What Is Backhaul? Meaning, Working, and Applications

• Backhaul is defined as the set of copper, fiber, or wireless links that connect the core (or backbone) networks with the smaller subnetworks towards the edge before users can access the internet by accessing the subnetwork. 
• Its role is to increase the expanse of network coverage. 
• This article explains the meaning, working, and applications of backhaul. 

What Is Backhaul?

When discussing access to the internet wirelessly, the term “backhaul” appears quite frequently. At the most fundamental level, a backhaul makes one‟s data communications access faster. In fact, users would not have any kind of internet connection if it were not for backhaul. The connection that flows from the wireless cell site to the internet is called the backhaul.

The backhaul component of a telecom network with a hierarchical topology comprises all of the intermediate connections that connect the central (or backbone) network to the minor subnetworks at the network’s periphery. 

Due to this, the definition of backhaul that is used in both the commercial and technical spheres often refers to the segment of the network responsible for communicating with the worldwide internet. It is acquired by purchasing wholesale commercial access to a core network access site, such as an internet exchange point.

Middle-mile networks may sometimes be found between the local area network (LAN) of the client and those exchanges. It’s possible that this would be a wide area network (WAN) link. The internet service provider (ISP) and also the high-speed world wide web are both connected to the middle mile infrastructure, which acts as a go-between for the two.

Although theoretically, backhauls might be utilized everywhere, the most typical kind of network in which they are deployed is a mobile network. Backhauls are used to transport data between base stations and mobile devices. Connecting a cell tower to the network infrastructure is the responsibility of the backhaul of a mobile network, which is also known as a mobile backhaul. Fiber-based backhaul and wireless point-to-point backhaul are the two primary approaches that are used to achieve this goal.

As capacity and latency requirements continue to rise in 4G LTE and 5G networks, many alternative technologies are being phased out in preparation for their eventual extinction. This includes technologies such as point-to-multipoint wireless, copper-based wireline, and satellite communications, all of which are no longer utilized extensively for backhauls.

What does the backhaul look like?

Routing information from one end (like your cellphone) to the other (like a website) and back is the most fundamental function that the public internet, as well as every other data network, is designed to carry out. However, this function is not entirely straightforward. Several different network segments are responsible for carrying out this task:

• • The access network is responsible for linking the endpoint devices to the network
  • The primary network is responsible for data distribution to the secondary networks.
  • The backhaul network serves as a connection between the core network infrastructure and the access network, as well as vice versa.

In this context, backhaul refers to the link between access nodes and the core network.

A local subnetwork is formed by a collection of mobile phones that can communicate with a particular cell tower. Now, the backhaul connection to the backbone of the ISP’s network serves as the starting point for the connection that exists across the cell site and the world at large (through a point of intersection).

This backhaul connection could include cables, fiber optics, or wireless components, depending on the circumstances. One could come across microwave bands, mesh network topologies, or edge network architectures inside the wireless sections. In order to transfer data packets from the cell tower to the microwave or fiber connections, the backhaul may also use a high-capacity wireless channel.

The planning of a backhaul network takes into account several criteria, the most important of which are the desired data transfer rate (often known as bandwidth) and also the length of time it requires for data to travel from one location to the other (also called latency). The backhaul has an effect on interruption, dependability, flexibility, and speed, all of which are traffic requirements that have a significant bearing on the end-user experience.

See More: What Is GSM (Global System for Mobile Communications)? Meaning, Working, Architecture, and Applications

Key types of backhaul

There are a few notable types of backhaul, some of which can be further classified into different categories:

Key Types of Backhaul

1. Wired backhaul

As the name suggests, the data is transmitted over wired lines in this type of backhaul. A vast majority of backhaul activity is carried over wired connections, typically over fiber-optic networks but also over older copper-based T-1 lines in certain cases. When it comes to the transmission of voice, video, and data traffic, fiber-optic systems are preferable to copper in matters of speed, latency, and capacity. A closer look at some of its subcategories will explain this in detail.

