the new trend in network design! So what are the requirements and benefits?

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F. Engmann, G. Walz

A. Bertout, J. Couet

Operational Excellence Any ServiceSupporting Quality of Service in Broadband Access Networks 128 Optimizing DSL for Multimedia ServicesLine optimization can increase DSL speed, quality and stability while reducing operating expenses.

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An optimal user experience for triple-play services can be assured thanks to QoS enablers in fixed and wireless access networks.

T. Bostoen, R. Oehen, J. Verlinden 4G Mobile4G will deliver low cost multi-megabit/s sessions any time, any place, using any terminal.

S. Ooghe, N. Drevon, R. Siebelink Access Network Enhancements for the Delivery of Video Services 134

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D. Rouffet, S. Kerboeuf, L. Cai, V. Capdevielle

Enhancements are being researched that will improve both the quality of video delivered over networks experiencing congestion or transmission errors, and the video channel changing performance.

R. Sharpe, D. Zriny, D. De Vleeschauwer

Customer Example3G Network Powers Intense Services 165The launch of Orange Intense marks the culmination of three successful years of close collaboration with Alcatel.

ConsolidationFixed Access Vision 140Guaranteed delivery of triple-play services making optimal use of valuable resources is the key driver moving fixed access forward as the world converges towards offering all services over ubiquitous broadband connectivity.

O. Perot, J-M. Perera, L. Byerley

J. van Bogaert, Y. TJoens, J-P. Lartigue WiMAX: From Fixed Wireless Access to Internet in the PocketWiMAX access can provide new service opportunities to fixed and mobile operators thanks to its flexible radio technology and innovative features.

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D. Renaudeau, D. Boettle, H. Steyaert

Customer Applications Notes www.alcatel.com/atr

Technology White Paper

Strategy White Paper

Technical Paper

2 nd Quarter 2005 - Alcatel Telecommunications Review -

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EDITORIAL

Ernie Carey

SBC PROJECT LIGHTSPEED

Ernie J. Carey Vice President, Network, IP Operations & Services SBC Inc

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BC companies are bringing a digital lifestyle to customers. As customers expect more bundled services, enriched video, data and voice experiences, SBC is moving quickly to offer next-generation communications and entertainment services. The success of these services depends on networks working together to help SBC companies compete in the Internet Protocol (IP) marketplace. Widespread availability of broadband is a key element in making the digital lifestyle a reality. Consumer broadband adoption levels are reaching critical mass. In fact, according to Yankee Group, at the end of 2004, about 30 million US households had broadband service. At the end of 2004, SBC companies reached a significant milestone of surpassing 5 million DSL lines in service. Increasing the bandwidth of broadband is critical to meeting the rapidly evolving demands of the marketplace that is, to provide IP-based services. Why is now the right time? Today, traditional telephone companies like SBC are competing against a variety of providers and technologies by offering bundles that include voice, video, data and wireless. Meanwhile, competitors are starting to enter traditional SBC markets. For example, cable companies, which have offered video and high-speed Internet service for years, are now getting into the voice business. Some are offering Voice over Internet Protocol (VoIP) a technology thats receiving a lot of buzz. Theres no doubt that the marketplace is growing increasingly competitive. At the same time, customer needs are changing. Today were seeing an appetite for cooler, smaller, faster and better digital devices. Whether its a wireless phone that can shoot video, or a PDA that doubles as a portable music player, or a PC that can be used as a media center and digital video recorder consumers want maximum functionality and flexibility, and they want many of these devices integrated so they work simply together. The digital lifestyle is no longer just a buzzword. Its a reality. So, by fully utilizing the capabilities of IP, fiber and wireless data technologies, SBC companies are working to build an even stronger presence in the marketplace with differentiated, competitively priced product offerings. IP services will enable integrated video, voice, data and other applications, potentially allowing customers to share any number of household devices such as TVs, set-top boxes, PCs, PDAs or phones over one network connection.

SBC companies expect to add approximately 38 000 miles of fiber through Project Lightspeed, an estimated $4 billion capital initiative to deploy both Fiber to the Node (FTTN) and Fiber to the Premises (FTTP) to 18 million homes by the end of 2007. In most new network builds, such as developing subdivisions, SBC companies are planning to bring fiber all the way to the customers homes. In neighborhoods with existing SBC services, SBC companies plan to use FTTN technology to push fiber much deeper in the network to nodes that serve 300 to 500 homes. FTTN enables significantly higher broadband speeds, with download speeds of 20 to 25 Mbit/s. Cost, demand, time for deployment and avoiding potential inconvenience for customers are all key factors in this decision to use FTTN for overbuilds. SBC companies have evaluated a full range of technologies and deployment scenarios and are confident that the joint FTTN/FTTP strategy is the right solution to deliver the next generation of IP services, and to evolve the SBC network to meet customers communications needs. To help build this new network, SBC announced a five-year, approximately $1.7 billion primary supplier agreement with Alcatel in October 2004 to provide network equipment and video system integration services. Alcatels network equipment will include core network access, aggregation and switching equipment platforms that will provide the IP, packet-based technologies over fiber optics that connect the neighborhoods to the central office. Additionally, Alcatel will work with SBC to ensure video systems integration. For the video network, instead of using a traditional legacy broadcast network which requires all television content to be transmitted to every customers set-top box all the time, SBC companies are conducting trials of a switched video distribution system. In the switched video environment, the content resides on SBC servers and only the content the customer requests is sent, freeing up bandwidth to be used for other applications. SBC announced a contract with Scientific-Atlanta to provide IP-based video equipment for Project Lightspeed. Alcatel will work with SBC and now Scientific-Atlanta to ensure seamless video systems integration. Additionally, last year, SBC announced a first-of-its-kind agreement with Microsoft Corp to use the Microsoft TV Internet Protocol Television (IPTV) Edition software platform. SBC Labs has been testing an IP-based television service built on the Microsoft TV IPTV Edition platform since June 2004.

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- Alcatel Telecommunications Review - 2 nd Quarter 2005

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SBC PROJECT LIGHTSPEED

SBC companies expect that this video distribution system coupled with its fiber-rich network will allow it to offer an IPTV service that offers features and functionality beyond todays existing broadcast-delivered digital TV networks. For example, in the future the SBC service could include a robust video-on-demand library, multiple picture-in-picture functionality, whole-house digital video recording, interactive program guides and more. And, with the remaining bandwidth, SBC plans to offer feature-rich VoIP and high speed Internet access. Some additional potential applications include: Using two-way broadband networks, SBC companies could be able to send alerts and notifications to customers watching TV in new ways. Some examples include the ability to alert a customer of upcoming favorite shows, or Caller ID and instant messaging on the TV screen.

The Microsoft TV IPTV Edition platform could enable new services and applications, such as tunerless picture-in-picture functionality. The picture-in-picture feature enables users to preview other shows and channels while the primary channel runs in the background. IP is the future, and SBC companies are embracing the future to deliver next-generation communications and entertainment services.

This article was written as of April 2005, and SBC disclaims any obligation to update or revise statements contained in this article based on new information or otherwise.

Ernie Carey began his career with Southwestern Bell in 1975, in Houston Texas, after graduating from college. He then progressed through a series of operations, engineering, and marketing jobs in Southwestern Bell, and is currently Vice President-Network with responsibility for network planning and engineering for Project Lightspeed. Mr Carey is on the Board of Directors of the Sam Houston Council of the Boy Scouts of America. He was appointed as a member of the Commission on State Emergency Communications and also served on the Board of Directors of the Greater Harris County E911 District for eight years. Currently he is on the board of the Texas Technology Opportunity Institute and the Engineering Advisory Board, Cullen College of Engineering, University of Houston.

www.alcatel.com/atr


91

INTRODUCTION

Michel Peruyero, Yves TJoens

INTRODUCTION

o realize a user-centric broadband world, service providers across the world will need to change their organizations and business models and to upgrade their networks. This transformation is being made necessary by the need of todays users to communicate more, while being less occupied with the underlying technologies. The initial step towards a user-centric broadband world is a ubiquitous broadband connection over which content and services can be made universally available. Connectivity is one of the users most basic requirements. This goes beyond broadband everywhere to a demand that access networks be invisible to the user, who doesnt want to have to choose which device, service and access to use. This implies the disappearance, in the users eyes, of distinctions between fixed, mobile and wireless access technologies. While this does not necessarily mean network convergence, it does entail service convergence from the users point of view (i.e. same device, same content, one bill, regardless of the access network), as well as seamless handovers between access networks. It also implies that broadband access technologies should become increasingly complementary. Broadband wireless technologies, such as WiMAX, will complement both mobile and fixed access, giving mobile users higher bandwidth data delivery in hotzones, and giving nomadic users DSL-equivalent service in rural and suburban areas. The key to a seamless broadband experience will be smooth handovers. Network operators facing the build-up of this new network are increasingly looking to reduce their overall operating costs. As well as investing in tools to ensure operational excellence, one will witness the first signs of network consolidation around this new paradigm of communication, with operators seeking to switch off their existing legacy telephony networks to consolidate all operations around a multimedia IP network, thus sowing the seeds for full fixed/mobile convergence. In this issue of the Alcatel Telecommunications Review, the emphasis is on Universal Broadband Access (see Figure 1). The article Making User-Centric Broadband in Access a Reality introduces the vision of future access network evolution with respect to fixed, mobile and broadcast access. The evolution of networks in general, and access networks in particular, in line with the universal access vision involves four dimensions: Any Access, Any Service, Consolidation and Operational Excellency. The Any Access dimension is paving the way to ubiquitous service delivery, which implies the availability of access92

