Small cells are one of the key digital infrastructure building blocks for 5G and take a variety of forms, including a microcell, picocell, and femtocell. Instead of replacing traditional macrocells (cell towers), small cells supplement this infrastructure to enhance network coverage and capacity in crowded city locations and inside buildings.
Small cells are low-powered cellular radio access points or “nodes” used for voice, video, and data transmission, which are designed to enhance network coverage and capacity in dense urban areas. These nodes are placed outdoors, as well as indoors, where 80% of all mobile data traffic is consumed.
Dgtl Infra provides an in-depth overview of small cells, including the three main types: microcells, picocells, and femtocells. Additionally, we compare small cells to the more widely known cell towers, which are referred to as macrocells. Finally, Dgtl Infra highlights examples of femtocells offered to consumers by wireless carriers Verizon, AT&T, and T-Mobile, which enhance 4G LTE coverage for an end user’s home or office.
What are Small Cells?
Small cells are low-powered cellular radio access points used for voice, video, and data transmission, which are designed to provide network coverage to smaller areas. These transmission points or “nodes” are placed close to end users, both indoors and outdoors, and operate in licensed, shared, or unlicensed spectrum.
Overall, small cells are a critical form of infrastructure for handling very dense voice, video, and data traffic demands because they provide capacity, which allows for faster, more reliable wireless service.
Power and Backhaul for Small Cells
Small cells require input power, separate backhaul connectivity, and proper siting of their dedicated radios to deliver optimal coverage:
- Power: small cells installed outdoors on city infrastructure like streetlights, utility poles, and light poles will often already have power infrastructure in-place. While small cells deployed indoors can source power from the building in which they provide service
- Backhaul: the method used to transport voice, video, and data traffic from a small cell will depend on the wireless carrier or infrastructure operator’s capabilities. While fiber-based transmission technology such as GPON and XGS-PON is optimal, often only hybrid fiber-coaxial (HFC) technology standards, such as DOCSIS 3.0 or DOCSIS 3.1 are available. In outdoor settings, wireless microwave connections can also be used for the purposes of small cell backhaul
Macrocell (Cell Tower) vs Small Cell
Macrocells, also known as cell towers, are tall, high-powered structures that keep the signals of wireless networks strong across large distances and wide areas. In contrast, small cells serve densely populated areas like city centers and stadiums, which have specific capacity needs.
Macrocell / Cell Tower (left) and Small Cell (right)
In terms of structure, macrocells typically range from 100 to 400 feet in height, while small cells are placed at heights of less than 100 feet – and often closer to 20 feet.
Also, small cells deliver higher throughput and data rates for end users which, in turn, provides additional capacity to a macro wireless network.
Finally, the build costs for a single small cell node and its corresponding fiber are less than $100,000, making these deployments more cost-effective than a single macrocell (cell tower) – however, several small cells would need to be built to even approximate the coverage of a macrocell.
READ MORE: How Much Does it Cost to Build a Cell Tower?
How Many Small Cells are in the United States?
In the United States, there are 450,000 small cell on-air nodes, primarily used by the wireless carriers Verizon, AT&T, and T-Mobile. These small cells have been built by infrastructure providers like Crown Castle and ExteNet Systems, or the wireless carriers themselves, which is known as self-performing.
How Many Small Cells are Needed for 5G?
In the United States, 5G is expected to be the dominant network technology by 2030, at which point, a total of 900,000 to 1 million small cell on-air nodes will be needed for 5G. As such, the small cell industry is forecasted to grow at an ~11% compound annual growth rate (CAGR) from present levels.
To this end, Airspan Networks, a provider of radio access network (RAN) equipment, highlights how 4G deployments utilize 80% macrocells and 20% microcells (small cells), while 5G deployments will employ the inverse, 20% macrocells and 80% microcells.
Moreover, as higher-band spectrum such as sub-6 gigahertz (GHz) and millimeter wave (mmWave) is deployed for 5G (light blue bars below), more radios and thus, small cells will be needed. This is because these 5G spectrum assets have more limited propagation characteristics (see coverage line below) compared to the lower-band spectrum that has historically been deployed on macrocells.
Network Densification in 4G and 5G Environments
Types of Small Cells – Microcell, Picocell, Femtocell
There are three main types of small cells: microcells, picocells, and femtocells. These cellular base stations typically cover a small area and are used to extend coverage to areas or to add network capacity in locations with very dense cell phone usage, such as hotels.
Types of Small Cells – Microcell, Picocell, Femtocell
Each type of small cell, whether it be a microcell, picocell, or femtocell, all have self-contained base stations, which are responsible for radio transmission and reception “to” or “from” the mobile station.
Below is a breakdown of the main differences between a microcell, picocell, and femtocell – which include location of the deployment, coverage range, number of simultaneous users supported, power supply to the node, and cost:
Key Differences of Small Cells – Microcell, Picocell, Femtocell
|Location||Outdoors||Indoors (large areas)||Indoors (small areas)|
|Range||600 feet to 3,000 feet||300 feet to 1,000 feet||less than 100 feet|
|Users||100 to 2,000||30 to 100||1 to 32|
|Power||2 to 20 watts||250 milliwatts to 2 watts||100 to 200 milliwatts|
What is a Microcell?
Microcells provide the greatest coverage and support the highest capacity for users amongst the small cell types. Typically, microcells are installed outdoors on city infrastructure like streetlights, utility poles, light poles, and slim line poles. However, given their range of 600 feet to 3,000 feet, microcells can serve both outdoor and indoor spaces simultaneously.
Usually, microcells are deployed in dense urban environments to cover a high-demand city block where macrocell (i.e., cell tower) coverage may not be sufficient. A microcell can support 100 to 2,000 users and typically has transmission power levels of 2 to 20 watts.
