LTE Advanced: 3GPP Solution for IMT-Advanced

8.2 Base Station Classes

Most of the base stations so far have been wide area macro cells that provide coverage for several square kilometers by using high mounted antennas and high power transmitters. Outdoor small cells are often called micro cells and provide coverage for a few hundred meters by using lower antenna installations. Indoor cells can be located in public premises, like shopping malls or office buildings, or at homes. The public indoor solutions have traditionally used indoor antennas and RF cables connected to a macro base station that is located in the same building, a solution called a Distributed Antenna System (DAS). The benefit of a DAS is that upgrading new radios is relatively simple – in the best case, one just has to plug in a new base station to the cable system without any upgrades to the cables or antennas. The drawback of DAS is that adding more antennas may only increase the coverage and provide a more homogeneous quality of service over the coverage area, but it cannot lead to a substantially increased capacity, as the same physically layer transmission resources are simply shared by a larger coverage area. If capacity is to be increased, this has to be done via cell splitting, which is complex and most likely requires major changes to the cabling.

Another indoor solution is a home base station, also known as a femto cell. Femto cells have been mainly deployed for improving the coverage and capacity in homes and in small offices. An overview of different ...