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technologies that are fit for the purpose (and seamless roaming between different access technologies), as well as multiservice support using QoS techniques and intelligent network support for data, voice and video services. Access technologies are proliferating, giving operators a diversity of choice to fit their architectures and service delivery models. This issue provides a broad overview of Alcatels access technologies, which illustrate the innovation power of Alcatel. These include Mobile and wireless: Universal Broadband Access: Going Wireless and Mobile and Software Defined Radio: A Promising Technology for Multi-standard Base Stations. DSL: Optimizing DSL for Multimedia Services and Standardization: Key to Mass Deployment. Fiber: Optical Fibers Pave the Way to Faster Broadband Access. Satellite: Extending Broadband Reach by Satellite. The second dimension is Any Services. Multi-service support across fixed and mobile networks is detailed in Supporting Quality of Service in Broadband Access Networks, which focuses on how different service streams receive the treatment they need across the access network. One particular service that benefits from intelligent access network enhancements is the video service; intelligent traffic

Figure 1: Universal broadband access

Every Terminal, Everywhere

Business Environment

Universal Broadband Access Wireline

Consumer Environment

Wireless Satellite Mobile

Service Aware Edge & Data Aware Transport

Open Services Delivery Environment

Operations & Business Support Systems Integration & Operations


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Any Content

Each User

management and advanced channel changing techniques enable operators to provide their customers with a unique experience. Recent innovations following on from Alcatel research are highlighted in Access Network Enhancements for the Delivery of Video Services. The third dimension of the universal access vision is based on Consolidation. Network consolidation is happening at various levels of the network, witnessed by the desire of operators to evolve their networks under themes such as fixed/mobile convergence and voice/data convergence. Voice/data convergence (Fixed Access Vision) using the newest generation of broadband loop carriers is fundamental to Alcatels view of how it can help operators to extend their offered services while controlling their capital and operational expenditures by means of network consolidation. The article WiMAX: From Fixed Wireless Access to Internet in the Pocket explains how WiMAX can be used as an enabler for fixed/mobile convergence. Furthermore, support for multiple radio technologies on a common infrastructure results in the consolidation of network equipment, leading to more costeffective solutions, as explained in Alcatel Evolium Multistandard Radio Access System. The fourth dimension of the universal access vision turns around Operational Excellence. Scaling the access network

in line with the proliferation in access technologies, the number of attached subscribers and the multiplication of service bundles, requires significant investments in service support systems. The tools offered in this respect for copper access networks are discussed in Optimizing DSL for Multimedia Services. Operational excellence is also a key driver for the future evolution of radio networks (4G Mobile). The aim is to realize service and application ubiquity, with a high degree of personalization and synchronization between the various appliances. This issue concludes with a real life network example which demonstrates how Alcatel is at the forefront in realizing the Universal Access Vision. This example covers the launch of Orange Intense (3G Network Powers Intense Services); it traces the Alcatel and Orange partnership from the pre-commercial phase to the commercial launch of Oranges 3G services offering. We hope that youll enjoy this issue, and that it will give you a valuable overview of the User-Centric Broadband world, with a special focus on the access part. Be ready for the rapidly approaching era of universal broadband access!

Michel Peruyero, Yves TJoens

Michel Peruyero is Executive Director in the Chief Technology Office of the Alcatel Mobile Communications Group, Vlizy, France. ([email protected]) Yves TJoens is Chief Technology Officer for the Alcatel Access Network Division. Prior to obtaining this position he acted as corporate strategy director for access, and ran the research group on access networking architectures. He is the author of multiple papers and actively contributed to the standardization of access networking in the areas of IP/Ethernet and the ATM access architecture. He is based in Antwerp, Belgium.

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93

STRATEGY WHITE PAPER

UNIVERSAL BROADBAND ACCESS

Ph. Lain, L. Le Gouriellec, J. De Vriendt

MAKING USER-CENTRIC BROADBAND IN ACCESS A REALITYA seamless combination of fixed, mobile and broadcast access offers users an always best connected experience.

Figure 1: Applications should travel with users wherever they are and whatever they do n entire range of new services emerged (e.g. mobile voice, Internet access) from a communication world that used to be Anywhere defined by simple fixed voice services. Else: Mobile Then the emergence of broadband enabled users to access all these new services more rapidly. Nevertheless, for Hot Zone users the promise of ubiquitous broadNomadic (WiFi, WDSL) band is far from being fulfilled. The proliferation of terminals (fixed phone, mobile phone, PC, personal digital Home assistant, etc) has been further comFixed (DSL, Eth., PON, plicated by the abundance of broadWDSL) band access options, including Digital Subscriber Line (DSL), cable, UniverMy My Practical Life My Clan/Tribe Office sal Mobile Telecommunications System Entertainment Toolset with me Fixed with me with me Convenience, Productivity (UMTS), Code Division Multiple (DSL, Eth., PON, WDSL) Access 2000 (CDMA2000), public My Profile with me Wireless Local Area Networks (WLAN) and satellite. These multiple access My Office technologies generate overlapping with me functionality with multiple accounts, My Profile & multiple subscriptions, multiple bills IM: Instant Messaging PON: Passive Optical Network VPN with me and multiple user names and passPTT: Push To Talk WDSL: Wireless DSL words. So, while broadband has opened up a new world with numerous appealing services, the delivery of these new and richer services Consumer Demands has come at the cost of greater The user-centric broadband experience is about the complexity and a fragmented user being able to use all the services to which he or experience linked to the various she has subscribed from any location, using any access technologies. device, even when moving from a location served by one To improve the users expeaccess technology to a location served by a different access rience, there is a move towards technology (see Figure 1). simplicity and convenience. The network should select the access solution that is most Here we review users needs convenient for the user and minimizes his or her costs. and describe some access soluTo fully meet the users expectations, these principles should tions that operators can deploy apply to all the applications he or she needs during a normal to make users lives easier by days activities. enabling them to access their Users should be able to access their services from anywhere applications via the best availat any time. Moreover, while running a given application, a user able network at the highest should be able to move from one place to another without possible data rate, all through experiencing any disruption. To achieve this, the new access a single subscription. network should support a minimum set of features and a minVoice & video Call/conference/IM/PTT Music/Video/TV Multicast/Broadcast VPN voice & video Call/IM/PTT/Net-meeting VPN Data: Email/SMS/MMS, Intra/Internet Email/SMS/MMS, Internet, Purchase Email/SMS/MMS Voice Calls/Chat Gaming Music

A

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MAKING USER-CENTRIC BROADBAND IN ACCESS A REALITY

Figure 2: Five services classes and their requirements

AP Hot Zone

AC Corporate Voice & Data VPN Multi/Unicast/Broadcast Video/TV/Music Combinational e.g. Multiplayer Gaming Calls & Conferencing Voice & Video & IM & PTT Inter/Intranet+email/MMS Leased Line QoS, Security Predictability, Availability Strict Multicast QoS Broadcast Capacity Interactivity QoS High Capacity Near or Real Time, Low Delay High Availability Best Effort No Impact

One or More Access Networks

Mobile

Fixed: DSL, Cable, etc.AC: Access Controller AP: Access Point

Access Network (3G, WiFi/WiMAX, Fixed DSL, Cable) Application

Requirements To Access Networks

imum capacity. Consequently, it is important to analyze the mandatory requirements that different applications place on an access network. Main types of service All applications ultimately fall into five service classes, as shown in Figure 2. Data services: Internet access and messaging These applications deal with Internet access, file downloading, and online usage of applications or services. They include all call services operated by Internet Service Providers (ISP), such as Skype, that use the Internet in a transparent way, as well as access to email, the Short Message Service (SMS) and the Multimedia Messaging Service (MMS). Conversational services: Carrier-grade voice/video calls and conferences This class of applications addresses peoples need to communicate in real-time or near real-time with one or more others, using voice, video or messaging. The key to such applications is the ability to provide continuous reachability over a variety of access technologies while the user is on the move. These services can be classified as follows:

Real-time voice and video calls and conferencing, whether based on circuit switching or Voice over Internet Protocol (VoIP). Fast handover is crucial to ensure a good user experience. An acceptable round-trip delay is also important in order to offer carrier-grade quality in all circumstances. Near-real-time rich call services, such as instant messaging, push to talk, push to view, see-what-I-see and conferencing tools. Video services: TV, video and music streaming Applications of this type address the need of users to access video services, such as TV and video on demand, and multimedia content, in most cases using a streaming mode. The access network must meet several criteria to support this type of service:

Push To Talk (PTT) A walkie-talkie like service that provides voice messaging to a closed user group at the touch of a button. PTT uses voice-over-packet techniques to minimize spectrum usage. PTT is one of the IP Multimedia Subsystem (IMS) services. Push To View (PTV) A service that allows images to be shared within a closed user group at the touch of a button. PTV is one of the IP Multimedia Subsystem (IMS) services.

