一, Functions of S1AP
1, E-RAB management function
2, responsible for setting up, modifying and releasing E-RABs, which are triggered by the MME
3, release and modification of E-RABs may be triggered by the eNB as well
4, Initial Context Transfer function
1), used to establish an S1UE context in the eNB
2), to setup the default IP connectivity
3), to setup one or more E-RAB if requested by the MME
4), to transfer NAS signalling related information to the eNB if needed
5, UE Capability Info Indication function
used to provide the UE Capability Info when received from the UE to the MME
6, Mobility functions (移动性管理)
1), a change of eNBs within SAE/LTE (Inter MME/Serving SAE-GW Handovers) via the S1 interface
2), a change of RAN nodes between different RATs (Inter-3GPP-RAT Handovers) via the S1 interface
7, Paging
provides the EPC with the capability to page the UE
8, S1 interface management functions
9, Reset function (重置功能)
10, Error Indication funcation (错误指示)
11, Overload function (负载)
12, Load balancing function (负载均衡)
13, S1 Setup function (S1 设置)
14, eNB and MME Configuration Update function (eNB 和 MME 的配置更新)
15, NAS Signalling transport function
1), to transfer and reroute NAS signalling related information and to establish the S1 UE context in the eNB
2), to transfer NAS signalling related information when the S1 UE context in the eNB is already established
16, S1 UE context Release function
17, UE Context Modification function
18, UE Context Resumption function (UE Context 恢复)
19, Status Transfer (状态转移)
20, Trace function (会话跟踪)
21, Location Reporting (位置上报)
24, LPPa Signalling transport
25, S1 CDMA2000 Tunnelling function
26, Warning message transmission function
27, RAN Information Management (RIM) function
28, Configuration Transfer function
29, UE Radio Capability Match function
30, PWS Restart Indication function
31, PWS Failure Indication function
32, Connection Establishment Indication function
33, Retrieve UE Information function
34, UE Information Transfer function
35, CP Relocation function
36, Report of Secondary RAT data volumes function
37, QMC function
