RAN

Answering Your Questions on Open RAN Innovation: Diving into the Vodafone RIC Trial, Part 2

In our last blog, we shared highlights from our webinar discussing Vodafone’s latest milestone in radio access network (RAN) transformation. We talked about how the multivendor proof of concept (PoC) demonstrated that, using VMware’s RAN Intelligent Controller (RIC) solution in a 5G network, Vodafone could effectively double capacity at RAN sites. This is a huge achievement—and a testament to the power of Open RAN (O-RAN), as well as all the innovative contributions from VMware, Cohere, Capgemini, Intel, and others.  

The webinar also reviewed several groundbreaking O-RAN solutions that can run on VMware’s RIC—Polte and Airhop Communications. Near the end of the webinar, the assembled experts took questions from the audience on the future of RIC and O-RAN. Following is a summary of their insights.  

Moving Beyond Conventional Network Optimization  

A representative from Facebook noted that most of the discussion around RIC involves self-optimizing network (SON) functionality. He asked how the RIC in Vodafone’s demonstration was able to support multi-user, multiple-input, multiple-output (MU-MIMO)—a wireless technology that promises huge improvements in network efficiency, but that the industry has been slow to capitalize on in real-world networks.  

  • Rakesh Misra, Director of R&D, VMware: “VMware offers two flavors of the RIC: a Near-Real-Time (Near-RT) RIC, which can support functions that require sub-second latencies (technically, 10 milliseconds to one second, as defined by O-RAN), and a Non-Real-Time (Non-RT) RIC, which supports functions that can tolerate latencies greater than one second. SON functions, which are typically less latency-sensitive, run on the Non-RT RIC. MU-MIMO, however, requires near-real-time functionality to be useful for two key aspects of MU-MIMO scheduling: MU-MIMO user pairing and MU-MIMO user precoding. Both can be hosted as xApps on a Near-RT RIC, as the Vodafone deployment showed.” 
  • Ravikanth Pasumarthy, Chief Architect and VP of Technology, Capgemini: “RIC and xApp technologies open up a lot of possibilities. Certainly, that includes SON use cases, as well as others, such as use cases related to Radio Resource Management (RRM) and O-RAN Distributed Unit (DU), which can be realized as well. The key item to consider is the round-trip processing latency from the E2 node to the xApp (including the xApp processing logic). For use cases like MU-MIMO, the round-trip latency must be within the limits that can be tolerated for application control via the RIC at the E2 node. In this case, we were able to demonstrate that a near-real-time xApp can be applied to the DU node as well.”  
  • Joe Thome, Vice President of Business Operations and Marketing, Airhop: “One key capability of the RIC is to enable network optimization applications that can receive RAN data and provide closed-loop control back to the RAN. Those optimization applications are not limited to traditional SON capabilities. There is tremendous opportunity for RAN optimization, via xApp and rApp innovations leveraging the RIC, across a variety of latency-sensitive use cases like MU-MIMO.” 

Building a Multivendor Solution 

An attendee from Mobile Experts asked the panel to detail the specifics of the deployment used in the trial.  

  • Ben Basler, Senior Director of Product Management – Service Provider and Edge, VMware: “The trial system consisted of a Cohere xApp that was built using the VMware RIC software development kit (SDK) and hosted on the VMware Near-RT RIC. The VMware RIC interoperated with Capgemini Centralized Unit (CU) and DU RAN components via the O-RAN E2 interface. All key components of the solution—the Cohere xApp, the RIC, and the CU/DU—were containerized and running on VMware Telco Cloud Platform, and were orchestrated and lifecycle-managed via VMware Telco Cloud Automation.” 

Another attendee requested more details on the number of E2 nodes considered for the demonstration. Specifically, he asked whether there was one E2 node per CU User Plane (CU-UP), CU Control Plane (CU-CP), and DU, or just one E2 node managing all three elements.  

  • Rakesh Misra, VMware: “The trial system had three E2 nodes. For context, ‘E2 node’ is a general term used to refer to any RAN node or network function that exposes an E2 interface towards a Near-RT RIC. In the trial, each component (CU-CP, CU-UP, and DU) was a separate network function that exposed an E2 interface towards the Near-RT RIC. So, there were three E2 nodes in the system.” 

Virtualizing RAN Applications 

A representative from NEC asked about virtualization in the RIC demonstration. Specifically, he asked what the advantage was of using virtualization in the DU, if each DU then requires a dedicated hardware accelerator, such as FlexRAN, to operate.  

  • Ravikanth Pasumarthy, Capgemini: “Physicallayer (PHY) processing does require some acceleration for some of the critical PHY-layer modules. There are multiple offload mechanisms being discussed as part of the International Federation for Information Processing (IFIP) Working Group 6 (WG6) work as well. In a FlexRAN context, some of the Forward Error Correction (FEC) functionality is offloaded to the field programmable gate array (FPGA) processor, but the rest of the PHY software is running as containerized network functions (CNFs). This affords more flexibility when the system needs to scale-up or down capacity from the PHY perspective as well.” 

