SLG Interface and SLh Interface – Diameter Protocol- LTE.
Both are 3GPP interfaces in the LTE network. SLG interface is between GMLC and MME, and the SLh interface is between HSS and GMLC for providing location-based services in LTE(4G). Like other LTE interfaces, the Diameter protocol provides transport for SLG and SLh interface messages.
In a 3G network that uses SS7 map protocol. In LTE, we have MME in place of MSC. In 3G, there is SMLC for location calculation, while in 4G, there is E SMLC. A GMLC first requests the identity and roaming information over the Slg interface and then sends a location request message to the MME over the SLG interface. MME does the signaling with e-SMLC for subscriber location.
SLG interface :
Slg interface does signaling between GMLC and MME for a location request. The following are the diameter protocol signaling messages.
- Provide Subscriber Location Request – GMLC sends this message to the MME for a location query.
- Provide Subscriber Location Response – On successful operation, have the location information.
The Sh interface is the diameter protocol interface between GMLC and MME.