• • Copper line backhaul: Copper-based backhaul has been the predominant technology used for 2G and 3G backhaul at one stage. The T1/E1 protocol, which permits data transfer rates of 1.5 Mbps to 2 Mbps, is at the core of copper-based backhaul. Today, fiber has replaced most copper lines.
  • Dark fiber backhaul: This is the source material for wireless network carriers. They can establish their own services, operate their personal networks, and achieve performance levels that are customized to their own requirements thanks to this capability. For instance, black fiber is rented out to wireless carriers in the form of specialized fiber pairs, which generally include anything from two to twelve fibers in total. The wireless carriers then “light” the fiber using their own optoelectronics.
  • Ethernet backhaul: Ethernet backhaul is a transport service that is based on fiber that allows wireless carriers to enhance the coverage of their networks by securing the final mile of connection. In particular, Ethernet circuits with backhaul are offered for sale with huge capacities of available bandwidth and are completely controlled by network service companies. This type of backhaul is overwhelmingly used by enterprises.

2. Wireless backhaul

The transmission of audio, video, as well as data traffic is accomplished by microwave connections, which are enabled by wireless spectrum. This is referred to as a wireless backhaul or fixed wireless backhaul. For the purpose of backhaul, a microwave dish is often installed on top of a cell tower by the wireless carrier. When it pertains to point-to-point data transmissions, a specific variety of antennae, called a microwave dish, is used.

Because cell sites in rural, isolated, and hard-to-reach locations require less bandwidth, wireless backhaul that is based on microwave technology is primarily focused on reaching these locations. This is because microwave technology doesn’t have enough capacity to meet the data traffic requirements in heavily populated urban/suburban regions.

To transmit sound, image, and data components, wireless backhaul uses the licensed wireless spectrum, especially millimeter wave (mmWave) bands.

3. Satellite backhauls

Satellite backhaul is employed in peripheral areas (like distant rural areas) and occasionally as an emergency or temporary measure by MNOs. This type of backhaul is considered a niche solution (for example, a disaster zone or a microwave link area while awaiting license approval). 

Backhaul, in cases such as these, and in general, is utilized in emerging markets as well as mature markets for the purpose of playing a complementing function. This technology has a downlink capacity of 150 Mbps and also an uplink capacity of 10 Mbps. However, there is an issue with latency because a geostationary satellite has a delay of around 500–600 milliseconds for a complete round-trip.

4. Wi-Fi backhaul

The assistance of tiny cells at the periphery of a wireless carrier’s network is offered through Wi-Fi backhaul. This is accomplished by placing a tiny cell (also called a femtocell) in the residence of the customer in order to enable wireless connection services both within and outside the customer’s home.

Wi-Fi backhaul, on the other hand, offers an alternative method of connection to customers who are situated outside the house. In other words, it makes it possible for wireless services to be supplied in locations that are not within the service area of a wireless provider.

Instead of employing a connection to a cell site, the wired Ethernet backhaul that is provided by the consumer’s gateway device (also called an access point) is used for the implementation of a Wi-Fi backhaul. In addition to their roles as transport nodes, these remotely deployable access points offer cellular connection services at the network’s periphery.

As a consequence of this, Wi-Fi backhaul makes it possible for wireless carriers to densify their networks in a manner that is more competitive financially while simultaneously enhancing coverage and capacity. Wi-Fi backhaul is ultimately a solution that may be used in locations where conventional dark fiber or microwave connectivity is either unavailable or too expensive to provide.

Fronthaul vs. backhaul

Fronthaul is that portion of the cellular connection that is responsible for the front-end interface. On the other hand, the back end of the cellular system is referred to as the backhaul, and it is the section of the network that links the voice/data channels with the fronthaul.

In the context of centralized radio access network (C-RAN) architecture, the term “fronthaul” describes the transmission of traffic from the centralized baseband unit (BBU) located at a cell tower down to a tiny cell, which is also referred to as a remote radio head (RRH). The deployment of fronthaul frees wireless carriers from the need to manage and deploy fully-featured ground (or base) stations or cells. This enables the carriers to use removable radio and baseband components.

