Small cell

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A small cell situated in the terrace of a building in Bangalore, India Small Cell by Samsung.jpg
A small cell situated in the terrace of a building in Bangalore, India
LTE Small cell operated by the German carrier Deutsche Telekom Telekom Small Cell.jpg
LTE Small cell operated by the German carrier Deutsche Telekom
Small Cell inside a shopping mall Small Cell.jpg
Small Cell inside a shopping mall

Small cells [1] 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 are being built, with larger numbers of small cells recognised [2] [3] [4] as an important method of increasing cellular network capacity, quality and resilience with a growing focus using LTE Advanced. [5]

A radio access network (RAN) is part of a mobile telecommunication system. It implements a radio access technology. Conceptually, it resides between a device such as a mobile phone, a computer, or any remotely controlled machine and provides connection with its core network (CN). Depending on the standard, mobile phones and other wireless connected devices are varyingly known as user equipment (UE), terminal equipment, mobile station (MS), etc. RAN functionality is typically provided by a silicon chip residing in both the core network as well as the user equipment. See the following diagram:

 CN  / ⧵  / ⧵  RAN RAN  / ⧵ / ⧵ UE UE UE UE 

A macrocell or macrosite is a cell in a mobile phone network that provides radio coverage served by a high power cell site. 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. Macrocell base stations have power outputs of typically tens of watts. Macrocell performance can be increased by increasing the efficiency of the transreciever.

LTE Advanced mobile communication standard and major enhancement of the Long Term Evolution (LTE) standard

LTE Advanced is a mobile communication standard and a major enhancement of the Long Term Evolution (LTE) standard. It was formally submitted as a candidate 4G to ITU-T in late 2009 as meeting the requirements of the IMT-Advanced standard, and was standardized by the 3rd Generation Partnership Project (3GPP) in March 2011 as 3GPP Release 10.


Types of small cells

Small cells may encompass femtocells, 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 operator s.

Femtocell Small, low-power cellular base station

In telecommunications, a femtocell is a small, low-power cellular base station, typically designed for use in a home or small business. A broader term which is more widespread in the industry is small cell, with femtocell as a subset. It is also called femto AccessPoint (AP). It connects to the service provider's network via broadband ; current designs typically support four to eight simultaneously active mobile phones in a residential setting depending on version number and femtocell hardware, and eight to sixteen mobile phones in enterprise settings. A femtocell allows service providers to extend service coverage indoors or at the cell edge, especially where access would otherwise be limited or unavailable. Although much attention is focused on WCDMA, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA, WiMAX and LTE solutions.

A picocell is a small cellular base station typically covering a small area, such as in-building, or more recently in-aircraft. In cellular networks, picocells are typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to add network capacity in areas with very dense phone usage, such as train stations or stadiums. Picocells provide coverage and capacity in areas difficult or expensive to reach using the more traditional macrocell approach.

A microcell is a cell in a mobile phone network served by a low power cellular base station (tower), covering a limited area such as a mall, a hotel, or a transportation hub. A microcell is usually larger than a picocell, though the distinction is not always clear. A microcell uses power control to limit the radius of its coverage area.

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.

A Self-Organizing Network (SON) is an automation technology designed to make the planning, configuration, management, optimization and healing of mobile radio access networks simpler and faster. SON functionality and behavior has been defined and specified in generally accepted mobile industry recommendations produced by organizations such as 3GPP and the NGMN.

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 and therefore cannot be managed as effectively as small cells utilising licensed spectrum. Small cell deployments vary according to the use case and radio technology employed.

GSM standard to describe protocols for second generation digital cellular networks used by mobile phones

The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used by mobile devices such as mobile phones and tablets. It was first deployed in Finland in December 1991.By the mid-2010s, it became a global standard for mobile communications achieving over 90% market share, and operating in over 193 countries and territories.


CDMA2000 is a family of 3G mobile technology standards for sending voice, data, and signaling data between mobile phones and cell sites. It is developed by 3GPP2 as a backwards-compatible successor to second-generation cdmaOne (IS-95) set of standards and used especially in North America and South Korea.

