Towers and Small Cells

The Cell-Site is used to identify the entire infrastructure (active and passive) be it antennas, buildings, telecom gears (comprising of the base station, Remote Radio Head), and power resources.

Cell towers are the poles or mast, on which antenna systems, RRH (Remote Radio Head) are installed. A cell tower can be shared by multiple wireless carriers, or a single wireless carrier can use it. Generally, the cell towers are taken on rent or lease by the wireless carrier to install the gears.

Read 5G Cell Towers: Introduction to get in-depth details on the cell towers.

Broadly the cell towers can be classified into four categories, specified below:

Monopole Towers

• • Built from a single tubular mast and requires only one foundation
  • Small footprint on the ground
  • Height can range from 40 feet tall to 200 feet tall across tenants
  • Antennas are attached to the exterior on the top of the tower
  • Some cities have banned the construction of new monopoles because they are eyesores.

Guyed Towers

• They have three guyed lines anchored to the ground, in addition to guy wires to anchor and support them.
• Requires larger amount of land, usually around 100 meters or more
• Height can range from 200 to 300 feet tall and can support multiple wireless tenants
• Antennas are attached to the exterior on the top of the tower

Lattice Cell Towers

• Self-supporting towers made of steel latticework in square or triangular shape
• They are very stable and easy to construct
• Height can range from 200 to 400 ft
• Antennas are attached to the exterior on the top of the tower.

Stealth Cell Towers

• • In some cities, zoning codes require that towers should blend in the surroundings
  • Typically a monopole tree is disguised as a tall tree e.g. palm tree or pine tree
  • They are costlier to build
  • They cannot provide the same amount of coverage to the tenants, like other types of towers

Read 5G Cell Towers: Introduction to get details on the above cell tower types.

Some of the criteria on which the cell tower coverage depends include antenna height, antenna orientation, the frequency band used for transmission.

A Cell site is either owned by a wireless carrier or taken on lease from Cell Tower companies. A particular cell site is used by a single wireless carrier, or it can also be shared among other wireless carriers.

Acquisition of a cell site by a wireless carrier involves handshakes with stakeholders from sourcing and network planning teams.

To give a perspective of the footprint of cell towers and their commercial dimension in the US, below are a few numbers from Vertical Consultants, updated in Sept 2020.

To get the complete list of criteria for cell tower coverage read the “How to select and upgrade to 5G towers?” article.

Macro Cell typically provides coverage to a large geographic area. They are typically installed on rooftops, poles, and in some instances, on Ground-Based Towers. The major advantage of using Macrocell in 5G is that it can provide 5G services to a large geographic area. 5G macro cells also use Massive MIMO technology, which allows large transmission and reception of data.

Small Cell is used to deploy legacy technologies like 3G and 4G and would play a more important role in 5G deployment. It empowers wireless carriers to deploy cell sites in strategic locations and offer higher capacities in the small coverage area.

To get more details on small cells and the difference between macrocells and small cells – read “5G Cells – What are macrocells, small cells, and DAS?” article.

Small cells can be classified into below 3 categories:

Femto Cells are small mobile base stations that are used to extend coverage in residential or small office complexes. They are used in areas with network congestion, and it acts to offload a Macro Cell. It can also serve to provide in-building coverage.

Pico Cells are small cellular base stations covering areas like buildings, hotels, hospitals, and shopping malls. They are generally used to extend coverage and increase throughput.

Micro Cells are generally a bit bigger in comparison to Pico and Femto Cells. They can support more no of connected users and cover a greater geographic area. They are mostly used for enterprise premises.

To get more details on microcell and the difference between microcell, picocell, and femtocell – read “5G Cells – What are macro cells, small cells, and DAS?” article.

DAS is a network of antennas that are connected to a common RF source and then distributed to a customer premise. They are generally used in large sporting stadiums or events where there is high densification of cellular networks.

How does DAS work?

A DAS is made up of two components, Signal Source and Distribution System.

