In this paper, we present a novel and efficient link level simulation framework for the donwlink (DL) of Long Term Evolution Advanced (LTE-A) cellular networks. The tool, called Wireless Mobile SIMulator Advanced (WM-SIMA), is available
to be downloaded so that researchers can use it to evaluate the performance for different network configurations. In this work, the main characteristics of WM-SIMA are presented. As
a case of use, the Average Spectral Efficiency (ASE) is obtained for the DL of a two-tier network, composed of Macro Access Points (MAPs) and Pico APs (PAPs). Simulation results confirms
that there exist an optimal Cell Range Expansion (CRE) bias in the cell association that maximizes the ASE. Interestingly, it is confirmed that this optimal bias does not depend on the number of PAPs, while increasing the number of PAPs leads to a higher ASE for the same bias.