Sufficient bandwidth to carry the required traffic. Quality of Service (QoS) and resource admission control to ensure a good user experience (low cell loss ratio, limited jitter, etc). It should be noted that in a mobile environment, the broadcast mode allows the same content to be distributed to95

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all users in the same coverage area, thereby compensating for the limited frequency availability. Gaming services This type of application involves many people interacting with one another via a central server. Access network requirements include: Good interactivity-oriented QoS (round trip delay, cell loss ratio, traffic priority). Rapid handover in the same way as real-time voice/video communications. Seamless handover of an ongoing multi-player gaming session is of paramount importance. A player involved in a game doesnt want to suffer any disruption while playing, or have to re-enter the game (at the risk of disturbing other players) when moving from place to place. Corporate VPN services: access to enterprise intranet/email This group of applications offers enterprise users exactly the same services as detailed above for residential users. The constraints to be addressed by the access networks include:

Access (HSDPA), or CDMA2000. Currently, the main applications used in such situations are voice calls, messaging and corporate VPN services. However, broadcast and gaming applications could soon become more important. The third situation for the user is full mobile usage, using any available mobile access network technologies, such as Enhanced Data rates for GSM Evolution (EDGE), UMTS / HSDPA and CDMA2000. Today voice is still the predominant service, followed by data messaging (SMS / MMS / email). However, there is a clear trend towards the increased use of data, video and gaming services.

Offer from the OperatorsOperators can provide user-centric broadband services to subscribers in many ways, the best solution being based on the operators current situation. Two main types of operator can be identified: vertically integrated operators controlling the different accesses (fixed, mobile, etc) and horizontally integrated operators offering services via roaming agreements or in close partnership with other operators. Vertically integrated operators are characterized by the fact that they control and offer converged services via the different accesses they control. Such operators can be further subdivided into: Incumbent operators that own both fixed and mobile networks and are becoming full service providers by integrating their fixed and mobile operations. They offer a mix of their own basic set of services together with a variety of additional rich services from partners. Fixed operators (competitive DSL, cable) can also take on the role of Mobile Virtual Network Operators (MVNO) or introduce wireless technology (WiFi, WiMAX) in their networks, enabling them to offer a similar (or the same) set of services as in the previous case. Mobile-only operators can extend their wireless access (coverage, speed) by deploying new wireless technologies, such

Voice and data Virtual Private Networks (VPN) must follow the employee wherever he or she goes. Thus all the access technologies that an employee might use in different situations have to interact to provide this feature. Security, QoS and performance levels must meet the stringent corporate requirements. Handover is mandatory. It should be rapid for established voice/video Figure 3: Typical user situations calls, but is less stringent for data sessions. Various user situations Three main types of user situation encountered are shown in Figure 3: fixed at home or in the office, nomadic in hot spots and hot zones, and mobile elsewhere. The first typical situation is fixed usage, either at home or in the office, using network technologies such as DSL, cable, satellite and fiber (Fiber To The Home, FTTH; Passive Optical Networks, PON; Ethernet) or fixed wireless access technologies, such as WiMAX, using any type of application, such as voice calls, Internet access, messaging, video and online gaming. The second situation is nomadic usage at hotels, airports or railway stations, making use of WiFi, WiMAX or mobile-oriented technologies, such as UMTS High Speed Downlink Packet96

Fiber, DSL, cable, fiber at the enterprise Fiber, DSL, cable, fiber at the enterprise

WiFi/DSL, cable, Sat at home

Internet

Corporate

AP

AC

Aggregation Network

WiFi hot spots WiMAX hot zone

BTS/Node B

BSC/RNC

2.5/3G RAN


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as WiFi and WiMAX. These operators will be limited in the bandwidth they can offer and possibly also in terms of coverage as they dont offer fixed high-speed access. To overcome this weakness, mobile-only operators are starting to offer DSL broadband services. All vertically integrated operators need roaming agreements with network access providers in regions where they dont own the access. These operators can also offer a single subscription, a single bill, a single directory and a single access portal. As horizontally integrated operators do not own different access technologies, they have to rely on (roaming) partners or run their services transparently over anothers network. Apart from the roaming cases, there will be a need for multiple subscriptions resulting in multiple bills and multiple service offers: Fixed operators can offer converged services via an application, such as the Alcatel Intelligent Mobile Redirect (IMR) solution, that directs calls to either a mobile or a fixed network, depending on the users location. However, it will be difficult to offer the same range of services as a vertically integrated full service provider. Nevertheless, evolution to the IP Multimedia Subsystem (IMS) will mean that simple roaming agreements will allow a fixed operator to offer all its services on any network, since IMS is common to fixed (Telecommunications and Internet converged Services and Protocols for Advanced Networking; TISPAN) and mobile (Third Generation Partnership Project; 3GPP) networks. Mobile operators can offer services by providing mobile services via fixed and mobile access, for example, using Unlicensed Mobile Access (UMA), with fixed broadband access used as a pure bit pipe. MVNOs own the service platform and the subscriber base, and are therefore similar to the mobile operators from a service perspective. ISPs and wireless ISPs taking on the role of application service provider may find it more difficult, unless they take on the role of an IMS provider without an access network.

The second solution, which is based on the Session Initiation Protocol (SIP), is IMR. This solution can be deployed by all operators and used by everyone, including large enterprises. IMR and UMA allow a user to be reached on one device, possibly using a single phone number, irrespective of where he or she is located [1]. Both solutions accomplish this by: Automatically selecting the most suitable access network (usually the one offering the cheapest tariff). This might be either a cellular access network or a WiFi / Bluetooth access network, which generally includes a broadband VoIP network. Rerouting incoming calls towards the appropriate access network.Table 1: Current solutions overviewSolution Control protocol LAN access technology Cellular access technology IMS support UMA UMA WiFi/Bluetooth GSM/GPRS/EDGE Yes IMR SIP WiFi/Bluetooth All (GSM, CDMA, etc) Yes

GPRS: General Packet Radio Service

Typical ImplementationsThree typical implementations will illustrate how operators can offer users an always best connected experience. Voice calls using various access networks As shown previously, the main requirement for a conversational service to different access networks is that the user should be reachable when on the move, with the voice VPN following the employee in the corporate case. In an enterprise, phones will combine WiFi, cellular connectivity and VoIP, while at home mobile phones will evolve towards Bluetooth or WiFi / cellular handsets. Two main solutions can be envisaged for making the seamless use of these dual-mode phones a reality: The first solution, based on UMA technology, allows real-time handover between access networks. However, it is mainly suitable for mobile operators (or possibly MVNOs); it can be used by residential users either at home or in public hot spots, or in combination with an (IP) Centrex solution.

Data services Mobile 3G networks offer significantly higher data rates than 2G networks. However, there is a trade-off between data rate and user mobility; a user who is traveling at high speed cannot expect the same high data rate as a user who is standing still. Recently, IP-based wireless technologies (in particular WiFi) have received a strong boost, providing relatively high data rates at low prices. They can complement mobile networks when necessary. This leads to the introduction of multiple access systems (cellular + IP based) within the same coverage area. Interworking between access technologies has already been demonstrated in 3GPP Release 6 with the work item for 3GPP WLAN interworking [1]. Multiple access systems mean new operator and user requirements; the user may wish to influence the selection of the access system based on such considerations as supported QoS, security level, mobility, price and coverage. On the other hand, the network operator might wish to influence access selection by setting policies. It is expected that customers using multiple access systems will require service continuity as they switch from one to another. This means that their sessions will be subjected to only minimal Access-aware interruption. In addition, the services service provided should be made access-aware The service is (e.g. choose video quality based on the adapted according available bandwidth) and homogeneous to the characteristics to enhance the user experience. of the access Mobility between access networks technology being (WLAN, WiMAX, UMTS, etc) could be used (e.g. video coordinated using the Mobile IP (MIP) quality based on protocol. This protocol reinforces the the available operatorcustomer relationship, bandwidth). enabling a mobile data service for users to be provided not only in the97

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operators own network but also in users enterprise networks and even in the access networks of other friendly network operators [2]. Video on mobile Mobile broadcasting is more than the simple extension of TV broadcasting to mobile terminals. It ranges from the delivery of live video content to customized information services using pushand-store mechanisms. Several technologies are competing for a place in the market for these services. They can be categorized into two main trends: Optimization of digital TV broadcast technologies to improve their performance in a mobile environment. Leveraging the complementary nature of fixed, cellular and broadcast technologies to benefit from their respective strengths. Terrestrial and satellite broadcasting networks are evolving by adapting their capabilities to the mobile environment with the development of the Digital Video Broadcast Handheld (DVB-H) and of the Satellite Digital Multimedia Broadcasting (S-DMB) standards. In the meantime, mobile service providers are starting to deliver streaming video on 2G/3G networks, with the objective of migrating towards the more efficient multicasting capabilities offered by the Multimedia Broadcast / Multicast Service (MBMS). A combination of these technologies is seen as the optimum model for the successful introduction of video on mobile by delivering content efficiently, and offering interactivity and personalization.

