. It should also be noted that the ALCAP protocol(s) in the transport network control plane is/are not used for setting up the signalling bearer for the application protocol or for the ALCAP during real time operation. The signalling bearer for the ALCAP may or may not be of the same type as the signal- ling bearer for the application protocol. The signalling bearer for ALCAP is always set up by O&M actions. 3.7.3.4 Transport Network User Plane The data bearer(s) in the user plane, and the signalling bearer(s) for application proto- col, belong also to the transport network user plane. As described in the previous sec- tion, the data bearers in the transport network user plane are directly controlled by the The UMTS Network and Radio Access Technology transport network control plane during real time operation, but the control actions re- quired for setting up the signalling bearer(s) for application protocol are considered O&M actions. The following section is an informative section which aims to provide an overall picture of how the MAC layer is distributed over Uu, lub and Iur for the RACH, FACH and DCH [7]. RADIO INTERFACE PROTOCOL ARCHITECTURE This section covers essential aspects on the radio interface protocols based on [9]. For completeness and to remain close to the technical specifications we use the same termi- nology and keep the approach of the proposed architecture. 3.8.1 Protocol Structure Radio interface protocols establish, adapt, and free radio bearer services in the UTRA platform. They have functions in Layers 1-3, i.e. physical (L1), link (L2) and network (L3) layers in the OSI terminology. L2 has in turn the following sub-layers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Broadcast/Multicast Control (BMC). L3 and RLC consist of Control (C) and User (U) planes. The PCDP and BMC sub-layers exist only in the U plane. Layer 3 has sub-layers in the C-plane. The lowest one, the Radio Resource Control (RRC), interfaces with L2 and terminates in 