What Are Radio Access Networks (RAN)? Complete Overview

Looking for a complete explanation? Here’s what radio access networks (RANs) are, the different types of RAN, how RANs work, RAN architecture, RAN components, and the 5G future for Radio Access Networks.

What is a Radio Access Network?

Radio access networks are the part of a communications system that traditionally connects cellular wireless capable (eg. 4G LTE, 5G) devices back to a public and / or private mobile core network via an existing network backbone.

Specifically, cell phones and other devices send and receive radio signals from the RAN network’s radio transceivers to connect to the core network.

Types of Radio Access Networks

There are many different types of radio networks, mainly GRAN, GERAN, UTRAN, and E-UTRAN. There are also a few other types, such as CRAN, VRAN, and ORAN.

GRAN: GSM Radio Access Network

Global System for Mobile Communications (GSM) is one of the earliest technologies seen in RANs, and was first introduced for protocols in the second-generation 2G cellular networks. After first being deployed in the late 1990s, it quickly became a global standard by 2010 with the mass adoption of 2G technologies.

GERAN: GSM EDGE Radio Access Network

This network standard uses the Enhanced Data Rates for GSM Evolution (EDGE) cellular technology that helps improve data transmission, and acts as a backwards compatible addition to standard GSM. EDGE technology was first used on GSM networks in 2003, and delivers three times the capacity and performance compared to GSM/GPRS alone.

UTRAN: UMTS Terrestrial Radio Access Network

This is a form of RAN that is responsible for connecting user equipment (UE) to the core network. The network consists of base stations and Radio Network Controllers which take the signal of a cellular device and process into the core network. The technology behind UMTS RANs are more commonly known as 3G to the public, and was the first form of RAN to make the first generation of smartphones possible.

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E-UTRAN: LTE UMTS Radio Access Network

This RAN was the next evolution of UTRAN that rolled out a new air interface system that could provide better data rates, lower latency, but most importantly was optimized for packet data. This form of RAN also began to use ODFMA digital modulation which dramatically helped reduce interference.

CRAN: Centralized RAN

Sometimes referred to as Cloud-RAN, this type of RAN architecture uses cloud computing as the core of its network and data processing for cellular signals. CRANs take advantage of different types of new technologies like the CPRI standard, which gives CRANs the ability to transmit over long distances reliably from a centralized tower deployment.

Notably CRAN also uses real-time visualization to allocate shared resources dynamically, and support multi-vendor environments. CRAN was the first RAN to use cloud computing and IT infrastructure to provide cellular improved cellular coverage, capacity, and reliability.

VRAN: Virtualized RAN

VRANs further leverage the virtualization seen in CRANs to support the evolution in cellular technology, especially 5G. This virtualization helps remove hardware restrictions across RANs and allows for better interoperability and communication across multi-vendor devices and networks.

VRANs will ultimately help the entire network as all vendors are able to communicate and adjust  cellular resources to improve the user experience as signals are handed off.

ORAN: Open Radio Access Network (Open RAN)

ORAN or Open RAN is an architecture as well as an organization that works to improve RANs through disaggregation of the elements of a RAN, as well as their instantiation in software based on open source technologies and open standards. Currently hardware across RANs is vendor specific, which can add to the cost of a RAN, as well as the flexibility to customize the network for your own needs.

An ORAN seeks to use software-defined elements deployed on standard servers to reduce costs and increase flexibility. 5G makes ORAN possible for large-scale private networks that serve IoT devices, autonomous vehicles, and smart cities. However, this technology is in its very earliest stages of development and requires a software-defined approach to eliminate the need for dedicated cabling and expensive effort to integrate technology solutions from multiple different vendors - in order to be fully accessible within enterprise environments.

Each of these types is a specific implementation of a radio network, but here’s how most Radio Access Networks (RAN) work in general.

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How does a Radio Access Network work?

At high level, modern RAN networks utilize radio transceivers to connect devices to the internet. RAN base stations that are part of a public mobile network are connected via fiber cables, microwave or other methods and aggregate signals to be sent to the public mobile core network. This is often referred to as backhaul.

