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). Similar to other LTE interfaces, the Diameter protocol provides transport for SLg and SLh interface messages.

In a 3G network which 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 E SMLC.  A GMLC first requests the identity and roaming information over Slg interface 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 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.