Handling of radio frequency front-end group delays for round trip time estimation
摘要
說明書
In a network-centric RTT estimation, the serving gNodeB (e.g., one of gNodeBs 202-206) instructs the UE (e.g., UE 102) to scan for/receive RTTM signals from one or more neighboring gNodeBs (one of more of gNodeBs 202-206). The one or more gNodeBs transmit the RTTM signals on low reuse resources, allocated by the network (e.g., location server 170). The UE records the arrival times of each RTTM(i) waveform, and transmits a common or individual RTTR signal(s) to the one or more gNodeBs (when instructed by its serving gNodeB).
An individual RTTR(i) signal directed at a particular gNodeB(i) may include, in its payload, the actual UE turn-around time (t3′?t2′). Alternatively, an individual RTTR(i) signal directed at a particular gNodeB(i) may include, in its payload, the measured UE turn-around time (t3?t2) and the transmission timing of the RTTR(i) signal may be altered.
The network may allocate low reuse resources for the UE to transmit the RTTR signals. Each gNodeB(i) that receives the RTTR signal records its RTTR arrival time t3. The gNodeB(i) can compute the RTT between the UE and itself according to equation (13). This computation may be performed either at the gNodeBs receiving the RTTR signal from the UE, or at a central location in the network (e.g., location server 170 or the serving gNodeB). The central location may have access to other information that helps improve the positioning accuracy, such as base station almanac (BSA), and other reports from UE and/or gNB (such as RSRP, AoA, AoD estimates, etc.). The RTTR payload carrying the UE turn-around time (actual and/or measured) could be addressed directly to the gNB or to the central location server via NAS containers within RRC messaging which may or may not be readable by the gNB.
