System-level Performance of Enhanced MIMO in LTE-A Downlink

Abstract

Cellular networks have evolved very rapidly in recent decades, and network capacity has increased significantly. In the future cellular networks are expected to continue to develop rapidly and at the same time user expectations are getting more demanding. For this reason, the cellular network standardization must take into account the increasing demands and expectations that are set to networks. Long Term Evolution (LTE) and its’ future evolution LTE-Advanced technologies answer to these future challenges.

In practice, the high data rates can be achieved with new radio technology introduced in LTE. This new radio interface will increase spectral efficiency significantly compared to previous technologies. In addition, wider bandwidth can be used and together with increased spectral efficiency this will lead to significantly higher data rates than achieved with previous technologies.

Multi-antenna techniques are one important factor when increasing the spectral efficiency of a cellular network. In order to maximize the radio channel capacity full channel knowledge is needed at both receiver and transmitter ends. This is achieved by signaling channel state from receiving end to transmitting end. Another substantial improvement which helps to achieve higher spectral efficiency is the efficient sharing of the radio resource between the users of cellular network. Both of these factors will improve theoretical capacity of the cellular network significantly, but in practical systems one will face a variety of non-idealities such as measurement errors that will limit the benefits of these techniques.

Studying the benefits of multi-antenna techniques and cellular networks can be done in various manners. Computer simulations are one of the most important and most effective research methods for cellular networks today. A simulation tool which models the realistic cellular network including several served users is used in this thesis. The focus of simulations is to compare LTE and LTE-Advanded based multi-antenna techniques in two different propagation environments. Based on the simulation results LTE-Advanced multi-antenna techniques provide significant improvement over earlier LTE based multi-antenna techniques in certain propagation environments. /Kir10