The growing deployments of 5G brings a new industry initiative called “Open RAN” (O-RAN). O-RAN is a broad movement that seeks to virtualize Radio Access Network (RAN) functions with standardized interfaces with a goal to maximize the use of common-off-the-shelf hardware and allow vendor diversity.
This is nothing but good news for Telcos building large-scale public cellular networks. Yet, the specific O-RAN architectures being espoused don’t fit well into existing enterprise IT infrastructures.
To step back, 5G deployments are on the rise. 5G introduces a new radio technology (5G NR) that brings with it a myriad of benefits, such as Ultra-Reliable-Low-Latency communications (URLLC) that effectively guarantees 1 to 10 milliseconds of packet latency while ensuring the reliability of a 10-5 to 10-6 packet error rate.
Combined with multi-gigabit data rates, 5G NR technology enables a truly wire-like reliability and seamless mobility while maintaining strict quality of service (QoS) for vital business applications that can’t tolerate any wireless problems.
Meanwhile, new private cellular spectrum bands are opening up for 5G NR worldwide, including the US (e.g., CBRS band), Germany, UK, Japan, and elsewhere. With this new cellular spectrum, enterprises can now own and operate their own local private 5G LANs without cost-prohibitive spectrum licenses.
However, O-RAN arcitectures require dedicated cabling, switches, and network control boxes that drive up cost and complexity.
Diving deeper into O-RAN
Driven by the O-RAN Alliance, Open RAN is a standardized framework to foster the interoperability between different virtualized cellular RAN functions running over COTS hardware through standardized interfaces.
O-RAN is implemented through the disaggregation of software from hardware which allows RAN software to run on any common hardware platform such as those based on Intel x86 and ARM architectures.
O-RAN seeks to create an avenue for introducing advanced RAN features and capabilities by building on the 3GPP standards and further specifying standardized open interfaces between RAN functions. This is achieved by leveraging a programmable open-software development approach.
Ultimately O-RAN aims to deliver additional flexibility to meet 5G application requirements such as 5G support for vertical applications with different network requirements for performance, capacity, or latency. Examples include Ultra-Reliable-Low-Latency Communication (URLLC) applications which are not fully supported in 4G LTE networks. This requires a flexible, software-programmable RAN architecture to accommodate the various vertical applications. For instance, with open programmable RAN interfaces, a centralized and virtualized baseband can provide pooled virtualized network functions that can dynamically allocate different resources through network slicing to efficiently create on-demand the requisite network service quality to fit the needs of the applications.
As fiber backhaul has become pervasive, so has an interest in virtualizing cellular network functions with the goal of following the cloud-native operation model. O-RAN takes this idea of virtualized software model and applies it to the RAN using common off-the-shelf (COTS) hardware to split radio functions and run them on distributed hardware platforms. O-RAN essentially breaks down the RAN into three key software components:
- The Remote Unit (RU) that performs lower layer signal and radio processing and RF functions
- The Distributed Unit (DU) that performs packet scheduler and MAC layer functions
- The Central Unit (CU) that performs the high-level packet processing and cyphering type functions
Since the RAN functions above have very strict delay and bandwidth requirements, typically, a very high speed and high-quality dedicated fiber cabling are required to connect them.
For mobile network operators, O-RAN architecture typically translates to RUs being deployed on top of the cellular tower or a lamp post. DUs are deployed as so-called "baseband units" (BBU) under the cellular tower or can be further aggregated into "BBU hotel" or in the central office, which is connected to the cell site over dedicated fiber. Finally, CUs can be further centralized in a regional data center similar to the cellular core network.
For indoor cellular deployments (e.g., venues) of O-RAN, the same architectural approach is preserved, and deployment looks very much like a traditional distributed antenna system (DAS). Essentially, traditional RF coax cables are replaced with high-quality cables such as fiber directly connecting multiple RU radios with multiple DUs deployed as baseband units in IDFs or equipment cabinets, further connected to a CU located inside the MDF or the basement equipment room.
Enterprise O-RAN to the rescue
But for enterprises, this type of Telco-driven O-RAN model essentially means a totally separate infrastructure just like a DAS system. With O-RAN, the cost and complexity are even higher due to high-end cabling like fiber and many separate baseband units that must be installed to connect all the various virtualized components.
Also, note that traditional cellular networks are composed of individual components that are sourced from multiple vendors and integrated by the mobile network operators. While this model continues in the telco 5G ecosystem, including the RAN, mobile core network, and orchestration layers, it does not work for enterprises because it leaves the heavy burden of integration to enterprise IT staff or system integrators. What’s more, enhanced 5G features such as network slicing with strict SLA requirements dictate tight integration from end-to-end.
Most enterprises don't want the complexity, cost, and massively long lead times associated with building an elaborate cellular network. Instead, they are looking for an all-in-one 5G LAN system. For the enterprise, simplicity, affordability, and seamless integration are imperative. Look no further to the evolution of enterprise Wi-Fi to see why.
Wireless LAN solutions typically come from a single vendor with a complete system that includes access points, controllers, and management platforms – all pre-packaged and tuned to work together.
Emerging enterprise 5G LANs should mirror this model.
Fortunately, new private mobile network platforms have emerged that deliver both integration as well the ability to disaggregate the RAN when and where it’s required. This means an enterprise can deploy a 5G LAN in a familiar fashion to Wi-Fi, and over time, move different radio functions in software to the core software system where and when they need.
Though there will be cases where large enterprises with extensive IT resources will embrace Telco driven O-RAN model to achieve the highest level of agility, the vast majority of enterprises looking to embrace 5G will want end-to-end 5G solutions designed for them, not the carrier.
Given the profound benefits of 5G technology, the widespread adoption by enterprises is undeniable. But to get there, a 5G radio access network should be deployed as an overlay on top of the enterprise LAN, just like a Wi-Fi network that uses the existing Ethernet cables, switches, and network policies already in place.
This approach radically reduces cost but also fully integrates the private 5G networks with the existing enterprise IT infrastructure to give organizations a clear path to capitalizing on the value of 5G.
Mehmet Yavuz is Co-Founder and CTO of Celona.