When defining the Doppler frequency to use for E-UTRA performance requirements, a principle similar to what was used for UTRA can be implemented. Each propagation condition is based on a max Doppler frequency and not on a specific UE speed. A set of three Doppler frequencies spanning the requirement range as high, middle and low Doppler frequencies is selected:
• The LTE requirements for mobility in TR 25.913 [6] state that "Mobility across the cellular network shall be maintained at speeds from 120 km/h to 350 km/h (or even up to 500 km/h depending on the frequency band)." It is also stated that this "…represents a special case such as high speed train environment." The maximum carrier frequency over all frequency bands is fc =2690 MHz and the corresponding maximum Doppler frequency at v=350 km/h is fD =843 Hz.
• There are more common high speed scenarios for moderately high mobile speeds. It is stated in TR 25.913 [6] that high performance should be maintained up to mobile speeds of 120 km/h. The corresponding maximum Doppler frequency for fc =2690 km/h is fD =299 Hz. Based on this, the high Doppler frequency is selected as 300 Hz.
• TR 25.913 [6] also state that "The E-UTRAN shall support mobility across the cellular network and should be optimized for low mobile speed from 0 to 15 km/h." For testing purposes, too low mobile speeds are not attractive, since testing times may be very long. The lowest Doppler frequency in UTRA propagation conditions is 5.4 Hz, corresponding to between 2.3 and 7 km/h in the existing frequency bands. Based on this, the low Doppler frequency is selected as 5 Hz.
• An intermediate Doppler frequency can be set at the "logarithmic" average of the 5 and 900 Hz, being 67 Hz. Based on this, the medium Doppler frequency is selected as 70 Hz.
The UE speed that the Doppler frequencies will correspond to will vary between the Operating bands, as shown in Tables B.2.2.5 and B.2.2.6 (informative), where the carrier frequencies at the centre of each uplink and downlink band are used to derive the corresponding UE speeds. |