Modernizing RAN – Big elephant in the room | HCLTech

Modernizing RAN – Big elephant in the room
October 21, 2021

In our we talked about the low-hanging fruits that service providers can connect their hooks to for taking the first step toward modernization.

While an entire industry is talking about network transformation with cloud-native Open RAN (O-RAN) at the core, it is still far away from reality in an enterprise-grade carrier network. Great steps are being taken to accelerate O-RAN standard developments, innovation, and improved ecosystem collaboration by forming integrated alliances such as O-Ran Alliance and Open RAN Policy Coalition between service providers, communication operators, system integrators, and academic contributors to enable faster innovation.

The ideal state is to achieve open protocol and interface architecture (between various subcomponents). However, it is a bit of a journey. Despite living in this age of limitless competition and modernization, most of the operators are still pulling the cart of the Traditional RAN layer!

Open RAN

Figure 1 - Traditional to Open RAN Architecture Evolution

O-RAN ALLIANCE's mission is to re-shape the RAN industry towards more intelligent, open, virtualized, and fully interoperable mobile networks

Why RAN modernization is so important

The three primary building blocks of modern Radio Network management are:

  • Radio Unit (RU) – Responsible for radio signal transmission, amplification, and digitization. The RU is located near or integrated into the antenna
  • Distributed Unit – Responsible for real-time, baseband processing (L1/ L2) functions. The DU can be deployed at the cell site or concentrated in aggregated locations
  • Central Unit – Responsible for less time-sensitive packet (Higher L2 / L3) processing. The CU sits in central DC

Although 70% of the telco spend is on the radio side, many CSPs are still running the traditional RAN architecture, which spikes up the cost and limits the flexibility. Until 3G, the RAN deployment was primarily traditional/classic mixed with a lot of real estate logistics.

The traditional RAN system (Radio, Hardware, Software) is very much proprietary, a monolith, and locked-in architecture. Nearly entire infrastructure comes from a single vendor, and operators cannot mix and match (i.e., radio from one network equipment provider and x86 compute + software from another). Virtualization gave some flexibility to run software on the x86 commodity compute, allowing scalable and cost-effective network deployments. However, the interfaces between RAN components remain closed.

Traditional RAN

Figure 2 - Traditional RAN Deployment Architecture

It means there is no interoperability and closed/embedded architecture. This type of deployment was also termed as Distributed RAN (D-RAN). In this deployment architecture, the base station is located at the cell/tower site itself.

This deployment posed several challenges and continues to do so for CSPs who have not moved to modern architecture. These are often sized for peak capacity and remained underutilized.

In the event of burst capacity requirements, the network drops as it was not designed to handle bursts or presented limited scalability options. This was all proprietary hardware and designed with no open interfaces and support for multi-vendor interoperability.

With 4G, the RAN got re-defined and Centralized RAN (C-RAN) architecture evolved, also known as RAN disaggregation. This allowed split deployment: RRU stayed at the cell site while BBUs are aggregated at the central site, often referred to as edge-dc or BBU Hotel. This broke the 1:1 connection and architecture of RRU + BBU at the cell site and allowed the virtualization of BBU (virtualized proprietary design). By aggregating the BBUs, telecom providers can better organize their computing resources, which helps reduce the costs of maintenance and support.

With 5G RAN architecture, a segregation of the BBU operational capability is observed over two units: a distributed unit (DU) and the centralized unit (CU). The DU manages the real-time L1 and L2 scheduling operations while the CU oversees the non-real-time, higher L2 and L3. A cloud-based 5G RAN enables the DU servers and related software to be hosted on the site or in an edge cloud, which can either be a data center or a central office. This is determined by the availability of transport and the fronthaul interface.

With this, the CU servers and related software can either be co-shared with DU or be hosted in a localized cloud data center. This allows independent component scaling as compared to monolith (locked-in proprietary hardware) scaling.


Figure 3 - Difference between C-RAN, V-RAN, and O-RAN

O-RAN is an ongoing transformation in mobile network architecture that will allow networks to be built using components from a mix of vendors. The key concept is “opening” up the protocols and interfaces between the various subcomponents (radio, hardware, and software) to realize increased network agility, flexibility, innovation, and cost savings.

While this engineering is a work in progress, in the interim, the CSPs who want to prepare for the 5G rollout in hopes of a solid investment and future-proofing business should start with Radio modernization. It is expected that 80% of the global CSPs are still operating with Distributed RAN architecture, which is their major spend.

Modernizing the RAN architecture will not only reduce CSPs’ expenditure but also help them innovate, adapt, and accelerate their service rollouts. With 5G, we expect more speed, bandwidth, and connected devices (/KM2). But to do this, you need adaptive and dynamic network architecture. To cater to the increased demand, the sites need to be brought up in minutes, just after the radio is installed versus days in previous implementation architecture. All of this is only possible if the current RAN architecture gives way to modern technology and architecture.

As 5G RAN will start replacing traditional RAN, a lot of architectural simplicity and flexibility will come into play. No longer will the integrated hardware deployments from the network equipment providers be needed. Hyper-Converged Infrastructure (general purpose/commodity hardware) with a cloud platform for virtualization (VMs and Containers) will take over the white-box architecture. This will bring immense cost savings, multi-operator network function platform, eliminate vendor lock-in (reduction in professional services (PS) and DAY 2 Opex savings), improved security, and end-to-end visibility across the ecosystem.

Virtualized network slicing to cater to the edge and MEC use cases will get a runtime launchpad to roll out services in minutes versus months of project planning.

Without this change, telecommunication providers will continue to be seen from the lens of pipe/connectivity providers. This is an opportunity for them to board the train of change and become more agile and efficient.

Role and opportunity for information technology system integrators

This opens a big opportunity window for technology system integrators to leverage their smart ecosystem, cloud capabilities, complex information system, and networks technology modernization and transformation experience to accelerate the 5G journey for telco operators. 

HCLTech is positioned very strongly to deliver the integrated business technology solutions and information management services in the telco vertical space. Our investments in technologies, platforms, innovation labs, and frameworks such as , , Cisco SON, , , , Data Analytics, CloudSmart serve as testaments to our strong focus in 5G innovations aimed at helping our CSP customers maximize their 5G investments.


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