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University: Hamburg University of Technology
Prof. Dr.-Ing. Andreas Timm-Giel  
Department: Institute of Communication Networks


Title: Performance analysis of Network Virtualization and Sharing for LTE Advanced

ITU study (2006) on spectrum requirements for mobile communications shows that the required spectrum until 2020 will be up to 1280-1720 MHz while the available spectrum today in Germany is only 612 MHz (May 2010). Since spectrum is scarce resource and LTE advanced could support 100 MHz bandwidth aggregation, most of the Mobile Network Operators (MNOs) don't have enough spectrums supporting the LTE advanced optimally. Some small MNOs even don't have spectrum available at all. Nevertheless, network virtualization and sharing provides an impressive way toward to overcome this obstacle. Network virtualization allows that multiple MNOs share their spectrum and infrastructure which could reduce the CAPEX and OPEX.

In case of network sharing, several MNOs will share the radio and infrastructure resources. As a result, the controlling algorithm for sharing should be investigated and evaluated. Different approaches from "fully split" to "fully unshared" for resources sharing at eNB level among MNOs are proposed. "Fully shared" means all the resources could be shared by all the MNOs. There are no resources reserved for specific MNOs. Inversely, "fully split" makes a strict reservation among MNOs. A compromise between "fully split" and "fully shared" has been made is called "Partial reservation" which allows to reserve certain amount of resources for each MNO while the rest could be shared by all MNOs. The reserved ratio for each MNO could be different from others.

The goal of the thesis is to implement a simplified LTE Advanced network model. The implementation should include traffic generators, mobility model, radio interface as well as MAC scheduling algorithms. Afterwards, by applying different DL/UL traffic settings, the performance for different capacity sharing schemes will be investigated. Finally, conclusions should be made and a guideline should be proposed.


Title: Transport Network Sharing for LTE and HSPA/UMTS systems

High-Speed Downlink Packet Access (HSDPA) and High-Speed Uplink Packet Access (HSUPA) together are called “High-Speed Packet Access" (HSPA). HSDPA is an enhanced 3G telecommunication protocol which was introduced as part of the 3rd Generation Partnership Project (3GPP) Release 5 in March 2002 while HSUPA became part of 3GPP Release 6 with the first specification version in December 2004. HSPA greatly improves the user experience by increase the peak data rate up to 14 Mbps in downlink and 5.8 Mbps in uplink in 3GPP Release 6. With a series of crucial technologies, such as 64 Quadrature Amplitude Modulation (64QAM), Multi-Input and Multi-Output (MIMO) and Dual Cell HSDPA (DC HSDPA), higher data rates could be reached by further HSPA evolution known as HSPA+. LTE Advanced will be standardized in the 3GPP specification Release 10 and will be designed to meet the 4G requirements as defined by ITU. A series of new thoughts are proposed by ITU including Multi-antenna solutions, Coordinated Multipoint, Home eNB, Relaying and so on. In comparison to current 3G mobile communication standards, LTE Advanced could dramatically improve the spectrum efficiency, increase system capacity and user Quality of Experience. The global 3G subscribers have reached 1 billion by 2010 and LTE system is expected to be widely commercially used from the year 2012. It is expected that during the next few years, LTE will gradually replace the 3G mobile communication systems. As a result, LTE and UMTS systems will coexist in this decade. The LTE system has a pure IP based architecture (Ethernet as layer 2). However, the current 3G transport networks rely on ATM/SDH technology. Most operators are migrating the ATM/SDH transport networks to IP based to meet the requirements of the increasing demands of 3G subscribers and incoming 4G networks. Consequently, how to solve the sharing of the transport networks between 3G and 4G, and simultaneously guarantee the QoS requirements by mapping different traffic classes/priorities to IP and Ethernet are increasingly interested by the mobile operators. In this work, a HSPA system model has to be implemented based on current LTE model in OPNET© simulator. Besides, a sharing mechanism should be designed to deal and optimize the system performance. Generally, there are two approaches proposed. The first idea is purely based on transport network sharing. The HSPA and LTE traffics are separated with each other. A hypervisor is responsible for controlling the transport bandwidth (by dynamically changing the Ethernet shaping rates) sharing between HSPA and LTE. The second proposal is to aggregate all the traffic from HSPA and LTE in an aggregation module. The traffics are forwarded over the transport network based on their traffic classes, e.g. Weighted Fair Queueing. Nevertheless, the traffic mapping can be different for HSPA and LTE systems to give them different priorities.


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