 #0 PRS #1 PRS #2 10 11 12 13 1 10 11 12 13 Figure 4.15. The occasion of the PRS signal The PRS mapping is transmitted in an RRC message through the dl-PRS- ResourceSet data structure: - in the time domain, the position of the first PRS symbol in the slot is transmitted by the dl-PRS-ResourceSymbolOffset-r16parameter and the number of symbols in the LPRS slot is defined by the dl-PRS-NumSymbols-r16 parameter; - in the frequency domain, the position of the first subcarrier is transmitted by the dl-PRS-ReOffset-r16 parameter. The PRS signal is transmitted in the form of a comb. The size of the KCOMB comb is passed in the dl-PRS-CombSizeN-r16 parameter. 118 NG-RAN and 5G-NR The PRS cannot be transmitted in the first three symbols. The {LPRS, KCOMB} pair defines the frequency offset of each symbol of the slot according to Table 4.9. The pair of values {LPRS, KCOMB} can take {2,2}, {4,2}, {6,2}, {12, 2},{4,4}, {12,4}, {6,6}, {12,6} and {12,12} as values. Offset applied to the symbol KCOMB Table 4.9. Frequency offset {LPRS, KCOMB}={4,2} {LPRS, KCOMB}={12,4} {LPRS, Kcomb}={12,12} Figure 4.16. The mapping of PRS 4.5.2.4. The physical RIM-RS signal For the TDD duplexing mode, the synchronization of gNBs is essential to prevent the downlink communications from one gNB interfering with the uplink communications between a user under the control of another gNB. Despite the presence of a guard interval in the time domain when switching the direction of communication uplink/downlink, atmospheric conditions can contribute to the propagation of the signal over long distances. Since the downlink signal power is higher than the uplink signal power, the downlink propagation distance is higher and the propagation delay may cause interference. This interference is called remote interference (RI). 5G-NR Radio Interface - The Physical Layer The physical RIM-RS signal is defined from Release R. 16 in order to estimate the downlink interference caused by the furthest gNB. The physical RIM-RS is a Gold sequence generated by the following f