Identification of femtocells in mobile networks

Abstract

The evolving mobile networks are requested to convey increasing data traffic as popularity of online services together with affordability of mobile devices is growing. One solution to mobile carriers, which can help them quickly deploy small base stations (BS) ensuring great indoor coverage with minimum costs, and high data rate capability, is femtocell technology. However, standard deployment techniques are unsatisfactory for these type of BSs. There are two main reasons for that. Firstly, femtocells will be deployed in great numbers. Secondly, they are deployed by users and are portable. It means their position is not known in advance, and can vary in time. Therefore, femtocells have to implement self-configuration principles. Physical Cell Identity is one of the most important parameters to be chosen automatically under defined conditions. It is crucial parameter, which allows them to convey a communication between a user equipment and a core network. A study on Physical Cell Identity issues in mobile networks with femtocells is presented in my thesis. For this purpose, I created two different models of femtocells deployment and deal with a collision and a confusion. They are two main problems, which threaten proper Physical Cell Identity assignment in mobile networks. Outputs of the thesis serves for better understanding of interrelations between differently placed femtocells in term of collision and confusion issue and as the basis to design the framework handling Physical Cell Identity allocation. The simulations conducted on proposed models were utilized to obtain probability characteristics and indicators based on graph theory. In the evaluation section, I appoint several characteristics as probability of collision, probability of confusion and maximal number of neighbourhood cells and some others to support solution of collision and confusion issue. I use results of evaluation and layout the framework for automated Physical Cell Identity assignment with two different approaches, the distributed one, and the centralized one. Since, femtocells are subcategory of small cells so findings, mentioned in this thesis, can also be used for other types of small cells.