Today, mobile networks are overwhelmingly single vendor, where one company provides and manages most of the RAN equipment at a cell site. Not surprisingly, both the hardware – distributed units (DUs) and radios for 5G – and the RAN software are predominantly proprietary in these networks. Custom legacy network services, such as time-division multiplexing (TDM) interfaces are used to interconnect the 5G DUs and radios together at a given cell site. There, you may also find a single, third-party cell site router (CSR) to backhaul traffic to the mobile central office, but this is one of the few exceptions to the rule. Although there unquestionably are some efficiencies that a single vendor model can provide, this paradigm leaves service provides beholden to these vendors, limiting innovation and network transformation and handing pricing power to the vendor.
Mobile network providers recognized that they needed to dramatically change the status quo and initiated the Open RAN (O-RAN) initiative to bring interoperability and flexibility into the wireless domain. O-RAN brings open interface standardization into the RAN network, and with that enters the potential for true RAN network transformation.
Defining characteristics for O-RAN standards include:
- Virtualization: The ability to put DU and RAN intelligent controller (RIC) software on any x86-based server that is not connected to custom, dedicated hardware.
- Interoperability: Multi-vendor use – the ability to use the radio of one vendor, the DU software of another vendor and the RIC software of a third vendor to manage a given cell site. Other use cases include deploying different optimization algorithms from different vendors (x-apps and r-apps) to manage the network.
- Standardized and Packetized Interfaces: The ability to interconnect various defined functions of the RAN network with standards-based Ethernet/IP over fiber.
Based on these defining characteristics, RAN networks based on O-RAN concepts are built around new, innovative network topologies that more closely align with today’s cloud architectures than yesterday’s legacy mobile networks.
Virtualization allows the RAN software to be removed from the cell site and placed in edge datacenters. Many cell sites within a roughly 20 KM radius can be managed from a single edge datacenter. A simple, high bandwidth Ethernet/IP connection is run from the datacenter to each of the cell sites.
With the edge datacenter in place, the O-RAN cell site is simplified. Proprietary baseband equipment is removed leaving just a specialized O-RAN CSR providing transport and synchronization for the radios, and the radios themselves. By eliminating much of the equipment, the need for an air-conditioned hut is also no longer a necessity saving significant installation time and costs. In many instances the higher frequency 5G radios come with integrated antennas essentially eliminating all coaxial cabling and external antennas at the site.
DZS was one of the first suppliers in the world to create a packet-based mobile xHaul solution, designed specifically for Rakuten Mobile’s groundbreaking O-RAN network that has scaled to over 6 million subscribers in Japan. This was the first global commercially scaled deployment of Open RAN 5G technology.
DZS remains laser focused on creating innovative O-RAN and 5G aligned optical edge transport solutions for the mobile industry that act as a catalyst for the 5G O-RAN transformation. Our solutions are currently deployed extensively in the world’s most advanced O-RAN networks and we continue to work closely with service providers and vendors to develop new products that illuminate the next generation of optical edge transport opportunities for mobile networks.
For more information, visit dzsi.com or contact DZS.