Communications and Signal Processing Lab (ComSP)

Title	Heterogeneous cellular networks under diverse coupling and association criteria
State	Finished
Author	Muhammad Mujtaba Shaikh
Director/s	Mª Carmen Aguayo Torres
University	Universidad de Málaga
Center	Escuela Técnica Superior de Ingeniería de Telecomunicación
Department	Ingeniería de Comunicaciones
Reading date	04/09/2017
File	PDF

Current networks are moving towards Heterogeneous Cellular Networks (HCN) arising from the combination of small cells with existing macrocells. The small cells are low power nodes such as microcells, picocells and femtocells. Each layer (tier) of the network contains all the elements of a certain type of cells, which transmit with the same power.

The aim of this thesis is to analyze various performance indicators of heterogeneous cellular networks. Performance indicators under investigation include the specific consideration of symmetric transmission and, therefore, of joint distributions. A two-layer heterogeneous cellular network has been considered in which macro and pico cell Base Stations (BS) and User Equipment (UE) are evenly distributed.

This thesis focuses on the criteria by which user equipment is associated with base stations. It can be done to the nearest cell in physical distance or the radio electric distance can be used, that is to say, the propagation losses. As the powers used by distinct layers are different, a common criterion is to associate the user equipment to the base station that is received with higher average power. For this case, we have taken into account the technique known as Cell Range Expansion (CRE) that tends to equalize the user sharing between macro and pico cells which, owing to the power difference, is otherwise very unbalanced.

As for the uplink, the cells currently in operation always associate user with the same cell that is considered in the downlink. New network architectures seem to allow the possibility of decoupling both associations. This thesis evaluates the gain obtained to analyze if it compensates its implementation difficulties. Fractional Power Control (FPC), which allows partial compensation of uplink losses, is also taken into account.