ConclusionToday, people want more than unrelated (i.e. standalone) broadband services. User-centric broadband means that customers share a unified experience using a single identity to obtain different services, without considering the access technology (fixed, mobile or broadcast), and without thinking about how to maintain the connection. User-centric broadband means network interoperability, but also interoperability of applications across a wide variety of devices. It enables people to use any device and always be connected to the most suitable network anytime and anywhere. The model changes from the view of killer applications delivered over a single infrastructure to one that embraces the demand for a customized user experience across multiple devices, networks and applications. Service providers will propose personalized services that recognize the unique needs of individuals. They will differentiate their offerings in a competitive marketplace with customized service bundles that can attract new consumers and corporate users, reduce churn and increase revenue. Alcatel provides communication solutions to telecommunication carriers, Internet service providers and enterprises for delivering voice, data and video applications to their customers and employees. Its leading position in fixed and mobile broadband networks, applications and services, will help partners and customers to build a user-centric broadband world.

References[1] Ph. Lain et al: Unbounded Mobility: Always Connected, Anywhere, Alcatel Technology White Paper, February 2005. [2] I. Gmez Vinagre et al: Mobile Broadcasting: Extending the Mobile Experience with Efficient Content Delivery, Alcatel Technology White Paper, January 2005.

Philippe Lain is Network Strategy Manager in the Alcatel Network Strategy Group, Paris, France. ([email protected])

Johan De Vriendt is Strategy Director NGN in the Alcatel Network Strategy Group, Antwerp, Belgium. ([email protected])

Louis Le Gouriellec is Networking Director in the Chief Technology Office of the Alcatel Mobile Communications Group, Vlizy, France. ([email protected])

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STRATEGY WHITE PAPER

ANY ACCESS

J-L.Hurel, J. Brouet, L. Le Gouriellec, M. Peruyero

UNIVERSAL BROADBAND ACCESS: GOING WIRELESS AND MOBILEAre the emerging broadband wireless and mobile technologies a threat or an opportunity? Will they compete or complement one another?

oing broadband wireless and mobile is not a question of if, but how and when? Be it with Universal Mobile Telecommunications System / High Speed Downlink Packet Access (UMTS/HSDPA), WiMAX, Code Division Multiple Access (CDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), UMTS Time Division Duplex (TDD), WiFi or mobile broadcast technologies, there is a market for it! Dont ask what the users would do with a higher bandwidth and improved Quality of Service (QoS)! Is there a need for mobile triple play? The answer is yes! Will many customers want to watch video clips on a small screen? Without doubt, yes! Users are ready to adopt and pay for services that are personalized, interactive, simple and carried over the best access. The radio access network is a masterpiece in the transport of ad hoc services and will demonstrate its flexibility to achieve the most stringent performanceto-cost ratio objectives. It offers multi-access provisioning, the highest data rates, the lowest latency and best QoS in the nomadic and mobile environFigure 1: Benefits of the ments.

G

All proposed services and solutions meet users needs: - Broadband must be accessible anywhere, in any situation: at home, at the office, outside and inside, on the pause and on the move. - Access to personal broadband services should be easy, whether fixed, nomadic or mobile. - Users want multimedia services and the largest possible bandwidth at attractive prices. Several criteria are crucial when selecting the right technology: - Optimization of coverage, throughput per user, capacity per site and per cell, mobility and nomadicity conditions. - High spectral efficiency solutions that optimize radio resources management, making it possible to increase traffic throughput. - Reliable handover, roaming and security. Access must be cost-effective and maximize use of the operators three major assets: subscriber base, base station sites and spectrum (licensed and unlicensed).

key access technologies

Driving Forces behind Broadband Wireless and MobileThe value-proposition offered by mobile and wireless operators is based on numerous multimedia services delivered over fixed or mobile networks, or the Internet. Alcatels aim is to provide these operators with all the business and technical tools they require to put the Internet in each pocket using the best broadband wireless technologies. A user-centric broadband world will be built using selected technologies; Alcatels technology-agnostic approach answers the key business, technical and strategic challenges. The key technologies are shown in Figure 1. The main driving forces for the success of broadband wireless and mobile are:

Speed/user

Very High 2-10 Mbit/s High 1-2 Mbit/s Medium 100-900 kbit/s

Broadband Wireless

FTTx xDSLBroadband Fixed: From DSL to FTTx

WiMAX WiFi TDD HCR

Broadband Mobile: From 3G to B3G

HSDPA UMTS TD-SCDMA EDGE

"Fixed"

"On the pause" Hot spots

"On the pause Always on" Hot zones Scattered coverage

"On the move" Global coverage

Mobility

3G: Third Generation B3G: Beyond Third Generation DSL: Digital Subscriber Line

EDGE: Enhanced Data rates for GSM Evolution HCR: High Chip Rate

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UNIVERSAL BROADBAND ACCESS: GOING WIRELESS AND MOBILE

The total cost of ownership at the access level must follow the general cost reduction trend, in line with devices and handsets, to ensure the widespread penetration of broadband services. To achieve this, various approaches are being used. High re-use of existing base station sites for rapid, low risk deployment. Flexible capacity growth and initial and additional investments that are closely aligned with the growth in capacity. Evolution to take advantage of new technologies in a futuresafe way. Alcatels radio access network solutions are based on three key pillars: 1 Moving from multi-standard to multi-access: A flexible, cost-effective base station architecture allows the deployment of not only GSM/EDGE and UMTS/HSDPA, but also WiMAX, TD-SCDMA, UMTS-TDD and satellite mobile broadcasting. 2 Cost optimization program every nine months to ensure the scalability needed to allow incremental investment in the infrastructure, hardware and software flexibility, and full backward compatibility to maximize the use of earlier investment. 3 Rapid introduction of new technologies via software upgrades. EDGE is being introduced via software activation; once UMTS is deployed, it will be possible to introduce HSDPA by upgrading the software. The same is true for the smart antennas solutions being introduced in base stations. Alcatels view is that a future radio access solution will be based on collaboration between various technologies to serve different market needs as efficiently as possible. Figure 2 shows the portfolio of solutions Alcatel is offering broadband mobile and wireless operators to meet their short- and mid-term objectives. Alcatels vision is based on various radio interfaces around a common network architecture, with full flexibility in the various building blocks, as depicted in Figure 3.

Coverage and the number of existing sites that can be reused to minimize deployment costs. Average and peak throughput per sector to evaluate the system capacity on the air interface and dimension the terrestrial interface that feeds the radio sites. Average and peak throughput per user, as this affects the types of service that can be offered to subscribers. The BWA technologies considered here are EDGE, UMTSFDD (Frequency Division Duplex) with HSDPA, UMTS-TDD with HSDPA, WiMAX and CDMA2000 1xE-DO.

Figure 2: Alcatel access technologies roadmap and evolution

TD-SCDMA CDMA 2000 UMTS FDD HSDPA HSDPA evolutions Convergence

Mobile

Nomadic UMTS TDD HCR Wireless DSL MC-CDMA 2004 WiMAX 802.162004 2005 Core Network Convergence 2006 WiMAX 802.16e Core & Radio Access + Service Bundling

Driving the convergence to provide truly multi-access broadbandMC-CDMA: Multi-Carrier CDMA

Figure 3: Towards a full multi-access platform

The Multi-access Platform GSM/EDGE, WCDMA, TD-SCDMA & WiMAX

Multi-standard cabinetS T U R M X U S T U R M X U S U T M R U X

Baseband Baseband Baseband

Multi-band RF Front-end Multi-standard Baseband Multi-standard Transceiver

Performance of Broadband Wireless TechnologiesThe technical characteristics of the various Broadband Wireless Access (BWA) solutions must be thoroughly assessed before one is chosen. Various radio performance indicators are needed as inputs to the economic assessment that identifies the optimum operator strategy:100

Multi-Standard & Multi-Access Base StationSUMU: Station Unit Mobile UMTS TRX: Transmitter/Receiver

Reconfigurable Radio Front-end & Baseband Processing using Software Defined Radio & IP TransportWCDMA: Wideband Code Division Multiple Access