Microcells are owned by wireless carriers like Verizon, AT&T, and T-Mobile or infrastructure operators such as Crown Castle and ExteNet Systems. While the transport of voice, video, and data traffic, also known as backhaul, from the microcell uses either wired (e.g., fiber) or wireless (e.g., microwave) connections.
Overall, of the different types of small cells, microcells are the costliest to deploy, requiring professional installation and zoning & permitting approvals. Still, microcells offer unique benefits, such as the ability to use software-defined connections to deal with limited line-of-sight in challenging urban environments. As such, microcells are critical components to the future of 5G networks.
What is a Picocell?
Picocells, which can also be referred to as a metrocell, provide a coverage range of 300 feet to 1,000 feet, which is smaller than microcells but greater than femtocells (see below). Typically, picocells are installed indoors, at large venues including airports, hotels, hospitals, offices, and universities.
Usually, picocells are deployed in these high-traffic indoor spaces, where a single coverage area has multiple picocells. A single picocell can support 30 to 100 users and has ‘medium’ transmission power levels of 250 milliwatts to 2 watts.
Picocells are owned by the enterprise or the landlord of the venue where they are deployed. While the transport of voice, video, and data traffic (backhaul) from the picocell uses a wired connection, such as fiber.
Overall, picocells cost less to deploy than microcells, given that their equipment size is smaller and they avoid certain costs associated with professional installation and zoning & permitting approvals.
What is a Femtocell?
Femtocells, which wireless carriers refer to as mini cell towers, provide the shortest coverage range and support the smallest capacity for users amongst the small cell types. Specifically, femtocells are compact equipment installed indoors for home and small office use, providing a coverage range of less than 100 feet.
In total, a single femtocell can support 1 to 32 users and has the lowest transmission power levels amongst small cell types of 100 to 200 milliwatts. Ultimately, the primary purpose of a femtocell is to improve signal quality.
Femtocells are owned by the end user or subscriber, often an individual, who either purchases the equipment directly or receives it as a subsidy from their wireless carrier, as part of their service plan. While the transport of voice, video, and data traffic (backhaul) from femtocells relies on the end user’s wired Ethernet broadband connection, leveraging either digital subscriber line (DSL), hybrid fiber-coaxial (HFC), or fiber optics – thus relying on the Internet for transport.
Overall, of the different types of small cells, femtocells are the cheapest to deploy – costing only hundreds of dollars – given that they are self-setup and have a small form factor. To this end, a femtocell base station’s condensed size is often similar in form to a Wi-Fi router.
Consumer Femtocells from Verizon, AT&T, and T-Mobile
Each of the major wireless carriers, including Verizon, AT&T, and T-Mobile, offer carrier-specific femtocells for the purposes of enhancing existing 4G LTE coverage for a subscriber’s home or office. Generally, these femtocells cost a few hundred dollars and have the ability to support up to 16 simultaneous users.
Below are further details on Verizon’s LTE Network Extender, AT&T’s Cell Booster and Cell Booster Pro, and T-Mobile’s 4G LTE CellSpot.
Verizon LTE Network Extender
Verizon markets its LTE Network Extender, which is a femtocell or “mini cell tower” that enhances existing 4G LTE coverage for a subscriber’s home or office. Particularly, the device simultaneously supports up to 16 active users with low transmission power of 50 milliwatts. Presently, Verizon prices the LTE Network Extender at $249.99.
The Verizon LTE Network Extender has good radio frequency (RF) performance, providing a coverage range of 50 feet with its internal antenna.
Verizon LTE Network Extender – Femtocell
Additionally, Verizon’s femtocell device connects to a user’s existing high-speed internet connection and only requires minimum download speeds of 10 megabits per second (Mbps) and upload speeds of 5 Mbps. However, Verizon recommends having an internet connection with download speeds of 20 Mbps and upload speeds of 10 Mbps, or higher.
Previously, Verizon also offered femtocells known simply as a Network Extender or MicroCell, however, these products have been discontinued and are no longer available for purchase.
AT&T Cell Booster and Cell Booster Pro
AT&T markets its Cell Booster and Cell Booster Pro, which are femtocells or “mini cell towers” that improve cell signals by using a subscriber’s internet connection. Specifically, the booster creates a 4G LTE cell signal for better indoor coverage, as well as more reliable voice calling, texting, and data speeds. Presently, AT&T prices the Cell Booster at $229.99 and the Cell Booster Pro at $699.00.
AT&T Cell Booster – Femtocell
Overall, the maximum range of AT&T’s Cell Booster is 3,000 square feet, while the company’s Cell Booster Pro has a range of 15,000 square feet.
Previously, AT&T also offered femtocells known as the AT&T MetroCell and the AT&T MicroCell, however, these products have been discontinued and are no longer available for purchase.
T-Mobile 4G LTE CellSpot
T-Mobile markets its 4G LTE CellSpot, which is a femtocell or “mini cell tower” that creates a 3G, 4G, and 4G LTE signal to deliver superior indoor coverage, more reliable voice calls, and consistent data speeds. This device resides in a user’s home or small office and can connect up to 16 simultaneous users (8 on 4G LTE and 8 on 3G/4G UMTS).
The T-Mobile 4G LTE CellSpot utilizes a high-speed internet connection, requiring minimum download speeds of 2 Mbps, upload speeds of 0.5 Mbps, and ping (latency) of 200 milliseconds or less.
T-Mobile 4G LTE CellSpot – Femtocell
Overall, the maximum range of T-Mobile’s 4G LTE CellSpot is approximately 3,000 square feet.