In at least one embodiment, S1 Application Protocol (S1-AP) layer (S1-AP layer 2222) may support functions of a S1 interface and comprise Elementary Procedures (EPs). In at least one embodiment, an EP is a unit of interaction between RAN 2016 and CN 2028. In at least one embodiment, S1-AP layer services may comprise two groups: UE-associated services and non UE-associated services. In at least one embodiment, these services perform functions including, but not limited to: E-UTRAN Radio Access Bearer (E-RAB) management, UE capability indication, mobility, NAS signaling transport, RAN Information Management (RIM), and configuration transfer.
In at least one embodiment, Stream Control Transmission Protocol (SCTP) layer (alternatively referred to as a stream control transmission protocol/internet protocol (SCTP/IP) layer) (SCTP layer 2220) may ensure reliable delivery of signaling messages between RAN 2016 and MME(s) 2028 based, in part, on an IP protocol, supported by an IP layer 2218. In at least one embodiment, L2 layer 2216 and an L1 layer 2214 may refer to communication links (e.g., wired or wireless) used by a RAN node and MME to exchange information.
In at least one embodiment, RAN 2016 and MME(s) 2028 may utilize an S1-MME interface to exchange control plane data via a protocol stack comprising a L1 layer 2214, L2 layer 2216, IP layer 2218, SCTP layer 2220, and S1-AP layer 2222.