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Overview of BWA standards Table 1 gives an overview of the parameters that influence radio performance. The frequency band has a major impact on the cell radius The higher the frequency band, the lower the range (cell radius), which is why high data rate technologies have a smaller maximum reach than that offered by GSM900 systems. The duplex mode defines the way in which bandwidth is shared between the downlink (base station to terminal) and the uplink (terminal to base station). It affects the system capacity and spectrum requirements. In FDD mode, the downlink and uplink use different frequency channels and are adapted to symmetric traffic. FDD requires paired spectrum allocation. In contrast, in TDD mode the uplink and downlink share the same frequency channel in time. This mode is suitable for asym-

Table 1: Main radio parameters for selected BWA systemsGSM-EDGE 2G (850/900/ 1800/1900 MHz) FDD 200 KHz UMTS-FDD (HSDPA) 3G (2.1 GHz) FDD 5 MHz DS+SS+AMC (QPSK/ 16QAM) CDMA UMTS-TDD (HSDPA) 3G+BWA TDD 5 MHz 10 MHz (BWA) DS+SS+AMC (QPSK/ 16QAM) TD-CDMA WiMAX CDMA 2000 (EV DO) 2G+3G+450 MHz FDD 1.25 MHz DS+SS+AMC (QPSK/8PSK/ 16QAM) CDMA

Frequency band Duplex mode Channel bandwidth

BWA (2.5/3.5GHz) TDD/FDD 1.25 to 20 MHz QFDM+AMC (QPSK/16QAM/ 64QAM) TD-OFDMA

Physical layer

AMC (GMSK/8PSK) TDMA 9 (traffic channel), 14 beacon channel 2x4.6 MHz

Access layer Frequency reuse Minimum spectrum

1

1

3 30 MHz (for 10 MHz channel)

1

2x5 MHz

1x5 MHz

2x1.25 MHz

AM: Amplitude Modulation QAM: Quadrature Amplitude Modulation GMSK: Gaussian Minimum Shift Keying

QPSK: Quaternary Phase Shift Keying PSK: Phase Shift Keying

Figure 4: Different multiple access modes

Power

Power and codes

200 KHz 600 KHz Time

Frequency

TDMA (GSM-EDGE)

5 MHz (UMTS FDD) 1.25 MHz (CDMA 2000) Time

Frequency

TD-CDMA (UMTS-TDD)

Power Power and codesUp lin k

10 to 15 MHz 5 MHz (UMTS FDD) 1.25 MHz (CDMA2000) Time Frequency Time 1.25 to 20 MHz

Frequency

CDMA (UMTS-FDD/CDMA2000)

TD-OFDMA (WiMAX)

Do

w

nl in

k

Do w

nl in

k

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Up

lin

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k


EDGE throughput can be optimized if EDGE carriers are metric traffic, since usually the ratio between uplink and downdeployed with higher frequency reuse (thanks to the reduction link is adjustable. TDD can be deployed in unpaired and in the level of interference). WiMAX has, by its nature, simipaired spectrum allocations. lar requirements to GSM/EDGE systems in terms of interferChannel bandwidth directly affects the throughput on the ence levels. However, adaptive antenna technology means that air interface. The greater the channel bandwidth, the higher WiMAX can be deployed with a frequency reuse of just three. the data rate, which is why WiMAX systems have much Table 1 shows the spectrum required for deploying a BWA soluhigher throughputs than others. tion, based on frequency reuse, channel bandwidth and The physical layer of any BWA systems is based on Adapduplex mode. tive Modulation and Coding (AMC) mechanisms. This enables the fluctuating propagation channel characteristics to be efficiently exploited by selecting higher level modulation schemes Radio throughputs of BWA technologies when possible to increase the throughput per sector. In addiThe results synthesized in Figure 5 assume that all the radio tion, the modulation technology affects the performance. network resources are being utilized; the comparisons were CDMA (UMTS and CDMA2000) use Direct Sequence Spread made using the same assumptions about the radio environments Spectrum (DSSS): narrowband signals are spread over a (e.g. same propagation conditions, same antenna height, larger bandwidth signal, which is more robust against interfersame indoor penetration requirements). The average throughence and has improved sensitivity (processing gain). puts can then be seen as the minimum achievable throughputs. GSM/EDGE and CDMA systems use single carrier modulation. In addition, a downlink / uplink ratio of 3:1 is assumed for TDD In contrast, WiMAX is based on Orthogonal Frequency Division systems (UMTS-TDD and WiMAX). Multiplexing (OFDM), which is a multiple carrier modulation In terms of throughput per sector, three performance system. The high data rate information flow is transmitted in groups can be derived: parallel on a higher number of orthogonal narrowband subcarriers (512, 1024 or 2048). OFDM offers the best performance 300 kbit/s: 2G technology (GSM/EDGE) can offer 320 kbit/s / complexity tradeoff for transmission bandwidths larger than per carrier on average 5 MHz, making it one of the main building blocks for fourth gen 700 kbit/s to 2 Mbit/s: 3G technologies enhanced with eration (4G) systems. UMTS/HSDPA or CDMA2000 1xEV-DO provide average data The multiple access scheme (see Figure 4) indicates how rates per sector of about 1 Mbit/s (from less than 1 Mbit/s for the available bandwidth is shared between users (which CDMA2000 1xEV-DO to around 2 Mbit/s for UMTS/HSDPA). impacts the throughput per user) and how the system could In these systems, the ratio between the average and peak be deployed (frequency reuse and average throughput per sector). In the case of GSM/EDGE using Time DiviFigure 5: Typical downlink throughputs sion Multiple Access (TDMA), the user data is divided between timeslots belonging to a given channel; the user WiMAX (10 MHz) data can be allocated to a maximum of WiMAX (5 MHz) four timeslots per TDMA frame; each timeslot can carry different user data. CDMA2000 EV-DO Average However, in UMTS-FDD and Peak CDMA2000 systems, which are based UMTS TDD (5 MHz) on CDMA, users share the whole sysThroughput tem bandwidth and are allocated difHSDPA FDD (5 MHz) per sector ferent codes and powers. The use of EDGE 900 (200 MHz) codes enables CDMA systems to operate with a high level of interference. 10 100 1000 10000 100000 Orthogonal Frequency Division Multiple Access (OFDMA) is used in Data rate [kbit/s] WiMAX systems. Frequency reuse defines the minimum number of frequency blocks WiMAX (10 MHz) that are required for cellular deployments in BWA systems. Indeed, since BWA systems use AMC, the throughput per sector depends on the level of interference created by the cells transmitting at the same frequency. In CDMA systems, a frequency reuse of 1 is common (only one paired frequency block is required to deploy a CDMA system). Of course, this generates a high level of interference across the cell. In the case of GSM/EDGE, a reuse of at least nine is required; the102

WiMAX (5 MHz) CDMA2000 EV-DO UMTS TDD (5 MHz) HSDPA FDD (5 MHz) EDGE 900 (200 MHz) 10 100 1000 10000 100000Average Peak Throughput per user

Data rate [kbit/s]


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rates is rather low because of the high level of interference across the cell resulting from a frequency reuse of 1. > 10 Mbit/s: WiMAX offers average data rates of around 15 Mbit/s, with peaks up to 22 Mbit/s. Considering the available data rates per subscriber, the various BWA options support Asymmetric Digital Subscriber Line (ADSL) like services at the following speeds: Up to 128 kbit/s for GSM/EDGE. Up to 512 bit/s for 3G technologies (data rate at the cell edge is lower). Up to several Mbit/s for WiMAX. Coverage and site reuse Coverage determines the number of sites that are required to serve the entire service area. It is thus of the utmost importance when considering the investment needed to introduce BWA. Figure 6 shows the cell ranges for dense urban and rural environments with the following constraints: Deep indoor penetration, which is essential for BWA systems. Minimum uplink data rate per user at cell edge of 64 kbit/s.

Figure 6: Typical range (uplink data rate 64 kbit/s at the cell edge)

WiMAX (RG) WiMAX (PCMCIA) CDMA2000 (2 GHz) UMTS TDD (3.5 GHz) UMTS TDD (2 GHz) HSDPA FDD (2 GHz) EDGE 1800 EDGE 900 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4Typical Range Dense Urban

Range [km]

WiMAX (RG) WiMAX (PCMCIA) CDMA2000 (2 GHz) UMTS TDD (3.5 GHz) UMTS TDD (2 GHz) HSDPA FDD (2 GHz) EDGE 1800 EDGE 900 0 1 2 3 4 5 6 7 8 9Typical Range Rural

Range [km]Figure 7: Performance metrics for BWA technologies

>

D. Renaudeau, D. Boettle, H. Steyaert: WiMAX: From Fixed Wireless Access to Internet in the Pocket, Alcatel Telecommunications Review, 2nd Quarter 2005, pp 144-149 (this issue).