Here’s how the backhaul and fronthaul work together – at the very core, there are mobile switching centers (MSCs). From there, data is transmitted to the BBU through the backhaul, which can be either copper or Ethernet lines (usually the latter). The fronthaul begins from the BBU. Here, the carrier transmits data from the BBU to the RRH via the backhaul. Users receive their connections from the RRH via the common public radio interface (CPRI). 

See More: LTE vs. 4G: Understanding The 8 Key Differences

How Does Backhaul Work?

The working of backhaul can be broken down as follows:

• • Backhaul enables the transport of sound, image, and data components originating from a wireless carrier’s mobile base station or cell tower to the carrier’s mobile switching center (MSC) or other central exchange points, where transmission is then shifted to a wireline telecommunications network. Backhaul can also refer to the technique of relocating traffic from a mobile base station to a cell tower.
  • Optical fiber, microwave (through wireless spectrum), as well as legacy copper connections, are the three basic transport modalities that are used to backhaul multimedia traffic. Connections of a network that use fiber and copper are instances of wire backhaul, while connections that use microwaves are examples of wireless backhaul techniques. The mobile switching center (MSC) is a facility where wireless carriers install their internet routers or voice-switching machinery. These connections transmit voice, video, and other content to the MSC.
  • When it comes to backhaul, fiber connections are employed wherever it is financially viable, and this is especially true in densely populated suburban and urban areas. Microwave connections are often used to expand service in locations that are rural, isolated, or otherwise difficult to access (like ski resorts, mountainous areas, or islands), where the expense of deploying fiber optics would be prohibitive.
  • Most cell towers in developed markets, such as the United States and the United Kingdom, are linked together by fiber optic networks. While the predominance of copper lines for backhaul is substantially greater in developing markets like Brazil and India, this is not the case in developed countries.

The backhaul is the transport network that links the mast/access point (cellular base station), which is a component of the RAN, to a core network. The core network is where the majority of the computing resources are situated.

Cell towers are generally linked to one another (rather than in a straight line) by use of a circle of fiber-optic cable, in which a number of masts are ringed together to create hubs. The design of this network provides redundancy, which means that in the event that one fiber-optic network has a disruption, a second network can easily take its place. Following these rings is an addition of fiber-optic cable linked to all cell towers.

Whenever anyone makes a phone call, backhaul transport covers the distance between the wireless cell towers and the fixed-line fiber-optic infrastructure. For instance, the following processes would take place whenever a user made a phone call:

1. 1. Mobile phones send their signals to an antenna perched atop a cell tower by way of the radio frequency spectrum. This transmission occurs wirelessly.
   2. Radio waves on the spectrum are converted into backhaul by the base station of the cell tower.
   3. The signal is sent to market-level aggregation stations via a backhaul (like fiber), for example.
   4. After that, traffic is consolidated before being delivered to the cellular core network infrastructure.
   5. In the last step, the network takes the call signals from the backhaul and changes them into a format that can be comprehended by the spectrum at another base station. It then uses an available cell tower to reach the device of a new user.

Who are the customers of backhaul?

Wireless carriers, fiber providers, and government entities are some of the organizations that use backhaul services. Permanent tenants for backhaul networks include industry leaders in telecommunications like AT&T, Verizon, T-Mobile, and DISH Network. However, Verizon is an instance of a wireless provider that now has insourced major amounts of its backhaul requirements in some locations. 

Bulk consumers for backhaul services include the suppliers of fiber optic Internet services. When they need to connect to towers that are either too expensive to reach with fiber or too difficult to reach, backhaul is a smart option, as opposed to installing fiber.

Finally, public organizations such as emergency response networks, organizations operating at the municipal level (like schools, hospitals, and city municipalities), and privatized commercial mobile networks all rent backhaul equipment and services.

