Small Cells

Small cells are low-powered cellular radio access nodes that operate in licensed and unlicensed spectrum that have a range of 10 meters to a few kilometers. They are "small" compared to a mobile macrocell, partly because they have a shorter range and partly because they typically handle fewer concurrent calls or sessions. They make best use of available spectrum by re-using the same frequencies many times within a geographical area. Fewer new macrocell sites being built, with larger numbers of small cells recognised as an important method of increasing cellular network capacity, quality and resilience with a growing focus using LTE Advanced.

Small cells may encompass , picocells, and microcells. Small-cell networks can also be realized by means of distributed radio technology using centralized baseband units and remote radio heads. Beamforming technology (focusing a radio signal on a very specific area) can further enhance or focus small cell coverage. These approaches to small cells all feature central management 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-organising 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 Node B (HNB) is a 3G femtocell. A Home eNode B (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 utilising licensed spectrum. The detail and best practice associated with the deployment of small cells varies according to use case and radio technology employed.

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