2G Site Reuse Urban1

0,1

Two scenarios are analyzed for the Frequency WiMAX system. WiMAX PCMCIA correReuse sponds to Internet in the Pocket, the terminal being a PCMCIA card that can be plugged into a laptop or a Personal Digital Assistant (PDA). The WiMAX residential gateway corresponds to a deployment targeting DSL-like wireless with the terminal having an ADSL modem form factor, including a small embedded antenna, and hence capable Maximum of higher transmission powers. Throughput Figure 6 clearly shows that the per Sector higher the frequency, the lower the range. A 900 MHz GSM/EDGE system provides the best coverage; EDGE coverage is the same as GSM coverage. For frequency bands of around 2 GHz and above, the range is at least halved compared with EDGE at 900 MHz. However, the ranges cited here are maximum ranges for GSM; in practice, GSM/EDGE ranges are limited by their capacity (typ-

2G Site Reuse Rural0,01

EDGE HSDFA-FDD CDMA2000 WiMAX RG WiMAX PCMCIA Average Throughput per Sector ically 400 m in dense urban areas, 7 km in rural areas). Consequently, in dense urban areas, 2G sites can be used to deploy any BWA technology while providing complete coverage for BWA services. This is a key feature considering the difficulty of finding additional sites in urban areas.103

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Comparative view Figure 7 compares the performances of GSM/EDGE, UMTS-HSDPA, CDMA2000 and WiMAX; the following conclusions can be reached:

Figure 8: Rural area cases: What technology best meets the service requirements

Data peak rate512 kbit/s Data Centric 100% data 15% voiceW CDMA W

WiMAX@3500W W

GSM/EDGE enables BWA to be introduced smoothly at low cost: no addi256 kbit/s tional sites are required, thereby optimizing capital expenditure and minMarketing Offers imizing operating expenses. EDGE can be introduced using a simple 128 kbit/s software upgrade; Alcatels EvoliumTM Voice Centric hardware has been EDGE ready since 15% data 2001. Services requiring data rates of 100% voice up to 128 kbit/s can be introduced. 45 kbit/s UMTS/HSDPA technology to support more users and higher data rates for BWA services in urban areas. Alcatel EvoliumTM multi-standard base stations make optimum use of earlier 2G investments by reusing the same cabinet for both GSM and UMTS. Users receive data throughputs of up to 512 kbit/s. WiMAX is a real Internet in the Pocket BWA solution, offering high data rates per sector, and data rates in excess of 1 Mbit/s per user. Alternatively, WiMAX can be viewed as a very high capacity solution for low data rate user services, or as an overlay fixed wireless access (using WiMAX PCMCIA). The performance results outlined here are fed into the economic models used to select the most suitable technology based on the target market, the target area and the shortest return on investment period.

CDMA

W CDMA

W

W

CDMA

CDMA EDGE

EDGE CDMA

EDGE CDMA

CDMA@450CDMA CDMA EDGE EDGE CDMA EDGE CDMA

EDGE@900 2/km2 7/km2 13/km2 20/km2

User Density

The following results show that both groups of wireless technologies offer specific benefits that are needed to offer a universal wireless service in any situation (full mobile, nomadic, fixed), in any area (rural or urban), at different bitrates, and whatever the subscriber density. The overall finding is that none of these technologies can provide the optimum solution for all the scenarios, hence they should to be used to complement one another, taking the best features from each (see Figure 8). WiMAX, EDGE and CDMA450A as fixed wireless access technologies for rural areas These three wireless technologies were compared to assess how they perform economically in different density zones in a rural area while supporting the required voice + data capability. The results show that all three technologies can be used, taking full advantage of the benefits of each. However, each solution has its limitations: WiMAX is not yet suited to voice-oriented services, mainly for handset availability reasons. Moreover (at least in the short term), because of its mobility limitations it cannot support a full voice service. GSM/EDGE and CDMA hardly achieve the data capacity needed to support high-speed Internet access. Nevertheless, each solution has its advantages: CDMA 450 is the most economic answer in very low density rural areas thanks to its unrivalled geographical reach. It fully supports the voice service, while offering an acceptable data rate (comparable to the lowest class of fixed DSL). It could be deployed with a WiMAX implementation so that high bitrates can be offered where the user density exceeds between two and seven subscribers per square kilometer. EDGE and CDMA 450 are profitable in rural areas with medium to high population densities, with data rates limited to 128 kbit/s. It could be complemented by a WiMAX solution to provide higher data rates.

Key Broadband Wireless Technologies for Rural and Urban EnvironmentsTo help understand the positioning of the different solutions, two wireless technology groups are compared for both rural and urban areas: first a data-oriented group using WiMAX, and second a mobile-oriented group featuring EDGE, CDMA2000 1xEV-DO using 450 MHz in rural areas (CDMA450) and UMTS/HSDPA CDMA2000 1xEV-DO in urban areas. Two dimensions have been used to highlight the differences in profitability between the technologies: Variations in density: Four cases for rural fixed wireless access and three urban cases: dense urban, urban and suburban. Variations in data rate requirements corresponding to different marketing packages; all include both voice and data: - Rural case: Four data rates corresponding to two voice-centric marketing offers (45 and 128 kbit/s) and two data-centric offers (356 and 512 kbit/s). - Urban case: Three data rates corresponding to three well known segments: a full mobile offer up to 512 kbit/s; a nomadic / hot-zone offer up to 1 Mbit/s, and a fixed wireless offer up to 2 Mbit/s. Note that regular design rules and classical business case rules were used to quantify the equipment needed and the profitability for each (density + data rate) case.104


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WiMAX is the best answer for data rates of up to 512 Mbit/s. This is no surprise as it is a data-built-in wireless technology. It can be deployed in overlay mode on top of either EDGE or CDMA, thus offering future-safe evolution. Increased demand for voice and data services could be met either using more WiMAX + EDGE or CDMA density extension, or simply by increasing WiMAX density, using Voice over Internet Protocol (VoIP) to carry voice as soon as terminals become available. WiMAX, UMTS/HSDPA and CDMA2000 1XEV-DO wireless technologies in urban areas The two groups of wireless technologies were compared to assess how they perform economically in the different density zones of an urban area while supporting the required voice + broadband data capacity. The results (see Figure 9) show that all three technologies can be used, taking advantage of their particular benefits.Figure 9: Urban area cases: comparing service requirements

usage flexibility, thereby enabling the existing mobile infrastructure and frequency resources to be reused when adding mobile / moderate nomadic broadband data services. WiMAX appears to be the best broadband data technology for any operator thanks to its DSL-like capacity, in all data-oriented cases, as already observed in the rural case. Consequently, it is the natural complement to HSDPA or EV-DO for operators that want to address all the mobile, nomadic and fixed wireless segments. WiMAX can be used for fixed wireless DSL application in areas with limited copper outside plant, as well as to provide a nomadic / hot zone wireless broadband service with HSDPA or EV-DO to meet the need for full mobility.

ConclusionSeveral broadband wireless access technologies are available for different uses, providing different performances and suited to different geographies. In all cases, the aim is to offer the best access network for users when and where needed. Alcatel can help broadband and mobile service providers to choose the best mix of these technologies as WiMAX there is no one fits all solution; it is essential that the technologies should complement one another. Alcatel offers three main advantages:WiMAX HSDPA EV-DO

Data rate

WiMAX

DSL-like DATA rate Home or office Marketing Case

2 Mbit/s

WiMAX

WiMAX

High DATA rate Nomadic, indoor/outdoor

1 Mbit/s

WiMAX HSDPA EV-DO

WiMAX HSDPA EV-DO

Moderate DATA rate Full mobile

HSDPA/EV-DO 512 kbit/sHSDPA EV-DO HSDPA EV-DO HSDPA EV-DO

Suburban:100

Urban:250

Dense Urban:500

Density Subscribers/km2 Economically speaking, the results show that all the technologies have limitations: WiMAX is not yet ready for a full mobile offer, primarily because of a lack of suitable handsets. HSDPA and CDMA EV-DO both achieve only limited profitability when addressing nomadic hot zones. Using them to offer a combined mobile data / nomadic package could be problematic, as the larger number of sites needed would adversely affect the business case. Other drawbacks are that more equipment (and therefore investment) is needed as the data rate increases (e.g. 2 Mbit/s instead of 1 Mbit/s for nomadic use would dramatically affect the business case), and that the peak rate at the cell edges is only 128 kbit/s, compared with around 4 Mbit/s for WiMAX. Again, each solution has specific benefits, so they can be used to complement one another: UMTS-HSDPA and CDMA 1xEV-DO are definitely the best fit for full mobile services, and can support a healthy throughput of 512 kbit/s on top of regular voice. They also offer greater

Its leading position in fixed and mobile broadband networks, applications and services, particularly its worldwide leadership in DSL. Its future-proof radio access network solutions which enable major new technologies, such as HSDPA, to be deployed by upgrading the UMTS software. Its strong commitment to optimum nomadic usage and service ubiquity combining open technology assessment, strong partnerships and network integration for the various wireless access technologies, including WiFi, WiMAX, UMTS TDD and mobile broadcast technologies.

