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YET ANOTHER O-RAN BLOG | THE PERSPECTIVE | HCL

October 9, 2020 |

Written by: Rahul Soundrarajan

Enterprise Architect, HCL

As part of the HCL’s 5G strategy, critical investments are being driven to enhance HCL’s play in the 5G O-RAN ecosystem. As the Radio Access Network (RAN) gets opened or disaggregated, there is plenty of scope for new players to provide radio focused or controller focused solutions. This is the 5G O-RAN buzz that has captured the telecom news and we in HCL’s Telecom Strategy and Solutions group (SSG) believe there is scope and opportunity for HCL to provide services that will help both vendors and CSPs to accelerate their deployment and improve RoI margins.

One of the key values the open-RAN initiative brings can be summarized below. It fundamentally challenges the way the network is traditionally built.

 O-RAN alliance
 O-RAN alliance

With its adoption, vendors are allowed to innovate in their focus areas (radio specific/controller specific) and deliver product-boxes such as a radio unit (RU) or controller unit (CU) or distributed unit (DU) implementing the RAN protocol stacks. Their adherence to standards will ensure they interwork with other vendor’s product boxes.

The splits:

In addition to opening the interfaces, standardization bodies have also proposed splits at various inter-protocol levels to gear the network to support a diversity of use-cases simultaneously. A traditional network blueprint now looks like fuzzy grey dashes (read grey cells).

An abstracted view of splits from NGMN is presented here. The splits not just provide options but the engineering requirements that need to be adhered.

Source: NGMN

Figure 1: Source: NGMN

The Cloud-factor | Virtualization | Orchestration

From O-RAN.WG6.CAD-v02.00 TR :

“The O-RAN Alliance seeks to improve RAN flexibility and deployment velocity, while at the same time reducing the capital and operating costs through the adoption of cloud architectures. A key principle is the decoupling of RAN hardware and software for all components including near-RT RIC, O-CU (O- CU-CP and O-CU-UP), O-DU, and O-RU, and the deployment of software components on commodity server architectures supplemented with programmable accelerators where necessary.“

Virtual Cu and DU

The challenges of scale and computation are resolved by encouraging the development of CU/DU software on a cloud-native environment. This way the challenges met by CSPs in sustaining the network would be arbitrated by an orchestration engine with an implementation-agnostic abstraction.

Virtual Cu and DU

Orchestration view

The orchestration defines specific interfaces to enable synergy between the virtualized CU/DU components. The near-real-time (RT) (RAN Intelligent Controller) RIC, O-CU-CP, O-CU-UP, O-DU, and O-RU are designed to be managed functions. APIs are engineered to enable even a multi operator coexistence. The management side constitutes service management and orchestration framework (including the Non-RT RIC).  

 O-RAN alliance

Figure 2: Source: O-RAN.WG1.Use case definitions | Operator A owns the site A and shares the PHY Layer (LOW) with Operator B (Shared O-RU).”In the NFV environment, O-RAN network elements can be implemented in a virtualized form, and thus include an infrastructure layer (e.g. COTS/White Box/Peripheral hardware and virtualization layer) and an infrastructure management framework.

The HCL O-RAN Lab:

As this CSP-driven O-RAN initiative forces vendors to open their implementation to a common open standard, it births a new opportunity space for interoperability, verification, conformance and orchestration services. This forms the charter of the O-RAN lab. HCL’s SMEs and partner engagements are currently in action to enable these offerings.

Terminolog

Terminology & Tech soup

The O-RAN initiative is driven by the O-RAN Alliance group. The RU-DU interface is referred to as the Fronthaul which will run over eCPRI or RoE defined by IEEE. The interoperability testing scope is well defined by WG4  and the cloud orchestration of O-RAN Alliance is defined by WG6.

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