Japanese operator NTT DoCoMo said that it is adopting open interface specifications from the O-RAN Alliance to allow it to mix and match its 4G and 5G networks. The operator is set to launch its commercial 5G network in “pre-service” operation on 20 September.
DoCoMo is adopting O-RAN specifications for the fronthaul links between base station baseband units and remote radio units. It is also using the O-RAN version of the X2 interface, which allows base stations themselves to connect to each other.
By doing that it says it can support a multi vendor network in its 5G RAN, so that a centralised BBU and the Remote Radio Unit can be from different vendors. It can also enable interworking between the 4G and 5G RANs, and therefore support dual connection in 5G NR NSA mode between a 5G layer and 4G layer from different vendors.
A principal selling point for established 5G RAN vendors has been that it is much easier for operators to use the same 4G and 5G vendor, so as to enable easier interworking between the layers. If operators are going to mandate O-RAN support from vendors and are able prove that out in a commercial network, then that becomes a different story and places much less of a premium on 4G incumbency.
AT&T, a key proponent of O-RAN adoption to date, has said that it foresees that it can bring the “whitebox” environment to the RAN by adopting such specifications.
DoCoMo says it is deploying the first commercial 4G/5G RAN to support multi vendor interworking based on O-RAN specifications. Rakuten has very publicly built out a multi-vendor RAN, with Altiostar CU-DUs for its vRAN split BBUs interfacing with Nokia RRHs, but they are not based on O-RAN specifications.
Getting serious about commercial O-RAN products
Meanwhile operators active in O-RAN are backing attempts to bring more commercially hardened disaggregated RAN components to market from a variety of vendors.
O-RAN has announced the Open Test and Integration Center (OTIC) – an initiative led by China Mobile and Reliance Jio along with participation from China Telecom, China Unicom, Intel, Radisys, Airspan, Baicells, CertusNet, Mavenir, Lenovo, Ruijie Network, Inspur, Samsung Electronics, Sylincom, WindRiver, ArrayComm, and Chengdu NTS.
The companies are collaborating on multi-vendor interoperability and validation activities for O-RAN compliant 5G access infrastructure. The initial focus is to ensure RAN components from multiple vendors support standard and open interfaces and can interoperate in accordance with O-RAN test specifications.
The OTIC initiative will test functional compliance of new product through verification, integration and testing of the disaggregated RAN components. O-RAN goes further than mandating interfaces between RAN elements such as NTT DoCoMo is deploying. It is targeting the standardisation of upper layer automation, for instance, as well as the adoption of a RAN Intelligent Controller that sits above the RAN layer and performs optimisation and other management functions.
“CMCC will initiate an OTIC in Beijing, China, which should provide the common platform for solutions to be operationally ready to enable end-to-end interoperability and deployment in scale; as well as to be hardened for reliability, performance, scalability, and security that operator networks require,” said Dr. Li Zhengmao, EVP of China Mobile.
“Jio is creating an OTIC to accelerate the telecom industry transformation by driving ready-for-commercialisation products and solutions,” said Mathew Oommen, President, Reliance Jio.