Jean-Louis Hurel was Product Marketing and Business Office Director in the Alcatel Mobile Radio Division until April 2005 and is now 2G Product Line Director in the same Division, Vlizy, France. ([email protected]) Jrme Brouet is Network Design Manager in the Alcatel Mobile Radio Division, Mobile Communications Group, Vlizy, France. ([email protected])

Louis Le Gouriellec is Networking Director in the Chief Technology Office of the Alcatel Mobile Communications Group, Vlizy, France. ([email protected]) Michel Peruyero is Executive Director in the Chief Technology Office of the Alcatel Mobile Communications Group, Vlizy, France. ([email protected])

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105

TECHNICAL PAPER

ANY ACCESS

B. Haberland, W. Koenig, A. Pascht, U. Weiss

SOFTWARE DEFINED RADIO: A PROMISING TECHNOLOGY FOR MULTI-STANDARD BASE STATIONSSDR is an important step towards offering every user at any location the best service, bandwidth and mobility, in line with Alcatels vision of a user-centric broadband world.

ireless systems are becoming more and more heterogeneous in terms of standards and the frequency bands they use. In the case of the Base Station Subsystem (BSS) and Radio Network Subsystem (RNS), the reusability of existing sites is particularly important when it comes to introducing a new radio standard because it has significant benefits for operators in terms of savings in both capital expenditure and operating expenses. Multi-standard multi-band solutions are essential to enable equipment suppliers to reduce the number of development cycles, thereby cutting R&D costs and shortening the Hot spot time-to-market. WLAN/WiMAX access point made Fewer variants publicly available mean much by a service lower mainteprovider. Refers to nance, manufaca single cell turing and modenvironment. ule improvement (cost reduction) Hot zone efforts. However, An assembly of all these advanseveral hot spots tages have to covering a larger compensate for area. Potentially the possibly supports multi-hop slightly higher connections. cost of Software Defined Radio (SDR) solutions compared with dedicated solutions. In beyond 3G systems, new air interfaces (e.g. WiMAX for hot spots and hot zones) and an extension of the multi-standard radio resource management procedures, are making SDR solutions ever more relevant for base station platforms. For the operator, SDR offers greater flexibility in the deployment of different106

W

standards and multiple frequency bands. For example, it can be used to rapidly introduce hot spots / hot zones reusing existing sites.

Basic Principles of Multi-Band/ Multi-Standard TransceiversA multi-band transceiver (TRX) is a radio front-end that can be operated in a number of frequency bands. This is interesting in conjunction with UMTS Frequency Division Duplexing (FDD), whereImplemented multi-band front-end demonstrator in operation with signal source, analyzer and control environment

Technical MotivationAlcatels SDR technologies are focusing on multi-band, multi-standard solutions. There is a differentiation between: Multi-band, single standard: - 1.8/2.1/2.6 GHz: Universal Mobile Telecommunications System (UMTS) R99. - 2.5/3.5 GHz: WiMAX according to the IEEE 802.16e standard. Multi-standard within one frequency band: - 2.1 GHz: UMTS R99, High Speed Downlink Packet Access (HSDPA), HSDPA enhancements, High Speed Uplink Packet Access (HSUPA) and the introduction of Orthogonal Frequency Division Multiplex (OFDM) in Third Generation (3G) systems. Multi-band, multi-standard: - 1.8/2.1/2.6 GHz: UMTS R99, HSDPA evolution, 3G OFDM. - 1.8/2.1/2.6 GHz / 3.5 GHz: UMTS R99, HSDPA evolution, 3G OFDM, WiMAX.

the standard already defines a set of operating bands. An Alcatel research project has successfully developed a first demonstration model of a Multi-Band Front-End (MBFE) operating in selected In addition, there is a work item in the frequency bands (see Table 1). Third Generation Partnership Project The frequency bands can easily be (3GPP) for UMTS900 that will pose addi- changed without modifying the hardtional challenges for SDR technology. ware, giving network operators considerable flexibility not only Table 1: Selected frequency bands for MBFE implementation when introducing new frequency Operating Band Receive Frequency Transmit Frequency bands, but also I 1920 1980 MHz 2110 2170 MHz for subsequent III 1710 1785 MHz 1805 1880 MHz network reconIV 1710 1755 MHz 2110 2155 MHz figuration and Extension Band 2500 2570 MHz 2620 2690 MHz optimization.


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SOFTWARE DEFINED RADIO: A PROMISING TECHNOLOGY FOR MULTI-STANDARD BASE STATIONS

Figure 1: Overall architecture of the MBFE

MBFE

LNA

Receiver Front-End

To BB processing

To/from O&M

ACE

ControlTo/from local control

Power Amplifier

Transmitter Front-End

From BB processing

BB: BaseBand

O&M: Operations and Maintenance

Figure 2: Implementation of (a) transmitter front-end, and (b) receiver front-end

a)

Transmit Front-EndLPF Gain Imbalance Compensation Gain Imbalance Compensation Offset Compensation +HBF +HBF A Offset Compensation Delay Compensation + Input Selection D

Clipping

BTI (I/Q) Debug

0+Phi 90+Phi NCO 0 90 +

LO 0 LPF 90 +

VGA PA

+HBF +HBF DAC

D

A

DFE AFE: Analog Front-End BTI(I/Q): Baseband to Transmitter Interface, delivering I and Q data DAC: DigitalAnalog Converter DFE: Digital Front-End HBF: Half Band Filter

AFE

LPF: Low Pass Filter PA: Power Amplifier Phi: Angle (for I/Q Phase Imbalance Compensation) VGA: Variable Gain Amplifier

mode or low IF mode, depending on the frequency of the Numerical Control Oscillator (NCO) in the digital front-end. When the NCO is set to 0 (zero IF mode), the carrier is located around frequency zero in the baseband (Figure 3a, left side) and therefore only a single carrier can be treated in this case. After conversion (mixing) to Radio Frequency (RF) (Figure 3a, right side), in the RF band the carrier then appears symmetrically to the Local Oscillator (LO) frequency set in the analog front-end section (see Figure 3a). In preparation for multi-carrier usage, the carrier can also be separated from the center frequency at a low IF, determined by the NCO frequency (see Figure 3b, left side). In this case, the carrier in the RF band (see Figure 3b, right side) appears to the left or right of the LO frequency. Emissions caused by imperfections in the analog In-phase and Quadrature (IQ) modulator (image and LO leakage) have to be eliminated (i.e. compensated). The extension of the MBFE to a multistandard base station covering UMTS FDD / HSDPA and WiMAX introduces new requirements. The multi-standard, multiband transmitter/receiver needs to handle additional frequency bands and an enlarged bandwidth of 20 MHz, as well as to meet more stringent performance requirements resulting from the need for WiMAX to support OFDM signals. Enabling components Many of the components used to build an MBFE are operated at the edge of what is feasible today. In some areas this will entail significant improvements and developments by the component manufacturers: Mixers: Highly linear IQ (de)modulators working over a wide frequency range are needed to implement the direct-conversion architecture. The first products are just appearing on the market. As part of a nationally funded research project, Alcatel and its partners Lucent and Infineon, have specified and manufactured early samples that meet the requirements. Synthesizer: Wideband synthesizers covering the required frequency range are not yet available. Special samples have been developed for the demonstrator. Converters: Commercial digital-analog and analog-digital converters capable of handling arbitrary carriers inside one band are available. Power amplifier: Wideband applications are impossible using conventional107

b)

Receive Front-EndBuffer LPF/AAF Data Format Adaptation Delay Compensation DC-Offset Correction Output Selection D CIC+ RCC+ Digital Gain Control A VGA LO 0 90 Buffer LPF/AAF A D IQ Imbalance Correction Carrier Selection

Baseband (I/Q) Data Logger

LAN

CIC+ RCC+

AFE AAF: Anti-Aliasing Filter ADC: AnalogDigital Conversion

ADC

DFE CIC: Cascaded Integrator-Comb filter RRC: Root Raised Cosine filter

Architecture of a multi-band transceiver Figure 1 depicts the modules deployed [1] in the MBFE, each of which must meet much more stringent requirements than those for a single-band approach. The power amplifier (for the selected bands) has to operate over a wide frequency range from 1800 to 2700 MHz. The Antenna Coupling Equipment (ACE) selects the required bands (to and from the antenna) and separates the corre-

sponding transmit (TX) and receive (RX) sections (duplexer). The Low Noise Amplifier (LNA) performs the initial amplification of the received signals. The entire operation of the MBFE is managed by the control module. The transmit and receive front-ends are both implemented using a direct conversion architecture (see Figure 2). The transmit front-end can be (re-)configured for two different modes of operation: zero Intermediate Frequency (IF)

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high power devices. However, new technologies (e.g. GaN) are emerging, but so far the achievable power is limited. Multi-band duplexers: Only dual-band duplexers are currently available. Today, the multi-band duplexer is a limiting factor because of its size and price. However, new technologies, like ceramic multi-mode filters, will help to reduce the size considerably. Pre-compensation of dirty RF Wherever analog components are used, it is essential to take account of their imperfections that affect the overall behavior. Many of these imperfections can be compensated using digital pre-processing. Image suppression and LO leakage suppression in the transmitter When operating in low IF mode to meet the spectrum emission mask requirements, the image and LO leakage have to be carefully suppressed. The image is a result of gain and phase imbalances in the I and Q (in phase and quadrature) branches of the analog IQ modulator, and can therefore be compensated by setting the corresponding gain and phase values appropriately in the digital part of these branches. LO leakage results from unpredicted DC offsets in the I and Q paths. In this case, compensation can be achieved by adding the inverse of the DC offset in the digital domain of each path. The values for the compensation parameters are determined by analyzing the analog output signal with the help of a feedback loop.

