Cell Sites

(Luzern, Switzerland - Alvin Wei-Cheng Wong)

Base Station (BTS, BS, eNB) Classes

Our thirst for high speed mobile data is insatiable. As we saturate the available RF spectrum in dense urban environments, it’s becoming apparent that there’s a need to increase the efficiency of how we transmit and receive data from wireless base stations.

A base transceiver station (BTS) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UEs are devices like mobile phones (handsets), WLL (Wireless Local Loop) phones, computers with wireless Internet connectivity. The network can be that of any of the wireless communication technologies like GSM, CDMA, wireless local loop, Wi-Fi, WiMAX or other wide area network (WAN) technology. 

BTS is also referred to as the node B (in 3G Networks) or, simply, the Base Station (BS). For discussion of the LTE standard the abbreviation eNB for evolved node B is widely used. As per 3GPP reference 36.104 release 12, four classes for the base stations based on the rated power are listed below:

The terms macro, micro, pico, and femto are not used in 3GPP to identify the base station classes; instead, the following terminology is used: wide area base station, medium area base station, local area base station, and home base station, respectively.

The term macrocell is used to describe the widest range of cell sizes. A macrocell or macrosite is a cell in a mobile phone network that provides radio coverage served by a high power cell site (tower, antenna or mast). 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 clear view over the surrounding buildings and terrain. Macrocells are found in rural areas or along highways. They can provide cellular network coverage for a large area which can span a large town. Macrocell base stations have power outputs of typically tens of watts. Macrocell performance can be increased by increasing the efficiency of the transreciever.

Fewer new macrocell sites are being built, with larger numbers of small cells recognized as an important method of increasing cellular network capacity, quality and resilience with a growing focus using LTE Advanced. 

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. Small cells can be used to provide in-building and outdoor wireless service. Mobile operators use them to extend their service coverage and/or increase network capacity. Small cells use much lower power and cover much smaller areas. Generally small cells will subdivide large cell areas to provide more local service.

Small cells, which have a smaller coverage area than base stations, are categorized as follows: Microcell (less than 2 kilometres), Picocell (less than 200 metres), Femtocell (around 10 metres). 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. 

Over a smaller cell area, a microcell is used in a densely populated urban area. Picocells are used for areas smaller than microcells, such as a large office, a mall, or train station. Currently the smallest area of coverage that can be implemented with a femtocell is a home or small office.