The very latest RANs often feature a controller which uses software-defined networking (SDN) to control cellular device coverage and capacity. By leveraging software and network function virtualization (NFV) these signals are able to be processed and transmitted at the speed and capacity needed to support 5G and future generation technologies.

The use of separate control, data, and management planes will be key for modern RANs in the future. This separation allows for improved privacy and security, as well features such as network slicing which will be at the cornerstone for reliable 5G wireless communication.

These RANs give mobile network operators (MNO) and enterprises using private LTE or private 5G the ability to enable network slicing, which allows an MNO to assign capacity to individual enterprise locations when splitting usage within a public mobile network.

Once made ready for enterprise environments, it also opens up the possibility for parts of a private LTE / 5G wireless network to support individual device groups and applications, such as autonomous vehicles or long distance IoT-based logistics in a private LTE / 5G network. Here at Celona, we have done exactly that with our unique Celona MicroSlicing™ technology.

At its core, RAN architecture simply connects devices to other parts of a network using radio signals. In modern RANs these signals are brought into the mobile core network and delegated by a RAN controller.

Components of a Radio Access Network (RAN)

In public Radio Access Networks a cellular device is often referred to as a UE or user equipment, this UE will facilitate a connection between a base station. This base station contains a Remote Radio Head (RHH) sometimes referred to as a Remote Radio Unit (RRU).

This RHH acts as a transceiver that connects to a centralized Base-Band Unit (BBU) pool. The BBU pool is usually centralized at a cloud or data center, and consistent with multiple nodes that are responsible for processing incoming signals, and dynamically allocating them to RHHs based on the current capacity and needs of the network through fronthaul links.

The BBU pool sends the UE data to the mobile core network for transmission via fiber or microwave backhaul links. Inside the mobile core network for a 4G LTE public mobile network, the EPC or Evolved Packet Core helps unify cellular data over internet-based protocols for further processing.

The EPC for 4G LTE wireless is made up of three components:

• Serving Gateway (S-gateway) - Sends packets across the network to their destination.
• Packet Data Node Gateway (PGW) - Acts as a bridge between the LTE network and other networks to provide QoS, packet inspection, and dynamic traffic optimization.
• Mobility Management Entity (MME) - Manages the different states a session may enter during handover and is responsible for authentication and identification of the UE.

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Why Radio Access Networks?

RANs offer LTE and 5G with what’s known as “deterministic” wireless performance, which means it can deliver ultra-reliable connectivity.

Traditionally the only way to get LTE or 5G was through a public commercial network owned by a mobile operator like Verizon, AT&T, T-Mobile, or Sprint. Having to pay-per-bit to send sensitive information over someone else’s network was not a great alternative to Wi-Fi.

But now, spectrum sharing options such as CBRS in the United States enable enterprise organizations to build and operate their own private mobile networks with LTE or 5G.

Once made accessible within the enterprise utilizing the right architecture and deployment framework, private LTE and 5G networks offer the superior performance required by enterprise organizations like warehousing, healthcare, manufacturing, and many more.

Private LTE & 5G RANs for Enterprise

Some enterprise organizations require the high reliability, tight security, wide coverage, and large capacity that only LTE and 5G wireless communication can offer. Use cases for private mobile networks span multiple industries across hospital clinics, college and university campuses, mining sites, factories, warehouses, transportation facilities (railroads, airports, shipping ports), and public venues (hotels, stadiums, amusement parks, government facilities) - where mission critical wireless connectivity is a must have for enterprise owned and staff operated mobile and IoT infrastructure.

Celona partners with organizations to help plan, deploy, and manage private mobile networks for enhanced reliability, speed, and capacity. We offer a specialized, pre-built product architecture that utilizes AI to automate connectivity and signal health across the RAN.

If you’re interested in learning more about RANs, or how Celona can help make private LTE / 5G wireless connectivity fully accessible within enterprise environments, give it a closer look by taking one of our product journeys for a product demo or a free trial.