Solution brief Communications Service Providers Cloud RAN Aricent* Demonstrates 4G Cloud RAN Evolution to 5G Using FlexRAN
Aricent’s cost-effective Cloud RAN offering leverages FlexRAN reference solution running on Intel® architecture servers to provide mobile network operators (MNOs) with a flexible, high-performance Cloud RAN solution that can evolve to support 5G networks.
Introduction The need for mobile bandwidth has been growing exponentially, making it necessary for mobile operators to scale their wireless networks and use of advanced wireless technologies. Demand for mobile data is increasing, and with introduction of new technologies, the expansion of existing networks puts pressure on operators’ capital and operational expenditures. Mobile network operators (MNOs) are turning to network functions virtualization (NFV) to flexibly and cost effectively support increased demand for mobile data services. This virtualization is essential for emerging 5G networks that deliver significant increases in bandwidth. MNOs expect the availability of higher- bandwidth 5G networks will drive increased data service demand. One part of the 4G and 5G network that can benefit significantly from virtualization is the radio access network (RAN). By virtualizing RAN functions, MNOs can move this functionality into the cloud (Cloud RAN). This is realized by replacing specialized hardware with general- purpose switches, storage, and servers powered by Intel® Xeon® Scalable processors. As the software is decoupled from the underlying hardware, the solution becomes more software-centric, which drives improvement in research and development cycle speeds and a reduction in total cost of deployment. Also, with Cloud RAN, MNOs can build out their infrastructure to support average cell loads instead of peak loads as new RAN services can be turned up quickly in the cloud data center. Cloud RAN reduces cell-site hardware costs through the use of common off- the-shelf servers and increases the utilization of the CPU cores by pooling traffic from multiple cells, which better handles peak and non-peak data traffic. Cloud RAN solutions also help in centralizing processing across multiple cells (at radio resource management (RRM) or L2/PHY layer depending on deployment), improving the overall network performance. The architecture provides a virtually edge-free network using spectral efficiency improvement features, such as coordinated multi-point (CoMP) transmission and enhanced inter-cell interference coordination (eICIC). Intel® Network Builders ecosystem member Aricent* is evolving its 4G Cloud RAN solution to support 5G networks.
The Solution Aricent leverages its end-to-end product engineering services and world-class eNodeB software to enable RAN solutions based on the Cloud RAN architecture supporting FlexRAN reference solution architecture. Solution Brief | Aricent* Demonstrates 4G Cloud RAN Evolution to 5G Using FlexRAN FlexRAN Solution Supporting this functionality is the FlexRAN SDK, which FlexRAN is a software-based radio reference architecture provides optimized signal processing libraries for Intel® developed by Intel to enable Cloud RAN in a variety of architecture CPUs; the FlexRAN Task Controller, which flexible configurations. The block diagram in Figure 1 shows facilitates scaling across multiple CPUs; and the Data the FlexRAN PHY Application, which takes radio signals from Plane Development Kit, which delivers platform services the RF front-end and provides real-time signal and physical such as high-throughput packet forwarding and memory layer processing adapted for servers that use Intel Xeon management. The FlexRAN platform is designed to run on Scalable processors and Intel Xeon D processors. WindRiver Titanium Server* as the NFV infrastructure.
FlexRAN Reference Application 3G Release 5G NR in development
FlexRan SDK FlexRan Task latform FlexRAN Test (module level Controller Services Infrastructure kernels optimized for (task oriented Intel® architecture software architecture D DK instruction set) Test MAC for task distribution) Test App nit Tests NFVI Radio Mode (Wind River Titanium Server) Testing Intel® Intel® Network Acceleration rocessors Cards Options Intel® Xeon® Scalable Intel® Gigabit Intel® F GA rocessors, Intel® thernet Controller Intel® uickAssist Xeon® D rocessors Technology
Figure 1. FlexRAN architecture
