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Why Open vRAN for 5G Slicing?

September 28, 2021

With 5G comes the promise to have a network that can accommodate different types of connectivity products, for diverse industries, and for devices with varying quality of experience and performance profiles.

At the same time however, delivering Enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communication (URLLC) and Massive Machine-Type Communications (mMTC) on a single physical network, is creating more complexity. With diverse 5G use cases, the one-size-fits-all approach for building the network is no longer a viable option. To meet the stringent requirements specified by 3GPP for these capabilities, it has become necessary to create multiple customized logical networks (slices), over a physical network where each logical network can guarantee the service level agreement (SLA) tailored for a particular use case or industry.

A typical 5G network slice is comprised of the RAN, transport and Core slices in their respective domains. 3GPP Rel-15 and beyond considers the virtualization of network functions in each domain. This development can enable dynamic services creation. However, it also presents a new challenge of orchestrating the allocation of resources across multiple domains for each slice in near real time.

To address this complexity, two aspects have emerged as critical for its success- first, the ability to automate the function of slice creation across domains using a cross-domain orchestrator and second, the need to have standardized interfaces between disaggregated components within each domain.

Role of Automation – Automation plays a critical role in realizing the dynamic 5G network slicing tailored for each use case. Every aspect of network slice management from design to creation, lifecycle management and resource assurance must be automated across multiple domains, to meet stringent service SLAs. The dynamic workflows, composed using service models, policy and context must be implemented with minimal manual intervention. The move towards a vendor neutral hardware and software defined networks, will enable a fully flexible, interoperable, and disaggregated networks all the way down to RAN with standardized interfaces between the different RAN components.

Automation will also enable slices to scale on-demand based on needs and simplified workflows for failover and auto-healing of the network functions. Also, the commissioning time will reduce from multiple man hours to a few minutes thereby ensuring OPEX savings.

Relevance of Open vRAN – Mobile Network Operators (MNOs) have been exploring new approaches to address the challenges faced by 5G network slicing. Specifically, in the RAN domain, the concept of open virtualized RAN (Open vRAN) is emerging as a promising solution. Open vRAN separates hardware from software and disaggregates the RAN into Radio Unit (RU), Distributed Unit (DU) and Centralized Unit (CU) with standardized interfaces between them. Open vRAN can help operators support multiple slices with different SLA requirements, supporting a guaranteed performance and promise future scalability while still monetizing their 5G investments by embracing Open vRAN framework.

NEC is an early pioneer in providing Open vRAN solutions that inter-work through open interfaces defined by the O-RAN Alliance, and its own high-performance open standard hardware is pre-integrated into its partner ecosystem to help MNOs to scale their network slices with lowest total cost of ownership (TCO).


Following are key factors on how Open vRAN enables slicing in carrier networks:

1. Open RAN Orchestration

One of the major benefits of the O-RAN framework is to enable automation, and virtualization by defining open APIs enabling multi-vendor environments. MNOs can pick and choose radio network components from multiple vendors and support interoperability across vendor equipment and software.

Comprehensive network automation is crucial to maintain operational efficiency and to incorporate the dynamic requirement onto slices with no service interruption in this virtualized open network.

NEC, along with its subsidiary Netcracker, brings fully automated RAN slicing to the RAN domain. Netcracker’s new windowRAN Domain Orchestration solution (RAN DO) simplifies the design, deployment and operations of virtualized and container-based RAN workloads and provides the 3GPP NSSMF function for RAN slicing. It automates design, instantiation, and provisioning of cell sites for different slices, provides RAN self-healing and self-optimization capabilities and integrates the RAN domain with the MNO’s BSS/OSS and virtualization management systems.

2. Intelligence and automation - Use of AI/ML and advanced analytics

A key component of Open RAN Domain Orchestration is the new windowNon-Real-Time RAN Intelligent Controller (Non-RT RIC) which provides advanced RAN optimization and Radio Resource Management applications using Data Analytics and Artificial Intelligence (AI)/Machine Learning (ML). Intelligence is embedded in the Non-RT-RIC by means of advanced AI/ML tools, leading to network efficiency through simplified operations. Non-RT RIC plays a critical role in 5G network slicing by ensuring feasibility checks for RAN slices and monitoring long-term performance trends with AI/ML-driven RAN slice subnet KPI assurance.

Furthermore, in addition to the provisioning of the eMBB slices, creating uRLLC slices and continuously ensuring specific latency requirement in dynamic conditions is still a daunting task. The near real-time (nearRT) RIC can manage the RAN components (RU/DU/CU) to optimize radios, dynamically tuning the channel conditions in near real-time and ensuring the specific latency requirements based on AI/ML technologies.

3. Faster Time-To-Market (TTM) and flexibility of vendor diversification

MNOs have made significant investments in spectrum acquisition to deploy large scale 5G networks.  They are keen to offer new services using network slicing to monetize the network while reducing the TCO of building and operating these networks. 

Open vRAN brings more flexibility in choosing components from a variety of vendors that conform to its standards. This will foster an ecosystem of vendors and promote supply chain diversification and price competition among vendors which helps to build a network which is flexible, based on best-of-breed products and yet cost effective without introducing additional complexity. Open vRANs play a crucial role in reducing these costs and reducing TTM by enabling rapid innovation, vendor diversification, higher automation, and capacity pooling.

Summary

While operators plan to support end-to-end network slicing, they want to do it with a network that is flexible, scalable, easy to deploy and fully automated.

Open RAN systems with standard conformance enable operators to select best of breed solutions from diverse vendors, streamline operations through automation, perform intelligent dynamic dimensioning and independent resource management of each isolated network slice.

This helps MNOs deploy Network Slicing and achieve improved network performance with tangible cost savings.

                   Rahul Chandra
                   Vice President
                   Global 5G Business Development
                   NEC Corporation of America