Applying RIC Innovation to 4G Networks 

An attendee from Appledore asked about the applicability of the RIC technology to 4G networks. He wondered whether RIC innovations like the one demonstrated by Vodafone might enable operators to get more capacity from their 4G networks—and potentially give them a reason to slow down 5G rollouts.  

  • Carlos Ubeda, Subject Matter Expert at Vodafone: “We believe RIC provides the necessary open framework to innovate in mobile networks. The xApp we demonstrated, which improves capacity in low- and mid-band frequencies, proves so. In the incoming years, we foresee a growth in new and groundbreaking use cases enabled by RIC that will contribute to enhance performance of current and future 4G and 5G deployments.”  
  • Joe Thome, Airhop: “RIC technology, along with xApps and rApps, provides operators with additional capabilities and flexibility for deployment, operation, and management of 4G, as well as 5G networks. In practice, we are seeing operators using RAN automation and optimization to stretch the capacity of their 4G networks. This can also help operators optimize network performance and manage the operational complexity of both 4G and 5G networks.” 

Delivering a “Spectrum Multiplier” Effect 

In response to attendee requests for more details, Prem Gopannan, Vice President of Product Architecture and Software Engineering for Cohere Technologies, offered an in-depth explanation of Cohere’s Spectrum Multiplier xApp for the VMware RIC:  

“Cohere Technologies has developed an O-RAN xApp that allows mobile operators to improve network and spectral efficiencies, and deliver new and differentiated experiences for their customers. VMware, Intel, and Cohere first showed a 4G PoC demonstration in February 2020, which generated a 2x spectrum multiplier effect on a 4G Frequency Division Duplexing (FDD) commercial network. As we entered 2021, VMware and Cohere demonstrated how a powerful platform built on O-RAN principles can further boost capacity by enabling MU-MIMO for 5G mobile networks in this trial with Vodafone. 

Cohere also evolved the Spectrum Multiplier’s channel estimation to include channel prediction, and developed a scheduler capable of running in the cloud as an xApp on the VMware RIC. As Vodafone recently announced, the solution dramatically increased total spectral efficiency, improving spectrum utilization by up to 2x for 4G or 5G networks. Used with VMware’s RIC in the VMware Telco Cloud, it also reduces the need for expensive and energy-consuming hardware in a mobile base station by up to a third. Together, Cohere and VMware can help empower operators to make better use of their spectrum assets to deliver bandwidth-sensitive services like augmented reality/virtual reality (AR/VR) streaming, 4K video, and immersive gaming, among others. 

Cohere is the first to overcome the complexity of accurate channel estimation and prediction for MU-MIMO. The result is a software solution that overcomes the roundtrip latency challenges of moving critical intelligence from the RAN to cloud. Cohere’s pioneering work in the Delay Doppler domain reduces computation complexity through concise channel representation. Since Cohere’s software takes advantage of existing user equipment (UE) feedback for channel measurement, no changes are needed to the 4G or 5G standards or to existing handsets. The longer “coherence time” enables Cohere’s intelligent cloud Scheduler to be deployed in an edge data center. This option forms the foundation for further improving cell edge performance via intercell coordination through Coordinated Multipoint (CoMP) techniques.   

The RIC is a new platform introduced by the O-RAN Alliance that enables CSPs to deploy cloud-native control and management applications in the RAN. Essentially, it draws on prior virtualization of RAN CUs and DUs, and exposes complex RAN intelligence that was previously embedded in closed base stations. The VMware RIC is an open platform that has been designed to keep the developer experience front and center. It provides an easy-to-use SDK for any third-party developer to build apps that can be deployed in the RAN. Today, most of these apps are geared toward making the network faster, including Cohere’s Spectrum Multiplier xApp. 

Start Your Journey to RIC Innovation 

Vodafone’s RIC deployment represented a major accomplishment on its own. But ultimately, we hope it inspires developers across the industry to start thinking about RAN innovation. For the first time, the RAN really is open to great new ideas from practically anywhere. And VMware has made significant investments to put developers front and center in the RIC ecosystem, and simplified xApps and rApps development. 

Rakesh Misra offered an overview of VMware’s RIC SDK, which companies like Cohere, Airhop, and Polte are already using to develop near-real-time and non-real-time RIC applications. The SDK includes everything needed to simplify the process of developing and packaging new RAN apps, including: 

  • API definitions and specifications 
  • Reference apps and starter code in multiple languages 
  • Core libraries for several value-added capabilities to help accelerate xApp development 
  • Custom resource definitions, schema, and examples 
  • Optional build tools 
  • Developer guide    

“We believe that true RAN innovation is possible only by opening the RAN up to a large ecosystem of vendors, and empowering them to easily develop new applications and features for automating, optimizing, and monetizing the RAN,” said Misra. “VMware designed our RIC SDKs to do precisely this.”  

Ready to start putting your own RAN ideas into action? The pre-general release RIC SDK—the same one Cohere used to develop the xApp used by Vodafone—is available now.  

And for more details on the Vodafone demonstration, check out the full webinar. 

We also welcome you to learn more about how we’re supporting the RAN transformation by visiting our websites: 

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