Aricent Cloud RAN Solution Based on FlexRAN As shown in Figure 2, Aricent offers a flexible architecture This FlexRAN solution was chosen by Aricent because it with different functional splits and fronthaul interface accelerates time to market for its solution. An important options. In this architecture: feature to the Aricent solution is FlexRAN’s ability to enable • Central unit (CU) functionality includes operations, and optimize macro- and small-cell solutions and support administration, and management (OAM), RRM/self- high-capacity and low-capacity use cases for rural and organizing network (SON), layer-three routing, and packet dense environments. The Aricent solution complies with all data convergence protocol (PDCP). industry standards set by the 3GPP,* TIP,* and the Open RAN (O-RAN) Alliance,* making it interoperable with other vendor • Distributed unit (DU) delivers radio link control (RLC), solutions. media access control (MAC) and upper-PHY or complete PHY services (as applicable). Aricent offers mature and proven eNodeB software frameworks for realizing Cloud RAN solutions. For 5G, the • Remote radio unit (RRU) corresponds to radio part and Aricent Software Framework solution supports fronthaul lower-PHY (as applicable). interfaces including enhanced common public radio interface (eCPRI) and radio over Ethernet (RoE) based on the Realization of RAN Split Option 7-x O-RAN interface specification. The company is working with There are multiple deployment options that can be realized Intel to integrate the software framework with Intel’s sub-6 for 4G LTE virtualized-RAN architecture (using FlexRAN GHz and millimeter-wave reference solutions. architecture), and salient factors of the Aricent solution include the following: Aricent Cloud RAN benefits from network function virtualization (NFV) for the centralized processing of • Support for both Ethernet-based fronthaul and common wireless functions. public radio interface (CPRI)-based fronthaul • In Ethernet-based fronthaul, there are multiple deployment options that are available:
2 Solution Brief | Aricent* Demonstrates 4G Cloud RAN Evolution to 5G Using FlexRAN
eNB Intel® eon® rocessor Based Server RRU MAC R C ARICENT Core ET ERNET RRC RRM SON Option DC GT RF MME SS CRF
S MME RRU R C MAC SON RRM ET ERNET (S ) ower ET ERNET Option DC U ER RRC SG G EMS RF GT S U ARICENT
RRU RRC RRM SON C RI E C Option RF DC GT MAC R C
Figure 2. Aricent RAN split options*
• Option 1: CU+DU and RU-based architecture with (OR) Ethernet as fronthaul based on RAN Split Option 7.x • Option 3: CU+DU and RU-based architecture with CPRI • Option 2: CU, DU and RU-based architecture with as fronthaul based on RAN Split Option 7.x Ethernet fronthaul based on RAN Split Option 7.x (and The Aricent software architecture for an Option 2 type of option 2 split between CU and DU) split with RAN Split Option 7-x, running on an Intel Xeon processor-based server, is shown in Figure 3.
Central Unit
L3 VM S A (I ) C OAM SON RRM GT U a er (Aricent VM Guest OS: CentOS or 3rd arty) S U (I ) L2 VM
DC
VM Guest OS: CentOS A (I ) L2 L L VM L2 L L VM eNB MAC R C ...... MAC R C n (Aricent Linux bridge / U (I ) or 3rd L Aricent D DK L arty) VM Guest OS: CentOS vSwitch VM Guest OS: CentOS
Intel® eon® processor based server ind River inux with D D
L L L L ... L L
Radio Unit Cell Radio Unit Cell Radio Unit Cell n RF RF ... RF
Third arty Intel L Aricent eNB ramework components thernet i/f Components (with modi ications)
Figure 3. Aricent virtualized-RAN architecture*
3 Solution Brief | Aricent* Demonstrates 4G Cloud RAN Evolution to 5G Using FlexRAN The key aspects of the Aricent solution supporting OAM, • Running stack components as part of different VMs gives RRM/SON, layer 3, layer 2, and layer 1 include the following: the flexibility to scale up/down the solution across the central unit. • Single S1 and X2 interface endpoints on a CU for all the cells. S1-AP and X2-AP for all the cells terminate at L3+ • Layer 1 can be flexibly split in upper layer 1 and lower VM on the CU. layer 1 in the following ways: • S1-U and X2-U terminate at layer 2 VM of the CU. Layer 2 • Option 1: Complete layer 1 shall be running in RU. can use the Data Plane Development Kit (DPDK) for data • Option 2: Upper layer 1 running on an Intel Xeon path acceleration. After upper layer 1 processing, data is processor-based server and lower layer-1 running on forwarded to the respective cell’s lower layer 1 running on RRU; upper and lower layer 1 interact using DPDK- DU. enhanced transport mechanism. • Multiple lower layer 2 instances, each serving multiple • Option 3: Complete layer 1 is running on an Intel Xeon cells (with support for carrier aggregation). processor-based server. • Aricent eNodeB stack components are built in a • Support for baseband unit (BBU) pooling framework in modular way to support virtualization and use the DPDK both layer 1 and layer 2 software for efficient usage of accelerator provided by Intel Xeon processor-based cores and improving the core-utilization factor. server to improve the system performance.
