Pico Cell Range Expansion toward LTE-Advanced Wireless Heterogeneous Networks

The Long Term Evolution (LTE) of the Third Generation Partnership project (3GPP) has recently been investigating new deployment options to deal with sudden increase in demand for mobile broadband services. These strategies are being included in the already frozen Release 10 and in the almost finished Release 11. The final aim is to provide a significant network performance leap especially in densely populated areas and cell-edges, where other advanced technologies, including LTE Release 8 and 9 are unable to achieve the performance required by the International Telecommunications Union (ITU) to be considered 4th Generation standards (4G) of mobile networks. Deploying low power nodes within a macro cell layout, also known as heterogeneous networks (HetNets), is a promising solution to enhance system performance overall, cell-edges and indoor coverage. Indeed this type of deployment leads to an improvement of spatial efficiency understood as bps/Hz/km2 and achieves kind of load balance by offloading macro cell traffic to low power nodes. Nevertheless, HetNets deployment includes new technical challenges related to interference issues and throughput degradation. To handle with them, advanced interference coordination techniques are introduced. In this sense, Range expansion allows attracting more users and thus achieving performance improvement, but causes extra downlink interference which becomes severe for higher bias values and so the benefits translate into important degradation. For that, range expansion should be jointly designed with inter-cell interference coordination/enhanced inter-cell interference coordination (ICIC/eICIC) schemes to overcome these issues. In this project, it is discussed LTE-Advance as evolution of LTE release 8, and describe the concept of HetNets, range expansion, the major technical challenges and interference coordination schemes. Finally, results are presented related to HetNets (Macro-Pico scenario) and range expansion with/without interference coordination techniques using system level simulation to evaluate their impact on system performance for different configurations.