The 3rd Generation Partnership Project (3GPP) is a standards organization which develops protocols for mobile telephony. Its best known work is the development and maintenance of:

Umbrella term

The most common form of small cells are femtocells. They were initially designed for residential and small business use, [6] 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. Small cells are sometimes, incorrectly, also used to describe distributed-antenna systems (DAS) which are not low-powered access nodes.

Distributed antenna system

A distributed antenna system, or DAS, is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure. DAS antenna elevations are generally at or below the clutter level, and node installations are compact. A distributed antenna system may be deployed indoors or outdoors.


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.

ABI Research argues that small cells also help service providers discover new revenue opportunities through their location and presence information. If a registered user enters a femtozone, the network is notified of their location. The service provider, with the user's permission, could share this location information to update user's social media status, for instance. Opening up small-cell APIs to the wider mobile ecosystem could enable a long-tail effect.

Rural coverage is also a key market that has developed as mobile operators have started to install public access metrocells in remote and rural areas that either have only 2G coverage or no coverage at all. The cost advantages of small cells compared with macro cells make it economically feasible to provide coverage of much smaller communities – from a few ten to a few hundred. The Small Cell Forum have published a white paper outlining the technology and business case aspects. [7] Mobile operators in both developing and developed countries are either trialing or installing such systems. The pioneer in providing rural coverage using small cells was SoftBank Mobile – the Japanese mobile operator – who have installed more than 3000 public access 3G small cells on post offices throughout rural Japan. In the UK, Vodafone's Rural Open Sure Signal program [8] and EE's rural 3G/4G scheme [9] increase geographic coverage.

Future mobile networks

Small cells are an integral part of future LTE networks. [10] In 3G networks, small cells are viewed as an offload technique [11] . In 4G networks, the principle of heterogeneous network (HetNet) is introduced where the mobile network is constructed with layers of small and large cells. [12] In LTE, all cells will be self-organizing, drawing upon the principles laid down in current Home NodeB (HNB), the 3GPP term for 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 many cubes are stacked together. [13]

The transmitting signal from MBS weakens quickly once the Macro Base Station (MBS) signal reaches indoors. Femtocells provide a solution to the difficulties present in macrocell-based system. Thus, Femto Base Station (FBS) network coverage is one of the prime concerns in indoor environment to get good quality of service (QoS). [14]

Market deployments to date

By December 2017 a total of over 12 million small cells have been deployed worldwide, with forecasts as high as 70 million by 2025. [15]

Small cell backhaul

Backhaul is needed to connect the small cells to the core network, internet and other services. For in-building use, existing broadband internet can be used. In urban outdoors, mobile operators consider this more challenging than macrocell backhaul because a) small cells are typically in hard-to-reach, near-street-level locations rather than in more open, above-rooftop locations and b) carrier grade connectivity must be provided at much lower cost per bit. Many different wireless and wired technologies have been proposed as solutions, and it is agreed that a ‘toolbox’ of these will be needed to address a range of deployment scenarios. An industry consensus view of how the different solution characteristics match with requirements is published by the Small Cell Forum. [16] The backhaul solution is influenced by a number of factors, including the operator’s original motivation to deploy small cells, which could be for targeted capacity, indoor or outdoor coverage. [17]

See also

Related Research Articles

Wireless network any network at least partly not connected by physical cables of any kind

A wireless network is a computer network that uses wireless data connections between network nodes.

WiMAX wireless broadband standard

WiMAX is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide multiple physical layer (PHY) and Media Access Control (MAC) options.

A heterogeneous network is a network connecting computers and other devices with different operating systems and/or protocols. For example, local area networks (LANs) that connect Microsoft Windows and Linux based personal computers with Apple Macintosh computers are heterogeneous. The word heterogeneous network is also used in wireless networks using different access technologies. For example, a wireless network that provides a service through a wireless LAN and is able to maintain the service when switching to a cellular network is called a wireless heterogeneous network.

Cellcom is a regional wireless service provider based in De Pere, Wisconsin, with roots that date back to 1910. Cellcom began providing service from its office in Green Bay in 1987, when its parent company, Nsight, entered the wireless industry.

In a hierarchical telecommunications network, the backhaul portion of the network comprises the intermediate links between the core network, or backbone network, and the small subnetworks at the edge of the network.

Cambridge Broadband

Cambridge Broadband Networks Limited (CBNL) develops and manufactures point-to-multipoint (PMP) wireless backhaul and access solutions, serving telecommunication customers in over 30 countries.

