Heterogeneous networks in LTE-Advanced

3GPP Long-term Evolution (LTE) allows operators to use new and wider spectrum and complements 3G networks with higher data rates, lower latency and a flat, IP-based architecture. To further improve the broadband user experience in an ubiquitous and cost-effective manner, 3GPP has been working on various aspects of LTE-Advanced. Since radio link performance is quickly approaching theoretical limits with 3G enhancements and LTE, the next performance leap will come from an evolved network topology. This paper discusses the need for an alternative deployment model and topology using heterogeneous networks. The concept of LTE-Advanced based heterogeneous networks is about improving spectral efficiency per unit area. Using a mix of macro, pico, femto and relay cells, heterogeneous networks enable flexible and low-cost deployments and provide a uniform broadband experience. To enhance the performance of these networks, advanced techniques are described, which are needed to manage and control interference and deliver the full benefits of such networks. These techniques include cell range expansion, adaptive inter cell interference coordination and interference cancellation receivers.