L1-L2 (VM) VM PHY PDCP PHY MAC UL RLC Aricent, DPDK RB Selection & IFFT DL Chain DL & UL HARQ Link Scheduler Management Adaption PRACH Front Processing WLS VM UL Chain L1-L2 Interface Resource Demux/Mux UL RLC CP removal & Half Cyclic Adaptation Allocator eGPTU Shift and FFT Controller PRACH RRC + S1AP+X2AP Compression / Decompression Control SAP Control Handling CPRI Conversion VM Encoder (MAC) + DL RLC OAM
MAC RRM DL RLC Encoder SON
Process Functional Block Threads
Figure 4. Aricent virtualized-RAN architecture*
The key benefits of virtualized RAN architecture include: with the plan to leverage the 4G FlexRAN architecture as a baseline and enhance it to meet 5G requirements. Non- • Solution can be run on virtualized general-purpose standalone (NSA) mode is currently under verification processors (along with field programmable gate array followed by support for standalone (SA) mode. (FPGA) for high-processing requirements like forward error correction, fronthaul processing, etc.). Ethernet-based fronthaul is being considered for 5G virtualized-RAN deployment and like 4G case, the focus is • Efficient scaling of resources (and cores) and scalability of on RAN Split Option-7.x (and in some deployments have the solution to meet capacity/performance requirements. Option-2 and Option-7.x split). • Load balancing of resources. The high-level software deployment model for 5G NSA • Concepts of pooling are employed for efficient utilization (combining 4G and 5G FlexRAN) is shown in Figure 5. In the of compute resources. below architecture, CU and DU shall be running on Intel Xeon processors, with PHY/layer-1 running in an Intel Xeon server • Leveraging the concept of centralized processing at layer 2. along with the RRU (for Option-7.x split). 5G Roadmap with FlexRAN To support use-cases and scenarios with low-latency Aricent and Intel have also collaborated in the 5G FlexRAN requirements, Aricent multi-access edge computing (MEC) to develop a virtualized RAN solution based on 3GPP Rel- solution can also be integrated as part of CU for 5G based 15 specifications for both sub-6 and mmWave scenarios, deployments.
4 Solution Brief | Aricent* Demonstrates 4G Cloud RAN Evolution to 5G Using FlexRAN
EPC PGW
MME MCG Split SGW bearer bearer
MeNB 5G SGNB-Central Unit (CU)
PDCP+eGTPU PDCP+eGTPU 5G L3+ 5G L2-U
RLC RLC EN-DC OAM SON PDCP Relay MAC RRM L3 S1U GTPU (RRC,X2AP, LTE L1 F1AP) X2U F1U
Air Interface F1-U Interface
5G/4G Non-standalone UE
Distributed Unit (DU)
4G 5G OAM DUMGR F1-U Air Interface RRC RRC RLC PDCP PDCP MAC RLC RLC 5G L1 MAC MAC
Aricent Intel
Figure 5. 5G non-standalone software deployment*
Support for Artificial Intelligence/Machine Learning in RAN As part of the 5G virtualized-RAN roadmap, Aricent plans to With networks becoming more complex, it is important to integrate the ML models within CU and DU and provide an make the network more intelligent and autonomic. This integrated solution to customers on Intel®-based platforms. can be achieved by applying artificial intelligence (AI) and machine learning(ML) techniques to the network. Some of Conclusion the areas where AI can be applied include the following: Aricent works with original equipment manufacturers to • Operations support system (OSS) plane develop and customize their LTE and 5G solution supporting FlexRAN architecture. By customizing the RAN solution as per • Core network (CN) FlexRAN architecture, Aricent virtualized-RAN based solution • Multi-access edge computing (MEC) can deliver significant business value, including: • RAN • Reducing risk through feature-rich and carrier-grade offerings. Within the RAN, the application of AI/ML can be categorized into two areas: real-time processing and non-real-time • Accelerating time-to-market. processing. • Solution availability on generic platforms. The ML model for real-time processing functionality includes • Extensive partner ecosystem with RRH suppliers. beam-forming, link-adaptation/power control, and other closed-loop functionality procedures that involve the air- • End-to-end product engineering services for Cloud RAN interface, while the ML model for non-real-time processing including consulting, design, development, integration, functionality includes handover optimization, mobility testing, support, and maintenance for a one-stop solution management, quality of experience (QOE) optimization, and for all engineering needs. related RRM/SON procedures. • Built-in flexibility for faster market response.
5 Solution Brief | Aricent* Demonstrates 4G Cloud RAN Evolution to 5G Using FlexRAN About Aricent Learn More Aricent is a global design and engineering company Find out more about what Aricent software frameworks innovating for customers in the digital era. We help our solutions can do for your company. To set up a call or clients lead into the future by solving their most complex meeting with an Aricent expert today, email marketing@ and mission critical issues through customized solutions. aricent.com. For decades, we have helped companies do new things and scale with intention. We bring differentiated value and capability in focused industries to help transform products, brands and companies. Based in San Francisco, frog, a global leader in innovation and design, is a part of Aricent. Aricent is a part of the Altran Group.
About Intel® Network Builders Intel Network Builders is an ecosystem of infrastructure, software, and technology vendors coming together with communications service providers and end users to accelerate the adoption of solutions based on network functions virtualization (NFV) and software defined networking (SDN) in telecommunications and data center networks. The program offers technical support, matchmaking, and co-marketing opportunities to help facilitate joint collaboration through to the trial and deployment of NFV and SDN solutions. Learn more at http://networkbuilders.intel.com.
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