LTE Control Plane - Protocol Stacks

eNodeB - MME

- S1 Application Protocol (S1-AP): Application Layer Protocol between the eNodeB and the MME.
- SCTP for the control plane (SCTP): This protocol guarantees delivery of signalling messages between MME and eNodeB (S1). SCTP is defined in RFC 2960 [35].

UE - MME

- NAS: The NAS protocol supports mobility management functionality and user plane bearer activation, modification and deactivation. It is also responsible of ciphering and integrity protection of NAS signalling.
- LTE-Uu: The radio protocol of E-UTRAN between the UE and the eNodeB is specified in TS 36.300 [5].
SGSN - MME

- GPRS Tunnelling Protocol for the control plane (GTP C): This protocol tunnels signalling messages between SGSN and MME (S3).
- User Datagram Protocol (UDP): This protocol transfers signalling messages. UDP is defined in RFC 768 [26].

SGSN - S GW

- GPRS Tunnelling Protocol for the control plane (GTP C): This protocol tunnels signalling messages between SGSN and S GW (S4).
- User Datagram Protocol (UDP): This protocol transfers signalling messages. UDP is defined in RFC 768 [26].

S GW - P GW

MME - MME

MME - S GW

MME - HSS

- Diameter: This protocol supports transferring of subscription and authentication data for authenticating/authorizing user access to the evolved system between MME and HSS (S6a). Diameter is defined in RFC 3588 [31].
- Stream Control Transmission Protocol (SCTP): This protocol transfers signalling messages. SCTP is defined in RFC 2960 [35].

MME - EIR

- Diameter: This protocol supports UE identity check procedure between MME and EIR (S13). Diameter is defined in RFC 3588 [31].
- Stream Control Transmission Protocol (SCTP): This protocol transfers signalling messages. SCTP is defined in RFC 2960 [35].