Interference Analysis of WCDMA and OFDMA femtocells

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Dr. Jeney Gábor
Department of Networked Systems and Services

The mobile service providers share is increasingly considerable in time on the telecommunication market. New services appearing and these services need huge bandwidth and quality of service parameters (QoS) that previously only wired technology could provide. To ensure the requirements above we can use femtocell system integrated to our mobile architecture.

The femtocell is a low-range, low power emission base station that the subscriber can use it to provide coverage and transmission speed at home or at the office. With this solution, a much higher transmission speeds and better QoS parameters can be achieve, rather than using only the macro base station at the street. The femtocell base station transports the subscriber traffic on wired technologies, causes lower load to the macrocell base station.

At the same time code division, which is used in 3G systems, is not using frequency or time sharing, the full bandwidth can be used by all of the users at the same time. The users can be distinguish from each other with their unique code. But if because they using the same bandwidth, they will that occurs interference to the others with their uplink or downlink transmission. It is also valid for the connection of macro and femtocell base station. Some of the interferences (generated by the femtocell) are following Levy distribution. The Levy distribution is a continuous, stable distribution, which has a closed form cumulative distribution function and probability density function.

In my thesis I would like to create a simulation environment (with MATLAB), simulate the interferences of CDMA and OFDMA two-tier networks. I also like to demonstrate that some of these interferences follow Levy distribution. Further aims of the simulations to give a maximum number of femtocells the can be integrated to the macrocell, without causing operation failure at the macrocell. The study will discuss both the uplink and downlink situation, considering the densely of population of the macrocell area. Further simulations are designed to show that two femtocell base stations disturb each other, and the macrocell users.


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