It is not a hidden fact that, in today s wireless and cellular networks, businesses and end users have clearly become dependent on mobility and the freedom of being always online. Smart phones, tablets and other devices are expected to be connected all the time and the applications on these devices are required to run smoothly. That is, for a mobile network to even be considered to have the minimum requirements from its users today, network problems like dropped calls, choppy videos and slow downloads should be out of the question. However, with the fast growth rate of wireless communication devices competing for spectrum, the mobile access networks that we have today will soon reach their maximum capacity. To address these high expectations, mobile network operators are employing new strategies in densely populated areas and commercial buildings where spectrum scarcity is highest. 3GPP has been working on LTE Advanced (Long Term Evolution - Advanced) in order to improve the spectral efficiency by employing Heterogeneous Networks (HetNets). HetNets improve the business model for mobile network operators and users by introducing network topologies which are less costly and are able to increase the capacity and coverage provided by the traditional macro cell mobile networks. HetNets are comprised of macro cells and low cost - low power base stations like picocells, femtocells, relays and other small cells along with WiFi-APs and distributed antenna systems (DAS). With HetNets a significant network capacity gain and uniform broadband experience can be provided to the users anywhere and at low cost, since the spectrum can be re-used across the multiple tiers in the network. However, HetNet deployments come with a lot of challenges and advanced interference control and management techniques are required to get the highest possible benefit from these networks. The enhanced Inter Cell Interference Coordination (eICIC) technique has been studied previously to address the interference problem that these small cells experience from macro cells. This thesis will concentrate on the performance improvement achieved when eICIC mechanisms are introduced to a simple HetNet. The eICIC approach as described in 3GPP s Release 10 involves two mechanisms, which this thesis also tries to take into consideration. These are the CRE (Cell Range Expansion) achieved through cell bias adjustments and ABS (Almost Blank Subframe) ratio. A discussion about the importance eICIC in SON - Serlf Organizing Networks will also be done.