r providing assistance data and calculat- ing the positions. The E-SMLC gets the LPP to request time-of-arrival data from the UE and sup- plies reference information to allow the UE to receive the signal. The E-SMLC uses the UE meas- urements and combines them with data on the location of eNBs to calculate the UE's position. The eNBs participating in LPP must be time-synchronized very accurately and reliably to provide precise location accuracy. At the speed of light, each nanosecond of error in timing translates into about 0.3 m of error in position. Hence, for an accurate determination of position, the synchroniza- tion accuracy requirements are dependent on the location accuracy required. For example, to achieve 40-60 m location accuracy, the maximum relative phase/time error needs to be less than around 200 ns between a minimum of three participating eNBs. Of course, both the geometry of the eNB around the UE and the number of participating signals are also factors that strongly influence the possible accuracy. The synchronization requirements for location accuracy or positioning are more stringent than those needed for communication. No matter what the level of accuracy in location that is achievable, it is even harder to try to determ- ine an accurate height (such as knowing on which level inside a building the UE is). Despite these stringent demands, the regulators are increasing the requirements for accuracy in location data, mainly to support the emergency services (these standards are known as E911 in North America and E112 in Europe). Current time synchronization requirements are shown in Table 10-10, whereas more accurate and stringent location-based services are not yet defined and for further study. Table 10-10 Time Synchronization Requirements for Location-Based Services Time Alignment Reference Error Location-based services using OTDOA 200 ns (relative) TR 37.857 (40 to 60 meter of location accuracy with minimum three base ITU-T G.8271 2020- stations) 10.3.1 Synchronization Requirements for LTE an