Electronica

Application of Fiber-Optic Techniques in the Transport and Access Transmission Networks of Mobile Systems
Dr.Attila Hilt
NPO, Network Planning and Optimization, Nokia Siemens Networks Kft., H-1092 Köztelek utca 6., Budapest, Hungary, attila.hilt@nsn.com
Abstract — fixed access networks widely employ fiber-optical techniques due to the extremely wide bandwidth offered to subscribers. In therecent years enormous increase of user data is visible in mobile systems too. Therefore the importance of fiberoptical techniques within the fixed transmission/transport part of mobile systems is inevitably increasing. This paper summarizes a few reasons and gives examples why and how fiber-optic techniques are employed efficiently in 2G networks. Index Terms — mobile networks, GSM, accesstransmission, transport, SDH, IP, mobile data, EDGE deployment, modernization, network upgrade

László Pozsonyi
NPO, Network Planning and Optimization, Nokia Siemens Networks, A-1030 Guglgasse 15., Wien, Austria, laszlo.pozsonyi@nsn.com the possibility of simultaneous optimization [2-5]. GSM network modernization aspects are presented with special emphasis on the application of fiber-optical techniquesin the fixed access transmission (TRS) and transport parts of second generation (2G) mobile systems. The paper shows some examples for the modernization of the 2G network elements (NE) in order to enable higher data rates in the existing GSM networks.

I. INTRODUCTION
IGITAL mobile telephony systems have been originally developed for circuit switched (CS) voice traffic. Continuously increasingdemand for mobile data services such as mobile Internet access resulted in an evergreen development and modernization of the initially pure circuit switched digital mobile networks towards the packet switched (PS) domain. Such services like mobile Internet, video streaming, gaming, navigation, banking, or mobile television (TV) require efficient networks that can provide very high user data rates.Fig.1 demonstrates the trend of enormous increase of user data rates in wireless systems in the last decade [1]. As a comparison wireline techniques are also shown on the chart. In Europe nowadays, the very first digital mobile networks (NW) are in operation for already two decades. Therefore in the past years a continuous upgrade and modernization of mobile networks were visible in terms of bothhardware (HW) and software (SW) of the existing components. In order to support higher and higher user data rates, major technology steps were the introduction of GPRS and EDGE in 2G, as well as launching 3G or UMTS, WiMax and recently LTE services. In this paper the main focus is on GSM networks, that are part of the above mentioned wireless/wireline access field. Modernization and optimizationof actual GSM networks give a continuous job for both network operators and equipment vendors. Modernization of mobile networks inherently offers

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Fig.1.

Increasing data in rates in fixed and mobile services

II. MOBILE SYSTEMS: ARCHITECTURE AND INCREASING ROLE OF FIBER OPTIC TECHNIQUES The role of fiber-optic techniques in the fixed part of mobile access networks is continuouslyincreasing. One main reason is already mentioned in the introduction, namely the continuously increasing amount of subscribers’ data. Microwave (MW) radio links and copper-based leased lines (LL) are extensively used in mobile access and transport networks (Fig.2.). However, the offered bandwidths of MW and LL are limited due to several technical and financial reasons, such as

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available radio spectrum, bandwidth, interference, hop distance, radio frequency or leased line fees and installation costs, etc. (Fig.2.). Recent trend is therefore to further extend the fiber-optic techniques from the BackBone/Transport part towards the Access Network. MW and LL technologies are more and more moving to the last mile of the access networks.
Access Network,...