VRAN vs. Open RAN: Analyzing the core difference!

The Radio Access Network (RAN) typically represents the majority of a network operator's capital expenses when constructing new wireless networks (CAPEX). The requirement for a significant amount of infrastructure and resources is characteristically the primary cause of this higher CAPEX.

Since its inception, RAN has been built on a monolithic architecture in which logical nodes and physical "proprietary" boxes hardly ever interact with one another.

Now, communication and collaboration between various components within radio and baseband units will be revolutionized by the Open and virtualized RAN, also known as O-RAN. The traditional expensive and rigid RAN is being replaced by a fully flexible, scalable, centralized, and cost-effective solution thanks to industry standards like Open RAN, Open vRAN solutions and C-RAN (Cloud-RAN).

The Equipment Footprint of the RAN

For its outset, RANs have operated according to a monolithic architecture in which each of their parts could only be used with a single unified unit, which consisted of a few connected proprietary "hardware" boxes.

The Remote Radio Unit (RRU) or Remote Radio Head (RRH) and the Baseband Unit (BBU), which can be connected using an outdoor (CPRI) fiber, make up the distributed units of a 3G or 4G RAN in most cases. For instance, hardware-based BBUs are typically positioned as close to the radio unit as possible in NodeBs used for 3G (UMTS) and eNodeBs used for 4G (LTE).

This baseband unit is typically housed in a cabinet at the base of the radio tower. The RRU and BBU's close proximity guarantees a low loss, increased security, and quickness. In addition, one BBU with a higher capacity can be front-haul connected to a number of RRHs and backhaul connected to the core network.

However, as a mobile network expands, the cost and upkeep of all this equipment tend to rise. The network becomes more rigid as more equipment is placed in use, and maintaining it costs more both in terms of money and labor.

The development of baseband and radio resource architecture

It is not a novel concept to separate the radio units and baseband units of Open and virtualized RAN. The practice of connecting RRHs to BBUs via protracted CPRI backhauls signaled the beginning of efforts to move away from rigid and expensive monolithic RAN architectures (source). This practice has become very popular, especially with the deployment of femtocells and microcells, where the adaptability and cost-effective radio resources were practically required.

As a result of all these efforts, the BBU can now be installed on the network of a nearby operator rather than on-site (i.e., a cell tower). This "remote RAN" was a significant step toward centralizing the entire RAN, and it was at this point that C-RAN was created.

Virtualized and centralized RANs

C-RAN, which stands for "Clean, Centralized processing, Collaborative radio, and a real-time Cloud Radio Access Network," gets its name from these four characteristics. A centralized cloud-based computing architecture called C-RAN was created for RAN. It supports all mobile network generations, particularly 5G, but also 2G, 3G, and 4G as well.

Across the entire mobile network, centralized RANs assist in concentrating the baseband operations on a smaller number of sites. Therefore, if a baseband unit is centrally located, it can also be virtualized (and containerized), which is how the concept of Open vRAN solutions came into picture.

On top of generic hardware, Open and virtualized RAN can function as a software instance. Moreover, different vendors can offer hardware and software components thanks to virtualization.

Open vRAN solutions in 5G rollouts

During the early stages of the 5G New Radio, these efforts to separate the traditional baseband (BBU) functions beyond the Radio Unit (RU) were pushed even further.

As an illustration, take Orange Poland, which is testing its new cloud-based radio access network as it continues to roll out 5G (as of July 2021). A virtualized baseband unit that is deployed in a 70-kilometer-remote data center and connected (BBU to RRU) front-haul via Ethernet transport media controls their radio sites.

This example shows that it is possible to run Open and virtualized RAN baseband functions on commercially available hardware rather than using a closed hardware/software single vendor with a proprietary box.

Over viewing the concept of Open RAN

The foundation for creating Open vRAN solutions deployed on open hardware and the cloud is called Open RAN (O-RAN). O-RAN was created using the concepts and tools of cloud-native virtualization (V-RAN) to address the problem of the absence of an adaptable and interoperable structure. Due to the interoperability of its components (hardware, software, cloud, or virtual), network engineers could combine devices from various vendors.

Engineers are given the option to select which unit should be deployed to which operation in order to maximize performance and achieve a balance between two frequently incompatible components thanks to Open and virtualized RAN.

The network engineer is given the choice to distribute Virtual Network Functions (VNF) across various components along a single path. The functional split is the term for this action. Despite the fact that the functional split was first used in 5G NR, it can also be used in 2G, 3G, and 4G.

How to locate if its OpenRAN?

It is crucial to understand that the Open and virtualized RAN concept differs from Open vRAN solutions or V-RAN. Not all radio networks would need to be fully virtualized with Open RAN. Numerous radios might still exist and be fully functional as particular pieces of standard hardware. However, while both Open V-RAN and V-RAN rely entirely on virtualization, the former is open and the latter is not.

The advantages of an open RAN

In addition to RAN components that can communicate with one another, Open RAN offers the following advantages:

Flexibility: Flexibility is offered by RAN component disaggregation. How, when, and where to deploy these network functions can be chosen by network operators. Additionally, what hardware/software solution should be used can also be determined.

Scalability: The Open and virtualized RAN architectures would offer more scalability in addition to flexibility. Network engineers can combine and match various RAN components as the network functions and expands as needed because hardware, software, and virtual components are interoperable.

Centralization: Virtualization was made possible by the operator's network's baseband resources being centrally located. Moreover, Network administrators can use virtualized BBUs (vBBUs) running on standard hardware to replace the massive number of BBUs that must be deployed on a data center for each RRU (antenna site). Besides, Network operators can minimize their hardware footprint by centralized resource management.

Cost reductions: Network operators would choose an open "disaggregated" architecture when they wanted to choose how, where, and when to deploy these network functions while also enhancing performance. Reduced equipment footprint and lower OPEX and CAPEX would result from the deployment of open software on generic hardware.

Open RN solutions

The Central Unit (CU) and Distributed Unit (DU) Radio Units (RU) concepts are used by the Open and virtualized RAN architecture to provide a functionality split (DU).

The CU and DU functions can operate as virtual instances deployed on common Commercial-Off-The-Shelf (COTS) hardware because the Open RAN functional split architecture is fully virtualized i.e Open vRAN solutions. This virtualization enables the deployment of numerous and various CU and DU functions on the same hardware in any RAN-based datacenter. RUs and DUs can function as containers or VMs as well.

For DU in a 5G Open RAN: The 1U rack-mountable Lanner NCA-4020 is an Open RAN appliance for DU in a 5G Open RAN. It can run multiple Virtual Network Functions and offers the best network performance (VNF).

For CU in a 5G Open RAN Lanner's HTCA-6200 can be used as a carrier-grade MEC appliance for CU in a 5G Open RAN. The HTCA-6200 is capable of providing the appropriate level of performance and time synchronization needed for mobile wireless communications.

Final words

Regardless of their distinctions, disaggregation of radio access network hardware and software is the aim of vRAN and Open RAN, which will aid operators in increasing flexibility, cutting costs, and meeting rising demand.

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