{{Short description|Open radio access network standard}} '''Open RAN''', or '''Open Radio Access Network''' architecture is based on 3GPP standards for Radio Access Networks (RAN) but contains many extensions, disaggregates RAN components and makes their interfaces open, aiming to improve flexibility and interoperability. RAN hardware and software are cloudified/virtualized, and it includes intelligent management (SMO).<ref name=Er>{{cite web |url=https://www.ericsson.com/en/openness-innovation/open-ran-explained |title=Open RAN (O RAN) |date=2025 |publisher=Ericsson}}</ref>

Those open interfaces aim for mixing components from different vendors and quicker deployment of new services.<ref name=Er/> Open RAN standardization is led by the O-RAN ALLIANCE.<ref>{{cite web |title=O-RAN ALLIANCE e.V. |url=https://www.o-ran.org |publisher=O-RAN ALLIANCE e.V.}}</ref>

''Cloudification'' means disaggregating hardware and software, making RAN software cloud-native functions running on a general-purpose hardware.<ref name=Er/>

''Intelligent open management'' includes automated management and orchestration systems which can utilize Artificial Intelligence and Machine Learning for life cycle management of network functions.<ref name=Er/>

''Open interfaces'': standardized open interfaces, such as the O-RAN ALLIANCE's specifications and 3GPP-defined interfaces, facilitate interoperability between disaggregated RAN components.<ref name=Er/>

== Key components == In Open RAN, the RAN is split into three main blocks: the Radio Unit (RU), the Distributed Unit (DU), and the Centralised Unit (CU).<ref>{{cite web |url=https://www.nokia.com/networks/radio-access-networks/open-ran/open-ran-explained/ |title=Update: Open RAN explained |publisher=Nokia}}</ref> The RU performs basic RF and low-PHY functions such as precoding and beamforming<ref name=":0">{{Citation |last=Polese |first=Michele |title=Understanding O-RAN: Architecture, Interfaces, Algorithms, Security, and Research Challenges |date=2022-08-01 |url=http://arxiv.org/abs/2202.01032 |access-date=2026-05-28 |publisher=arXiv |doi=10.48550/arXiv.2202.01032 |id=arXiv:2202.01032 |last2=Bonati |first2=Leonardo |last3=D'Oro |first3=Salvatore |last4=Basagni |first4=Stefano |last5=Melodia |first5=Tommaso}}</ref>. The DU performs additional PHY functions such as scrambling and modulation, and handles MAC and RLC functions such as radio resource allocation<ref name=":0" />. The CU handles functions such as SDAP and RRC<ref name=":0" />. thumb|The disaggregation scheme of O-RAN according to a 7.2x functional split. ''RAN Intelligent Controller'' (RIC) is an optional virtualized optimization technology for 5G. It adds programmability to a new or existing RAN and allows SON-like (Self-Optimizing Networks) capabilities. The optimization in RIC is boosted by policy-driven closed loop automation and AI/ML.<ref name=NOR/> In O-RAN deployments, there are the ''near real-time RIC'' (near-RT RIC) which operates on sub-100 millisecond intervals, and the ''non real-time RIC'' (non-RT RIC) which operates on intervals longer than 1 second<ref name=":0" />.

The near-RT RIC houses ''xApps'', which are programs that optimize functions such as beamforming, traffic steering, and power control. The non-RT RIC houses ''rApps'', which manage longer-term policies such as network slicing<ref name=":0" />.

The fronthaul interface lies between radio Units (RU) and baseband units (Distributed Units (DU)). It is a focus area in Open RAN.<ref name=NOR/>

O-RAN has specified an eCPRI-based 7.2x open interface to be used in the fronthaul, allowing connections between radio units and baseband units of different vendors.<ref name=NOR/>

=== Near-RT RIC === The near-RT RIC really houses multiple interworking components.

* ''Internal messaging infrastructure'' connects the xApps, platform services, and interface (O1, A1, E2) terminations to each other. O-RAN Alliance specifies not what technology the near-RT RIC must use, but there are certain functionalities that this internal messaging infrastructure must provide<ref name=":0" />. * The ''subscription manager'' allows xApps to listen to functions exposed over the E2 interface<ref name=":0" />. * The ''security sub-system'' prevents malicious xApps from leaking sensitive RAN data or negatively affecting RAN performance<ref name=":0" />. * The RAN ''Network Information Base (NIB) Database'' stores information from the E2 interface, typically KPMs from RANs and UEs. The UE-NIB contains information about UEs, specifically their identity key (UE-ID), which allows for xApps to control UEs. These NIBs may be queried through the ''Shared Data Layer API'', usually by xApps<ref name=":0" />. * ''Conflict mitigation'' prevents RAN performance from being degraded by xApps making conflicting managing decisions on RANs. This is an emerging functionality and is not included in all near-RT RIC implementations<ref name=":0" />. * xApps are the meat and potatoes of the near-RT RIC, and the other components exist to support the xApps. xApps are typically realized as Kubernetes or Docker containers. The O-RAN alliance only stipulates that a few KPIs are exposed to the xApps<ref name=":0" />.

== O-RAN ALLIANCE == O-RAN ALLIANCE (O-RAN) was founded in 2018 by AT&T, China Mobile, Deutsche Telekom, NTT DOCOMO and Orange to promote open mobile networks.<ref>{{cite web |title=About O-RAN ALLIANCE |url=https://www.o-ran.org/about |publisher=O-RAN ALLIANCE e.V.}}</ref><ref name=Er/> O-RAN has over 30 operator members and almost 300 contributors.<ref name=Er/>

O-RAN specifications define the parts of the O-RAN Architecture, which can be used to develop Open RAN solutions. <ref>{{cite web |title=What We Do |url=https://www.o-ran.org/what-we-do |publisher=O-RAN ALLIANCE e.V.}}</ref>

O-RAN ALLIANCE also handles the activities of the earlier xRAN and C-RAN forums.<ref name=NOR>{{cite web |url=https://www.nokia.com/mobile-networks/ran/anyran/open-ran/ |title=Open RAN |publisher=Nokia}}</ref>

== References == {{Reflist}}

== External links == * [https://www.o-ran.org O-RAN ALLIANCE]

Category:Radio technology