ETSI Group Specifications (GS) are deliverables produced by Industry Specification Groups (ISG). GSs are written with the style of a Technical Specification (TS)@ and represent the sole view of the ISG members. The present document describes system-level requirements that apply to the Open Radio equipment Interface (ORI) and ORI nodes for Release 4. NOTE: Requirements comply with CPRI specification of CPRI forum [1] and focuses on the following 3GPP radio access technologies namely UTRA-FDD [3]@ [4] and [5]@ E-UTRA-FDD [6]@ E-UTRA-TDD [6] and GSM [12]. Multiplexing between any combination of UTRA-FDD@ E-UTRA-FDD@ and GSM on an ORI link is also considered.