Single Source:

A distributed antenna system can’t generate signals on its own. Instead, it needs a signal source that needs to be fed to the antenna system, which is then distributed to the entire customer premise.

The source can be an RF module of a wireless carrier, or it can be a small cell too. The signal source is one of the key factors in the coverage and capacity metric of DAS. A DAS system can have an excellent distribution system, but it will be of no use if the signal source is not efficient.

Distribution system:

Once the signal source is generated it needs to be amplified and distributed in the customer premise. It can be distributed via active, passive, hybrid, and digital distribution technologies. A distributed antenna system’s performance (i.e. capacity and coverage) depends on the type of technology it uses.

For details on different types of DAS distribution technologies, read this article.

5G era will usher to unlimited possibilities and innovation. It will bring a transformation that will alter the canvas of services being offered to customers and change the competitive landscape. The peak data rate for 5G will be a 20 fold increase than the current LTE-A peak data rate, and latency will decrease by tenfold.

According to Deloitte, the number of connected devices will reach One trillion by 2030. This massive number of connected devices needs to be supported by a network with very little latency. It can be achieved by a split of traditional network architecture and improved transport network.

1 Trillion connected devices look very encouraging from the revenue perspective of Telcos, but monetization of their assets is not all so rosy. Telcos now need to compete not only with their incumbent peers but also with disruptors like OTTs.

OTT operation is very intriguing for Telecos. They use the telco’s infrastructure to provide their services and monetize them but eat away the core offerings of Telcos like voice and SMS. Just compare the adoption of Whatsapp voice and messaging services with traditional SMS and voice calls. The difference in features and offerings are quite striking between the two.

To provide the subscribers of the OTT platforms with high-quality content, OTTs like Amazon Google are building up their high-capacity data center and backbone transport network. This enables them to bring their content as close as possible to the access network to support ultra-low-latency.

So it is quite obvious for wireless carriers to build and develop a robust and highly responsive transport network for 5G. This will help them fight the competition and provide more business use cases.

What is the role of fiber in 5G infrastructure?

For an efficient 5G network to build, wireless carriers need to focus on the disaggregation of their Access Network, introduce virtualization and build an efficient transport network. Disaggregation: Disaggregation of the access network is generally the split of the Access architecture into Centralized Unit (CU), Distributed Unit (DU), Radio Unit (RU), Fronthaul Interface (RU-DU), Midhaul Interface (DU-CU), and Backhaul Interface (DU-Core).

The transport network will encompass all the interfaces, but the transport requirement for backhaul will draw the highest traction. Since 5G use-cases will require low latency and high speed, this will be attained by using the high-frequency spectrum. This will essentially mean the densification of the network. Also, all the cell sites need to be connected to a 5G core network with a high-speed backbone.

We can have several transmission architectures based on Microwave, Copper, and Fiber, but the 5G benefits can be leveraged by using a Fiber transport network. Challenge for the operator is to find the ideal mix and match between different deployment technologies as the backhaul.

The transport network will encompass all the interfaces, but the transport requirement for backhaul will draw the highest traction. Since 5G use-cases will require low latency and high speed, this will be attained by using the high-frequency spectrum. This will essentially mean the densification of the network. Also, all the cell sites need to be connected to a 5G core network with a high-speed backbone. We can have several transmission architectures based on Microwave, Copper, and Fiber, but the 5G benefits can be leveraged by using a Fiber transport network. Challenge for the operator is to find the ideal mix and match between different deployment technologies as the backhaul.

Let us take a quick comparison between different transport mediums for backhaul. As noted in the below table, fiber comes out to be the most viable option for 5G use-cases in terms of bandwidth.

FIBER AVAILABILITY = FASTER 5G DEPLOYMENT = FASTER TIME TO MARKET FOR WIRELESS CARRIERS

From a Wireless carrier perspective, 5G deployments will happen in the Macro Cells and Small cell sites. Macro Cell Site deployment will generally occur in rural areas, whereas small cell deployment will occur in urban and suburban areas. Since the TCO for Fiber (Fixed Backhaul) is higher than Microwave (Wireless Backhaul), it is imperative that there will be a mix and match of both fixed and wireless backhaul during deployment. The Reason being carriers will try to cost optimize and increase their ROI (Return on investments).

