Small Cells are low-powered radio access nodes that operate in licensed and unlicensed spectrum that have a range of 10 meter to 200 meters, compared to a mobile Macrocell which might have a range of a few kilometres. With mobile operators struggling to support the growth in mobile data traffic, many are using Mobile data offloading as a more efficient use of radio spectrum. Small cells are a vital element to 3G data off-loading, and many mobile network operators see small cells as vital to managing LTE Advanced spectrum more efficiently compared to using just macrocells.
Small cells can be used to provide in-building and outdoor wireless service. Mobile operators use small cells to extend their service coverage and/or increase network capacity. With small cells, mobile operators can offload traffic as much as 80% during peak times.
Small cells cover Femtocells, Picocells, and Microcells. Small cell networks can also be realized by means of distributed radio technology consisting of centralized baseband units and remote radio heads. Beamforming technology (focusing a radio signal on a very specific area) can be utilized to further enhance or focus small cell coverage. A common factor in all these approaches to small cells is that they are centrally managed by mobile network operators.
Small cells provide a small radio footprint, which can range from 10 meters within urban and in-building locations to 2 km for a rural location. Picocells and microcells can also have a range of a few hundred meters to a few kilometers, but they differ from femtocells in that they do not always have self-organizing and self-management capabilities.
Small cells are available for a wide range of air interfaces including GSM, CDMA2000, TD-SCDMA, W-CDMA, LTE and WiMax. In 3GPP terminology, a Home NodeB (HNB) is a 3G femtocell. A Home eNodeB (HeNB) is an LTE femtocell. Wi-Fi is a small cell but does not operate in licensed spectrum therefore cannot be managed as effectively as small cells utilizing licensed spectrum.
The most common form of small cells are femtocells. Femtocells were initially designed for residential and small business use, with a short range and a limited number of channels. Femtocells with increased range and capacity spawned a proliferation of terms: metrocells, metro femtocells, public access femtocells, enterprise femtocells, super femtos, Class 3 femto, greater femtos and microcells. The term small cells is frequently used by analysts and the industry as an umbrella to describe the different implementations of femtocells, and to clear up any confusion that femtocells are limited to residential uses.
Future mobile networks
Small cells are an integral part of LTE networks. In 3G networks, small cells are viewed as an offload technique. In 4G networks, the principal of heterogeneous network (HetNet) is introduced where the mobile network is constructed with layers of small and large cells. In LTE, all cells will be self-organizing, drawing upon the principles laid down in current residential femtocells.
Future innovations in radio access design introduce the idea of an almost flat architecture where the difference between a small cell and a macrocell depends on how may cubes are stacked together. With software-defined radio, a base station could be 2G, 3G or 4G at the flick of a switch, and the antenna range can easily be tuned.
More than 3 million femtocells have been deployed as of December 2011 and new categories of carrier-grade femtocells and picocells are coming to market during 2012. Deployment is expected to grow to 20 million units per year by 2016.
A macrocell is a cell in a mobile phone network that provides radio coverage served by a high power cellular base station (tower). Generally, macrocells provide coverage larger than microcell. The antennas for macrocells are mounted on ground-based masts, rooftops and other existing structures, at a height that provides a…