Performance evaluation of packet switched services in UMTS

ABSTRACT I n order to deal with the increasing demands for high bit rate data services the Universal Mobile Telecommunications System (UMTS) has been introduced as a 3rd Generation (3G) system for mobile communication. With the goal to achieve high spectrum efficiency and differentiated Quality of Service (QoS) provisioning, UMTS traversed several evolutionary steps. From Release 99 to Release 7 of the 3rd Generation Partnership Project (3GPP) specifications numerous features have been added and have been extended. Especially new transport channels like the High Speed Downlink Shared Channel (HS-DSCH) as part of the High Speed Downlink Packet Access (HSDPA) significantly improved the performance for Packet Switched (PS) services. At the time of the introduction of UMTS in 2002 the Release 99 systems only reached a relatively low maximum data rate of less than 400 kbit/s. With the Release 5 HS-DSCH, deployed in Germany since 2007, data rates of up to 3.6 Mbit/s are offered. In certain areas an even higher theoretical throughput of 7.2 Mbit/s was made available. The maximum theoretical Release 5 throughput which is upper bounded to 14.4 Mbit/s was planned to be useable in Germany in 2010. Further enhancements as studied within this thesis are introduced in later releases. This thesis gives a comprehensive overview of UMTS with respect to its possibilities for the provision of PS services. The central question this thesis gives answers to is in how far the individual release of UMTS improve the ability to support mobile Internet services. Based on both link-level as well as system-level simulation the performance of the available options, i. e. Release 99 without HSDPA and the various HSDPA releases, are quantitatively compared. By referring to analytical models or related empirical work the results are being validated. Furthermore, the acquired results are benchmarked with the performance of Mobile Worldwide Interoperability for Microwave Access (WiMAX), another state-of-the-art system. With these comparisons conclusions about the possibilities and limitations of third generation mobile networks are given. Within the evaluations special focus is being put on the HSDPA as the most promising technology for the delivery of PS services. In this context in-depth analyses of the most important features, i. e. Adaptive Modulation and Coding (AMC), Hybrid ARQ (HARQ) and fast scheduling, are performed. For vendor specific algorithms, e. g. receiver algorithms, scheduling algorithms or HARQ schemes, comparative analyses in terms of complexity and achievable performance are made. By presenting the release specific options and their performance, the system capacity and efficiency, the technical limitations and drawbacks as well as possibilities for optimization and improvement, an audience including operators, vendors, interested users and mainly researchers is addressed.