In some cases, the position calculation is conducted by a positioning server, such as an Enhanced Serving Mobile Location Center (E-SMLC) or a Secure User-Plane Location (SUPL) Location Platform (SLP) in LTE. In other cases, the position calculation is carried out by the UE. The latter approach is known as the UE-based positioning mode, while the former approach includes both network-based positioning, i.e., position calculation in a network node based on measurements collected from network nodes such as LMUs or eNodeBs, and UE-assisted positioning, where the position calculation in the positioning network node is based on measurements received from UE.

LTE Positioning Protocol (LPP) is a positioning protocol for control plane signaling between a UE and an E-SMLC, which is used by the E-SMLC to provide assistance data to the UE and by the UE for reporting measurements to the E-SMLC. LPP has been designed in such a way that it can also be utilized outside the control plane domain such as in the user plane in the context of SUPL. LPP is currently used for downlink positioning.

LTE Positioning Protocol Annex (LPPa), sometimes referred to as LTE Positioning Protocol A, is a protocol between the eNodeB and the E-SMLC, and is specified only for control-plane positioning procedures, although it still can assist user-plane positioning by querying eNodeBs for information. For example, LPPa can be used to retrieve information such as positioning reference symbol (PRS) configuration in a cell for OTDOA positioning, or UE sounding reference signal (SRS) configuration for UTDOA positioning, and/or eNodeB measurements. LPPa may be used for downlink positioning and uplink positioning.