What is Backhaul in Networking? Functions, Architecture & Real-World Uses

Backhaul can be described as a set of wireless links, fiber which are needed for the connection of a major network to the subnetworks so users can access the internet. Its major function is to expand the coverage of the network.

In the article, we will learn more about backhaul, major types, and key applications.

What is backhaul

Backhaul is a huge basis for the wireless internet connection. In fact, there won’t be any internet connection if not backhaul.

Backhaul of the network has a specific hierarchy where all the connections are linked to the central network. This part of the connection is responsible for the communication with the internet. The access to the core network is received by purchasing wholesale commercial access.

There might be middle-mile networks between the Internet exchange point and the local area network (LAN). This might be a WAN link. Internet service providers are surely connected to the middle-mile infrastructure.

Theoretically, backhauls can be used everywhere, but practically, they are more popular in the mobile network. They are necessary for transmitting information from the base station to the mobile devices.   

What a backhaul network looks like

To route information from one end to the other and back on the internet, there should be several segments for the process completion. Here are some of them:

• Access network for linking the endpoint and the network.
• The primary network is needed for information distribution to the secondary network.
• Backhaul is a connection between the access network and the core network.

Backhaul connection may include wireless, optical, and fiber components. Several important criteria should be considered when planning backhaul, it is transfer rate or bandwidth and also latency. Backhaul directly impacts the flexibility, interruption, and speed of the traffic that reaches the end-user.

Main types of backhaul

Let’s discuss the main types of backhaul, which can also be divided into additional categories.

1. Wired backhaul

As is clear from the name, this type of backhaul predominantly consists of wired lines, usually over fiber-optic networks. In some situations, connections can be made over copper-based T-1 lines. Of course, fiber-optic networks are way better in terms of capacity and speed.

Here are the main subcategories of wired backhaul:

• Copper line. This is a technology mostly used for 2G and 3G. This variant was very popular at some point, but it has been mostly replaced by fiber.
• Dark fiber. This material is specifically needed for the wireless carriers. These fibers can be rented by wireless carriers in the form of 2 to 12 fibers in total.
• Ethernet. This option gives a huge capacity of bandwidth and is fully controlled by network service companies. This type is mostly used by enterprises.

2. Wireless backhaul

Wireless connections are possible to achieve with microwaves. Usually, to get such connections, a microwave dish is installed on the top of a cell tower. Specific antennas are used to transmit the signal.

Cell sites in isolated and rural locations need less bandwidth, and wireless backhaul is focused on reaching these locations. Microwave technology could not reach traffic requirements in urban regions.

For the transmission of image and sound data, there is used licensed wireless spectrum called mmWave.  

3. Satellite backhaul

This type of connection is used in case of emergency and is considered to be a niche solution for the rare case scenarios. For instance, when there is a disaster zone which imminently requires connection.

This technology offers access to a capacity of 10 – 150 Mbps. However, there might be some risks with latency, and there might be some delays.

4. Wi-Fi backhaul

Wi-Fi backhaul functions by placing a femtocell in the user’s place to guarantee wireless connection in/outside this specific location. Also, this connection offers access to alternative options for users who are outside their home. That’s why it is possible to get a connection even when you are not in the service area of your provider.

Instead of connecting to a cell site, an access point (wired Ethernet backhaul) is applied for the Wi-Fi backhaul. They function as transport nodes and deploy access points at the network’s periphery.

As a result, Wi-Fi backhaul makes it possible to enhance the capacity and coverage of the wireless carriers. This is a great solution for the locations where other options are either unavailable or too expensive.

Difference between fronthaul and backhaul

Fronthaul is a part of the connection that is necessary for the front-end interface. The backhaul is the part that is needed for linking the data channels with the front interface.

For instance, in C-RAN or centralized radio access network, the fronthaul describes the transmission from BBU to RRH. Because of this fronthaul technology, wireless carriers can use baseband and removable radio elements.

Now, let’s try to explain how front/backhaul functions together. From MSCs, information is transmitted to BBU via the backhaul, which can be done with Ethernet lines (more often than not). Then fronthaul starts when data is transmitted from BBU to RRH via backhaul. Users get the connection via CPRI.  

How backhaul works

Here is how backhaul functions:

• Backhaul data, including images and sound materials from the wireless mobile base station, is transmitted to the MSC or other possible central points of exchange. After that, the transmission is done to a wireless telecommunications network. Also, this approach is needed for the traffic relocation from the mobile station to the cell tower.
• The process of transmission is usually done via microwaves or fiber/copper. An MSC, or mobile switching center, is a place where internet routers are installed by the carriers. The connections transmit data to the MSC.
• Fiber connections are mostly used in dense urban areas, whereas microwave is more often used in rural and isolated areas such as mountains, islands, and more.
• Most cell towers are usually linked with fiber optic networks in developed markets. Whereas copper lines can still be used in developing ones.
• Let’s review how backhauls function when taking a phone call as an example:
• A signal from the mobile phone is sent to the antenna by a radio frequency spectrum.
• These radio waves are converted into backhaul in the cell tower.
• This signal is then sent to the aggregation station via backhaul.
• Then, before the delivery, traffic is consolidated.
• The call signal is taken from backhaul and changed in the needed format, and uses a cell tower to reach the needed user.

Who uses backhaul technology

The backhaul technology is predominantly used by governmental organizations, fiber providers, and wireless carriers. If talking specifically, the companies that use this technology can relate to the telecommunications sector, such as T-Mobile and others. One of the wireless providers that uses backhaul is Verizon.

Backhaul can be a great choice for the suppliers of fiber optic services when the usage of the fiber is too expensive for them or the location is unreachable otherwise. Also, emergency response networks can rent such services in case of necessity.

Key applications of backhaul

The immense rise of data and video content also raises the demand for backhaul. Right now, backhaul has a key application in most spheres, so let’s review some of them.

1. Expanding public connectivity in a metropolitan area network (MAN)

Some cities use MAN, or metropolitan area network. They are needed to expand public connectivity in areas such as streets, parks, shops, and others. This connection is accessible to the users even without the cabling installed.

2. Enhancing operational security

With the use of this technology, it is possible to enhance operational security. Just imagine that the monitoring networks track possible criminal activity, but the link stops for some reason. In such a way, it is possible to miss crucial information, and the connection can be reinforced by wireless backhaul. Also, it is possible to get direct access to the Internet.

3. Supporting 5G deployment

5G backhaul may be wireless, wired, or fiber-optic and gives a broader possibility to the wireless carriers as well as private corporations. Such opportunities are open for the private and public sectors.

4. Solving mobile networking issues

Lots of mobile network issues can be solved with this technology, specifically, we are talking about 5G network densification and provision of more capacity. With backhauls, it is possible to lower latency, manage different services, and even increase capacity.

5. Strengthening private networks

Private networks give broader access to the IoT and other institutional settings. There is a huge need for capacity for enterprise apps, and backhaul can be a great option for this. This technology is an important component of private networks’ architecture.

6. Modernizing critical infrastructure

Critical infrastructure should be extremely safe and at the same time very accessible. This infrastructure was using restrictive technologies for a long time, but now everything is slowly changing. Lots of companies are starting to use 4G and 5G, and these technologies require backhaul.

Final thoughts

Backhaul is an extremely important technology that most end users don’t even know about. However, it directly impacts the internet experience, specifically for mobile users. That’s why companies and major organizations should try to understand this practice and use it effectively.