The future of Communication is Wireless, but the future of Wireless is Fixed.

Although fiber provides significant bandwidth, several complex technologies are involved so that there is the optimal usage of the capacity. However, with time there has been a significant reduction in cost fiber deployment cost with solutions like micro-trenching and fiber optic insertions.

Wavelength Division Multiplexing (WDM)

WDM is the technique used in fiber optic communication. It multiplexes several optical carrier signals in a single fiber by using different wavelengths. WDM is divided into three different wavelength patterns.

Using these technologies of WDM, modern Fiber systems can handle a capacity of 1.6Tbps per fiber. But for the wireless carriers, the major challenge in deploying fiber is cost, logistics, and insertion in underground tunnels. With the inter-site distance becoming less due to the densification of networks, the amount of person-hour and operational and maintenance costs in deploying fiber will increase. New business models where fibers can be shared between different operators (railway, wireless carrier) are also up ticking, making economic sense in terms of cost of network deployment. Although there is a significant reduction in fiber implementation with modern technologies, the large-scale deployment of 5G networks will see several other technologies also acting as mobile backhaul.

Microwave Backhaul

5G use case requirement and deployment strategies have stimulated the splitting of the NR Radio access into three different segments, fronthaul, Midhaul, and backhaul, as highlighted in the RAN access split diagram. These three tiers of network segment are called X-HAUL or anyhaul. This X-HAUL interface will need connectivity options and has motivated the development of different Transport gears.

Wireless Mobile backhaul can operate in the below spectrum ranges:

• Microwave (7-40 GHz)
• V-band (60GHz)
• E Band (70/80 GHz)

Microwave has been the dominant technology for mobile backhaul for years. Although predominantly used in MACRO cell sites, its wide operating frequency range can also be used to cater to small cell transport networks. Lower frequency ranges are generally used for fronthaul or Midhaul scenarios, whereas spectrum bands above 20GHz can be used for Backhaul links.

Higher frequency bands will allow the provision of higher bandwidth. E band and V Band are generally used for radar communicator and research purposes. But recently, some Governments like the US, France, Poland have allocated 80GHZ for wireless backhaul. Microwave deployment for these bands will be mostly restricted for small cell deployments. But migration to these bands is still underway, and the adoption rate is still at the nascent stage.

The following table highlights the performance metrics of different spectrum bands. As noted in the below table, fiber comes out to be the most viable option for 5G use-cases in terms of bandwidth. 

SWOT analysis of Fixed vs Wireless Backhaul

SWOT analysis of fixed vs Wireless backhaul – TeckNexus

Integrated Access Backhaul

Fiber and Microwave are the two predominant backhaul connectivity choices for 5G deployment with each having its pros and cons. With commercial deployments happening for mmWave, a new wireless backhaul solution, Integrated Access Backhaul (IAB), is introduced by 3GPP from Release 16. In IAB, the NR radio uses part of the radio spectrum for backhaul connectivity. Although IAB can operate in any frequency band but from a deployment perspective, to maintain network quality mmWave is ideal. IAB can use the same frequency that is used for access for backhaul, or it can also have different frequencies for access and backhaul.

IAB Pre-requisite

IAB has got some prerequisite conditions for implementation

• The gNB should be split into CU and DU
• Mm-Wave Deployment

IAB Donor

IAB donor is a gNB that is directly connected to a backhaul by fiber and provides network access to UE and wireless backhaul connectivity to other IAB nodes. The IAB donor connects with the IAB node using the New Radio access interface and communicates over the FI interface. The Routing functionalities are performed by BAP (Backhaul Adaption Protocol).

IAB Node

IAB node connects with IAB donor and subsequently connected to another IAB node. It provides radio access to UE and backhaul connectivity to the downstream IAB nodes. The IAB can use a separate antenna called Mobile Termination (MT) for Backhaul traffic, or it can share its access antenna for Backhaul Traffic and UE traffic.

