Fig. 3
From: Low PAPR reference signal transceiver design for 3GPP 5G NR uplink

Port mapping for FDM method of reference signal multiplexing for MIMO stream transmissions in 3GPP
From: Low PAPR reference signal transceiver design for 3GPP 5G NR uplink
Port mapping for FDM method of reference signal multiplexing for MIMO stream transmissions in 3GPP