Paper Title
Performance Analysis of LTE-A Systems With Femtocell Overlays Using Different Modulation Techniques Under Different Multipath Fading

Abstract
The developments in mobile communication systems from 1G to 5G have increased demands on the network due to the increased number of devices and increasing volume of data. Therefore, networks need to be more efficient to deliver the expected increase in volume. Femtocells are identified as a crucial way to the delivery of the increased demands for heterogeneous networks in which macrocells work in combination with femtocells to provide coverage to offices, homes and enterprise. A simulation framework is used to implement the LTE-A system of macrocells with femtocell overlays. A comprehensive and easy to use Graphical User Interface has been set up with the desired two-tier network topology. It estimates the throughput and path loss of all femto and macro users for all operating frequencies of an LTE-A system using different modulation schemes. A series of tests are carried out using the simulator for a range of scenarios. The LTE-A system performance is analysed in terms of throughput and path loss in an urban environment taking into account the attenuation and penetration losses because of multipath fading. It is concluded that for any operating frequency of an LTE-A system with femtocell overlays, the throughput of a femto user is increased two times for 16QAM modulation scheme as compared to QPSK/4QAM. The throughput is increased to three times for 64QAM as compared to QPSK. It is also deduced that path loss is independent of the modulation scheme and increases with the increase of distance from its base station. Keywords - Quadrature Amplitude Modulation, Femtocells, Main Base Station, Long Term Evolution – Advanced and Multipath Fading.