IAB Advantages

• The solution comes integrated with the gNB; hence no additional site infrastructure is required.
• The solution can be migrated to fiber when it becomes available.
• The solution can support star and cascaded topologies.

IAB Disadvantages

• As more IAB nodes are cascaded, it will increase latency in the network.
• Since the Radio Access BW is shared, capacity can be a concern at some point.

Use Cases of IAB

• Cell Densification
• To fill coverage holes
• Extension of coverage along street and highway

China Towers with 1.2 million communications towers is the global leader in terms of the total number of towers owned by the company. They are the primary infrastructure supplier to three major China National Carriers, China Mobile, China Telecom, and China Unicom, and is spread across 31 provinces in China. 

American Tower Company with 214,000 communications sites including 43,000 properties in the United States and Canada and more than 171,000 properties internationally is the leader in the Americas. They are a global company with infrastructure across the United States, Argentina, Australia, Brazil, Burkina Faso, Canada, Chile, Colombia, Costa Rica, France, Germany, Ghana, India, Kenya, Mexico, Niger, Nigeria, Paraguay, Peru, Philippines, Poland, South Africa, Spain, and Uganda. 

Indus Towers (formed by the merger of Bharti Infratel Limited and Indus Towers) with 183,462 towers and 332,551 colocations (as of 30th September 2021) has a nationwide presence in India covering all 22 telecom circles. Indus’ leading customers are Bharti Airtel, Vodafone Idea Limited, and Reliance Jio Infocomm Limited, the leading wireless telecommunications service providers in India by revenue.

Read “Top 12 – global 5G cell tower companies of 2021” to get info on additional leading global Tower companies globally.

The key business drivers resulting in upshoot of the number of towers include:

• Exponential data growth
• Upgrade of technologies from 3G to 4G and subsequently to 5G
• New Customer segments generated by Government initiatives.
• Growing subscriber base.

However, there are challenges and risks in this landscape.

Although there is much fanfare about the changes 5G will bring to both economy and society by the variety of use cases, there is not too much headwind available how that will benefit in a linear fashion with the operator revenues.

It is agreed that 5G will open up new avenues for revenue streams, but the market data shows a subsequent decline in ARPU (Average Revenue per user). This will, in turn, affect the tower companies too. The major risk for them are: 

• Consolidation happening in Operator Business
• Wireless carriers now opting for shared infrastructure
• Spectrum Sharing between different wireless carriers
• New Alternate technologies like WiFi hot spots

Startups like Sitenna are now helping tower companies to find space where they can install new towers. Daniel Campion and Brian Sexton, founders of Sitenna, saw a huge opportunity in mitigating the problems of tower companies. It has built an ecosystem where property owners can validate if their available real estate is suitable for tower construction. There is subsequent digitization involved in securing contracts and signing deals. It essentially creates a marketplace for landowners, tower companies, and wireless carriers. 

The company has kicked off its pilot with Vodafone and its Tower partner Cornerstone and has plans to foray into the US market soon. 

One of the major expenditures for Tower Companies is power provisioning at the cell towers. It is mostly based on electricity in urban areas, but in rural areas they are highly dependent on diesel. With rising awareness of clean environments, there has been a continuous focus from Tower companies to implement greener power like Solar Panels. 

As 5G has gained momentum in 2020 and 2021, activists have raised concerns over the radiation from 5G. Their fears were mainly that 5G radiation causes cancer, and it induces weakness that cripples the body’s immune system, leading to Covid-19. 

But scientific studies have explained and demonstrated that these are wrong perceptions and fears are overblown and exaggerated. 

Radiation from Cell Towers ≠ Radioactivity 

To understand the above statement, it is imperative to know how Telecom transmission works. According to some research, 5G will have lesser risk than existing standards like 4G. The reason being 5G will have a dense network which will mean less radiated power, and also it will use beamforming to target specific users using directed beams. 

The statement that is doing rounds that 5G radiation transmits Covid-19 has been put as utterly bogus and baseless.