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Load Sharing in Multi-Standard Heterogeneous Communication Systems

General Topic

GSM and UMTS mobile communication networks exist concurrently and therefore create a heterogeneous mobile environment. Since radio resources and mobile communication infrastructure are costly, the need for more intelligent mechanisms to balance the load between the two systems arises. Sharing the load between the multiple systems allows for a better utilization of the radio resource as well as the installed Radio Access Network (RAN) infrastructures. Thus the cost per call including installation, operation and maintenance costs can be reduced. This is, among others, due to the exploitation of the multiplexing gain of the combined system compared to disjunct systems. Additional gains can be achieved if the specifics of the different radio technologies are taken into account. An obvious load balancing strategy for co-located cells would be to move voice calls with poor radio conditions in UMTS towards GSM. A better load sharing strategy could be achieved by including and intelligently combining additional influencing factors like utilization, service type or location information.

Company

In 2003 I worked for six months for Lucent Technologies (today: Alcatel-Lucent) in Nuremberg (Bavaria) at the Wireless Advanced Technologies Lab. This work was connected to my diploma thesis that has been supervised by Prof. Dr.-Ing. Andreas Mitschele-Thiel. At that time the areas of expertise of the Wireless Advanced Technologies Lab were the development and standardization of new technologies for infrastructure based mobile communication systems — especially the evolution of 3G systems.

Task

My task was to develop and test a load sharing algorithm for a combined GSM/UMTS communication system. The algorithm should be easy implementable in a real system and it should take care for several different influencing factors. The C++ based system level simulation tool STEAM (Simulation Tool for the Evaluation of Algorithms in Mobile Networks) of Lucent Technologies was available for the simulative investigation of the algorithm. I had to adapt and extend the necessary functions of the STEAM simulation tool to make possible a common management of GSM and UMTS connections and to include my load sharing algorithm.

Gained Experience

I have gathered experience in the architecture and radio resource management principles of GSM and UMTS based mobile communication systems. During the development of the load sharing algorithm I have gathered and combined comprehensive theoretical knowledge of load sharing algorithms, load models and quality of service mechanisms for heterogeneous systems. Because of the programming work for the adaptation of the STEAM simulator I have increased my C++ programming skills. I also gathered knowledge in the usage of the MATLAB environment by programming evaluation scripts for visualizing the simulation results. Due to the multi-national team at the Wireless Advanced Technologies Lab I have experience with international working environments.
Two scientific papers have been the direct result of my diploma thesis. The paper “Force-based Load Balancing in Co-located UMTS/GSM Networks” has been cited many times because it described one of the first working algorithms for the purpose of advanced load sharing between 2G and 3G mobile communication systems. Please refer to this Dagstuhl research seminar presentation and to IEEE for more information about the algorithm. Please see this link for legal notices.