Figure 3: Spectrum of direct upconversion (a) from zero IF, and (b) from low IFa) possible frequency channel positions wanted channel (rest of) LO image

f=0b) possible frequency channel positions wanted channel (rest of) LO image

fRF = fLO

wanted channel

f=0

fRFC = fLO be driven to the nonlinear part of its transfer characteristic, leading to an additional improvement in efficiency. To adjust the pre-distortion parameters adaptively, the output signal of the power amplifier has to be compared with the input signal of the pre-distortion [2]. Figure 5 shows the spectra of a one- and a four-carrier signal with and without digital pre-distortion. Lab test results In the receive chain, with regard to IQ demodulation and analog/digital conversion, it has been proven that the reference sensitivity level can be achieved over all the bands [1]. The current MBFE lab demonstrator comprises up-conversion, including all the reconfiguration and compensation mechanisms plus the wideband power amplifier driver stages. In zero IF mode operation, the specifications can be met across all bands. In low IF mode operation, the compensation mechanisms for image and LO suppression are working well to meet all the requirements, including the spectrum emission mask, which is the most challenging in this case (see Figure 6).

Normalized Signal Magnitude

Peak-to-average reduction This enables the power amplifier to be operated in a more efficient region. Because of the Quaternary Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM) scheme used in Wideband Code Division Multiple Access (WCDMA) and OFDM systems, the generated multi-carrier signal can feature a high peak-to-average power ratio of more than 10 dB. Without additional measures, the power amplifier would have to be operated with a high back-off from its 1 dB compression point in order to avoid large inter-modulation products. The peak-to-average reduction shown in Figure 4 enables the peaks to be reduced, leading to a peak-toaverage ratio of around 5 dB. The peak-toFigure 4: Peak power reduction average reduction must not generate 3GPP Test Model 3 with 32 Dedicated Physical Channels spectral components outside the Original Signal channel and the Signal with Reduced Peak Power 0.6 error vector magnitude of the result0.5 ing signal must stay within the 0.4 3GPP specification.0.3 0.2 0.1 0 8.4

8.45

8.5

8.55

8.6

8.65

8.7

8.75

8.8

Samples in Time Domain

Power amplifier linearization The signal data is pre-distorted with a nonlinear transfer characteristic inverse to the nonlinear transfer characteristic of the power amplifier. Consequently, the power amplifier can

Architecture of a MultiStandard Baseband PlatformA multi-standard base station consists of a universal hardware platform that can be configured for a specific air interface by downloading the appropriate functional software. This should be possible during operation without any downtime of the base station. The functionality of the downloaded software components ranges from protocol stacks to physical layer processing algorithms.

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A multi-standard baseband platform must fit with the requirements of the applications to be supported (radio standards, operating modes) and has to dynamically support varying traffic mixes. Compared with conventional solutions, clear advantages can be obtained in terms of more efficient use of the existing hardware resources and the attainable Quality of Service (QoS). High granularity is needed for the resources allocated to downlink and uplink signal processing. This requires architectural enhancements and intelligent and dynamic hardware resource management. A number of Digital Signal Processors (DSP) and hardware accelerator blocks are used for high bitrate and high volume data processing, as required for bit stream oriented functions. These elements are interconnected via a high speed data and control bus, and supervised by a control system (general purpose processor) (see Figure 7). SDR baseband software library A software library provides the signal processing building blocks needed to generate standard specific processing chains

Figure 5: Spectra of (top) a one-carrier and (bottom) a four-carrier signal (red) without and (blue) with pre-distortion.

Spectral Power Density (dBm/Hz)

20 15 10 5 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -552.120 2.125 2.130 2.135 2.140 2.145 2.150 2.155 2.160

Frequency (GHz)Spectral Power Density (dBm/Hz)20 10 0 -10 -20 -30 -40 -50

High granularity Refers to the degree of flexibility regarding the allocation of software tasks to processing elements like DSPs and FPGAs. In the context of re-configuration and load-sharing between different air interface standards it defines how finely the available processing performance can be split and assigned to different air interface functions.

Frequency (GHz)

Figure 6: Direct conversion operated in low IF mode (a) without compensation and (b) with compensation

a)

b)

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109


for downloading the downlink and uplink radio functionality to the processing elements, as required by the actual configuration. A suitable real-time operating system on the DSP level provides low layer functions to operate the hardware elements, for example, task management and scheduling. Resource and load management functions are realized using a hierarchical approach from the control system. Before the runtime software is downloaded to the processing elements it is parameterized and linked together according to the required functionality. A scheduler in the DSP then calls the processing blocks in the appropriate way. The processing chains (UMTS or WiMAX entity, etc) can be composed and configured from the dedicated part, the common part and the common algo-

Figure 7: Baseband hardware architecture rithm part of the system library, depending on the Controller Downlink/Uplink required air interData/Control bus face protocol ... (Figure 8). Dedicated system libraries provide the unique ... DSP DSP DSP FPGA FPGA functions for a specific air interface environment, FPGA: Field Programmable Gate Array defined by the given standard (e.g. transport block concatenation, match the funcinterleaving, radio frame segmentation). tionality of a parFast Fourier Common system libraries consist of sys- ticular standard. Transform (FFT) tem functions that are common to different Functions to be Computationally efficient algorithm air interfaces, which may need to be config- considered here for performing a ured by setting suitable parameters to include, for examcomplete discrete ple, cyclic redunFourier transform, dancy checking, i.e. a transform of a spreading, moduFigure 8: Hierarchical SDR library concept for baseband signal processing signal from the time lation and power domain into the control. UMTS WiMax MAC Scrambling Channel EST. scheduling IOTA frequency domain. Common algorithm libraries generally consist of basic functions that are widely used in the WiMax Dedicated OFDM HSDPA UMTS WiMax Entity scientific and telecom fields, such as filterSystem part 3G Library Library Library ing functions, complex/real Fast Fourier Transform (FFT) functions and vector Spreading, maths functions. Turbo Code, The application of a hierarchical SDR library concept has the potential to proCommon vide cost-effective solutions not only for System part software development, but also with inc. Parameterization Common Filtering respect to the memory required to store UMTS Library Functions Entity the huge volume of software codes. However, further studies and evaluations are Common necessary to prove the practicality of this Algorithm part approach [3]. inc. Parameterization DSPLibrary

Figure 9: SDR will merge todays separate implementations into a single future-proof module

Impact of SDR Technologies on the Node B Product PortfolioAlcatel base station Today dedicated solutions are available for different standards (see Figure 9). SDR technologies will enable the processing units to become more flexible in their treatment of different standards and frequency bands, thereby minimizing the number of hardware variants. In addition, it allows dynamic reconfiguration and parallel operation of different standards on the same platform at the same time. Thus it improves utilization of the processing power and therefore the overall system performance. It is clear that multi-standard O&M and transport termination solutions are needed for the Station Unit Module Universal (SUMU). These are realized by software. The introduction of IP transport makes it easier to share the Iub transport

BBMA BBMC SUMU NEMO

TEU ANRU Twin/TEUC ANRU WiMAX

SDR MSBB

SDR MSBB

Transport

BasebandPlatform

Transceiver Front-ends

ANRU: Antenna Network and Receiver UMTS BBMA: BaseBand Module revision A BBMC: BaseBand Module revision C

NEMO: Network and Modem MSBB: Multi-Standard BaseBand TEU: Transmitter Equipment UMTS

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resources than was the case with the Asynchronous Transfer Mode (ATM). Baseband processing is done primarily with programmable software devices, such as DSPs and hardware accelerators (e.g. field programmable gate arrays). This is an opportunity to introduce multistandard solutions. Shifting most of the complexity of the transceiver architecture (e.g. TEU; ANRU) to the digital part, enables operation in different bands and to different standards. This also has a positive effect on costs, because the price of digital processing components is approximately halving every year, whereas the prices for analog RF components are declining at no more than 10% per year. Evolutionary phases Different evolutionary phases with increasing complexity and flexibility for the operator ca

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