Airvana was acquired by CommScope in 2015. Prior to that, the company was an independent provider of small cells and femtocells based on fourth generation (4G) Long Term Evolution (LTE) and third-generation (3G) CDMA2000 EV-DO mobile broadband technologies. Airvana products enable mobile operators to deliver 3G and 4G cellular data services indoors.

In telecommunication, Long-Term Evolution (LTE) is a standard for wireless broadband communication for mobile devices and data terminals, based on the GSM/EDGE and UMTS/HSPA technologies. It increases the capacity and speed using a different radio interface together with core network improvements. The standard is developed by the 3GPP and is specified in its Release 8 document series, with minor enhancements described in Release 9. LTE is the upgrade path for carriers with both GSM/UMTS networks and CDMA2000 networks. The different LTE frequencies and bands used in different countries mean that only multi-band phones are able to use LTE in all countries where it is supported.

Founded in 1998, Continuous Computing is a privately held company based in San Diego that provides telecom systems made up of telecom platforms and Trillium software, including protocol software stacks for femtocells and 4G wireless / Long Term Evolution (LTE). The company also sells standalone Trillium software products and ATCA hardware components, as well as professional services. Continuous Computing’s Trillium software addresses LTE Femtocells and pico / macro eNodeBs, as well as the Evolved Packet Core (EPC), Mobility Management Entity (MME), Serving Gateway (SWG) and Evolved Packet Data Gateway (ePDG).

Next Generation Mobile Networks

The Next Generation Mobile Networks (NGMN) Alliance is a mobile telecommunications association of mobile operators, vendors, manufacturers and research institutes. It was founded by major mobile operators in 2006 as an open forum to evaluate candidate technologies to develop a common view of solutions for the next evolution of wireless networks. Its objective is to ensure the successful commercial launch of future mobile broadband networks through a roadmap for technology and friendly user trials. Its office is in Frankfurt, Germany.


ip.access Limited is a multinational corporation that designs, manufactures, and markets small cells technologies and infrastructure equipment for GSM, GPRS, EDGE, 3G, 4G and 5G. The firm has headquarters in Cambourne, England, the company also maintains operations and offices in Bellevue, United States, and Gurgaon and Pune, India.

AirHop Communications is a privately funded American corporation based in San Diego, CA. AirHop develops radio access network (RAN) software that addresses the installation, operation and performance challenges of multi-layer deployments of small cells in 3G and 4G networks. AirHop’s customers are typically base station equipment vendors for wireless network operators.

SpiderCloud Wireless was founded in November 2006 as Evoke Networks by Peter Wexler, Allan Baw, and Mark Gallagher in downtown Palo Alto. The trio incubated the company as Copivia Inc. and hired Mike Gallagher as CEO in October 2007. The company closed Series-A funding in January 2008 and soon after changed the company name to SpiderCloud Wireless. The company is now headquartered in Milpitas, California. The company is backed by investors Charles River Ventures, Matrix Partners, Opus Capital and Shasta Ventures. It has raised around $125 million in venture capital and is generating revenue from customers such as Vodafone UK, Vodafone Netherlands, Verizon Wireless, Warid Telecom and more. The company helps mobile operators improve service quality for enterprise customers.

Smart Cells are innovative ubiquitous radio access nodes that provide wireless connectivity across multiple spectrum ranges and technologies. As of January 2014, Macrocells, Small Cells, and Wi-Fi connections were the primary means of data connectivity. For these types of cells, the spectrum utilized is static and is based on the antenna installed. A Smart Cell may transmit multiple frequencies and technologies which are controlled by the software and not the hardware (antenna).

LTE-WLAN aggregation (LWA) is a technology defined by the 3GPP. In LWA, a mobile handset supporting both LTE and Wi-Fi may be configured by the network to utilize both links simultaneously. It provides an alternative method of using LTE in unlicensed spectrum, which unlike LAA/LTE-U can be deployed without hardware changes to the network infrastructure equipment and mobile devices, while providing similar performance to that of LAA. Unlike other methods of using LTE and WLAN simultaneously, LWA allows using both links for a single traffic flow and is generally more efficient, due to coordination at lower protocol stack layers.


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