See More: What Is Network Topology? Definition, Types With Diagrams, and Selection Best Practices for 2022

Critical Applications of Backhaul

Demand for backhaul services is driven primarily by the worldwide rollout of 5G, the ongoing rise in mobile video content and data usage, as well as the geospatial coverage and network capacity extension being undertaken by wireless carriers. This demand is leading to a spike in need for high-capacity connections.

Critical Applications of Backhaul

Indeed, backhaul has vital applications in nearly every sphere of connectivity, particularly the ones outlined below:

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

Several cities use metropolitan area networks, often known as MANs. These networks, which basically leverage wireless backhaul to spread a high-bandwidth “Wi-Fi net” throughout an area, are used by these cities. Connecting to this network is possible for users or subscribers even if they do not have cabling installed in their homes or workplaces. They are able to depend on this network since the wireless backhaul makes it possible for reliable connections in locations such as shops, parks, and even city streets.

2. Driving more secure operations

Using backhauls, organizations may enhance the security levels of their operations. For instance, monitoring networks keep an eye out for criminal activity, but if the link suddenly drops, the system can overlook a crucial moment. This link may be reinforced through the use of wireless backhaul, which also enables last-mile aggregation. Direct connection may be obtained to the internet, which eliminates the need to go through a number of intermediary steps. These wireless networks are able to transmit thousands of data channels and enable data, video, and voice throughput, which is efficient and unfettered.

3. Supporting the rise of 5G

The use of wireless backhaul that is most significant and expansion-focused is 5G. The architecture of 5G backhaul, which can be wired, fiber-optic, or wireless, offers a number of possibilities to expand and enhance broadband access for wireless carriers and their clients as well as for private corporations working with 5G networks. These opportunities are available in both the public and private sectors.

4. Solving mobile networking challenges

There are a number of changes happening in networks that will lead to fresh challenges for wireless carriers and mobile virtual network operators (MVNOs). The provision of up to one hundred times more capacity is among these problems; another is the management of 5G network densification. Backhauls provide an opportunity to address and overcome many of these issues.

Backhauls, in particular, are crucial in the deployment of additional cellular sites that have increased capacity, lower latency, and the ability to manage various services. When designing, identifying, and purchasing new cell sites enables operators to minimize dependence on the availability of fiber as well as the practicality of using fiber.

5. Strengthening private networks

Private networks are quickly becoming the preferred method for supplying broadband access to the industrial internet of things (IoT) environment, as well as to corporate campuses and other sorts of institutional settings. There is a large need for capacity from enterprise applications, multimedia traffic, and even fundamental intra- and inter-organizational communications. Backhaul, which is also sometimes alluded to as transmission networks, is a significant component of the architecture of private networks.

See More: What Is Wifi 6? Meaning, Speed, Features, and Benefits 

6. Modernizing critical infrastructure

Consumers of critical infrastructure have very stringent requirements, and they need their connections to be both accessible and safe at all times. Public health and safety services, utilities, transportation firms, and other specialists are examples of critical communications users. 

The currently available mission-critical networks are founded on specialized digital technologies, and as a result, they are voice-centric and restricted in bandwidth.

Despite this, the critical infrastructure sector is witnessing rapid change, and many public safety groups are exploring 4G and 5G technologies, both of which require backhauls in order to function properly.

FirstNet in the United States, Emergency Services Network (ESN) in the United Kingdom, and SafeNet in the Korean Republic are among the first examples of public safety broadband networks across the globe. Backhaul is, as it was in the earlier examples, the most important component in the process of constructing these mission-critical computer networks.

See More: GSM vs. CDMA: Understanding the 10 Key Differences

Takeaway

Backhaul is one of those essential network components working away in the background without the end user’s knowledge. Yet, they fundamentally shape internet experiences, particularly on mobile networks and devices. As 4G gives way to 5G and eventually 6G, last-mile connectivity is more important than ever before. This makes it essential for organizations to understand and utilize backhaul properly. 

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