t-haul portion of the network. The specification is in- tended to drive interoperability between the base station or baseband units and the remote radio heads, even if they are from different vendors. In February 2018, the xRAN Forum announced its intent to merge with the C-RAN Alliance to form a worldwide, carrier-led effort toward openness in the RAN of next-generation mobile sys- items. The new alliance is called the O-RAN Alliance. The xRAN open front-haul interface specific- ations are now under Working Group 4 of the O-RAN alliance. The O-RAN Alliance, originally founded by AT&T, China Mobile, Deutsche Telekom, NTT DOCOMO, and Orange, held its first board meeting at MWC Shanghai in June 2018. Seven new members were also approved, including Bharti Airtel, China Telecom, KT, Singtel, SK Telecom, Telefonica, and Telstra. The articles constituting the O-RAN Alliance are cosigned by delegates from 12 operators as the official foundation of the operator-driven initiative. The O-RAN architecture (see Figure 4-5) defines standardized interfaces to enable an open, interop- erable ecosystem that complements the standards promoted by 3GPP and other SDOs. Design Inventory Policy Configuration RAN Intelligent Controller (non-RT) Orchestration & automation (such as ONAP): MANO, NMS RAN Intelligent Controller (near-RT) Applications layer Third-party Radio connection Mobility Interference Trained mgmt. mgmt. mgmt. mgmt. model Radio network information base E2: between near-RT and CU/DU CU-CP CU-UP Multi-RAT CU protocol stack PDCP-C PDCP-U NFVI Platform: Virtualization layer and COTS platform O-DU: RLC/MAC/PHY-high Open Fronthaul O-RU: PHY-low/RF Figure 4-5 O-RAN Architecture The O-RAN Alliance defines nine technical working groups (WG), all of them under the supervi- sion of the Technical Steering Committee. The technical WGs have specific focus areas and are open to all members and contributors. The workgroups are as follows: WG1: Use Cases and Overall Architecture Workgroup Identifies tasks to be completed within the sco